AU2021209192A1

AU2021209192A1 - A Processing Machine for an Additive Manufacturing Build Assembly

Info

Publication number: AU2021209192A1
Application number: AU2021209192A
Authority: AU
Inventors: Peter Farrer; Benjamin Kyle Wilson
Original assignee: Ampro Innovations Pty Ltd
Current assignee: Ampro Innovations Pty Ltd
Priority date: 2020-07-27
Filing date: 2021-07-27
Publication date: 2022-02-10
Also published as: WO2022020883A1

Abstract

A glove box machine suitable for recovery of unfused powder from a build assembly removed from a build chamber of an SLM installation, after completion of a build cycle for the production of at least one component by a selective laser melting (SLM) process, has a housing having a volume sufficient to accommodate a build assembly up to designed maximum dimensions. The volume is defined by at least two parts of the housing with a support device is adjustably mounted in relation to one housing part. The housing parts are relatively movable between a first, open position enabling a build assembly to be received within the volume and secured by a build plate of the assembly on the support device and a second, closed position in which the housing parts enclose a build assembly when secured on the support device. At least one housing part has at least two access ports each comprising a glove port with a fitted respective glove whereby the hands of an operator can be inserted to perform within the housing tasks required for recovery of the unfused powder. The support device is movable to enable adjustment of the orientation of the build assembly to facilitate powder recovery from the build assembly. 766 787 3--88 89 FIG 1

Description

787

3--88 89

FIG 1

A Processing Machine for an Additive Manufacturing Build Assembly

Field of the Invention

001. The present invention relates to a glove box machine for use in processing an additive manufacturing build assembly, comprising a build plate and at least one attached build component, for the recovery of unfused powder contained in the assembly after completion of a build cycle by a selective laser melting (SLM) process in an SLM installation.

Background to the Invention

002. The production of at least one build component by an SLM process involves the spreading of successive thin layers of powder in a process chamber of an SLM installation, over a build plane above a build plate initially at the base of the process chamber. Each layer of powder is scanned by a laser and thereby subjected to selective melting to form, in the build plane, a respective slice of at least one required component, before spreading of the next layer of powder. The first slice bonds to the build plate or a support structure, while subsequent slices bond to a preceding slice, to progressively build up a complete component, or a plurality of complete components. After each slice is formed, the build plate is lowered away from the process chamber into a build chamber of the SLM installation, to offset the increased height of material building up on the build plate and to maintain a constant build plane at which the laser scans and selectively melts the powder of each successive layer. Thus, the completed build creating the at least one component is contained within the build chamber, along with unfused powder of the successive layers that was not subjected to selective melting by the laser.

003. The SLM process is conducted under an inert or protective atmosphere maintained in both the process and build chambers. The considerable temperatures generated during each SLM cycle of operation to produce components necessitates maintenance of the protective atmosphere after completion of the build, until the contents of the build chamber cool sufficiently, such as to a temperature below 40 °C. In many arrangements cooling is conducted within the SLM installation, after which the build plate is raised back to or towards the level of the build plane to thereby lift both the build and the unfused powder. The process chamber then is accessed to enable recovery of at least a major part of the unfused powder, usually by means of brushes or a suction line. Subsequently an assembly comprising the build plate with the still attached build, and a residue of the unfused powder, is removed from the SLM installation and transferred to a glove box to enable recovery of the residue of unfused powder. After the assembly is removed from the glove box, the build is separated from the build plate and the build plate then can be prepared and repositioned in the SLM installation for re-use.

004. The assembly of the build plate, the still attached build and the residue of unfused powder requires care in being transferred to the glove box. Also, it can be necessary to vary the orientation of the glove box and the contained assembly to facilitate access by an operator responsible for recovery of the powder, usually by means of a manually manoeuvred hose by which a blow gun device is connected to a source of pressurised gas, such as air or nitrogen, for providing a sufficiently strong gas jet able to be inserted into internal channels, ducts and complex internal architectures for removal of unfused powder. These operations can be difficult enough with an assembly from a many current SLM installations having a build chamber of up to about 250 x 250 x 250 mm, although they are becoming increasingly more difficult as build chambers increase in size up to 1000 x 800 x 500 mm, and progressively higher. This increase in size, of course, leads to an even greater corresponding increase in possible weight and volume of the build plate and attached build, and a consequential increase in handling difficulties. The volume of the build chamber determines the maximum size of a component able to be built, while a doubling of dimensions results in an 8-fold increase in volume and up to about an 8-fold increase in weight. Volume and weight are limiting factors for manoeuvring an assembly to a location suitable for powder recovery but are even further limiting on requirements for adjusting the orientation of the assembly, as required during powder recovery.

005. The present invention is directed to providing a glove box machine suitable for use in additive manufacturing, specifically for use in recovery of unfused powder contained in a build and build plate assembly (herein a build assembly) from SLM installation, after completion of an SLM process build cycle.

