WO2024099580A1

WO2024099580A1 - An additive manufacturing apparatus for additively manufacturing a three-dimensional object by curing a photocurable resin

Info

Publication number: WO2024099580A1
Application number: PCT/EP2022/081688
Authority: WO
Inventors: Gianni ZITELLI; Federico Iacovella
Original assignee: AXTRA3D Inc.
Priority date: 2022-11-13
Filing date: 2022-11-13
Publication date: 2024-05-16

Abstract

An additive manufacturing apparatus for additively manufacturing a three-dimensional object by curing a photocurable resin, comprising: • - a vat device (3) delimiting a vat volume (3.1) for receiving a photocurable resin; • - a build platform device (5) comprising a build platform (5.1); • - at least one irradiation device (2) configured to emit electromagnetic radiation to selectively and successively cure a photocurable resin provided in the vat volume (3.1) to additively manufacture a three-dimensional object; • - a support device (6) for moveably supporting the build platform device (5) relative to the vat device (3) in at least one degree of freedom of motion; wherein the support device (6) comprises at least two support structures (6.1, 6.2), wherein the build platform device (5) is moveably supported by the at least two separate support structures (6.1,6.2) in the at least one degree of freedom of motion.

Description

An additive manufacturing apparatus for additively manufacturing a three-dimensional object by curing a photocurable resin

The invention relates to an additive manufacturing apparatus for additively manufacturing a three- dimensional object by curing a photocurable resin.

Respective additive manufacturing apparatuses are generally known from the prior art and are configured for additively manufacturing a three-dimensional object by photocuring a photocurable resin via electromagnetic radiation. The base configuration of respective apparatuses typically, comprises a vat device delimiting a vat volume for receiving a photocurable resin, a build platform device comprising a build platform, and an irradiation device, e.g. a digital light projector device, configured to emit electromagnetic radiation to selectively and successively cure the photocurable resin provided in the vat volume to additively manufacture a three-dimensional object in a build direction. The basic operation of respective apparatuses is well-known and needs no further explanation.

Notably, respective apparatuses also comprise a support device for moveably supporting the build platform device relative to the vat device in at least one degree of freedom of motion.

The configuration of respective support devices is of high importance for the additive manufacturing process implemented with the apparatus which particularly, applies because a highly exact and stable support of the build platform has an influence on the orientation and/or position of the build platform relative to the vat device, i.e. particularly the bottom of the vat device, which is decisive for the quality of the additive build process and the three-dimensional objects resulting therefrom.

While respective support devices have been continuously improved, there still remain challenges which respect to assuring a highly exact and stable orientation and/or position of the build platform relative to the vat device, i.e. particularly the bottom of the vat device.

Hence, there exists a need for a further improved additive manufacturing apparatus for additively manufacturing a three-dimensional object by photocuring a photocurable resin.

It is therefore, an object of the present invention to provide an improved additive manufacturing apparatus for additively manufacturing a three-dimensional object by photocuring a photocurable resin.

The object is particularly achieved by the subject-matter of the appended Claims. A first aspect of the invention relates to an additive manufacturing apparatus (“apparatus”) for additively manufacturing a three-dimensional object by photocuring a photocurable resin. The apparatus is thus, generally configured to additively manufacture a three-dimensional object by photocuring a photocurable resin. Curing a photocurable resin typically, comprises a successive layerwise selective irradiation of the photocurable resin with electromagnetic energy (light) emitted form at least one irradiation device to successively generate cured resin layers of the three-dimensional object to be additively manufactured, wherein each cured resin layer represents a cross-section of the three-dimensional object to be additively manufactured.

The apparatus comprises a vat device. The vat device delimits a vat volume (receiving volume) for receiving a photocurable resin. A respective photocurable resin can be a polyamide resin, for instance. The vat device can comprise one or more vat device elements. The one or more vat device elements can form one or more walls of the vat device which are arranged and/or oriented to delimit the vat volume for receiving the photocurable resin.

The bottom of the vat device or the bottom of the vat volume of the vat device, respectively can be built by a or comprise at least one membrane. The membrane can be attachable or attached to one or more vat device elements of the vat device. The membrane is typically, transmissive to electromagnetic radiation (light) emitted from the at least one irradiation device of the apparatus. The membrane thus, has transmissive properties at least with respect to the electromagnetic radiation emitted from the at least one irradiation device of the apparatus. The membrane can thus, be transparent (at least with respect to the properties, e.g. wavelength, of the electromagnetic radiation emitted from the at least one irradiation device of the apparatus). The membrane typically, has a plane base shape. The membrane is typically, elastic and/or flexible. The membrane can thus, exhibit a reversible deflection and/or deformation behavior upon exertion of forces, such as pressure forces, during operation of the apparatus. Respective forces can directly or indirectly result from a motion of a build platform of the apparatus relative to the membrane. The membrane can thus, be reversibly deflected and/or deformed with respect to a zero state upon exertion of respective forces. Hence, the membrane can be built of an elastic and/or flexible material or of an elastic and/or flexible material structure enabling the respective reversible deflection and/or deformation behavior. A respective elastic and/or flexible material can be a polymer material and a respective elastic and/or flexible material structure can be a polymer material structure, for instance.

The apparatus further comprises a build platform device. The build platform device comprises a build platform. The build platform defines a build surface on which a three-dimensional object can be additively manufactured. The build surface typically, comprises a plane surface facing the bottom of the vat device or vat volume of the vat device, respectively. As will be apparent from further below, the build platform is moveably supported relative to the vat device in at least one degree of freedom of motion. The apparatus further comprises at least one irradiation device, such as e.g. a digital light projector device, configured to emit electromagnetic radiation (light) to selectively and successively cure the or a resin provided in the vat volume to additively manufacture a three- dimensional object. The wavelength of the electromagnetic radiation emitted by the at least one irradiation device is typically chosen with respect to the photocuring behavior of the photocurable resin to be processed with the apparatus. As an example, the wavelength of the of the electromagnetic radiation emitted by the at least one irradiation device can be in a range between 375 nm and 425 nm, particularly in a range between 385 nm and 415 nm, more particularly in a range between 395 and 405 nm.

The at least one irradiation device is typically, arranged below the vat device. The same applies when the apparatus comprises at least two different irradiation devices.

In exemplary embodiments, the apparatus can comprise at least two different irradiation devices. In an exemplary configuration of the apparatus with at least two different irradiation devices, a first irradiation device can be or comprise a digital light projector device and a second irradiation device can be or comprise a laser device. The at least two different irradiation devices can be configured to emit electromagnetic radiation of (substantially) the same wavelength or of similar wavelength. Similar wavelength can mean that the wavelength of the respective electromagnetic radiation differs no more than 10%, particularly no more than 5%, from each other. The apparatus can comprise one or more optical devices assigned to the one or more irradiation devices. Respective optical devices can be arranged in the optical path between the one or more irradiation devices and the membrane. Respective optical devices can comprise at least one of: a beam combining device, a collimating device, an expanding device, a focusing device, a polarizing device, a beam splitting device, etc.

The apparatus further comprises a support device for moveably supporting the build platform device relative to the vat device in (the) at least one degree of freedom of motion. The build platform device is thus, moveably supported relative to the vat device, particularly the membrane, in at least one degree of freedom of motion. The at least one degree of freedom of motion is typically, a translatory freedom of motion along a translatory axis. The translatory axis is typically, arranged and oriented, respectively perpendicular relative to a base plane of the bottom of the vat device or vat volume of the vat device, respectively. The support device can comprise one or more actuators or drive devices, such as one or more electromotors, configured to effect motions of the build platform device relative to the vat device along the translatory axis. The one or more actuators or drive devices can be particularly, configured to effect reciprocal motions of the build platform device along the translatory axis; the build platform device can thus, be moved in two directions, e.g. upward and downward, along the translatory axis. The build platform device is typically, arranged above the membrane. The apparatus can thus, have a so-called bottom-up configuration. However, at least some of the aspects or features of the apparatus specified in the following could also be implemented in so-called top-down configuration. As such, the apparatus can also have a so-called top-down configuration.

