Post Processing Arrangement For Shaped Bodies Manufactured Additively By Photopolymerization

Abstract

The present invention relates to a post processing arrangement for shaped bodies additively manufactured by photopolymerization, which arrangement includes a cleaning station holding ready a cleaning basin, and a finishing station for post-exposure of the shaped bodies, wherein the cleaning station (22) and the finishing station (42) are accommodated in a housing (2) in which in a lower section (20) the cleaning station (22) is located and vertically on top of it in an upper section (40) the finishing station (42) is accommodated, wherein the sections (20, 40) are in communication through a passage.

Claims

1. A post processing arrangement for shaped bodies manufactured additively by photopolymerization comprising a cleaning station for holding ready a cleaning basin for the shaped body, and a finishing station for post-exposure of the shaped body, wherein the cleaning station (22) and the finishing station (42) are housed in a housing (2) capable of standing on a horizontal stand surface, in which housing the cleaning station (22) is housed in a lower section (20) and the finishing station (42) is housed in an upper section (40) lying vertically on top of the lower section, wherein the lower and upper sections (20, 40) are connected to each other by a passage, wherein a holder (48) is mounted in the finishing station (42), on which holder the shaped body (1) can be suspended directly or indirectly, wherein the cleaning basin (26) is carried by a lifting apparatus (46), wherein a control unit (4) is arranged to control the operation of the lifting apparatus and the cleaning and finishing stations (22, 42) in such a manner that after positioning the shaped body on the holder (48) the lifting apparatus (46) lifts the cleaning basin (26) to a cleaning position in order to clean the shaped body (1) with cleaning liquid in the cleaning basin, and, after completion of the cleaning process, moves the cleaning basin (26) by the lifting apparatus (46) downwardly to a holding position in the cleaning station, and controls operation of the finishing station (42) thereafter for post-exposure.

2. The post processing arrangement according to claim 1, wherein the passage is either (i) provided with a closure (24) adapted to be opened and closed by the control unit controlling an actuator, wherein the control unit is arranged to open the closure (24) before the cleaning basin (26) is lifted by the lifting apparatus and passes the passage, and to close the closure (24) after the cleaning basin (26) is moved by the lifting apparatus (46) downwardly into the cleaning station after completion of the cleaning process, or (ii) is provided with a closure which is passively opened by the cleaning basin (26) when the cleaning basis is lifted up, and which is passively closed after lowering the cleaning basin (26) again.

3. The post processing arrangement according to claim 1, wherein the holder (48) is mounted to be rotatable about a vertical axis, and wherein a motor is provided which drives the holder (48) in order to set the holder with the shaped body suspended thereon in rotation in order to clean the shaped body by centrifuging off still adhering photopolymerizable liquid therefrom.

4. The post processing arrangement according to claim 1, wherein the cleaning station (22) is provided with a feeding device (30, 32) which is connected to at least one container (28) holding cleaning liquid, wherein the feeding device is connected by a flexible conduit (33) to the cleaning basin (26), wherein the flexible conduit (33) has a length that is sufficient in order to extend from the feeding device to the cleaning basin (26) in the cleaning position, wherein the control unit (4) is arranged to control the feeding device such that the cleaning basin (26), while being lifted up by the lifting apparatus (46) to the cleaning position and/or after having been lifted up by the lifting apparatus (46) to the cleaning position, is filled with cleaning liquid, and wherein the control unit is configured to control the operation of the cleaning station during the cleaning process.

5. The post processing arrangement according to claim 3, wherein the control unit (4) is furthermore arranged to activate the motor connected to the holder (48) while the cleaning process is carried out and to set the shaped body (1) in rotation in the cleaning liquid in order to intensify the cleaning effect.

6. The post processing arrangement according to claim 4, wherein the cleaning station (22) is connected to at least two containers (28) holding cleaning liquids, and wherein the feeding device is provided with a pump (30) and valves (32) which under control of the control unit selectively feed cleaning liquid from a selected one of the at least two containers (28) into the cleaning basin (26) and pump the cleaning liquid out of the cleaning basin (26) again after completion of the cleaning process.