Broad Summary of the Invention

006. According to the present invention there is provided a glove box machine suitable for recovery of unfused powder from a build assembly removed from a build chamber of an SLM installation, after completion of a build cycle for producing at least one component by a selective laser melting (SLM) process. The machine has a housing that defines an openable chamber which, when closed, has a volume for accommodating a build assembly up to designed maximum dimensions, with the chamber defined by at least two parts of the housing. The machine also includes a support device adjustably mounted in relation to one housing part. The housing parts are relatively movable between a first, open position enabling a build assembly to be received onto the support device and secured by the build plate of the build assembly on the support device and a second, closed position in which the housing parts enclose a build assembly when secured on the support device. At least one housing part has at least two access ports each comprising a glove (or gauntlet) port with a fitted respective glove (or gauntlet), such as a resistive rubber glove, whereby operators can insert their hands to perform within the housing tasks required for recovery of the unfused powder. The support device is movable to enable adjustment of the orientation of the build assembly to facilitate recovery of unfused powder from the build assembly. While the housing volume can accommodate a build assembly up to designed maximum dimensions, the machine can be made on whatever scale is required to enable the housing to accommodate larger build assemblies produced in progressively larger SLM installations now being proposed.

007. The glove box machine enables a build assembly to be received onto the support device, on being transferred from the SLM installation, while the build assembly still is relatively hot due to the temperature attained in the process chamber. As in the SLM installation, an inert or protective atmosphere needs to be provided in the glove box machine before an operator commences exposing the build by removal of unfused powder. Conventional glove boxes for this purpose usually have a main powder recovery chamber into and from which a build assembly can pass via a smaller antechamber that functions in the manner of an air-lock, through an external door of the antechamber and an inner door enabling or precluding communication between the recovery chamber and the antechamber. An inert or protective atmosphere at a slight over-pressure needs to be maintained in the recovery chamber of the conventional machine while an operator works through gloves to remove unfused powder from a build. The protective atmosphere needs to be present in the antechamber while the inner door is open, and the external door is closed, for the passage of a build assembly between the recovery chamber and the antechamber. With the inner door closed to maintain the atmosphere in the recovery chamber, the passage of a build assembly into or from the antechamber is enabled via the open external door, but with inevitable ingress of oxygen from ambient air into the antechamber. Before the reverse passage of a build assembly from or into the recovery chamber, through the open inner door with the external door closed, gas in the antechamber must be evacuated from the closed antechamber with re-introduction of protective atmosphere, a procedure that typically requires a number of cycles and can be time consuming to ensure a sufficiently low level of oxygen required to avoid contamination of some metal powders. The time required for this is considerably less than would be required in an otherwise conventional love box without provision of an antechamber for evacuating and re-establishing a sufficiently protective atmosphere in the recovery chamber. However, an antechamber provides a severe limitation on the size of a build assembly able to be accommodated to enable an operator working through gloves to remove unfused powder from the build of the assembly.

008. The glove box machine of the invention does not require an antechamber and preferasbly does not include a feature corresponding to an antechamber. Rather, in having a housing of least two parts that are relatively movable between an open position enabling a build assembly to be received and a closed position in which the housing parts enclose a received build assembly when secured on the support device, the machine necessitates a control system enabling evacuation of the closed housing and establishment of a protective atmosphere before an operator commences recovery of unfused powder from the build of the assembly. As a benefit of the glove box machine is the ability to accommodate an assembly that is large relative to the volume of the housing the control system most preferably is efficient in evacuating and establishing a protective atmosphere, while control system may have facility for recovery of at least part of the protective atmosphere prior to opening the housing on completion of unfused powder recovery from a build assembly.

009. The support device may be adjustable mounted in relation to the one housing part, most conveniently a fixed, basal housing part, so the support device is movable by rotation on at least one axis. The support device preferably is movable by rotation on two mutually perpendicular axes, and it also may enable a third degree of linear movement along one axis. The arrangement is such that the support device is movable so that the orientation of a build assembly secured on the support device can be varied to facilitate access for removal of unfused powder, such as inverted to enable at least some of the unfused powder to flow under the influence of gravity from the build assembly.

010. The housing of the glove box machine may be mounted on a fixed base, or it may be mounted on wheels enabling its movement from one station to another, such as to enable use adjacent a selected one of a plurality of SLM installations. In either case, particularly when of a size able to accommodate large build assemblies, the build assembly may be moved from an SLM installation to the glove box machine, such as by use of a forklift vehicle. However, whether fixed or mobile, the machine of the invention may have facility for conducting powder that is recovered from the build assembly, within the housing, to a suitable container that is separable from the machine and in which the powder can be moved, such as for reprocessing required to enable the powder to be re-used. Also, where the build assembly is to be conveyed to the machine by a forklift vehicle, the machine most preferably is configured not only to enable the tines of the vehicle to approach the support device for positioning the assembly on the support device, but also to enable wheel mounted footings of the vehicle to straddle the machine laterally below the housing.

011. In one convenient arrangement, the housing has a fixed lower or basal housing part that is in the form of an upwardly open vessel, of rectangular or other convenient shape in plan view, into which unfused powder released from the build of the assembly can be received under the influence of gravity. With such fixed basal part, the housing may have a downwardly open upper or cover housing part that can be raised and lowered relative to the basal housing part. The cover housing part may be vertically movable relative to the basal housing part by means of a vertically acting extension device, such as a hydraulic or pneumatic device or a rack and pinion device. Alternatively, the cover housing part may be movable relative to the basal part by pivoting, such as on a horizontally extending hinge line along which the cover and basal housing parts are connected together. With either type of movement, the basal housing part may have an upwardly projecting sidewall, such as on which the extension device acts or on an upper edge of which the hinge line extends. Where such a sidewall is provided the support device for the build assembly may be movably mounted on the sidewall.