Notably, the support device comprises at least two separate support structures. The build platform device is thus, moveably supported by the at least two support structures in the at least one degree of freedom of motion. In other words, the build platform device is supported by at least two support structures. The at least two support structures can be arranged in parallel. The at least two support structures can each define a longitudinal axis which is oriented perpendicular to the base plane of the bottom of the vat device or vat volume of the vat device, respectively. The longitudinal axes of the at least two support structures can define the translational axis along which the build platform device is moveable. As such, the longitudinal axes of the at least two support structures can also define the build direction of a three-dimensional object to be additively manufactured with the apparatus. Each of the at least two support structures can also be deemed or denoted as z-axis.

Each of the at least two support structures can be built as or comprise a support bar, a support column, a support rail, a support rod, or a support wall, for instance. As such, a respective support structure can also be provided as a two-dimensional wall element, particularly a wall element at least partly delimiting a process chamber of the apparatus in which the actual additive build-up of a three-dimensional object to be additively manufactured with the apparatus is carried out.

Supporting the build platform device with at least two support structures provides additional mechanical stability, particularly rigidity, to the build platform device such that undesired effects, such as tilting of the build platform due to the hydraulic pressure of the photocurable resin which occurs during operation of the apparatus, can be avoided or at least reduced. Supporting the build platform device with at least two support structures can increase the stability and rigidity, particularly of the entire apparatus and ensures a desired alignment of the build platform in (essentially) any operating condition; this specifically, applies to operation of the apparatus with (highly) viscous materials, where the hydraulic pressure can be so high that maintaining the build platform device in a desired orientation and/or position has been difficult with conventional support devices.

As such, an improved apparatus for additively manufacturing a three-dimensional object is given.

The at least two separate support structures can be mounted on a base plate, which is connected to a machine frame or printer structure of the apparatus. Such a configuration can enable, a good absorption or compensation of forces, such as e.g. tensile forces, stress, etc., acting on the at least two support structures during operation of the apparatus. Further, one or more vibration-dampening elements can be provided with the connection between the base plate and the machine frame of the apparatus. The one or more vibration-dampening elements can particularly, be interposed between the base plate and the machine frame of the apparatus, particularly such that possible vibrations, e.g. during operation or shipment of the apparatus, cannot be transferred from the machine frame of the apparatus into the base plate and the at least two support structures or vice versa. As such, the base plate and/or the at least two support structures can be vibrationally decoupled from the machine frame of the apparatus, and vice versa. A respective vibrational decoupling can improve the quality of the additive build process and the three-dimensional objects resulting therefrom since external vibrations can be hindered from negatively affecting e.g. the alignment of the build platform device relative to the vat device. The one or more vibration-dampening elements can be made from an elastic material and/or an elastic material structure; an elastic material and/or an elastic material structure can comprise one or more elastomeric materials, for instance. The one or more vibration-dampening elements can thus, be or comprise elastomeric bearings, for instance.

The apparatus can further comprise a bridge-like carrier element connecting the at least two support structures. Connecting the at least two support structures with the bridge-like carrier element provides the support device with further mechanical stability and can particularly avoid or reduce bending forces which might possibly act on the at least two support structures during operation of the apparatus. Hence, the bridge-like carrier element is typically, made from a stable material or a highly stable material structure; a respective material and/or a respective material structure can comprise metals, (hard) plastics, composite materials, etc. The bridge-like carrier element can be built as or comprise a transverse bar, for instance.

The bridge-like carrier element can be moveably supported by the at least two support structures in the at least one degree of freedom of motion. The build platform device can be attachable or attached to the bridge-like carrier element. The build platform device can thus, be indirectly connected with the at least two support structures via the bridge-like carrier element which can also contribute to an improved support of the build platform device, e.g. because forces acting on the build platform device during operation of the apparatus might be transferred to the bridge-like carrier element and further into the at least two support structures. Hence, indirectly connecting the build platform device with the at least two support structures via the bridge-like carrier element can also positively affect maintaining the build platform device in a desired orientation and/or position. The bridge-like carrier element and the build platform device can comprise corresponding attachment interfaces which are configured to co-act, e.g. via a chemical and/or physical interaction, to enable an attachment of the build platform device to the bridge-like carrier element. A respective chemical interaction can be a realized through gluing, welding, soldering, etc. A respective physical interaction can be a mechanical interaction which can be realized through clamping, riveting, screwing, etc. To ease service and/or repair works, the build platform device can be detachably attached to the bridge-like carrier element. At least one of the at least two support structures can comprise an attachment interface for attaching at least one functional component of the apparatus. Hence, the at least two support structures cannot only have a supporting function with respect to the build platform device but also with respect to at least one other functional component of the apparatus. A respective attachment interface can be provided with an external and/or internal surface of a respective support structure; as such, at least one respective support structure can comprise an internal space delimited by internal surfaces at which one or more attachment interfaces can be provided. Using respective internal spaces for attaching a respective functional component can contribute to a highly integrated constructive design of the apparatus.

Exemplary and thus, non-limiting functional components of the apparatus are a drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device in the at least one degree of freedom of motion, a stop device for stopping a motion of the build platform device beyond an upper and/or lower threshold position, a sensor device for sensing at least one parameter indicative of the motion and/or position of the build platform device. Hence, the apparatus can comprise at least one of: a drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device in the at least one degree of freedom of motion, a stop device for stopping a motion of the build platform device beyond an upper and/or lower threshold position, a sensor device for sensing at least one parameter indicative of the motion and/or position of the build platform device.

One, more, or all of the at least two support structures can be provided with at least one linear drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device in the at least one degree of freedom of motion. A respective linear drive device enables a highly precise motion of the build platform device in the at least one degree of freedom of motion and can be built as or comprise at least one of a spindle axis, toothed belt axis, glide axis, etc., for instance. A respective linear drive device can also be deemed a respective functional component of the apparatus and can thus, be arranged in a respective internal space of a respective support structure.

Further, one, more, or all of the at least two support structures can be provided with at least one linear guide device for providing a guided motion of the build platform device in the at least one degree of freedom of motion. A respective linear guide device enables a highly precise guided motion of the build platform device in the at least one degree of freedom of motion and be built as or comprise at least one of a guide bearing or a guide rail, for instance. A respective linear guide device can also be deemed a respective functional component of the apparatus and can thus, be arranged in a respective internal space of a respective support structure. The build platform device can comprise an attachment structure for the build platform. The attachment structure comprises at least one attachment element for releasably attaching the or a build platform thereto. Hence, the build platform device can comprise a separate attachment provision for releasably attaching the or a build platform thereto. This generally enables that the build platform device can be used with different build platforms since the configuration of the attachment structure enables an exchange of build platforms. This is not only advantageous with respect to the compatibility of the build platform device since different build platforms, e.g. plane platforms, holed platforms, grooved platforms, textured platforms, surface-treated platforms, etc., can be used but also with respect to possible service and/or repair works since build platforms can be easily monitored, repaired, etc.

The at least one attachment element can comprise a bracket- or yoke-configuration. Particularly, the at least one attachment element can comprise a bracket- or yoke-like base body having two or more free ends each provided with at least one attachment interface for releasably attaching a build platform thereto. A respective attachment interface can e.g. be a mechanical interface enabling a mechanical attachment of the build platform to the, e.g. via clamping, screwing, etc. The at least one attachment element, particularly the bracket- or yoke-like base body, can comprise two or more separate gripping portions at which the at least one attachment element can be gripped by a user or by a handling device. Respective gripping portions can be provided with first and second distal portions of the at least one attachment element, for instance. As such, the at least one attachment element can be gripped with either a left hand, a right hand, or both hands which improves handling of the build platform device, e.g. in context with removing same (together with an additively manufactured three-dimensional object) from the apparatus after an additive manufacturing process is completed.

The apparatus can further comprise a locking structure for releasably locking the attachment structure, particularly the attachment element, to a build platform alignment assembly of the build platform device. The possibility of releasably locking the attachment structure, particularly the attachment element, to a build platform alignment assembly of the build platform device also contributes to the aforementioned handling improvement, but also assures, in a locked state of the locking structure, a fixation of the attachment structure in a specific orientation and/or position relative to the vat device which is of high importance for maintaining a desired orientation and/or position of the build platform relative to the vat device, i.e. particularly the bottom of the vat device, which is decisive for the quality of the additive build process and the three-dimensional objects resulting therefrom.