7. The post processing arrangement according to claim 1, wherein the finishing station (42) is provided with at least two light sources for post-exposure with different wavelengths, wherein the different wavelengths are within the range from 300 nm to 500 nm.

8. The post processing arrangement according to claim 1, wherein the control unit (4) is connected to an input apparatus for receiving information about properties of the shaped body to be finished and is provided with a memory in which operating programs for the cleaning station (20) and the finishing station (42) and an allocation specification are stored which allocates operating programs according to the information on the properties of the shaped body, and wherein the control unit is arranged to retrieve the allocated operating programs after the information about the properties of the shaped body has been received and to control the cleaning station (22) and the finishing station (42) by execution of the retrieved operating programs.

9. The post processing arrangement according to claim 8, wherein the input device is a manual input device for manual input of information about properties of the shaped body by a user.

10. The post processing arrangement according to claim 8, wherein the input device comprises an automatic reading device which is designed to read a data storage medium including information on the properties of the shaped body, which data storage medium is connected to or assigned to the shaped body.

11. The post processing arrangement according to claim 1, wherein the holder (48) for suspending the shaped body (1) is configured such that the shaped body (1) is held hanging thereon such that that the shaped body is freely accessible at least from an entire lower hemisphere for the radiation of the finishing station and the cleaning liquid of the cleaning basin (26) during the cleaning process.

12. The post processing arrangement according to claim 11, wherein the holder (48) is configured such that a construction platform (6) with one or more shaped bodies (1) adhering thereto can be suspended on the holder or inserted in the holder, wherein the shaped body or the shaped bodies (1) are hanging thereon in a downwardly hanging orientation.

13. The post processing arrangement according to claim 1, wherein the upper section (40) of the housing in which the finishing station (42) is accommodated, comprises, in an outer wall, a flap (44) which is configured to be opened and which, when opened, allows access to the interior of the finishing station to suspend a shaped body (1) to be post-processed on the holder (48), and to allow for removal of a finished shaped body therefrom.

14. The post processing arrangement according to claim 1, wherein the upper section (40) and the lower section (20) of the housing are detachably connected to each other.

15. The post processing arrangement according to claim 1, wherein the upper section (40) has in a bottom wall an opening, and wherein the lower section (20) has an opening in a top wall which is aligned with the opening of the bottom wall of the upper section, wherein the openings together form the passage, and wherein the closure (24) for selectively opening and closing the passage is arranged at the opening in the bottom wall of the upper section (40) or at the opening in the top wall of the lower section (20).

16. The post processing arrangement according to claim 14, wherein the control unit (4) is housed in a detachable third section (60) of the housing, wherein the lower section (20) and the third section of the housing are designed such that the third section (60) is configured for attachment to the lower section (20) underneath the lower section, and wherein there is an electrical connection between the control unit (4) in the third section (60) and the lower and upper sections (20, 40).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention is described below with reference to exemplary embodiments in the drawings in which:

[0029] FIGS. 1 and 2 show schematic cross-sectional views of a finishing station for the post processing arrangement shown in FIG. 3,

[0030] FIG. 3 shows a schematic cross-sectional view of an embodiment of the post processing arrangement,

[0031] FIG. 4 shows a cross-sectional view of the post processing arrangement of FIG. 3, wherein parts that can be detached from each other have been detached from each other,

[0032] FIGS. 5a to 5c show cross-sectional views of the post processing arrangement in three subsequent states in the course of a post processing procedure, and

[0033] FIGS. 6a to 6c show schematic cross-sectional views of three further states of the post processing procedure following the states of FIGS. 5a to 5c.

DETAILED DESCRIPTION

[0034] In FIGS. 1 and 2, a finishing station 42 is first shown which is shown detached from a cleaning station of a post processing arrangement in order to illustrate the design and function of the finishing station. The finishing station 42 has a cylindrical upper housing section 40 in which close to its upper and lower ends circumferentially extending reflectors 50 are attached which reflect light from light sources (not shown) which are disposed circumferentially distributed, into a central exposure area. Due to the shape of the reflectors 52, the light reflected is distributed over a wide range along a central axis and distributed about the central axis over a larger area. The light beams which are reflected by the reflectors 52 are shown in FIG. 2 by a group of arrows. Several types of light sources with different maximum emissions can be disposed circumferentially distributed such that exposures with desired wavelengths can be carried out.