012. The basal part of the housing may be secured against, or integral with, an upwardly extending sidewall of an upstanding column. The cover part of the housing may be connected to the column by a hinge coupling to the sidewall in a manner enabling the cover part of the housing to be pivoted upwardly from the closed position to the open position. In the closed position, the cover part attains a sealing engagement with the basal part, either to provide a substantially gas- tight seal or a seal enabling maintenance of an over-pressure in the housing that precludes the ingress of external atmosphere. With the cover part in the closed position, the sealing engagement may be provided around contiguous peripheral edges of the cover and basal parts. Alternatively, the sealing engagement may in part be provided by such edges of the cover and basal parts and in part by engagement portion of the peripheral edge of the cover part with the upwardly extending wall of the upstanding column. In one preferred arrangement, a substantially gas-tight seal is provided by an inflatable seal element between and around the opposed peripheries off the cover and basal parts of the housing. Such seal preferably is inflatable and deflatable, as required, by timing determined and actuation initiated by the control system.

013. Particularly where the support device is mounted on an upwardly extending sidewall, such as of an upwardly extending column, the support device may have a mounting section connected to the sidewall so as to be rotatable on an axis projecting from the sidewall, and a support section extending from the mounting section on which a build assembly can be secured. With that arrangement, the support section may have a turntable on which the build plate can be secured, with the turntable section rotatable relative to the support section, such as on an axis substantially perpendicular to the axis projecting from the sidewall. A drive motor for rotating the support device on the axis projecting from the sidewall may be mounted on a rear face, or to the rear of, the sidewall, such as within the column. A drive motor for the turntable may be provided within the support device, such as adjacent a plane in which the turntable is rotatable.

014. Where the glove box machine has an upstanding column on which the support device is mounted, the column may house the control system enabling evacuation of the closed housing and establishment of a protective atmosphere required before an operator commences recovery of unfused powder from the build of the assembly. Primary functioning of the control system relies on the system including a low-pressure, high-flow regulator. An inlet supply to the regulator is controlled via two solenoids enabling a high flow and low flow condition to be met. The regulator can be set to a level, of the order of mbar, that removes the safety concern related to overpressure due to filter blockage when using flowmeters to control the flow into the system. By using the low pressure regulator, the sizing of tubing and of an associated exhaust solenoid valve chosen to ensure that the inlet flowrate could be maximised. An oxygen sensor and a pressure sensor are integrated into the control system to allow closed loop system control and allow pneumatic accessories to be used inside the chamber without causing the gloves to explode outwardly.

015. In the machine of the invention, the control system preferably is adapted to enable recovery of at least part of the protective atmosphere prior to opening the housing on completion of unfused powder recovery from a build assembly. Where the glove box machine has an upstanding column on which the support device is mounted, the column preferably houses the control system for enabling evacuation of the closed housing and establishment of a protective atmosphere. Functioning of the control system preferably is enabled by the system including a low-pressure, high-flow regulator.

016. In the glove box machine of the invention, an inlet supply to the regulator, including a pressurised source of an inert or protective gas suitable for providing a substantially oxygen-free atmosphere in the chamber of the housing, may be controlled via two solenoids enabling a high flow and low flow condition for the gas. The regulator may be set to a level, of the order of mbar, that substantially precludes an overpressure in the event of a due to filter blockage when using flowmeters to control the flow into the system. For using the low- pressure regulator, the sizing of tubing and of an associated exhaust solenoid valve are adapted to ensure that the inlet flowrate can be maximised.

017. The glove box machine of the invention may have an oxygen sensor and a pressure sensor are integrated into the control system to allow closed loop system control and allow pneumatic accessories to be used inside the chamber without causing the gloves to explode outwardly.

018. The control system preferably has gas flow circuit that has a higher-pressure side and a lower-pressure side and provides overall gas flow is from the higher side to the chamber of the housing and from the chamber to the lower-pressure side. The flow may be generated from a cylinder or other suitable source of pressurised inert or protective gas whereby the gas is able to flow through the circuit via an inlet line that communicates with inlet pressure regulator to purge oxygen-containing gas from the chamber of the housing and establish a substantially oxygen-free atmosphere in the chamber. Gas purged from the chamber may discharge through an exhaust butterfly valve and an outlet line.

019. The glove box machine of the invention may include a 'start-cycle' button. With intervention by an operator pressing the 'start-cycle' button, the control system operates to actuate a door interlock to secure the container parts together. At the same time, the control system can operate to actuate an inflatable pneumatic seal for sealing the container via seal pressure regulator, such as at about 3 bar. With the door interlock actuated and the seal inflated, a high-flow solenoid valve of the control system is openable to enable inert or protective gas to enter the housing, such as with about 200 litre per minute of gas entering the chamber at about 5 millibar, with this low pressure set by a regulator of the control system and purging oxygen-containing gas from the housing. While the high-flow solenoid valve and the low-pressure setting regulator are operable to enable the gas flow, a larger flow, electrically actuated exhaust valve opens, while an inlet butterfly valve opens. via actuation of a filter isolation solenoid valve, with a lower flow exhaust valve also actuated by the filter isolation valve and allowing for a constant "maintenance flow" which makes sure the oxygen sensor always reads representative fresh oxygen values in chamber.