The locking structure can comprise at least one locking element which is moveably supported in a locking orientation and/or position (locking state), in which a locking force is exerted on the attachment structure which locks the attachment structure in the defined orientation and/or position, and in a unlocking orientation and/or position (unlocked state), in which no locking force is exerted on the attachment structure which locks the attachment structure in the defined orientation and/or position. For transferring the at least one locking element in the respective locking orientation and/or position and/or unlocking orientation and/or position, the at least one locking element can be moveably supported in at least one translational and/or rotational degree of freedom of motion. As an example, the at least one locking element can be moveably supported in a rotational degree of freedom of motion about a rotational axis, e.g. a horizontal or vertical axis, such that the at least one locking element can be pivoted about the rotational axis for transferring it into the respective locking orientation and/or position and/or unlocking orientation and/or position. The at least one locking element can thus, be configured as a pivotable locking lever, for instance.

The locking structure can particularly, comprise a locking mechanism which comprises the at least one locking element. The at least one locking element can be mechanically couplable or coupled with at least one attachment structure, particularly at least one attachment element, in the locking orientation and/or position so as to exert the locking force on the at least one attachment structure, particularly the at least one attachment element. Particularly, the at least one locking element can be configured to clamp the at least one attachment structure, particularly the at least one attachment element, against at least one alignment plate of a build platform alignment assembly of the build platform device in the locking orientation and/or position, thereby exerting a clamping force on the at least one attachment structure, particularly at least one attachment element, against the at least one alignment plate of the build platform alignment assembly. As such, the at least one locking element can comprise a clamping element or can be couplable or coupled with at least one clamping element configured to exert a respective clamping force on the at least one attachment structure in the locking orientation and/or position of the locking element. The locking force can thus, be a clamping force, particularly an upward clamping force. Clamping the at least one attachment structure, particularly the at least one attachment element, against the at least one alignment plate of the build platform alignment assembly enables a highly exact and stable orienting and/or positioning of the at least one attachment structure and the components, such as the at least one attachment element and the build platform, attached thereto. Clamping particularly, enables that the at least one attachment structure, particularly the at least one attachment element, is locked against any movement and thus, fixed in x-, y-, and z-direction at least relative to the alignment plate.

The locking structure can further comprise at least one lever element coupled with the at least one locking element. Also the at least one lever element is moveably supported in a locking orientation and/or position (locking state), in which the at least one locking element exerts, due to the coupling, a respective locking force on the at least one attachment structure, particularly the at least one attachment element, such that the at least one attachment structure, particularly the at least one attachment element, is locked in the defined orientation and/or position, and in an unlocking orientation and/or position (unlocked state), in which the at least one locking element does not exert, due to the coupling, a locking force on the at least one attachment structure, particularly the at least one attachment element, such that the at least one attachment structure, particularly the at least one attachment element, is not locked in the defined orientation and/or position.

As is apparent from further above, the build platform device can further comprise a build platform alignment assembly configured to align the orientation and/or position of the build platform and/or at least one attachment structure to which the build platform is attached in a defined orientation and/or position relative to a build plane of the apparatus, particularly relative to a bottom plane of the vat device. Hence, the build platform device can comprise a separate provision for aligning the build platform and/or the at least one attachment structure to which the build platform is attached in a defined orientation and/or position relative to a build plane of the apparatus, particularly relative to a bottom plane of the vat device, which facilitates generating and maintaining highly precise alignment of the build platform and/or the at least one attachment structure in a desired orientation and/or position.

The build platform alignment assembly can be attached to the bridge-like carrier element. At least one alignment plate of the build platform alignment assembly can be firmly attached to the bridgelike carrier element such that it cannot be moved relative to the bridge-like carrier element.

The build platform alignment assembly can comprise an upper and a lower alignment plate. The build platform alignment assembly can thus, generally comprise two alignment plates in a vertically stacked arrangement. The lower alignment plate can be moveably supported relative to the upper alignment plate in one or more degrees of freedom of motion, particularly in at least two degrees of freedom of motion. Particularly, the lower alignment plate can be translated and/or rotated along or about an x-axis and in a y-axis, i.e. particularly translated along the axes which defined the build plane, and translated and/or rotated along or about a z-axis, i.e. particularly along the axis which defines the build direction. As such, the lower alignment plate can particularly, be pivoted or tilted relative to a build plane of the apparatus about the x- and/or y- axis via respective pivot or tilting motions. Further, the z-distance of the lower alignment plate relative to the build plane of the apparatus can be adjusted by respective vertical motions of the (pivoted or tilted) lower alignment plate to provide planarity. As such, the build surface of the build platform can essentially be adjusted to any build plane configuration. Specifically, possible deviations of a build plane, e.g. a membrane or membrane supporting structure, such as a glass element, with respect to a nominal and/or reference state can be compensated for because the build platform alignment assembly can still assure a desired alignment of the build platform due to adapting the orientation and/or position of the build platform to the build plane by moving the lower alignment plate in the at least one degree of freedom of motion. As indicated further above, the upper alignment plate is typically not moveably supported but firmly attached to the bridgelike carrier element. It is apparent from the above that the lower alignment plate can be provided with a connection interface for connecting the build platform or a respective attachment structure for the build platform therewith. A respective connection interface can e.g. be a mechanical interface enabling a mechanical connection of the build platform or a respective attachment structure for the build platform to the, e.g. via clamping, screwing, etc.

The lower alignment plate can be suspended with the upper alignment plate via one or more floating suspension devices. Each floating suspension device is configured to provide the lower alignment plate with at least one degree of freedom of motion. Typically, each floating suspension device is configured to provide the lower alignment plate with at least two degrees of freedom of motion. Particularly, each floating suspension device can be configured to provide the lower alignment plate with one or more pivoting and/or tilting degrees of freedom of motion relative to the upper alignment plate and the membrane, respectively.

Each respective floating suspension device can comprise two floating suspension elements, wherein a first floating suspension element is firmly attached to the lower alignment plate and a second floating suspension element is moveably supported relative to the first floating suspension element. Typically, the second floating suspension element faces the upper alignment plate. Hence, the respective second floating suspension element can be transferred into a specific orientation and/or position relative to the upper alignment plate independent from the first floating suspension element and particularly, without the requirement of changing a given orientation and/or position of the lower alignment plate, which might be adapted to the build plane of the apparatus in orientation and/or position to provide planarity with the membrane, for instance.

A respective floating suspension device can be built as or comprise at least one levelling washer assembly, particularly at least one spherical levelling washer assembly. Levelling washer assemblies, particularly spherical leveling washer assemblies, typically comprise a first ring-like washer element forming first floating suspension element and a second ring-like washer element forming a second floating suspension element. Typically, the first washer element typically, comprises a receiving portion for receiving the second washer element which is moveably supported relative to the first washer element. Both the receiving portion of the first washer element and the second washer element can at least partly have a spherical shape which enables moving, e.g. by pivoting or tilting, the second washer element relative to the first washer element. Levelling washer assemblies are reliable components enabling, in a respective configuration as specified above, that a respective second floating suspension element can be moved, e.g. by pivoting or tilting relative to the first floating suspension element, into a specific orientation and/or position relative to the upper alignment plate independent from a respective first floating suspension element of a floating suspension device. The build platform alignment assembly can further comprise one or more fastening elements configured to fasten the lower alignment plate in a specific orientation and/or position relative to the upper alignment plate. Particularly, the build platform alignment assembly can comprise one or more first fastening elements for fastening the orientation and/or position of the lower alignment plate with respect to the x-axis and/or the y-axis and one or more second fastening elements for fastening the orientation and/or position of the lower alignment plate with respect to the z-axis. Respective first and second fastening elements are typically supported by the upper alignment plate which can comprise receiving portions, such as receiving bores, holes, etc. for one or more first and/or second fastening elements.

Each respective first fastening element can be transferred in a fastening state, in which it enables fastening the orientation and/or position of the lower alignment plate with respect to the x-axis and/or the y-axis, and a non-fastening state, in which it does not enable fastening the orientation and/or position of the lower alignment plate with respect to the x-axis and/or the y-axis. Transferring a respective first fastening element in its fastening state and/or non-fastening state can comprise a motion of the first fastening element in at least one degree of freedom of motion, e.g. in a translational and/or in rotational motion about a motion axis. A respective motion axis can be an axis parallel to the build direction (build axis or z-axis), for instance. A respective motion for transferring a respective first fastening element in its fastening state and/or non-fastening state can comprise a motion of the first fastening element relative to the upper and/or lower alignment plate.