[0035] On the left hand side in FIG. 1 shaped bodies 1, here in the form of dental prosthesis bases, are represented schematically, which shaped bodies after manufacture by stereolithography are still hanging on a construction platform 6. The construction platform 6 has been removed after termination of the building process from a stereolithography 3D printer. The construction platform 6 is, with the shaped bodies 1 hanging thereon, moved through an opening in the outer wall of the upper section 40 of the housing, provided with a flap 44, into the interior of the finishing station 42, as schematically indicated by the arrow in FIG. 1, and in the interior is suspended on a holder 48. The holder 48 may for example comprise a plurality of bars projecting into the interior of the finishing station, which bars have, at their ends in the interior space of the finishing station, angled, horizontal end sections which can engage the lower surface of the construction platform 6 such that the construction platform rests on these horizontal end sections.

[0036] The bars of the holder 48 may be elastic to allow construction platforms over a certain size range to be suspended in such holder 48.

[0037] Once the shaped body 1 is suspended with the construction platform 6 on the holder 48, in principle the exposure of the shaped bodies 1 for their finishing, shown in FIG. 2, cold be carried out. In a post processing arrangement according to the invention first a cleaning process is conducted after the finishing station 42 is supplied with the construction platform 6 including shaped bodies 1, which cleaning process is described further below.

[0038] The finishing station 42 is provided with schematically represented fans 50 which dry the shaped bodies, after the cleaning, by a generated airflow and which cool the finishing station 42 during the post-exposure. In addition, the fans 50 guarantee that solvent vapours are discharged from the finishing station in order to prevent a possible ignition during the post-exposure.

[0039] FIGS. 1 and 2 show the upper housing section 40 placed on a third housing section 60 in which a control unit 4 for controlling the different components of the post processing arrangement is housed. In this configuration the finishing station 42 can also be operated separately. In FIG. 4, the electrical connection is indicated by a dashed line 66 within the cleaning station 22, which conducting line indicates the connection of the finishing station to the control unit 4 when all housing sections are arranged on top of each other and are connected to each other.

[0040] In FIG. 3 the post processing arrangement having a housing 2 in the assembled state is shown in a schematic cross-sectional view.

[0041] The cleaning station 22 is disposed in the lower section 20 of the housing 2. The upper wall of the lower housing section 20 is provided with an opening having a closure 24 which is shown in the opened state in FIG. 3. The closure 24 can be operated by a schematically indicated motor M which is controlled by control unit 4 to open or close closure 24. Alternatively the closure can be passively opened by lifting up the cleaning basin to push open the closure. In the bottom wall of the upper section 40 of the housing 2 there is an opening which is aligned to the opening with the closure 24 such that after opening of the closure 24 a passage from the interior space of the lower section 20 into the interior space of the upper section 40 is open.

[0042] In the cleaning station 22 in the lower housing section 20 there is a cleaning basin or vat 26 open at the top, wherein the cleaning basin 26 is disposed in the cleaning station 22 if the cleaning basin 26 is in the holding position. The cleaning station 22 furthermore comprises a pump 30 and a series of valves 32 connected to the pump. External containers 28 including cleaning liquids are connected to the valves 32. The pump 30 is connected to the cleaning basin 26 by a schematically indicated conduit 33.

[0043] The cleaning basin 26 is furthermore provided with a magnetic stirrer 25 which, when the cleaning basin 26 is filled with cleaning liquid, sets the cleaning liquid in motion in order to intensify the cleaning process. Alternatively or in addition to the magnetic stirrer an ultrasonic actuator may be provided at the lower surface of the cleaning basin bottom or on the sidewalls of the cleaning basin.