Brief Description of the Drawings

020. Figure 1 is a perspective view of a glove box machine according to the invention, viewed from the front and in a closed condition;

021. Figure 2 is a front elevation of the machine of Figure 1;

022. Figure 3 is an end elevation of the machine of Figure 1, as viewed from the left of Figure 2;

023. Figure 4 corresponds to Figure 1, but shows the machine in an open condition in readiness for receiving a build assembly;

024. Figure 5 corresponds to Figure 4, as viewed after initial positioning of a build assembly;

025. Figure 6 corresponds to Figure 1 after closing the machine and a partial change to alter the orientation of the build assembly;

026. Figure 7 corresponds to Figure 6, but after complete inversion of the orientation of the build assembly from that of Figure 6;

027. Figure 8 is a perspective view of the machine of Figure 6, but viewed from the rear and with the build assembly in an orientation intermediate the orientations of Figures 6 and 7;

028. Figure 9 is a rear elevation of the machine of Figure 1, with the build assembly in the orientation shown in Figure 7;

029. Figure 10 corresponds to Figure 5, but prior to rotation and as viewed from the left hand end;

030. Figure 11 shows detail of the machine of Figures 1 to 10 but taken from a different perspective and schematically showing the degrees of freedom for movement of the build assembly;

031. Figure 12 is a front-to-rear sectional view of the machine, taken on line XII XII of Figure 2; and

032. Figure 13 is a schematic diagram illustrating components of a gas flow circuit of the control system.

Detailed Description of the Drawings

033. Figures 1 to 12 show a glove box machine 10 according to the invention. The machine 10 has a housing 12 mounted on a support pedestal 14. The pedestal 14 is of T-shape in plan view and has an end-to-end central section 16 and, at one end of section 16, a front-to-rear section 18. Upstanding from section 18 the housing 12 has a column 20 that forms part of housing 12. The housing 12 has a fixed lower or basal part 22, comprising an upwardly open vessel in the form of a rectangular funnel, and a movable upper or cover part 24. The basal part 22 of housing 12 is supported on section 16 of the pedestal 14 and is connected to a lower section of a sidewall 20a of the upstanding column 20, of above pedestal 14. The upper extent of wall 20a and the cover part 24 of housing 12 together have the form of a downwardly open vessel when the cover part 24 of housing 12 is in the position shown in Figures 1 to 3 and 6 to 12. However, as is evident from Figures 4 and 5, the housing cover part 24 is movable relative to the basal part 22 by pivoting on hinges 23 that have a horizontally extending hinge line X-X (shown in Figures 1) along a horizontally extending top edge of sidewall 20a at the top of column 20. The arrangement is such that the cover part 24 can be pivoted on axis X-X relative to column 20 to move between the open position away from basal part 22 shown in Figures 4 and 5 and the closed position shown in each other of the Figures. Raising cover part 24 to the open position and lowering it to the closed position can be performed manually, such as with the aid of handle 24a, by means of gas struts 27 or the like, or an actuator.

034. As illustrated in each of the Figures 5 to 11, the housing 12 encloses a chamber 13 that defines a volume enabling a build assembly 26 of up to a designed maximum dimensions to be accommodated therein. The build assembly 26 comprises a build plate 28 and a "build" 30. For ease of illustration, the build 30 is depicted as having a somewhat cubic form that corresponds to the envelope of the contents of the build chamber, above plate 28, on completion of a build cycle. However, as will be appreciated, the build 30 can have any required form and typically will have a considerably smaller volume, with the difference in volume corresponding to unfused powder removed from the processing chamber prior to removal of the assembly 26 from an SLM installation (not shown) or after removal of the assembly 26 from the SLM installation and prior to the assembly 26 being positioned in the glove box machine 10. The machine 10 additionally includes a support device 32 on which the build assembly 26, when received within the housing 12, can be secured by engagement between the device 32 and the build plate 28 of the assembly 26. The support device 32 is secured on wall 20, within the part of the volume of housing 12 contained above the basal part 22 and within cover part 24.

035. The support device 32 includes an L-shaped member 34 that has an upright first arm 34a extending substantially parallel to the inner face of wall 20a of column , and a second 25 arm 34b extending in a horizontal direction from that face. The end of arm 34a remote from arm 34b is secured to a horizontally extending drive shaft 36 that projects through sidewall 22a and a disc 37 mounted on column 22 and that is rotatable by means of motor M and intervening gears system G mounted in column 22 (as shown in Figure 12). Thus, the device 32 is mounted for rotation on a horizontally extending axis that is perpendicular to wall 20. Also, the arm 34a of member 34 extends radially across the face of disc 37 remote from wall 20a with arm 34a able to slide longitudinally in a keyway defined in that remote face of disc 37. The device 32 includes a second disc 38 that is mounted on arm 34b of member 34, with the disc 38 rotatable on an axis substantially perpendicular to the axis of shaft 36. The arrangement is such that disc 38 can function as a turntable for rotation of a build assembly 26, when the assembly 26 is secured on device 32 by engagement of the build plate 28 with the disc 38. Thus, the assembly 26 supported on the support device 32 can be rotated on the horizontally extending axis of shaft 36, between the respective orientations shown in Figures 1 and 7, through that in Figure 6, as depicted by arrow A in Figure 11. Also, when in the orientation shown in Figure 1, the build assembly 26 can be raised or lowered by member 34 moving diametrically with respect to disc 36, as depicted by arrow B in Figure 11. Additionally, as depicted by arrow C in Figure 11, the build assembly 26 when in the orientation of Figure 1 can be rotated around an upright axis.

