Nozzle lifting assembly

A nozzle lifting assembly for an additive manufacturing system includes a base member and a lift member relatively movable with respect thereto, a first nozzle body arranged for being lifted by the lift member and a second nozzle body disposed on the base member. A wedge member is movably arranged relative to the base member and in wedging engagement with the lift member between a first and second wedge position, wherein the first and second wedge position correspond to a lowered position and a lifted position of the first nozzle body with respect to the second nozzle body, respectively.

FIELD OF THE INVENTION

The present invention relates to a nozzle lifting assembly, in particular to a nozzle lifting assembly for an additive manufacturing system.

BACKGROUND

U.S. Pat. No. 5,503,785 discloses an apparatus and process for making three-dimensional objects of a predetermined shape. The apparatus comprises a first dispensing head which is mounted for relative movement with respect to a second dispensing head so as to be able to deposit material in multiple passes and layers to form an object of a predetermined shape. The first dispensing head may be connected to a lift device, such as a hydraulic fluid cylinder or a spring loaded solenoid for providing relative movement of the first dispensing head with respect to the second dispensing head.

US patent application US 2015/0290861 A1 discloses a barrel for use in an additive manufacturing machine comprising a sleeve extending along a longitudinal axis; a conduit extending along the longitudinal axis through the sleeve; and an actuating system associated with the sleeve, wherein the actuating system is configured to move the conduit along the longitudinal axis relative to the sleeve between a first position and a second position. The barrel further comprises a nozzle associated with the conduit, wherein the nozzle is movable with the conduit relative to the sleeve between the first position and the second position. In an embodiment the actuating system may comprise a solenoid actuator or a servo actuator.

SUMMARY

The present invention seeks to provide a nozzle lifting assembly for an additive manufacturing system having an improved reproducibility of positional changes between a first and second nozzle during operation of the nozzle lifting assembly. In particular, the nozzle lifting assembly provides accurate and reproducible height changes of the first nozzle with respect to the second nozzle, wherein the reproducibility of height changes is more robust against e.g. wear between components of the nozzle lifting assembly, temperature changes during nozzle extrusion processes as well as pollution of component over extended periods of time.

According to the present invention, a nozzle lifting assembly of the type defined in the preamble is provided, wherein the nozzle lifting assembly comprises a base member and a lift member relatively moveable with respect thereto, a first nozzle body disposed on the lift member and a second nozzle body disposed on the base member, and wherein a wedge member is movably arranged on the base member and in wedging engagement with the lift member between a first and second wedge position, wherein the first and second wedge position correspond to a lowered position and a lifted position of the first nozzle body with respect to the second nozzle body, respectively.

The wedging engagement between the wedge member and the lift member allows the nozzle lifting assembly of the present invention to reliably reproduce a lifted and a lowered position of the first nozzle body with respect to the second nozzle body, so that switching, e.g. activation/deactivation, between the first and the second nozzle body during additive manufacturing processes remains accurate for many lifting cycles and hours of use of the nozzle lifting assembly.

DETAILED DESCRIPTION

FIGS. 1 and 2each show an embodiment of a nozzle lifting assembly in a lifted position and a lowered positioned, respectively, according to the present invention. In the embodiments shown, the nozzle lifting assembly1comprises a base member10and a lift member20relatively moveable with respect to the base member10, wherein a first nozzle body30is disposed on the lift member20and a second nozzle body40is disposed on the base member20. Further, a wedge member50is provided that is movably arranged on the base member10and in wedging engagement with the lift member20between a first and second wedge position. The first and second wedge position correspond to a lowered position and a lifted position of the first nozzle body30with respect to the second nozzle body40, respectively. That is,FIG. 1depicts the second wedge position of the wedge member50, wherein the first nozzle body30is in a lifted position with respect to the second nozzle body40, and whereFIG. 2depicts the first wedge position, wherein the first nozzle body30is in a lowered position with respect to the second nozzle body40.

In an embodiment, the nozzle lifting assembly1further comprises a nozzle heating unit in heating engagement with the first and second nozzle body30,40so as to heat extrusion material as it travels through the first and/or second nozzle body30,40during an additive manufacturing cycle. The heating unit may comprise a separate nozzle heater for each nozzle, e.g. a first nozzle heater35in heating engagement with the first nozzle body30and a second nozzle heater45in heating engagement with the second nozzle body45.