Likewise, each respective second fastening element can be transferred in a fastening state, in which it enables fastening the orientation and/or position of the lower alignment plate with respect to the z-axis, and in a non-fastening state, in which it does not enable fastening the orientation and/or position of the lower alignment plate with respect to the z-axis. Transferring a respective second fastening element in its fastening state and/or non-fastening state can comprise a motion of the second fastening element in at least one degree of freedom of motion, e.g. in a translational and/or in rotational motion about a motion axis. A respective motion axis can be an axis parallel to the build direction (build axis or z-axis), for instance. A respective motion for transferring a respective second fastening element in its fastening state and/or non-fastening state can comprise a motion of the second fastening element relative to the upper and/or lower alignment plate.

As an example, the one or more first and/or second fastening elements can be built as or compromise at least one of a fastening bolt, a fastening knob, or a fastening screw.

A respective first fastening element can comprise a receiving space, such as e.g. a bore, a hole, a threaded bore, a threaded hole, etc., for receiving a respective second fastening element. Receiving the second fastening element in a respective receiving space can still enable a motion of the second fastening element relative to and independent from the first fastening element. As such, the first and second fastening elements can be transferred independently from each other in their respective fastening state, e.g. by first transferring a first fastening element in its fastening state, e.g. by a translational and/or a rotational motion, so as to fasten the orientation and/or position of the lower alignment plate with respect to the x-axis and/or the y-axis, and then transfer the second fastening element in its fastening state, e.g. by a translational and/or a rotational motion relative to the first fastening element, so as to so as to fasten the orientation and/or position of the lower alignment plate with respect to the z-axis.

In the fastening state of a respective first fastening element, the first fastening element can tightly abut against a floating suspension device, particularly against a second floating suspension element, thereby fastening the floating suspension device and further the lower alignment plate in its current orientation and/or position with respect to the x-axis and/or y-axis. A respective first fastening element can thus, comprise an abutment surface configured to being abutted against a floating suspension device, i.e. particularly against a respective freely exposed surface of the floating suspension device, particularly provided with the second floating suspension element. As will be apparent from further below, typically at least two first fastening elements can tightly abut against a floating suspension device, particularly against a second floating suspension element, to fasten the lower alignment plate in its current orientation and/or position.

In the fastening state of a respective second fastening element, the second fastening element can engage with a floating suspension device, particularly with a receiving opening of a floating suspension device, more particularly with a receiving opening provided at least with a second floating suspension element, thereby fastening the floating suspension device and further the lower alignment plate in its current orientation and/or position with respect to the z-axis. A respective second fastening element can thus, comprise an engagement portion configured to engage with a floating suspension device, particularly with a respective receiving opening of the floating suspension device, more particularly provided with a respective receiving opening provided with the second floating suspension element. A respective engagement portion and a respective receiving portion can be provided with corresponding threads. As will be apparent from further below, typically at least two second fastening elements will engage with at least two floating suspension devices, particularly with a second floating suspension element, to fasten the lower alignment plate element in its current orientation and/or position.

As is apparent from above, the floating suspension device can generally, be configured to fasten a defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via at least one fixed alignment point, which can be implemented via a respective second fastening element, and two or more floating alignment points, which can be implemented via respective first fastening elements. Alternatively, the floating suspension device can generally, be configured to fasten a defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via at least three first and/or second fastening elements.

The platform alignment assembly can further comprise one or more connecting elements, particularly attractive springs, connecting the upper alignment plate with the lower alignment plate. Hence, a mechanical connection of the two alignment plates can be achieved via respective connecting elements. In case that the connecting elements provide an attractive force attracting the two alignment plates together, the connecting can also form part of the floating suspension device because can enable a floating suspension of the lower alignment plate relative to the first alignment plate.

A second aspect of the invention pertains to a method of operating an additive manufacturing apparatus according to the first aspect of the method. The method can particularly, be a method of aligning the orientation and/or position of a build platform and/or an attachment structure to which the build platform is attached via a build platform alignment assembly in a defined orientation and/or position relative to a build plane of the apparatus, particularly relative to a bottom plane of the vat device of the apparatus. The method can particularly comprise the steps of: providing build platform alignment assembly in which the lower alignment plate is moveably supported relative to the upper alignment plate in at least one degree of freedom of motion; aligning the lower alignment plate relative to a reference plane, e.g. the bottom plane of the vat device, by transferring the lower alignment plate in a defined orientation and/or position in which the build platform is parallel to the reference plane; and fastening the defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via one or more fastening elements. The aligning can comprise moving the build platform against the reference plane, particularly against the bottom plane of the vat device, such that the build surface of the build plane directly contacts the bottom plane of the vat device.

All annotations concerning the apparatus of the first aspect of the invention also apply to the method of the second aspect of the invention and vice versa.

The disclosure will also be readily understood by the following description of exemplary embodiments in conjunction with the accompanying drawings in which:

Fig.1 illustrates a principle drawing of an additive manufacturing apparatus in accordance with an exemplary embodiment;

Fig. 2, 3 each illustrate a principle drawing of an attachment structure of an additive manufacturing apparatus in accordance with an exemplary embodiment; Fig. 4 - 6 each illustrate a principle drawing of build platform alignment assembly of an additive manufacturing apparatus in accordance with another exemplary embodiment; and

Fig. 7 illustrates a principle drawing of a floating suspension device in accordance with an exemplary embodiment.

Fig.1 illustrates a principle drawing of an additive manufacturing apparatus 1 (“apparatus”) in accordance with an exemplary embodiment. The apparatus 1 is generally configured to additively manufacture a three-dimensional object (not shown) by photocuring a photocurable resin. Curing a photocurable resin via the apparatus 1 typically, comprises a successive layerwise selective irradiation of the photocurable resin with electromagnetic radiation (light) emitted from an irradiation device 2, e.g. a digital light projector device, to successively generate respective cured resin layers of the three-dimensional object to be additively manufactured, wherein each cured resin layer represents a cross-section of the three-dimensional object to be additively manufactured.

The apparatus 1 comprises a vat device 3. The vat device 3 delimits a vat volume 3.1 for receiving the photocurable resin. The vat device 3 can comprise one or more vat device elements at least some of them forming a wall of the vat device 3 which is arranged and/or oriented to delimit the vat volume 3.1 for receiving the photocurable resin. The bottom of the vat volume 3.1 can be defined by a membrane 4 which is transmissive to the electromagnetic radiation emitted from the irradiation device 2. The membrane 4 thus, has transmissive properties at least with respect to the electromagnetic radiation emitted from the irradiation device 2. The membrane 4 can thus, be built from an elastic and/or flexible polymer or a polymer structure which is transparent (at least with respect to the properties, e.g. wavelength, of the electromagnetic radiation emitted from the irradiation device 2).

The apparatus 1 further comprises a build platform device 5. The build platform device 5 comprises a build platform 5.1 which defines a build surface 5.2 on which a three-dimensional object can be additively manufactured. The build surface 5.2 typically, comprises a plane surface facing the bottom of the vat device 3 or vat volume 3.1 , respectively. As will be apparent from further below, the build platform 5.1 is moveably supported relative to the vat device 3 in at least one degree of freedom of motion.

As is apparent, the build platform device 5 is arranged above the vat device 3 and the irradiation device 2 is arranged below the vat device 3; the apparatus 1 thus, has a so-called bottom-up configuration.

The apparatus 1 further comprises a support device 6 for moveably supporting the build platform device 5 relative to the vat device 3 in the at least one degree of freedom of motion. The at least one degree of freedom of motion is typically, a translatory freedom of motion along a translatory axis A1 which is arranged and oriented, respectively perpendicular relative to a base plane of the bottom of the vat device 3 or vat volume 3.1 , respectively. The support device 6 can comprise one or more drive devices (not shown), such as one or more electromotors, configured to effect motions of the build platform device 5 relative to the vat device 3 along the translatory axis A1 . The one or more drive devices can be particularly, configured to effect reciprocal motions of the build platform device 5 along the translatory axis A1 ; as indicated by double-arrow P1 , the build platform device 5 can thus, be moved in two directions, e.g. upward and downward, along the translatory axis A1.