036. Basal part 22 of housing 12 typically is of an opaque material such as sheet metal, while the cover part 24 is transparent and typically of heat shaped glass panels 35 mounted in a rigid frame 35a. With the housing 12 closed, sections of frame 35a that abut edges of basal part 22, and sections that abut sidewall 22a of column 22, are provided with sealant material 39 that substantially seals housing 12 when closed. An operator intending to use the machine 10 would stand or sit in from of the machine as viewed in Figures 1 and 2 and be able to view an assembly on support device 32. The front transparent panel of cover part 24 of housing 12 is provided with a spaced pair of glove ports 40. While not shown for ease of illustration, a respective glove, such as a resistive rubber glove, is fitted to each port 40 to enable an operator standing or seated in front of machine 10 to insert their hands into the gloves, within the housing 12, to perform tasks required for recovery of the unfused powder from the build assembly 26. For this purpose, the machine 10 typically will have flexible conduit or hose extending into the housing from an external source of pressurised gas, such as air or nitrogen, to enable an operator to manually manoeuvre the conduit or hose connected to a source of pressurised gas, such as air or nitrogen, and providing a sufficiently strong gas jet the operator can direct or insert into internal channels, ducts and complex internal architectures for removal of unfused powder. Thus, unfused power can either sucked or blown from the build assembly 26. At least with the build assembly 26 partly or fully inverted, as shown in Figures 6 and 7, unfused powder will tend to fall from the build under gravity, although the extent to which this will occur will depend in part on the configuration of the build 30. However, powder that does fall will combine with any powder blown from the assembly by a gas jet and collected in the basal part 22.

037. The machine 10 may include a foot-controlled pedal (not shown) located, for example, in the forward end of section 18 of pedestal 14. The pedal may be coupled an actuator for motor M for controlling rotation of shaft 36 and, hence, the build assembly 26 secured on device 32. Thus, an operator, while acting to remove and recover unfused powder from the assembly 26 can change the orientation of the assembly 26 as required for observing any remaining powder and action for its removal from the assembly 26. Alternatively, such control may be enabled by means of control knob 43.

038. As is evident from several of the Figures, such as Figure 1, the basal part 22 of housing 12 has a bottom wall 22a that inclines down from wall 20 to the far end of the housing 12, as well as opposed side walls 22b that are inclined downwardly towards each other and to bottom wall 22a. These walls 22a and 22b, along with upright end wall 22c opposed to bottom wall 22a, give basal part 22 of housing 12 its form of a rectangular funnel mentioned above. That form is quite asymmetric and, combined with the usual good flow characteristics of the powder, particularly metal powders, such that powder collecting in basal part 22 will strongly tend to collect adjacent end wall 22c.

039. As can be appreciated from a comparison of Figures 1 and 10, basal part 22 of housing 12 has an outlet port 44, provided with an internal feed control device comprising a slide valve 46 (see Figure 9), or other suitable form of valve, adjustable by an external handle 48. The port 44 is spaced above a seat 16a defined by pedestal 14, at the free end of section 16 remote from section 18. A container (not shown) can be positioned on seat 16a, in engagement with the mouth of outlet port 44. The arrangement enables slide 46 to be adjusted by handle 48 for dispensing a required quantity of powder to container, while the container can be secured in position on seat 16a by retaining bracket (also not shown) engaging with section 16 of pedestal 14.

040. The form of pedestal 14 is such that a special forklift vehicle, with straddle legs that extend in the same direction as tines of the vehicle, is able to approach towards the end of the machine shown in Figure 3, which is from the left as the machine is viewed in Figure 2. Assuming the cover part 24 is in the open position, this enables the end-to-end section 16 of the pedestal 14 to be accommodated between the straddle legs of the vehicle to thereby enable the tines of the vehicle to reach over the basal part 22 of housing 12 to position the build assembly 26 on the support device 32 or to recover assembly 26 from device 32.

041. The upstanding column 22 of the glove box machine 10 houses a control system 50. In addition to motor M and gear system G, the control system 50 enables evacuation of the closed housing 12 and establishment of a protective atmosphere required before an operator commences recovery of unfused powder from the build of the assembly 26. Primary functioning of the control system relies on the system including a low-pressure, high-flow regulator. An inlet supply to the regulator is controlled via two solenoids enabling a high flow and low flow condition to be met. The regulator can be set to a level, of the order of 5 mbar, that removes the safety concern related to overpressure due to filter blockage when using flowmeters to control the flow into the system. By using the low pressure regulator, the sizing of tubing and of an associated exhaust solenoid valve was chosen to ensure that the inlet flowrate could be maximised. An oxygen sensor and a pressure sensor are integrated into the control system to allow closed loop system control and allow pneumatic accessories to be used inside the chamber without causing the gloves to explode outwardly. The system 50, of which several components are shown in the diagram of Figure 13, includes:

- a pneumatic butterfly valve 52;

- a filter assembly 54 with, for example, an HE850 from Solberg International (Australia) Pty Ltd;

- a low pressure regulator 56, such as a Fairchild 11114UNKNEB;

- an oxygen sensor58;

- an exhaust solenoid valve 60, such as a VXZ260KZ2A from SMC Corporation (SMC);

- an inflatable seal pressure regulator 62, such as from SMC;

- an inlet pressure regulator 64, also from SMC;

- an isolator switch 66;

- an electrical box 68;

- a blow gun solenoid valve 70, such as an SMC VT307K-5DZ1-02-F-Q;

- a low-flow hi-flow inlet solenoid valve 72 combination, such as an SMC VX21OHG + AS2002F, VX21OHG;

- a filter isolation solenoid valve 74, such as an SMC VT307K-5DZ1-02-F-Q;

- an inflatable seal solenoid valve 76, such as an SMC VT307K-5DZ1-02-F-Q;

- a pressure sensor 80, with adequate resolution in the 1 to 10 millibar range;

- a pilot valve 82 for oxygen sensor bleed line (to ensure accurate oxygen readings);

- a door interlock 84;

- an indicator lamp 87;

- a 'start-cycle' button 88; and

- an 'end-cycle' button 89.

042. With a build assembly 26 positioned on the support device 32, and secured, the cover part 24 of the housing 12 is lowered onto basal part 22 to enclose the assembly 26 in chamber 13. As explained later herein, the control system 50 then is actuated to lock and seal the housing 12, before operating to achieve a short gas down time in which oxygen-containing air, or mixture of air and inert or other protective gas, is evacuated from the chamber 13 to ensure a sufficiently low content of oxygen in chamber 13 before establishing an inert or protective atmosphere, such as with not more than 5 volume percent oxygen, in which the build assembly can be processed safely for removal of residual unfused powder from the build. The gas down has to be repeated at the start of each cycle of operation for processing a build assembly because the inert of protective atmosphere is almost entirely lost each time the housing is opened. For practical operation, a gas-down time of less than 10 minutes is required, most preferably less than 5 minutes, such as less than 3 minutes, for attaining not more than 5% oxygen in a substantially protective or inert atmosphere within the closed housing 12. A primary contributor enabling such practical gas-down times this is the combination of operation of the low-pressure regulator 56 and the internal diameter of the outlet pipe 56a (see Figures 3 and 10) by which regulator 56 is in communication with the interior of the closed housing 12 through wall 20a of column 20. The position of regulator 56 relative to the chamber 13 of the closed housing 12, and the internal diameter of outlet pipe 56a, are chosen to achieve a required flow rate and pressure. These two parameters preferably are such that the diameter of pipe 56a is maximised and the position of regulator 56 is as close as practicable to thechamber 13. These two design parameters preferably enable a flow rate of about 200 litre per minute with a pressure of about 5 millibar in the closed housing 12, such as to achieve not more than 5% oxygen in housing 12 within 5 minutes.

043. Attainment of a suitable gas-down is communicated to an operator by a visual signal provided by a green indicator lamp of a 'start-cycle' button 87 that, as shown in Figure 12, is adjacent to a door interlock 84 by which housing 12 is secured closed by cover part 24 being locked in relation to lower or base part 22. However, as shown in Figure 2, button 87 is located above an 'end-cycle' button 88 having a red lamp and an 'emergency-stop' button 89. Once permitted by the signal shown by lamp of button 87, the operator's can commence a gas- down cycle by pressing the 'start-cycle' button 87, thereby enabling the system 50 automatically to actuate the various valves of system 50 at pre-determined correct time intervals and order. Similarly, on completion of treatment of removal of unfused powder from a build assembly 26, the operator can open the housing 12 by pressing the 'end-cycle' button 88, enabling the system 50 first to automatically close the various valves and perform the required safety checks prior to releasing the door interlock 84.