In contrast to prior art nozzle lifting assemblies, the nozzle lifting assembly1of the present invention allows for high reproducibility of the lifted and lowered position of the first nozzle body30with respect to the second nozzle body40. The wedging engagement between the wedge member50and lift member20not only ensures that an accurate lifted and lowered position of the first nozzle body30is achieved, but the accuracy is reproducible over many lifting cycles during additive manufacturing. It is determined that more than 750.000 reproducible lifting cycles are possible, so wherein the first nozzle body30moves from a lifted to a lowered position or via versa. In advantageous embodiments, the lifted and lowered position of the first nozzle body30with respect to the second nozzle body40may be accurate up to +/−0.05 mm along a path of displacement between the lifted and lowered position, wherein the path of displacement between the lifted and lowered position may be envisaged as being substantially linear.

To clarify the above further, in an embodiment the first and second nozzle body30,40each comprise a longitudinal axis31,41that is substantially perpendicular to the base member10. The first and second nozzle body30,40each comprise an extrusion outlet32,42exhibiting a positional difference Lh, e.g. a height difference, along the longitudinal axis31of the first nozzle body30in the lifted or lowered position thereof. In an advantageous embodiment the positional or height difference Lh is about 0.8 mm to 1.2 mm, e.g. 1 mm. In a further advantageous embodiment the positional or height difference Lh is about 0.8 mm to 1.2 mm, e.g. 1 mm, with an accuracy of at least +/−0.1 mm, e.g. +/−0.08, e.g. +/−0.06, e.g. +/−0.04 mm.

As depicted in the embodiments ofFIGS. 1 and 2, the extrusion outlet32of the first nozzle body30is positioned lower than an extrusion outlet42of the second nozzle body40in the first wedge position, and wherein the extrusion outlet32of the first nozzle body30is positioned higher than the extrusion outlet42of the second nozzle body40in the second wedge position. This avoids interference between the first and second nozzle bodies if one of them is actively extruding material and the other nozzle is momentarily idle. As shown, the positional or height difference Lh between the extrusion outlet32of the first nozzle body30and the extrusion outlet42of the second nozzle body is about 0.8 mm to 1.2 mm, e.g. 1 mm, thereby providing sufficient clearance between the first or second nozzle body30,40and a layer being deposited.

In view of the invention, the lift member20and wedge member50ensure that the positional or height difference Lh is mechanically guaranteed as no electronic control and regulation is necessary to achieve and maintain accurate positioning of the first nozzle body30in the lifted or lowered position. That is, positioning accuracy is by and large dependent on dimensional accuracy and precise manufacturing of the lift member20and wedge member50, keeping manufacturing tolerances to a minimum, so that the wedging engagement is accurate and precise. The positional or height difference Lh therefore correlates with a size of the wedge member, such as a wedge thickness profile thereof.

FIG. 3shows a three dimensional view of an embodiment of a base member10, lift member20and wedge member20in the first wedge position, whereasFIG. 4adepicts a three dimensional view of an embodiment of a base member10, lift member20and wedge member50in the second wedge position.

In the embodiments shown, the lift member20comprises a first end21in rotational engagement with the base member10and a second end22in contact engagement with the first nozzle body6. Note that the first nozzle body30is not shown for clarity.

The rotational engagement of the first end21of the lift member20with the base member10allows for a displacement of the second end22of the first nozzle body30to a lowered position of the first nozzle body30as well as a displacement to the lifted position of the first nozzle body30. The positional or height difference Lh as mentioned above may be adjusted as required by choosing a suitable distance between the first and second end21,22. For example, increasing a linear distance between the first and second end21,22allows for an increased displacement of the first nozzle body30from the lowered to the lifted position or vice versa. Of course, in another embodiment, increasing e.g. a thickness profile of the wedge member50allows for a larger displacement of the first nozzle body30between the lowered and lifted position thereof. In an embodiment the wedge member50is in wedging engagement between the first and second end21,22of the lift member20, allowing for a rotational motion of the lift member20when in wedging engagement therewith without inferring with the first nozzle body30, which is arranged at the second end22thereof.

In an embodiment, the lift member20may comprise a flat or planar like shape arranged substantially parallel to the base member10in the first wedge position and arranged at an angle to the base member10in the second wedge position. The flat or planar shape of the lift member20allows for a compact design over a given rotational angle between the first and second wedge position.