[0044] The cleaning station 22 is further provided with a lifting apparatus 46 which in FIGS. 5a to 5c and 6a to 6b is illustrated by a schematically indicated motor and by a spindle. The lifting apparatus 46 may be implemented with a spindle drive. Alternatively, a toothed rack may be mounted on an inner wall of the lower housing section 20 which is engaged by a motor driven gear wheel, wherein the motor also carries the cleaning basin 26, which is capable of moving the cleaning basin 26 from the holding position in the lower section 20 of the housing vertically upwards into the finishing station 42 into the cleaning position and subsequently lowering the cleaning basin again into the holding position in the cleaning station 22. In the cleaning position the shaped body suspended on the holder 48 is surrounded by the cleaning basin, i.e. the upper edge of the sidewalls of the cleaning basin 26 is located vertically above the shaped body 1 so that after filling the cleaning basin 26 with cleaning liquid the shaped bodies 1 are completely immersed in cleaning liquid.

[0045] In principle also telescopic rods having a plurality of intertwined telescope elements can be utilized for the lifting apparatus, which telescopic rods carry the cleaning basin 26 and which are adjustable in terms of their lengths to be able to lift the cleaning basin 26 from the holding position in the cleaning station 22 up into the cleaning position in the finishing station 42 and to lower it down again. Alternatively scissor lift mechanisms may be used for this purpose.

[0046] In FIG. 4 the modular design of the housing of the post processing arrangement is illustrated: The upper section 40, the lower section 20 and the third section 60 are shown here detached from each other. The sections can be connected to each other by plug-in connecting structures which are not shown in further detail here. At the third section 60 a contact 62 is schematically indicated which comes into conducting contact with a contact 64 at the lower section 20 when the third section 60 and the lower section 20 are connected to each other. In fact the contacts 62, 64 may include several separate contacts so that besides an energy supply connection also one or more parallel data transfer line or a data bus can be connected. The dashed line 66 indicates connecting cables which lead from the contact 64 through the lower section to a contact at the upper end of the lower section 20 which in turn is in conducting connection with a contact at the lower end of the upper section. In this manner the lower and upper sections 20, 40 can be supplied with electric energy and can exchange data with the control unit 4 when the control unit controls the operation of the cleaning station and of the finishing station as will be described in the following example.

[0047] Now an exemplary embodiment will be described as to how the control unit 4 may control the various components for carrying out the finishing process, wherein first reference is made to FIGS. 5a to 5c. In FIG. 5a the flap 44 at the top of the finishing station 42 is opened. A construction platform 6 with shaped bodies 1 hanging thereon is lowered from above through the opening of the flap 44 into the finishing station 42 and is lowered into the interior space until outer edge regions of the construction platform 6 rest on the holder 48 such that the construction platform 6 is suspended on the holder 48. The beginning of this process is shown in FIG. 5a, and the suspended state of the construction platform 6 with the shaped bodies 1 in the holder 48 is shown in FIG. 5b. In FIGS. 5a and 5b the cleaning basin 26 is shown as already moved by the lifting apparatus 46 into the elevated cleaning position in which the cleaning basin 26 is located in the interior space of the finishing station 42. In this cleaning position of the cleaning basin 26 the cleaning basin 26 surrounds the shaped bodies 1, i.e. the shaped bodies 1 are located below the upper edge of the cleaning basin 26. After insertion of the construction platform 6 into the holder 48 and after closing the flap 44 the cleaning process is started by the control unit 4 controlling the pump 33 and the valves 32 in order to pump a selected cleaning liquid through the conduit 33 into the cleaning basin 26. The cleaning basin 26 is shown in FIG. 5c in the completely filled state.

[0048] The conduit 33 is illustrated in FIGS. 5a to 5c as a flexible conduit, illustrated in a simplified manner by a line with a curved extension; the length of the conduit 33 is sufficient such that the end of the line connected to the cleaning basin 26 may follow the movement of the cleaning basin 26 into the elevated cleaning position in the finishing station 42. The flexible conduit 32 for supplying cleaning liquid can be laid in a helical configuration to be able to extend over a larger length when the cleaning basin 26 is lifted up from the holding position into the cleaning position shown in FIGS. 5a to 5c. In FIGS. 5a to 5c the filling of the cleaning basin 26 with cleaning liquid starts when the cleaning basin 26 is already located in the elevated cleaning position. In principle, also embodiments are possible in which the filling of the cleaning basin 26 by activation of the pump 30 already start at the same time as the lifting process such that the cleaning basin 26 may already be partially or completely filled when it reaches the elevated cleaning position. It is also conceivable that the lifting process for raising the cleaning basin 26 by the lifting apparatus 46 into the elevated cleaning position only starts after the construction platform with the shaped bodies 1 has been inserted into the holder 48.