044. The arrangement of the gas flow circuit of the control system is such that, as viewed in Figure 13, the left side is a higher-pressure side, and the right side is a lower-pressure side. Overall gas flow is from left side to right side and is generated from a cylinder C, or other suitable source, of pressurised inert or protective gas that is able to flow through the circuit via an inlet line 90 that communicates with inlet pressure regulator 64, while gas passing from the chamber 13 of housing 12 is able to discharge through exhaust butterfly valve 60 and outlet line 90a. When an operator presses 'start-cycle' button 87, the control system 50 activates door interlock 84 and inflatable pneumatic seal pressurised via 76, with pressure set via seal pressure regulator 62 such as at about 3 bar. Hi-flow solenoid valve 94 is opened, and inert or protective gas enters the housing 12 at about 200 litre per minute of inert gas enters chamber at about 5 millibar, with this low pressure is set by regulator 56, with oxygen-containing gas being displaced from housing 12. At the same time, larger flow, electrically actuated exhaust valve 60 opens, while inlet butterfly valve 52 opens via actuation of filter isolation solenoid valve 74, with lower flow exhaust valve 92 also is actuated by filter isolation valve 74, with exhaust valve 92 allowing for a constant "maintenance flow" which makes sure the oxygen sensor 58 always reads representative fresh oxygen values in chamber 13. Once the oxygen sensor 58 senses a decreased oxygen content as low as about5 5%, exhaust valve 60 shuts and safety circuit requirements are satisfied. Next, maintenance low flow inlet valve 72 is activated, as set by the speed controller 96, with the oxygen bleed valve 82 always remaining open during the cycle such that the oxygen sensor 58 continuously receives a representative sample of the atmosphere with the housing 12. A maintenance flowrate is kept at about 5 litre per minute. If the pressure sensor 80 senses a reading above 7 millibar, such as due to the operator inserting his hands through the glove ports and thereby expanding the gloves, the exhaust valve 60 is opened to relieve the resultant pressure increase. Once sensor determines the required oxygen level 58 is satisfied, electric rotation operations, such as illustrated in Figure 11, are enabled with support device 32, but with rotation of the build assembly 26 with device 32 limited via inductive limit switches to ensure operator safety. Also, the blowgun valve 70 is activated to enable the operator to utilise a blow gun device (not shown) for displacing unfused powder from the build. When the blow gun is triggered, the pressure sensor 80 will spike above 7 millibar, immediately opening the exhaust valve 60, thereby allowing the blowgun to be operated at machine supply pressure of about 6 bar, as determined by inlet regulator 64, without risk of exploding the gloves in ports 40.

045. On completion of a cycle of operation in displacing unfused powder from the build of an assembly 26, the operator will press the 'end-cycle' button 88, causing the blow gun valve 70 to exhaust such that the operator cannot accidently purge a pressurised line for the blow gun in an unsafe condition. To ensure that the operator is not exposed to a powder plume, there is a 30 sec powder settling time built into the system during which the door interlock 84 remains activated and cover part 24 of the housing 12 is unable to be raised. Similarly, the cover part 24 cannot be raised unless the second arm 24b of rotatable support device 32 is in the horizontal position, again for safety reasons to ensure the build assembly 26 is fully supported, as sensed via the inductive sensors. Once both safety conditions are met the inflatable air seal will de-pressurise 76 and the door interlock 84 will be released. When the machine is in the standby condition the filter 54 is isolated from atmosphere via 52 staying normally closed. Valves 60 and 76 also are normally closed to isolate the filter 54 from the other pressure side.

046. Pressure regulation is important and is facilitated by the glove box machine of the invention. The gloves or gauntlets, that enable an operator to work within the chamber 13 of the housing in displacing residual unfused powder, occupy a significant volume compared to the total volume of the chamber. This volume can completely invert to be fully expanded outside of the chamber, increasing the overall volume of the system, or they can be fully expanded inside the chamber when worn, which decreases the overall volume of the system. Therefore, when the operator manipulates the gauntlets, and particularly when they insert their hands into the gauntlets or withdraw their hands from the gauntlets, the volume displacement can exceed the allowable pressure in the chamber or, conversely, produce a relative vacuum in the chamber. The operation of the blow gun introduces a high rate of gas flow into the system, which without appropriate response would quickly exceed the allowable pressure in the chamber. Given these phenomena, the system needs to be able to quickly and smoothly react to large displacements in the chamber and this process is automated by a programmable logic controller P, housed in electrical cabinet 68 and forming at least part of an electrical control panel programmed to run the components of the control system 50. Thus, the PLC controls operation of solenoid valve 72, large solenoid valve 60, butterfly valve 52, measuring pressure with sensor 80, and measuring oxygen with sensor 58. When the maximum allowable pressure is exceeded, butterfly valve 52 and large solenoid valve 60 open to allow a high flow of exhaust gas which is filtered by assembly 54. Valves 52 and are sized to allow even the largest filling displacements introduce into the chamber to be evacuated without a dangerous pressure increase. When the pressure drops to below the minimum allowable level, solenoid valve 94 is opened to quickly backfill new purge gas, while valves 52 and 60 are opened to allow exhausted purge gas to be drawn back into the chamber. To prevent air being drawn back through valves 52 and 60, there is a long coil of hose connected to the output of valve 60 which acts as a reservoir of exhausted inert gas ready to be drawn back into the chamber if required. The hose H is on the outlet side of the machine and its purpose is to act as a reservoir of inert gas on the exhaust side, in case a relative vacuum inside the chamber 13 (caused by, for example, pulling the gauntlets outside of the machine) causes gas to be drawn in through the exhaust. If the line of hose H was not there, the chamber 13 would be likely to draw in air and thereby compromise the inert atmosphere. If the exhaust valves were left closed, the vacuum inside the chamber 13 could reach dangerous levels, as the high flow inlet valve may not be able to feed inert gas fast enough to counteract the vacuum.