In an embodiment, the rotational engagement between the lift member20and base member10may exhibit resiliency, so that the rotational engagement comprises a biasing arrangement imposing an associated biasing rotational force or torque on the lift member20, wherein the second end22of the lift member20is biased to move to the lowered position when the wedge member50moves from the second to the first wedge position. As such, the resiliency of the rotational engagement facilitates a displacement from the lifted position toward the lowered position of the first nozzle body30when the wedge member50moves from the second to the first wedge position. The rotational engagement between the lift member10and the base member10may be embodied in various ways. In an exemplary embodiment, the first end21of the lift member20may be resiliently connected to the base member10, thereby defining a biasing arrangement there between imposing a biasing torque onto the lift member20.The resilient connection may be further embodied by the lift member20being a planar, pliable lift member20, wherein the first end21thereof is rigidly connected to the base member10. In an embodiment, the first end21of the lift member20is integrated with the base member10and/or the lift member20itself is integrated with the base member10, i.e. in an embodiment the base member10and lift member20may comprise a one piece component, reducing the number of components used for the nozzle lifting assembly as well as associated costs.

Referring to theFIGS. 1 to 3 and 4a, in the embodiments depicted the first nozzle body30may comprise a conical section33extending through a lift member hole23in the second end22of the lift member20and the second nozzle body40may comprise a conical section43extending through a base member hole11in the base member10, wherein the conical section33of the first nozzle body30and the conical section43of the second nozzle body40are in circumferential contact engagement with, respectively, the lift member hole23, e.g. a circumferential rim thereof, and the base member hole11, e.g. a circumferential rim thereof. It is important to note that the circumferential contact engagement may be envisaged as a line or point contact engagement between the conical section33,43of the first and second nozzle body30,40and the lift member hole23and base member hole11.

The conical section33,43of the first and second nozzle body30,40are advantageous as a laterally centred alignment of the first and second nozzle body30,40is guaranteed with respect to the lift member hole23and base member hole10. Consequently, lateral positioning of the first and second nozzle body30,40, in particular their respective extrusion outlets32,42, is highly accurate and reproducible over many lifting cycles. For example, the conical section33of the first nozzle body30and conical section43of the second nozzle body40allow for a centred engagement with the lift member hole23and base member hole11, respectively. This yields an exemplary embodiment wherein lateral positioning accuracy of the first and second nozzle body30,40, i.e. the respective extrusion outlets32,42thereof , is at least 0.08 mm, e.g. 0.05 mm, e.g. 0.02 mm.

Naturally, the more accurate the conical sections33,43and lift member hole23and base member hole11are manufactured, the higher the lateral positioning accuracy will be. Moreover, not only lateral positioning is highly accurate as mentioned above, but also longitudinal positioning of the first and second nozzle body30,40is facilitated by the conical sections33,43, the lift member hole23and based plate hole11. In an exemplary embodiment, longitudinal positioning accuracy of the first and second nozzle body30,40, i.e. the respective extrusion outlets32,42thereof, is at least 0.08 mm, e.g. 0.05 mm, e.g. 0.02 mm.

An important requirement and advantage of the nozzle lifting assembly1of the present invention is ease of use and, in particular, allowing convenient replacement of the first and second nozzle body30,40whenever necessary. To that end an embodiment is provided wherein the lift member20and base member10each comprise a side opening24,12extending toward the lift member hole23and base member hole11, respectively. From a user point of view the side opening24of the lift member20and side opening12of the base member10enables fast and convenient removal and placement of a new nozzle body if so required. The first and second nozzle body30,40only need a lateral approach and retrieval, wherein the conical sections33,34disclosed above guarantee accurate alignment to 0.08 mm or even less when in contact engagement with the associated lift member hole23and base member hole11. Hence, the user need not accurately place the first and/or the second nozzle body30,40within the nozzle lifting assembly1as alignment is guaranteed.

As disclosed hereinabove, the wedge member50is movably arranged on the base member10and in wedging engagement with the lift member20between a first and second wedge position, wherein the first and second wedge position correspond to a lowered position and a lifted position of the first nozzle body30with respect to the second nozzle body40, respectively. In view of the invention, in an embodiment the wedge member50may be linearly movable with respect to the base member10between the first and second wedge position. In an alternative advantageous embodiment, such as depicted inFIGS. 3 and 4a, the wedge member50is pivotally arranged on the base member10between a first pivot angle (α1) and a second pivot angle (α2). This embodiment provides secure connection of the wedge member50to the base member10yet allow the wedge member50to move along the base member10for wedging engagement between the base member10and the lift member20.