Notably, the support device 6 comprises at least two separate support structures 6.1 , 6.2 which can be arranged in parallel. The build platform device 5 is thus, moveably supported by the at least two support structures 6.1 , 6.2 in the at least one degree of freedom of motion. In other words, the build platform device 5 is supported by at least two support structures 6.1 , 6.2. As is apparent from Fig. 1 , the at least two support structures 6.1 , 6.2 each define a longitudinal axis which is oriented perpendicular to the base plane of the bottom of the vat device 3 or vat volume 3.1 , respectively. The longitudinal axes of the at least two support structures 6.1 , 6.2 can thus, define the translational axis A1 along which the build platform device 5 is moveable. As such, the longitudinal axes of the at least two support structures 6.1 , 6.2 can also define the build direction of a three-dimensional object to be additively manufactured with the apparatus 1 . Each of the at least two support structures 6.1 , 6.2 can also be deemed or denoted as z-axis.

Each of the at least two support structures 6.1 , 6.2 can be built as or comprise a support bar, a support column, a support rail, a support rod, or a support wall, for instance. As such, a respective support structure 6.1 , 6.2 can also be provided as a two-dimensional wall element, particularly a wall element at least partly delimiting a process chamber PC of the apparatus 1 in which the actual additive build-up of a three-dimensional object to be additively manufactured with the apparatus 1 is carried out.

Supporting the build platform device 5 with at least two support structures 6.1 , 6.2 provides additional mechanical stability, particularly rigidity, to the build platform device 5 such that undesired effects, such as tilting of the build platform 5.1. due to the hydraulic pressure of the photocurable resin which occurs during operation of the apparatus 1 , can be avoided or at least reduced. Supporting the build platform device 5 with the at least two support structures 6.1 , 6.2 can increase the stability and rigidity, particularly of the entire apparatus 1 and ensures a desired alignment of the build platform 5.1 in (essentially) any operating condition; this specifically, applies to operation of the apparatus 1 with (highly) viscous materials, where the hydraulic pressure can be so high that maintaining the build platform 5.1 device in a desired orientation and/or position has been difficult with conventional support devices. The at least two separate support structures 6.1 , 6.2 can be mounted on a base plate 7, which is connected to a machine frame 8 of the apparatus 1 . Such a configuration can enable, a good absorption or compensation of forces, such as e.g. tensile forces, stress, etc., acting on the at least two support structures 6.1 , 6.2 during operation of the apparatus 1 .

One or more vibration-dampening elements 9 can be provided with the connection between the base plate 7 and the machine frame 8 of the apparatus 1. The one or more vibration-dampening elements 9 can particularly, be interposed between the base plate 7 and the machine frame 8 of the apparatus 1 , particularly such that possible vibrations, e.g. during operation or shipment of the apparatus 1 , cannot be transferred from the machine frame 8 of the apparatus 1 into the base plate 7 and the at least two support structures 6.1 , 6.2 or vice versa. As such, the base plate 7 and/or the at least two support structures 6.1 , 6.2 can be vibrationally decoupled from the machine frame 8 of the apparatus 1 , and vice versa. A respective vibrational decoupling can improve the quality of the additive build process and the three-dimensional objects resulting therefrom since external vibrations can be hindered from negatively affecting e.g. the alignment of the build platform device 5 relative to the vat device 3. The one or more vibration-dampening elements 9 can be made from an elastic material and/or an elastic material structure; an elastic material and/or an elastic material structure can comprise one or more elastomeric materials, for instance. The one or more vibration-dampening elements 9 can thus, be or comprise elastomeric bearings, for instance.

The apparatus 1 further comprises a bridge-like carrier element 10 connecting the at least two support structures 6.1 , 6.2. Connecting the at least two support structures 6.1 , 6.2 with the bridgelike carrier element provides the support device 6 with further mechanical stability and can particularly avoid or reduce bending forces which might possibly act on the at least two support structures 6.1 , 6.2 during operation of the apparatus 1. Hence, the bridge-like carrier element 10 is typically, made from a stable material or a highly stable material structure; a respective material and/or a respective material structure can comprise metals, (hard) plastics, composite materials, etc. As is apparent from Fig. 1 , the bridge-like carrier element 10 can be built as or comprise a transverse bar, for instance.

The bridge-like carrier element 10 is moveably supported by the at least two support structures 6.1 , 6.2 in the at least one degree of freedom of motion. The build platform device 5 is attached to the bridge-like carrier element 10. The build platform device 5 can thus, be indirectly connected with the at least two support structures 6.1 , 6.2 via the bridge-like carrier element 10 which can also contribute to an improved support of the build platform device 5, e.g. because forces acting on the build platform device 5 during operation of the apparatus 1 might be transferred to the bridge-like carrier element 10 and further into the at least two support structures 6.1 , 6.2. Hence, indirectly connecting the build platform device 5 with the at least two support structures 6.1 , 6.2 via the bridge-like carrier element 10 can also positively affect maintaining the build platform device 5 in a desired orientation and/or position. The bridge-like carrier element 10 and the build platform device 5 can comprise corresponding attachment interfaces which are configured to coact, e.g. via a chemical and/or physical interaction, to enable an attachment of the build platform device 5 to the bridge-like carrier element 10. A respective chemical interaction can be a realized through gluing, welding, soldering, etc. A respective physical interaction can be a mechanical interaction which can be realized through clamping, riveting, screwing, etc. To ease service and/or repair works, the build platform device 5 can be detachably attached to the bridge-like carrier element 10.

At least one of the at least two support structures 6.1 , 6.2 can comprise an attachment interface for attaching at least one functional component of the apparatus 1. Hence, the at least two support structures 6.1 , 6.2 cannot only have a supporting function with respect to the build platform device 5 but also with respect to at least one other functional component of the apparatus 1 . A respective attachment interface can be provided with an external and/or internal surface of a respective support structure 6.1 , 6.2; as such, at least one respective support structure 6.1 , 6.2 can comprise an internal space delimited by internal surfaces at which one or more attachment interfaces can be provided. Using respective internal spaces for attaching a respective functional component can contribute to a highly integrated constructive design of the apparatus 1.

Exemplary and thus, non-limiting functional components of the apparatus 1 are a drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device 5 in the at least one degree of freedom of motion, a stop device for stopping a motion of the build platform device 5 beyond an upper and/or lower threshold position, a sensor device for sensing at least one parameter indicative of the motion and/or position of the build platform device 5. Hence, the apparatus 1 can comprise at least one of: a drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device 5 in the at least one degree of freedom of motion, a stop device for stopping a motion of the build platform device 5 beyond an upper and/or lower threshold position, a sensor device for sensing at least one parameter indicative of the motion and/or position of the build platform device 5. The functional components of the apparatus 1 are not shown since they are per se known.

One, more, or all of the at least two support structures 6.1 , 6.2 can be provided with at least one linear drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device 5 in the at least one degree of freedom of motion. A respective linear drive device enables a highly precise motion of the build platform device 5 in the at least one degree of freedom of motion and can be built as or comprise at least one of a spindle axis, toothed belt axis, glide axis, etc., for instance. A respective linear drive device can also be deemed a respective functional component of the apparatus 1 and can thus, be arranged in a respective internal space of a respective support structure 6.1 , 6.2. Further, one, more, or all of the at least two support structures 6.1 , 6.2 can be provided with at least one linear guide device for providing a guided motion of the build platform device 5 in the at least one degree of freedom of motion. A respective linear guide device 5 enables a highly precise guided motion of the build platform device 5 in the at least one degree of freedom of motion and be built as or comprise at least one of a guide bearing or a guide rail, for instance. A respective linear guide device can also be deemed a respective functional component of the apparatus 1 and can thus, be arranged in a respective internal space of a respective support structure 6.1 , 6.2.

The build platform device 5 can comprise an attachment structure 11 for the build platform 5.1. The attachment structure 11 comprises an attachment element 11.1 for releasably attaching the or a build platform 5.1 thereto. Hence, the build platform device 5 can comprise a separate attachment provision for releasably attaching the or a build platform 5.1 thereto. This generally enables that the build platform device 5 can be used with different build platforms 5 since the configuration of the attachment structure 11 enables an exchange of build platforms 5.1 . This is not only advantageous with respect to the compatibility of the build platform device 5 since different build platforms 5.1 , e.g. plane platforms, holed platforms, grooved platforms, textured platforms, surface-treated platforms, etc., can be used but also with respect to possible service and/or repair works since build platforms 5.1 can be easily monitored, repaired, etc.