[0049] After termination of the cleaning step the pump 30 pumps the cleaning liquid out of the cleaning basin 26 again, wherein in most cases the cleaning liquid is then pumped back into the container 28 (see FIGS. 3 and 4) from which it was extracted before and pumped into the cleaning basin. In this manner the cleaning liquid may be used again. The containers may hold cleaning liquids of different types or of different purities such that subsequent cleaning steps with different cleaning liquids can be carried out by successively pumping cleaning liquids out of particular containers 28. For example, first a cause cleaning may be carried out by feeling a first cleaning liquid from a first of the containers 28, and after pumping out the cleaning liquid for the cause cleaning, a cleaning liquid of higher purity is extracted from another of the containers 28 and pumped into the cleaning basin in order to carry out a posed cleaning step.

[0050] FIG. 6a which shows a state after termination of the last cleaning step when the cleaning liquid used in the last step has already been pumped out of the cleaning basin 26 again. Thereafter the control unit 4 controls the operation of the post processing arrangement further by activating the lifting apparatus 46 in order to lower the cleaning basin from the elevated cleaning position in FIG. 6a vertically downwards, wherein in FIG. 6b an intermediate point in time during the lowering process is shown in which the cleaning basin is already lowered part of the way downwards into the cleaning station 22. When the cleaning basin 26 has been completely lowered into the cleaning station 22 in the lower section 20 of the housing, as shown in FIG. 6c, the control unit 4 stops operation of the lifting apparatus 46 and closes the closure 24 such that the interior space of the finishing station 42 now is closed against the interior space of the cleaning station 22. Thereafter, the control unit 4 activates the fans 50, in order to dry the shaped bodies 1 to which cleaning liquid may still adhere.

[0051] Thereafter the control unit may initiate post-exposure as shown in FIG. 6c. For this purpose the control unit 4 executes a selected operating program operating predefined light sources for each case a light source with predefined intensity over an exposure time which is likewise predetermined by the operating program in order to completely polymerize not yet fully cured zones in the shaped body. Finally, after completion of the post-exposure, the flap 44 of the upper housing section 40 may be opened, and the construction platform 6 with the shaped bodies 1 thereon may be lifted up out of the holder 48 and may be removed from the finishing station 42, which terminates the post processing of the shaped body 1.

[0052] After introducing the shaped bodies to be post-processed into the post processing arrangement in FIG. 5a and before removing the shaped bodies 1 therefrom as just described, all post processing steps as described before can be carried out automatically and controlled by the control unit 4 in which a selected stored operating program is executed. The finishing process is in this manner less personnel-intensive, and there are no risks of individual steps being carried out incorrectly or inadequately by the personnel, as the steps run according to predefined programs.

[0053] As an alternative to drying by use of the fans 50, in an embodiment not shown in the Figures the post processing arrangement may comprise a pressurized air source which is controlled by the control unit 4 and which after termination of the cleaning procedure directs pressurized air from the pressurized air source through nozzles in order to blow away still adhering cleaning liquid by means of pressurized air to thereby improve the cleaning and drying process of the shaped bodies. In a preferred embodiment air nozzles can be provided in the form of air valves, i.e. the valve opening is shaped as an elongated valve slit which extends for example in an angular manner around the shaped bodies 1, when these are suspended in the holder 48, in order to direct pressurized air from all directions to the shaped bodies 1 in order to remove residual cleaning liquid in a particularly effective manner and to dry the shaped bodies.

[0054] In a further embodiment the holder 48 may be mounted to be rotatable about a vertical axis of the finishing station, and a motor may be provided which is capable of setting holder with the shaped bodies suspended thereon in rotation in order to spin off residual, adhering cleaning agent, instead of blowing it off. In such an embodiment the shaped bodies may, for example in the stage shown in FIG. 5b before beginning of the cleaning process, set into fast rotation in order to centrifuged or spin off still adhering, unpolymerized building material from the building process before the further cleaning with cleaning liquids is carried out.