In an embodiment the wedge member50comprises a first end51pivotally connected to the base member10and a wedge portion53arranged at a distance from the first end51of the wedge member50. The wedge portion53thus moves along a substantially circular path between the first and second pivot angle (α1, α2). The distance of the wedge portion53to the first end51determines an angle range over which the contact engagement occurs between the wedge member50and the lift member, which angle range may comprise an entire angle range between the first and second pivot angle (α1, α2). The wedge portion53may be embodied as a local protrusion having a wedge engagement surface for sliding engagement along a corresponding wedge engagement surface of the lift member20. In a further embodiment the wedge portion53may even be embodied as a roller element for rolling engagement with a wedge engagement surface of the lift member20, wherein the roller element reduces friction forces etc.

In an embodiment, the base member10comprises a locking member in locking engagement with the wedge member50in the first wedge position. This embodiment is advantageous in case use is made of a biasing force arrangement for moving the wedge member50from the first wedge position to the second wedge position, i.e. from the first pivot angle (α1) to the second pivot angel (α2), wherein the biasing force arrangement imposes a constant force or torque onto the wedge member50in the direction from the first to the second wedge position. In an exemplary embodiment of the biasing force arrangement, a spring unit may be connected to the base member10and the wedge member50, wherein the spring unit is under tension or compression in the first wedge position.

FIG. 4bshows a side view of an embodiment of a base member10, a lift member20and a wedge member50in a wedged arrangement. The depicted embodiment corresponds to a side view in the direction of line IV b inFIG. 4a. In the embodiment the lift member20is in wedging engagement with the wedge member50, in particular the wedge portion53, in the second wedge position. The wedge portion53engages the lift member20between the first end21and second end22thereof. As the lift member20is attached to the base member10and in rotational engagement therewith, the second end of the lift member20is displaced in the longitudinal direction of the longitudinal axis31as shown inFIGS. 1 and 2, thus providing the position or height displacement Lh for the first nozzle body30as desired. In the second wedge position the lift member20is at a lift angle (β) with respect to the base member10. The lift angle (β) may be adapted, hence the height displacement Lh, by arranging the wedge portion53closer to the first or second end21,22of the lift member20. As such the positional or height displacement can be accurately designed as required for particular applications, thereby guaranteeing sufficient clearance between the extrusion outlet32of the first nozzle body30and the extrusion outlet42of the second nozzle body40during an additive manufacturing process.

FIG. 5ashows an embodiment of a wedge member50as used in the present invention. In the embodiment shown the wedge member50comprises the first end51and a second end52having there between a wedge portion53for wedging engagement with the lift member20. In an embodiment, the wedge member50may comprise a pivot hole arranged at the first end51for pivotally connecting the wedge member50to the base member10, thereby allowing the wedge portion53to move along the base member10from the first wedge position to the second wedge position.

In a further embodiment, the wedge member50, e.g. the wedge portion53, comprises a ramp section54in sliding engagement with the lift member20. The ramp section54improves wedging and facilitates displacement of the lift member20between the lowered and lifted position thereof. The ramp section54also reduces friction forces between the wedge member50and the lift member20, allowing for smaller forces or torques for moving the wedge member50from the first to the second wedge position or vice versa.

In the exemplary embodiment as depicted inFIG. 5a, the wedge member50may comprise a wedge portion53embodied as a projection for wedging engagement with the lift member20. To facilitate wedging and to e.g. reduce wedging forces, the wedge portion53may comprises a ramp section54as mentioned earlier. In a particular embodiment the ramp section54comprises a projected ramp surface55, which, when in wedging engagement with the lift member20, imposes a moment onto the wedge member50around a longitudinal axis thereof. To absorb this moment, in an embodiment the wedge member50may comprises a planar stabilizing section56substantially parallel to the base member10and slidingly arranged thereon. The planar stabilizing section56prevents longitudinal rotation of the wedge member50when the projected ramp surfaces5656is in contact engagement with the lift member20. As a result, any moments imposed on the first end51of the wedge member50are eliminated, thereby protecting, for example, a pivot connection between the wedge member50and the base member10. In case the pivot connection utilizes a plain bearing or ball bearing, for example, the planar stabilizing section56ensures that the pivot connection is subjected to radial forces only.

FIG. 5bshows an embodiment of a base member10as used in the present invention. In the embodiment shown the base member10comprises a side opening12extending toward a base member hole11for accommodating the second nozzle body40As mentioned hereinabove, the side opening12allows for convenient lateral placement or removal of a nozzle body, i.e. the second nozzle body40. In a further embodiment, the base member10may also comprise a further base member hole15and further side opening16, which also provide convenient lateral removal or placement of a further nozzle body, i.e. the first nozzle body30.