As is apparent from the Fig., the attachment element 11.1 can comprise a bracket- or yokeconfiguration. Particularly, the attachment element 11.1 can comprise a bracket- or yoke-like base body having two or more free ends each provided with an attachment interface 11.2 for releasably attaching a build platform 5.1 thereto. A respective attachment interface can e.g. be a mechanical interface enabling a mechanical attachment of the build platform to the, e.g. via clamping, screwing, etc. The at least one attachment element 11.1 , particularly the bracket- or yoke-like base body, can comprise two or more separate gripping portions 11.3, 11.4 at which the attachment element 11.1 can be gripped by a user or by a handling device. Respective gripping portions 11.3, 11.4 can be provided with first and second distal portions of the attachment element 11 , for instance. As such, the attachment element 11 can be gripped with either a left hand, a right hand, or both hands which improves handling of the build platform device 5, e.g. in context with removing same (together with an additively manufactured three-dimensional object) from the apparatus 1 after an additive manufacturing process is completed.

As is particularly apparent from Fig. 2 and 3, the apparatus 1 can further comprise a locking structure 12 for releasably locking the attachment structure 11 , particularly the attachment element 11.1 , to a build platform alignment assembly 13 of the build platform device 5. The possibility of releasably locking the attachment structure 11 , particularly the attachment element 11.1 , to the build platform alignment assembly 13 also contributes to the aforementioned handling improvement, but also assures, in a locked state of the locking structure 12, a fixation of the attachment of the attachment structure 11 in a specific orientation and/or position relative to the vat device 3 which is of high importance for maintaining a desired orientation and/or position of the build platform 5.1 relative to the vat device 3, i.e. particularly the bottom of the vat device 3, which is decisive for the quality of the additive build process and the three-dimensional objects resulting therefrom.

The locking structure 12 can comprise a locking element 12.1 which is moveably supported in a locking orientation and/or position (locking state shown in Fig. 2), in which a locking force is exerted on the attachment structure 11 which locks the attachment structure 11 in the defined orientation and/or position, and in a unlocking orientation and/or position (unlocked state shown in Fig. 3), in which no locking force is exerted on the attachment structure 11 which locks the attachment structure 11 in the defined orientation and/or position. For transferring the locking element 12.1 in the respective locking orientation and/or position and/or unlocking orientation and/or position, the locking element 12.1 can be moveably supported in at least one translational and/or rotational degree of freedom of motion. As shown in Fig. 2 and 3, the locking element 12.1 can be moveably supported in a rotational degree of freedom of motion about a rotational axis, e.g. a horizontal or vertical axis, such that the locking element 12.1 can be pivoted about the rotational axis for transferring it into the respective locking orientation and/or position and/or unlocking orientation and/or position. The locking element 12.1 can thus, be configured as a pivotable locking lever, for instance.

As is apparent from Fig. 2 and 3, the locking structure 12 can particularly, comprise a locking mechanism which comprises the locking element 12.1. The locking element 12.1 can be mechanically couplable or coupled with the attachment structure 11 , particularly the attachment element 12.1 , in the locking orientation and/or position so as to exert the locking force on the attachment structure 11. Particularly, the locking element 12.1 can be configured to clamp the attachment element 12.1 against at least one alignment plate 13.2 of the build platform alignment assembly 13 in the locking orientation and/or position, thereby exerting an upward clamping force on the attachment element 11.1 against the alignment plate 13.2. As indicated in Fig. 2 and 3, the locking element 12.1 can be coupled with a clamping element 12.2 configured to exert a respective clamping force on the attachment element 11.1 in the locking orientation and/or position of the locking element 12.1 (see Fig. 2). Clamping the attachment element 11.1 against the alignment plate 13.2 enables a highly exact and stable orienting and/or positioning of the attachment element 11.1 and the build platform 5.1 attached thereto.

The locking structure 12 can further comprise a lever element 12.3 coupled with the locking element 12.1. As is apparent from Fig. 2 and 3, also the lever element 12.3 is moveably supported in a locking orientation and/or position (locking state shown in Fig. 2), in which the locking element 12.1 exerts, due to the coupling, a respective locking force on the attachment element 11.1 such that the attachment element 11.1 is locked in the defined orientation and/or position, and in a unlocking orientation and/or position (unlocked state shown in Fig. 3), in which the locking element 12.1 does not exert, due to the coupling, a locking force on the attachment element 11.1 such that the attachment element 11.1 is not locked in the defined orientation and/or position.

As is apparent from further above, the build platform device 5 can further comprise the build platform alignment assembly 13 configured to align the orientation and/or position of the build platform 5.1 and/or the attachment structure 11 to which the build platform 5.1 is attached in a defined orientation and/or position relative to the build plane of the apparatus 1 , i.e. particularly relative to a bottom plane of the vat device 3. Hence, the build platform device 5 can comprise a separate provision for aligning the build platform 5.1 and/or the attachment structure 11 to which the build platform 5.1 is attached in a defined orientation and/or position relative to the build plane of the apparatus 1 and thus, relative to a bottom plane of the vat device 3 which facilitates generating and maintaining highly precise alignment of the build platform 5.1 and/or the attachment structure 11 in a desired orientation and/or position.

As is apparent from Fig. 1 - 3, the build platform alignment assembly 13 can be attached to the bridge-like carrier element 10. Particularly, an upper alignment plate 13.1 of the build platform alignment assembly 13 can be firmly attached to the bridge-like carrier element 10 such that it cannot be moved relative to the bridge-like carrier element 10.

As is apparent from Fig. 4 - 6 which show the build platform alignment assembly 13 in isolated manner, the build platform alignment assembly 13 can comprise an upper alignment plate 13.1 and a lower alignment plate 13.2. The build platform alignment assembly 13 can thus, generally comprise two alignment plates 13.1 , 13.2 in a vertically stacked arrangement. The lower alignment plate 13.2 is moveably supported relative to the upper alignment plate 13.2 in one or more degrees of freedom of motion, particularly in at least two degrees of freedom of motion. Particularly, the lower alignment plate 13.2 can be rotated (pivoted or tilted) about an x-axis and a y-axis and translated along the z-axis (which also defines the build direction). As such, the lower alignment plate 13.2 can be pivoted or tilted relative to a build plane of the apparatus 1 about the x- and/or y-axis. Further, the z-distance of the lower alignment plate 13.2 relative to the build plane of the apparatus 1 can be adjusted by respective vertical motions of the (pivoted or tilted) lower alignment plate 13.2. As such, the build surface 5.2 of the build platform 5.1 can essentially be adjusted to any build plane configuration to provide planarity. Specifically, possible deviations of a build plane, e.g. a membrane 4 or membrane supporting structure, such as a glass element, with respect to a nominal and/or reference state can be compensated for because the build platform alignment assembly 13 can still assure a desired alignment of the build platform 5.1 due to adapting the orientation and/or position of the build platform 5.1 to the build plane of the apparatus 1 by moving the lower alignment plate 13.1 in the at least one degree of freedom of motion. As indicated further above, the upper alignment plate 13.1 is typically not moveably supported but firmly attached to the bridge-like carrier element 10. It is apparent from the Fig. that the lower alignment plate 13.2 is typically, provided with a connection interface 13.3 for connecting the build platform 5.1 or the respective attachment structure 11 for the build platform 5.1 therewith. The Fig. indicate that a respective connection interface 13.3 can be a mechanical interface enabling a mechanical connection of the build platform 5.1 or the attachment structure 11 to the lower alignment plate 13.2 via clamping (as specified above).

Fig. 4 - 6 further show that the lower alignment plate 13.2 is suspended with the upper alignment plate 13.1 via one or more floating suspension devices 13.4. Each floating suspension device 13.4 is configured to provide the lower alignment plate 13.2 with at least one degree of freedom of motion. Typically, each floating suspension device 13.4 is configured to provide the lower alignment plate 13.2 with at least two degrees of freedom of motion. Particularly, each floating suspension device 13.4 can be configured to provide the lower alignment plate 13.2 with one or more pivoting and/or tilting degrees of freedom of motion relative to the upper alignment plate

13.1 and the membrane 4, respectively.