[0055] The rotation of the holder about a vertical axis can also be used in the stage shown in FIG. 5c in order to rotate the shaped bodies in the cleaning liquid in the cleaning basin 26 to thereby intensify the cleaning effect by relative motion of the cleaning liquid with respect to the shaped bodies, wherein such rotation in the cleaning liquid is to be carried out with lower rotational frequency as a possible rotation of the shaped body for spinning off of adhering liquid.

[0056] The manner of the cleaning to be carried out and the manner of the post-exposure to be carried out generally depend on properties of the shaped bodies to be finished. For example, the selection of both of the wavelengths and the intensities of the post-exposure to be carried out depends on the size, the shape and the type of material of the shaped body and the type of photopolymer which was used to produce the shaped body. The cleaning steps to be performed likewise depend on properties of the shaped body to be finished in the specific case. For these reasons the post processing arrangement is advantageously connected to an input device for receiving information about the properties of the shaped body to be finished. The input device can be part of the post processing arrangement and can be connected to the control unit and/or computer. Furthermore, the control unit is provided with a number of stored operating programs for the cleaning station and the finishing station as well as with an assignment or allocation specification which links information on the properties of the shaped bodies to particular operating programs suitable for the properties of the shaped bodies according to the information. The information received by the input device regarding the properties of the shaped body can be used by the control unit in order to retrieve, using the allocation specification, one or more suitable operating programs, and to execute these programs in the desired manner, wherein the operation of the post processing arrangement is carried out in accordance with this or these operating programs in a completely automatic manner, without need for intervention by personnel.

[0057] The input device for the information about the properties of the shaped body can be a manual input device for manual input of information about properties of the shaped body by a user, for example a keyboard or a touch-screen. Alternatively, an automatic reading device can act as the input device, which reading device is set up to read a data storage medium connected to the shaped body or assigned to it and including the information on the properties of the shaped body. For example, a data storage medium in the form of a barcode or a data matrix code can be attached to the upper side of the construction platform 6 facing away from the shaped bodies 1 or can be part of the shaped body and can contain information about the manufactured shaped bodies 1 suspended thereon. This storage medium can be read out by a code reader as an input device, in order to transmit this information regarding the shaped bodies 1 to control unit 4 which then uses a stored allocation or assignment specification to allocate one or more operating programs in accordance with the received information for controlling the post processing arrangement by execution of this/these operating programs. The entire processing process can be carried out in this manner in a completely automatic manner in a compact post processing arrangement, without any need for an operator to intervene, except for the introduction of shaped bodies and their removal after the post processing. Furthermore, there is no risk for any operating personnel to come into contact with cleaning liquids or the like.

[0058] In some embodiments, the control unit can be a processor such as a single processor having one or more cores, or a plurality of processors connected by a bus, network, or other data link. The electronic data storage unit can be any form of non-transitory computer-readable storage medium suitable for storing the data produced by the system.

[0059] In some embodiments, the processor is in communication over a network, which could be wired or wireless, with an external processor used for performing one or more calculation steps and/or a network-attached electronic data storage unit. In some embodiments, the present disclosure makes use of cloud computing to perform one or more calculations steps remotely and/or remote storage to enable the storage of data remotely for collaborative or remote analysis.

[0060] In some embodiments, a computer may be utilized as the control unit or processor and can include any computational device that performs logical and arithmetic operations. For example, in some cases, a computer comprises an electronic computational device, such as an integrated circuit, a microprocessor, a mobile computing device, a laptop computer, a tablet computer, a personal computer, or a mainframe computer. In some cases, a computer comprises: (a) a central processing unit, (b) an ALU (arithmetic logic unit), (c) a memory unit, and (d) a control unit that controls actions of other components of the computer so that encoded steps of a program are executed in a sequence. In some cases, a computer also includes peripheral units including an auxiliary memory storage device (e.g., a disk drive or flash memory), or includes signal processing circuitry.

[0061] Although the invention is illustrated above, partly with reference to some preferred embodiments, it must be understood that numerous modifications and combinations of different features of the embodiments can be made. All of these modifications lie within the scope of the appended claims.