In an embodiment, the base member10comprises a pivot member14for pivotal engagement with the wedge member50. The pivot member14may comprise a plain bearing, a roller bearing and the like, but it may also comprise a plain shaft member extending through the pivot hole56as shown inFIG. 5a.

As mentioned above, the wedge member50may comprise a ramp section54having a projected ramp surface54arranged to come into contact with the lift member20when the wedge member50moves along the base member10. To facilitate wedging, the ramp section54, in particular the projected ramp surface55thereof, may be disposed at an angle to allow for smooth wedging, hence smooth lifting of the lift member20. As the wedge member50and the wedge section53move along the base member10during a lifting cycle, an embodiment is provided wherein the base member10comprises a wedge section recess13, wherein the wedge member50extends at least in part into the wedge section recess13. In a further embodiment, the wedge section53of the wedge member50extends at least in part in the wedge section recess13. The wedge section recess13is operable to receive at least in part the wedge section53, e.g. the ramp section54thereof, to minimize the size of the nozzle lifting assembly1, in particular a height or thickness of the base member10and wedge member50disposed thereon.

FIG. 5cshows an embodiment of a lift member20as used in the present invention. In the embodiment shown the lift member20comprises a first end21and a second end22, wherein the second end22comprises the lift member hole23and the side opening24. The side opening24facilitates convenient lateral placement and removal of a nozzle body, i.e. the first nozzle body30. In an embodiment, the lift member20further comprises a wedge section25in wedging engagement with the wedge member50. The wedge section25of the lift member25may be disposed at an angle substantially equal to an angle of the wedge section53of the wedge member50. Both angles may be adapted so as to provide smooth wedging by reducing friction forces.

In an embodiment, the lift member20comprises a further lift member hole26and a further side opening27. The further side opening27allows convenient removal or placement of a nozzle body, e.g. the second nozzle body40.

FIG. 6ashows a side view of a nozzle lifting assembly according to the present invention, in particular a lateral alignment member as used in the nozzle lifting assembly. In the embodiment shown, the nozzle lifting assembly1comprises a lateral alignment member60in sliding engagement with an inlet end34of the first nozzle body30. The alignment member60ensures that the first nozzle body30and its longitudinal axis31remain substantially perpendicular to the base member10when the first nozzle assembly30is in the lowered or lifted position. In the depicted embodiment the first nozzle body30is in the lowered position, wherein the lift member20is embodied as a flat plate lift member arranged substantially parallel to the base member10in the first wedge position. The conic section33of the first nozzle body30extends through the lift member hole23and is in circumferential contact engagement therewith, thereby guaranteeing lateral as well as longitudinal positioning accuracy of the first nozzle body30and the extrusion outlet32thereof with respect to the second nozzle body40and the extrusion outlet42thereof.

In an embodiment, the nozzle lifting assembly1further comprises a positioning unit imposing a positioning force F as indicatedFIG. 6aon the first nozzle body30and inlet end34thereof. In particular, a positioning unit may be provided in contact engagement with the inlet end34of the first nozzle body30, wherein the positioning unit is configured to provide a downward positioning force in the longitudinal direction31and a lateral positioning force onto the first nozzle body30. The downward positioning force acting upon the first nozzle body30ensures that the conic section33is pressed downward against an edge of the lift member hole23as it extends there through, and wherein the lateral positioning force ensures that the inlet end34of the first nozzle body30is positioned against the alignment member60. As a result, the first nozzle body30remains accurately aligned in three dimensions with respect to the base member10, the second nozzle body40and the extrusion outlet42thereof. In an embodiment the downward positioning force may be between 10 N to 20 N.

FIG. 6bshows a top view of a lateral alignment member as used in the present invention. In the embodiment shown, the lateral alignment member60is in contact engagement with the inlet end34of the first nozzle body30, ensuring lateral positioning accuracy in the indicated X and Y directions of the nozzle body30and the inlet end34thereof. As mentioned earlier, in a further embodiment a positioning unit may be provided imposing a positioning force F onto the first nozzle body30, such as a longitudinal force (e.g. downward) as well as a lateral force (e.g. sideways) onto the first nozzle body30. In an advantageous embodiment, the lateral alignment member60comprises a v-shaped recess61. The V-shaped recess allows contact engagement between the inlet end34of the first nozzle body30and the lateral alignment member60, wherein the first nozzle body30remains movably arranged with respect to the alignment member60for lifting motion of the first nozzle body30(e.g. upward, downward). In an exemplary embodiment the positioning unit provides a lateral force for ensuring the first end34of the first nozzle body30is firmly arranged within the V-shaped recess and against the lateral alignment member60, ensuring lateral positioning accuracy in the depicted X and Y directions.