As is apparent from Fig. 7, each respective floating suspension device 13.4 can comprise two floating suspension elements 13.4.1 , 13.4.2, wherein a first or lower floating suspension element

13.4.1 is firmly attached to the lower alignment plate 13.2 and a second (upper) floating suspension element 13.4.2 is moveably supported relative to the first floating suspension element 13.4.1. The second floating suspension element 13.4.2 faces the upper alignment plate 13.1. Hence, the respective second floating suspension element 13.4.2 can be transferred into a specific orientation and/or position relative to the upper alignment plate 13.1 independent from the first floating suspension element 13.4.1 and particularly, without the requirement of changing a given orientation and/or position of the lower alignment plate 13.2, which might be adapted to the build plane of the apparatus 1 in orientation and/or position to provide planarity with the membrane 4, for instance.

Fig. 7 shows that a respective floating suspension device 13.4 can be built as or comprise at least one levelling washer assembly, particularly at least one spherical levelling washer assembly, which comprises a first ring-like washer element forming a first floating suspension element 13.4.1 and a second ring-like washer element forming a second floating suspension element 13.4.2. The first washer element comprises a receiving portion for receiving the second washer element which is moveably supported relative to the first washer element. Fig. 7 also shows that both the receiving portion of the first washer element and the second washer element can at least partly have a spherical shape which enables moving, e.g. by pivoting or tilting, the second washer element relative to the first washer element. Levelling washer assemblies thus enable that a respective second floating suspension element 13.4.2 can be moved, e.g. by pivoting or tilting relative to the first floating suspension element 13.4.1 , into a specific orientation and/or position e.g. relative to the upper alignment plate 13.1 independent from a respective first floating suspension element 13.4.1 of a floating suspension device 13.4.

Fig. 4 - 6 further shows that the build platform alignment assembly can comprise one or more fastening elements 13.5, 13.6 configured to fasten the lower alignment plate 13.2 in a specific orientation and/or position relative to the upper alignment plate 13.1. Particularly, the build platform alignment assembly 13 can comprise one or more first fastening elements 13.5, for fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the x- axis and/or the y-axis and one or more second fastening elements 13.6 for fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the z-axis. Respective first and second fastening elements 13.5, 13.6 are typically supported by the upper alignment plate 13.1 which can comprise receiving portions, such as receiving bores, holes, etc. for one or more first and/or second fastening elements 13.5, 13.6.

Each respective first fastening element 13.5 can be transferred in a fastening state (shown in Fig. 5 and Fig. 6), in which it enables fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the x-axis and/or the y-axis, and a non-fastening state (shown in Fig. 4), in which it does not enable fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the x-axis and/or the y-axis. Transferring a respective first fastening element 13.5 in its fastening state and/or non-fastening state can comprise a motion of the first fastening element 13.5 in at least one degree of freedom of motion, e.g. in a translational motion about a motion axis as indicated by arrow P2 in Fig. 5. As further indicated in Fig. 5, a respective motion axis can be an axis parallel to the build direction (build- or z-axis), for instance. Fig. 5 also shows that a respective motion for transferring a respective first fastening element 13.5 in its fastening state and/or non-fastening state can comprise a motion of the first fastening element 13.5 relative to the upper and/or lower alignment plate 13.1 , 13.2.

Likewise, each respective second fastening element 13.6 can be transferred in a fastening state (shown in Fig. 6), in which it enables fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the z-axis, and in a non-fastening state (shown in Fig. 4 and Fig. 5), in which it does not enable fastening the orientation and/or position of the lower alignment plate 13.2 with respect to the z-axis. Transferring a respective second fastening element 13.6 in its fastening state and/or non-fastening state can comprise a motion of the second fastening element 13.6 in at least one degree of freedom of motion, e.g. in a translational motion about a motion axis as indicated by arrow P3 in Fig. 6. A respective motion axis can be an axis parallel to the build direction (build- or z-axis), for instance. A respective motion for transferring a respective second fastening element 13.6 in its fastening state and/or non-fastening state can comprise a motion of the second fastening element 13.6 relative to the upper and/or lower alignment plate 13.1 , 13.2. As an example, the one or more first and/or second fastening elements 13.5, 13.6 can be built as or compromise at least one of a fastening bolt, a fastening knob, or a fastening screw.

Fig. 4 - 6 further show that a respective first fastening element 13.5 can comprise a receiving space, such as e.g. a bore, a hole, a threaded bore, a threaded hole, etc., for receiving a respective second fastening element 13.6. Receiving the second fastening element 13.6 in a respective receiving space can still enable a motion of the second fastening element relative 13.6 to and independent from the first fastening element 13.5. As such, the first and second fastening elements 13.5, 13.6 can be transferred independently from each other in their respective fastening state, e.g. by first transferring a first fastening element 13.5 in its fastening state, e.g. by a respective translational motion, so as to fasten the orientation and/or position of the lower alignment plate 13.2 with respect to the x-axis and/or the y-axis, and then transfer the second fastening element 13.6 in its fastening state, e.g. by a respective translational motion relative to the first fastening element 13.5, so as to so as to fasten the orientation and/or position of the lower alignment plate 13.2 with respect to the z-axis.

Fig. 5 and Fig. 6 show that in the fastening state of a respective first fastening element 13.5, the first fastening element 13.5 can tightly abut against a floating suspension device 13.4, particularly against a second floating suspension element 13.4.2, thereby fastening the floating suspension device 13.4 and further the lower alignment plate 13.2 in its current orientation and/or position with respect to the x-and/or y-axis. A respective first fastening element 13.5 can thus, comprise an abutment surface configured to being abutted against a floating suspension device 13.4, i.e. particularly against a respective freely exposed surface of the floating suspension device 13.4, particularly provided with the second floating suspension element 13.4.2. As shown in Fig. 6, typically at least two first fastening elements 13.5 can tightly abut against respective floating suspension devices 13.4 to fasten the lower alignment plate in its current orientation and/or position.

Fig. 6 shows that in the fastening state of a respective second fastening element 13.6, the second fastening element 13.6 can engage with a floating suspension device 13.4, particularly with a receiving opening of a floating suspension device 13.4, more particularly with a receiving opening provided at least with a second floating suspension element 13.4.2, thereby fastening the floating suspension device 13.4 and further the lower alignment plate 13.2 in its current orientation and/or position with respect to the z-axis. A respective second fastening element 13.6 can thus, comprise an engagement portion configured to engage with a floating suspension device 13.4, i.e. particularly with a respective receiving opening of the floating suspension device 13.4, more particularly a respective receiving opening provided with the second floating suspension element 13.4.2. The engagement portion and the receiving portion can be provided with corresponding threads to build a threaded connection. As shown in Fig. 6, typically at least two second fastening elements 13.6 will engage with at least two floating suspension devices 13.4 to fasten the lower alignment plate element 13.2 in its current orientation and/or position.

As is apparent from Fig. 4 - 6, the floating suspension device13.4 can generally, be configured to fasten a defined orientation and/or position of the lower alignment plate 13.2 relative to the upper alignment plate 13.1 via at least one fixed alignment point, which can be implemented via a respective second fastening element 13.5, and two or more floating alignment points, which can be implemented via respective first fastening elements 13.6. Alternatively, the floating suspension device 13.4 can generally, be configured to fasten a defined orientation and/or position of the lower alignment plate 13.2 relative to the upper alignment plate 13.1 via at least three first and/or second fastening elements 13.5, 13.6.

Fig. 4 - 6 further show that the platform alignment assembly 13 can further comprise one or more connecting elements 13.7, particularly attractive springs, connecting the upper alignment plate

13.1 with the lower alignment plate 13.2. Hence, a mechanical connection of the alignment plates

13.1 , 13.2 can be achieved via respective connecting elements 13.7. In case that the connecting elements 13.7 provide an attractive force attracting the alignment plates 13.1. 13.2 together, the connecting elements 13.7 can also form part of the floating suspension device because they can enable a floating suspension of the lower alignment plate 13.2 relative to the first alignment plate

13.1.