To facilitate motion of the first nozzle body30between the lifted and lowered potions thereof during an additive manufacturing cycle, the lateral alignment member60may be of a plastic material. In a further embodiment, the lateral alignment member60may comprise a coating, such as a PTFE (“Teflon”) coating. The plastic material of the lateral alignment member60reduces friction forces during lifting cycles of the first nozzle body30, wherein a coating on the lateral alignment member60may contribute to a further reduction of friction forces when the first nozzle body30is firmly arranged against the lateral alignment member60.

In view of the lateral alignment member60and positioning unit as described above, the second nozzle body40may also be in contact engagement with the lateral alignment member60in a manner similar to the first nozzle body30. That is, the positioning unit may also subject the second nozzle body40to a downward positioning force in longitudinal direction41of the second nozzle body40as well as a lateral positioning force. The downward positioning force ensures that the conic section43of the second nozzle body40is firmly arranged against an edge of the base member hole11, and the lateral positioning force ensures firm contact engagement of an inlet end of the second nozzle body40with the lateral alignment member60. As a result, three dimensional positioning accuracy of the second nozzle body40and the extrusion outlet42thereof is guaranteed with respect to the base member10, the first nozzle body30and the extrusion outlet32thereof.

With reference toFIGS. 3, 4a,5band5c, it is important to note that in alternative embodiments the base member11and the lift member20may be integrated into a one-piece component or may be separate component of the nozzle lifting assembly1. In case the base member10and the lift member20are integrated, then the base member hole11and side opening12of the base member10may coincide with the further lift member hole26and further side opening27of the lift member20.

In any embodiment, however, accurate alignment in three dimensions between the first and second nozzle body30,40and extrusion outlets32,42thereof is guaranteed by the conical sections33,43. That is, the conical section33of the first nozzle body30is in contact engagement with the lift member hole23and the second nozzle body40is in contact engagement with an edge of the base member hole11or further lift member hole27.

In light of the present invention it is further noted that the first nozzle body30may comprise the lift member20, thus wherein the lift member20is fixedly attached to the first nozzle body30and the wedge member50is in wedging engagement with the lift member20between the first and second wedge position. In an exemplary embodiment, the lift member20may be embodied as a local protrusion or projection of the first nozzle body30in e.g. sliding engagement with the wedge member50between the lowered and lifted position of the first nozzle body30.

The nozzle lifting assembly1of the present invention may be implemented alternatively as the further embodiments as shown in theFIGS. 7 to 11.

FIGS. 7 and 8each show a partial cross section of an alternative embodiment of the nozzle lifting assembly1in a lowered position and a lifted position, respectively. In the embodiments shown, the lift member20is movably arranged with respect to the base member10in a vertical direction VLas indicated by the double arrow, wherein the first nozzle body30is arranged for being lifted by the lift member20.

Note that in contrast to the embodiments shown inFIGS. 1 to 6, the lift member20as discussed below in light of in deFIGS. 7 to 11is not in rational engagement with the base member10but is linearly moveable in the vertical direction VLonly.

In comparable fashion with the previous embodiments, the first nozzle body30may comprise a conical section33extending through a base member hole11of the base member10, wherein the conical section33of the first nozzle body30is in circumferential contact engagement with the base member hole11. This ensures accurate lateral alignment of the first nozzle body30.

The second nozzle body40is stationary in vertical direction with respect to the base member10during an additive manufacturing process. In an embodiment the lift member20comprises a first end21in wedging engagement with the wedge member50and a second end22which is in contact engagement with the first nozzle body30. As depicted, the contact engagement may be obtained through the second end22of the lift member20, wherein the second end22may be envisaged as in inwardly protruding rim or ridge22arranged along a circumference of the lift member20and encircling, at least in part, an inlet end34of the first nozzle body30. The inlet end34may be provided with an outwardly protruding flange36having a larger diameter than a diameter of the protruding rim22, so that the flange36latches against the rim or ridge22as the lift member20is in a lifted position in the vertical direction VL. As shown inFIG. 8, the second end22, e.g. the rim or ridge22, contacts the flange36when the lift member20is in the lifted positioned corresponding to the second wedge position, wherein the extrusion outlet32of the first nozzle body30extends above the extrusion outlet42of the second nozzle body40at a positional or height difference Lh. As already discussed above, in light of the invention the wedge member50is movably arranged relative to the base member10and in wedging engagement with the lift member20between a first and second wedge position, wherein the first and second wedge position correspond to a lowered position and a lifted position of the first nozzle body30with respect to the second nozzle body40, respectively.

In the embodiments ofFIGS. 7 and 8, the wedge member50may comprise a ramp section54in sliding engagement with the lift member20, e.g. in sliding engagement with a ramp section28the lift member20. The ramp section54of the wedge member50allows the lift member20and thus the first nozzle body30to be lowered and lifted in the vertical direction VLby the first and second wedge position of the wedge member50respectively. In an exemplary embodiment, the ramp section54of the wedge member50may comprise an upward projecting ramp section54.

To further clarify on how the wedge member50allows for lowering and lifting the first nozzle body30, reference is made toFIGS. 9 and 10.FIG. 9shows an exploded view of an embodiment of a lift member20and a wedge member50as used in the present invention.FIG. 10shows a side view of an embodiment of a lift member20and a wedge member50in a second wedging position according to the present invention.

As depicted inFIGS. 9 and 10, the wedge member50may comprise a ramp section54in sliding engagement with the lift member20. In an embodiment, a ramp section28may also be provided to the lift member20, so that the ramp section54of the wedge member50may be in sliding engagement congruent to the ramp section28of the lift member20, thereby providing smooth sliding between the first and second wedge position with minimal friction forces.

In the embodiments shown, the wedge member50is rotationally arranged with respect to the base member10between a first wedging angle γ1and a second wedging angle γ2. The first wedging angle γ1corresponds to the first wedge position and the second wedging angle γ2corresponds to the second wedge position. As depicted, the first and second wedging angle γ1, γ2may be measured from a virtual midpoint, so the first wedging angle γ1may be taken in counter clockwise direction as shown and the second wedging angle γ2may be taken in the clockwise direction as shown. For example, when the first and second wedging angle γ1, γ2equals zero, then this may be considered as a wedge position of the wedge member50wherein the extrusion outlet32of the first nozzle body30is positioned at equal height with the extrusion outlet42of the second nozzle body40.

The first wedging angle γ1therefore corresponds to a lowered position of the first nozzle body30and the second wedging angle γ2corresponds to a lifted (“raised”) position. Note that since the lift member20is movable in the vertical direction VLonly, the wedge member50is also rotationally arranged with respect to the lift member20between the first wedging angle γ1and the second wedging angle γ2.

From a functional point of view, through a rotation around the longitudinal axis31from the first wedging angle γ1toward the second wedging angle γ2, the ramp section54of the wedge member50wedges against the lift member20and raises or lifts the first nozzle body30in upward fashion along the vertical direction VL. The first wedging angle γ1and the second wedging angle γ2may therefore define an angle range over which the wedge member50can be rotated to achieve desired lifting or lowering of the first nozzle body30.

In an embodiment, the ramp section54can be configured to have a predetermined ramp angle or ramp incline determining a lifting height for the lift member20that can be obtained by the ramp section54of the wedge member50between the first and second wedging angles γ1, γ2.

In an advantageous embodiment, the wedge member50may also comprise a further ramp section57projecting in an opposite direction to the ramp section54of the wedge member50and in sliding engagement with the base member10. This embodiment allows for an increased lifting height HLthat would otherwise require a single ramp section54having a large ramp angle or ramp incline. However, having a large ramp angle or ramp incline may impose friction forces during sliding engagement that are too high and exceed predetermined values. So in case the wedge member50comprises two opposing ramp sections54,57, e.g. an upward projecting ramp section54and a downward projecting further ramp section57, then an increased lifting height HLcan be obtained for a given ramp angle or ramp incline.

In an advantageous embodiment, the wedge member50comprises a lever member51arranged for rotating the wedge member50, thereby providing reliable actuation of the wedge member50for rotation over the first wedging angle γ1or the second wedging angle γ2.

In the embodiments shown inFIGS. 7 to 10, the nozzle lifting assembly1may further comprise a resilient biasing member29connected to the lift member20and in downward biasing engagement therewith. The resilient biasing member29allows downward biasing of the lift member20along the vertical direction VL. In an exemplary embodiment as depicted, the biasing member29may comprise a spring-like element continuously pushing the lift member20downward, and thus biasing the first nozzle body30downward. Moving the wedge member50from the first wedge position to the second wedge position will therefore store potential energy in the biasing member29when, e.g., the lever member51is moved from the first wedging angle γ1to the second wedging angle γ2.