The apparatus 1 enables implementing a method of operating an additive manufacturing apparatus. The method can particularly, be a method of aligning the orientation and/or position of a build platform 5.1 and/or an attachment structure 11 to which the build platform 5.1 is attached via a build platform alignment assembly 13 in a defined orientation and/or position relative to a build plane of the apparatus 1 , particularly relative to a bottom plane of the vat device 3 of the apparatus. The method can particularly comprise the steps of: providing build platform alignment assembly 13 in which the lower alignment plate 13.2 is moveably supported relative to the upper alignment plate 13.1 in at least one degree of freedom of motion; aligning the lower alignment plate 13.2 relative to a reference plane, e.g. the bottom plane of the vat device 3, by transferring the lower alignment plate 13.2 in a defined orientation and/or position in which the build platform

5.1 is parallel to the reference plane to provide planarity; and fastening the defined orientation and/or position of the lower alignment plate 13.2 relative to the upper alignment plate 13.1 via one or more first and second fastening elements 13.5, 13.6. The aligning can comprise moving the build platform 5.1 against the reference plane, particularly against the bottom plane of the vat device 3, such that the build surface of the build plane directly contacts the bottom plane of the vat device 3 to provide planarity.

Although not shown in the Fig., the apparatus 1 could also comprise at least two different irradiation devices 2. In an exemplary configuration of the apparatus 1 with at least two different irradiation devices 2, a first irradiation device 2 can be or comprise a digital light projector device and a second irradiation device 2 can be or comprise a laser device. The at least two different irradiation devices 2 can be configured to emit electromagnetic radiation of (substantially) the same wavelength or of similar wavelength.

The apparatus 1 can generally comprise one or more optical devices (not shown) assigned to the one or more irradiation devices 2. Respective optical devices can be arranged in the optical path between the one or more irradiation devices 2 and the vat device 3. Respective optical devices can comprise at least one of: a beam combining device, a collimating device, an expanding device, a focusing device, a polarizing device, a beam splitting device, etc.

One or more features mentioned in context with a specific embodiment of the apparatus 1 can be combined with one or more features of at least one other embodiment of the apparatus 1.

Claims

CLAI M S

1 . An additive manufacturing apparatus for additively manufacturing a three-dimensional object by curing a photocurable resin, comprising:

- a vat device delimiting a vat volume for receiving a photocurable resin;

- a build platform device comprising a build platform;

- at least one irradiation device configured to emit electromagnetic radiation to selectively and successively cure a photocurable resin provided in the vat volume to additively manufacture a three-dimensional object;

- a support device for moveably supporting the build platform device relative to the vat device in at least one degree of freedom of motion; wherein the support device comprises at least two support structures, wherein the build platform device is moveably supported by the at least two separate support structures in the at least one degree of freedom of motion.

2. The additive manufacturing apparatus of claim 1 , further comprising a bridge-like carrier element connecting the at least two separate support structures, wherein the bridge-like carrier element is moveably supported by the at least two separate support structures in the at least one degree of freedom of motion; wherein the build platform device is attachable or attached to the bridge-like carrier element.

3. The additive manufacturing apparatus of claim 1 or 2, wherein the at least two separate support structures are mounted on a base plate, which is connected to a machine frame of the additive manufacturing apparatus, wherein one or more vibration-dampening elements are provided with the connection between the base plate and the machine frame of the additive manufacturing apparatus.

4. The additive manufacturing apparatus of claim 3, wherein the at least one or more vibrationdampening elements are interposed between the base plate and the machine frame of the apparatus, particularly such that possible vibrations cannot be transferred from the machine frame of the additive manufacturing apparatus into the base plate or vice versa.

5. The additive manufacturing apparatus of any one of the preceding claims, wherein at least one of the at least two separate support structures comprises an attachment interface for attaching at least one functional component of the additive manufacturing apparatus, e.g. a drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device in the at least one degree of freedom of motion, a stop device for stopping a motion of the build platform device beyond an upper and/or lower threshold position, a sensor device for sensing at least one parameter indicative of the motion and/or position of the build platform device.

6. The additive manufacturing apparatus of any one of the preceding claims, wherein at least one of the at least two separate support structures is provided with at least one linear drive device for generating a drive force and/or drive momentum for effecting a motion of the build platform device in the at least one degree of freedom of motion and/or at least one linear guide device for providing a guided motion of the build platform device in the at least one degree of freedom of motion.

7. The additive manufacturing apparatus of any one of the preceding claims, wherein the build platform device comprises an attachment structure for the build platform, the attachment structure comprising at least one attachment element for releasably attaching a build platform thereto.

8. The additive manufacturing apparatus of claim 7, wherein the at least one attachment element comprises a bracket- or yoke-configuration, comprising a bracket- or yoke-like base body having two or more free ends each provided with at least one attachment interface for releasably attaching a build platform thereto.

9. The additive manufacturing apparatus of any one of the preceding claims, further comprising a locking structure for releasably locking the attachment structure to a build platform alignment assembly of the build platform device a defined orientation and/or position.

10. The additive manufacturing apparatus of any one of the preceding claims, wherein the locking structure comprises at least one locking element being moveably supported in a locking orientation and/or position, in which a locking force is exerted on the attachment structure which locks the attachment structure in the defined orientation and/or position, and in a unlocking orientation and/or position, in which no locking force is exerted on the attachment structure which locks the attachment structure in the defined orientation and/or position.

11. The additive manufacturing apparatus of claim 10, wherein the locking structure is configured for clamping the attachment structure against at least one alignment plate of the build platform alignment assembly, particularly in the locking orientation and/or position, the locking element is configured for exerting a clamping force on the attachment structure which clamps the attachment structure against at least one alignment plate of the build platform alignment assembly.

12. The additive manufacturing apparatus of any one of the preceding claims, further comprising a build platform alignment assembly configured to align the orientation and/or position of the build platform and/or an attachment structure to which the build platform is attached in a defined orientation and/or position relative to a build plane of the apparatus, particularly relative to a bottom plane of the vat device.

13. The additive manufacturing apparatus of claim 12, wherein the build platform alignment assembly comprises an upper and a lower alignment plate, wherein the lower alignment plate is moveably supported relative to the upper alignment plate in one or more degrees, particularly at least two, of freedom of motion, particularly in at least one degree of freedom of motion parallel to a bottom plane of the vat device and in at least one degree of freedom of motion perpendicular to the bottom plane of the vat device

14. The additive manufacturing apparatus of claim 13, wherein the lower alignment plate is suspended with the upper alignment plate via one or more floating suspension devices comprising two floating suspension elements, wherein a first floating suspension element is firmly attached to the lower alignment plate and a second floating suspension element is moveably supported relative to the first floating suspension element, wherein the second floating suspension element faces the upper alignment plate.

15. The additive manufacturing apparatus of claim 14, wherein the floating suspension device is built as or comprises at least one levelling washer, particularly at least one spherical levelling washer.

16. The additive manufacturing apparatus of any one of claims 12 - 15, wherein the build platform alignment assembly comprises one or more fastening elements configured to fasten the lower alignment plate in a specific orientation and/or position to the upper alignment plate.

17. The additive manufacturing apparatus of claim 16, wherein the one or more fastening elements are built as fastening bolts or screws configured to penetrate into a receiving space of a respective floating suspension device so as to fix a defined orientation and/or position of the lower alignment plate relative to the upper alignment plate.

18. The additive manufacturing apparatus of any one of claims 12 - 17, wherein the floating suspension device is configured to fasten a defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via at least one fixed alignment point and two or more floating alignment points, or wherein the floating suspension device is configured to fasten a defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via at least three fastening elements.

19. The additive manufacturing apparatus of any one of claims 12 - 18, wherein the build platform alignment assembly comprises one or more connecting elements, particularly attractive springs, connecting the upper alignment plate with the lower alignment plate.

20. The additive manufacturing apparatus of any one of claims 12 - 19 and claim 2, wherein the build platform alignment assembly is attached to the bridge-like carrier element.

21. A method of aligning the orientation and/or position of a build platform and/or an attachment structure to which the build platform is attached via a build platform alignment assembly of an additive manufacturing apparatus according to any one of the preceding claims in a defined orientation and/or position relative to a build plane of the apparatus, particularly relative to a bottom plane of the vat device, the method comprising:

- providing build platform alignment assembly in which the lower alignment plate is moveably supported relative to the upper alignment plate in at least one degree of freedom of motion;

- aligning the lower alignment plate relative to a reference plane, e.g. the bottom plane of the vat device, by transferring the lower alignment plate in a defined orientation and/or position in which the build platform is parallel to the reference plane,

- fastening the defined orientation and/or position of the lower alignment plate relative to the upper alignment plate via one or more fastening elements.