As further depicted inFIG. 9, the lift member20and the wedge member50may each comprise a side opening24,58arranged for receiving the first nozzle body30such as an inlet end34thereof. In particular, the side opening24of the lift member20and the side opening58of the lift member50allow for easy placement and removal of the first nozzle body30, wherein the inlet end34can be easily received within the lift member20and the wedge member50both of which enclose at least in part the inlet end34of the first nozzle body30.

In the embodiments ofFIGS. 7 to 10, the nozzle lifting assembly1may further comprise a lateral alignment member60in sliding engagement with an inlet end34of the first nozzle body30.FIG. 11shows a top view of an embodiment of a lateral alignment member60according to the present invention.

In the embodiments shown, the lateral alignment member60may be arranged between the wedge member50and the base member10. The lateral alignment member60may be fixedly mounted on the base member10so that the wedge member50is rotationally arranged with respect to the lateral alignment member60and in sliding engagement therewith. For lateral stability and lateral alignment accuracy, an embodiment is provided wherein the lateral alignment member60comprises a V-shaped recess61. The V-shaped recess61allows point contact between the first nozzle boy30, and the inlet end34thereof, and the lateral alignment member60. The point contact minimizes friction forces when the first nozzle body30is lowered or lifted. Furthermore, the point contact also ensures that lateral positioning of the first nozzle body30and the inlet end34is accurate and reliable even under the influence of surface irregularities of the inlet end34.

In an embodiment, to ensure that the inlet end34of the first nozzle body30is in point contact with the lateral alignment member60, the nozzle lifting assembly1may further comprise a positioning unit (not shown) in contact engagement with the inlet end34, wherein the positioning unit is configured to provide a lateral positioning force FL onto the inlet end34. The lateral positioning force FL thus provides a lateral biasing force pushing the inlet end34against the lateral alignment member60, in particular the V-shaped recess61.

Comparable to the lift member20and the wedge member50, in an advantageous embodiment the lateral alignment member60may be provided with a side opening63arranged for receiving the inlet end34of the first nozzle body30. The side opening63of the lateral alignment member60allows for easy placement and removal of the first nozzle body30, wherein the inlet end34can be easily received within the lateral alignment member60which encloses, at least in part, the inlet end34of the first nozzle body30.

As discussed above, the wedge member50may comprise a further ramp section57in sliding engagement with the base member10. In an embodiment, the further ramp section57may project in opposite direction to the ramp section54of the wedge member50. In an exemplary embodiment, seeFIG. 10, the ramp section54of the wedge member50may comprise an upward projecting ramp section54and the further ramp section57may comprise a downward projecting ramp section57. Both ramp sections54,57may have identical ramp angles or ramp inclines but this need not be the case.

The ramp section54and further ramp section57of the wedge member50provide an increased lifting height HLfor a given ramp angle or ramp incline. For example, in case the wedge member50merely comprises a single ramp section54, then in order to achieve the increased lifting height HLit may be required that the single ramp section54has a relatively steep ramp incline, which may increase friction forces beyond acceptable values. Therefore, having two opposing ramp sections54,57allows the increased lifting height HLto be possible for moderate ramp angles or ramp inclines without increasing friction forces excessively.

In an advantageous embodiment the wedge member50may also comprise a further ramp section57in sliding engagement with a ramp section62of the lateral alignment member60. For example, in an embodiment the wedge member50may comprise a downward projecting ramp section57in sliding engagement with a ramp section62of the lateral alignment member60. In an embodiment the ramp section62of the lateral alignment member60may also comprise a downward projecting ramp section62that is congruent to a downward projecting further ramp section57of the wedge member50.

Note that the terms “upward projecting” and “downward projecting” may be associated with a positive and negative slope, respectively, when going in a direction from left to right inFIG. 10. That is, the ramp section28of the lift member20and the ramp section54of the wedge member50may be considered to comprise a positive slope (going “upward”) when reading from left to right. Conversely, the further ramp section57of the wedge member50and the ramp section of the lateral alignment member60may be considered to comprise a negative slope (going “downward”) when reading from left to right inFIG. 10.

In light of the invention is can be argued that during an additive manufacturing process the first nozzle body30may be lowered and lifted many times. To keep wear of the lift member20, the wedge member50, and/or the lateral alignment member60to a minimum, the lift member20, the wedge member50and/or the lateral alignment member60may advantageously comprise a plastic material, such as a self-lubricating plastic material. The plastic material reduces friction forces between the various ramp sections28,54,57,62of the lift member20, wedge member50and/or the lateral alignment member60, so that wear of the various ramp sections28,54,57,62is minimized.

The present invention embodiments have been described above with reference to a number of exemplary embodiments as shown in and described with reference to the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.