047. Oxygen regulation is required in order to ensure that safe operation of the machine. For this, oxygen levels are maintained below a set threshold, with this achieved by pneumatic needle valves are used on the output of valve 72 and at 82 to control the flow in and out in conjunction with low pressure regulator 56. These valves and regulators are tuned in order to provide a constant low pressure, low volume flow of gas into the system, which produces a corresponding exhaust flow which passes by oxygen sensor 58 and allows for real time sampling of the gas contents in the chamber. If there was no such maintenance flow, a slow leak of air into the chamber compromising the inert atmosphere would not be detected for an extremely long period of time which would be a dangerous hazard. If the chamber reaches an excessive level of oxygen during operation, the automation system deactivates the blow gun and arm rotation until the oxygen threshold has been met again

048. The glove box machine of the invention may include a pneumatic vibrator to aid in the removal of unfused powder. The vibrator may mount on a secondary table which is vibrationally isolated from the main table with rubber isolators. The machine may feature programmable cycles that able to allow for arm movements and vibrations to be automated, such as to allow at least some of the unfused powder to be removed without an operator. Once this is complete, the operator can then return and use the blowgun to remove the remaining unfused powder.

Claims

Claims:

1. A glove box machine suitable for recovery of unfused powder from a build assembly removed from a build chamber of an SLM installation, after completion of a build cycle for the production of at least one component by a selective laser melting (SLM) process, wherein the machine has a housing having a volume sufficient to accommodate a build assembly up to designed maximum dimensions, with the volume defined by at least two parts of the housing; the machine also includes a support device adjustably mounted in relation to one housing part; the housing parts are relatively movable between a first, open position enabling a build assembly to be received within the volume and secured by a build plate of the build assembly on the support device and a second, closed position in which the housing parts enclose a build assembly when secured on the support device; at least one housing part has at least two access ports each comprising a glove port with a fitted respective glove, such as a resistive rubber glove, whereby operators can insert their hands to perform within the housing tasks required for recovery of the unfused powder, such as directing or inserting a pressurised gas jet or removal of unfused powder from internal channels, ducts and complex internal architectures; and wherein the support device is movable to enable adjustment of the orientation of the build assembly to facilitate powder recovery from the build assembly; the machine including a control system enabling evacuation of the closed housing and establishment of a protective atmosphere before an operator commences recovery of unfused powder from the build of the assembly.

2. The machine of claim 1, wherein the control system is adapted to enable recovery of at least part of the protective atmosphere prior to opening the housing on completion of unfused powder recovery from a build assembly.

3. The machine of claim 1 or claim 2, wherein a substantially gas-tight seal is provided by an inflatable seal element between and around the opposed peripheries off the cover and basal parts of the housing, with the seal preferably inflatable and deflatable, as required, by timing determined by the control system.

4. The machine of any one of claims 1 to 3, wherein the glove box machine has an upstanding column on which the support device is mounted, with the column housing the control system enabling evacuation of the closed housing and establishment of a protective atmosphere.

5. The machine of any one of claims 1 to 4, wherein functioning of the control system is enabled by the system including a low-pressure, high-flow regulator.

6. The machine of claim 5, wherein an inlet supply to the regulator, including a pressurised source of an inert or protective gas suitable for providing a substantially oxygen-free atmosphere in the chamber of the housing, is controlled via two solenoids enabling a high flow and low flow condition for the gas.

7. The machine of claim 6, wherein the regulator can be set to a level, of the order of mbar, that substantially precludes an overpressure in the event of a due to filter blockage when using flowmeters to control the flow into the system.

8. The machine of claim 7, wherein for using the low- pressure regulator, the sizing of tubing and of an associated exhaust solenoid valve are adapted to ensure that the inlet flowrate can be maximised.

9. The machine of claim 6 or claim 7, wherein an oxygen sensor and a pressure sensor are integrated into the control system to allow closed loop system control and allow pneumatic accessories to be used inside the chamber without causing the gloves to explode outwardly.

10. The machine according to any one of claims 1 to 9, wherein the control system has gas flow circuit that has a higher-pressure side and a lower-pressure side and provides overall gas flow is from the higher side to the chamber of the housing and from the chamber to the lower-pressure side, with the flow generated from a cylinder or other suitable source of pressurised inert or protective gas whereby the gas is able to flow through the circuit via an inlet line that communicates with inlet pressure regulator to purge oxygen-containing gas from the chamber of the housing and establish a substantially oxygen-free atmosphere in the chamber, with gas purged from the chamber discharging through an exhaust butterfly valve and an outlet line,.

11. The machine of any one of claims 1 to 10, wherein the machine further includes a 'start-cycle' button that, via intervention by an operator, enables the control system to actuate a door interlock to secure the container parts together and to actuate an inflatable pneumatic seal for sealing the container via seal pressure regulator, such as at about 3 bar.

12. The machine of claim 11, wherein with the door interlock actuated and the seal inflated, a high-flow solenoid valve of the control system is openable to enable inert or protective gas to enter the housing, such as with about 200 litre per minute of gas entering the chamber at about 5 millibar, with this low pressure set by a regulator of the control system and purging oxygen-containing gas from the housing.

13. The machine of claim 12, wherein while the high-flow solenoid valve and the low pressure setting regulator are operable to enable the gas flow, a larger flow, electrically actuated exhaust valve opens, while an inlet butterfly valve opens. via actuation of a filter isolation solenoid valve, with a lower flow exhaust valve also actuated by the filter isolation valve and allowing for a constant "maintenance flow" which makes sure the oxygen sensor always reads representative fresh oxygen values in chamber.

14. The machine of any one of claims 1 to 13, wherein the support device is movable so that the orientation of a build assembly secured on the support device can be varied to facilitate access for removal of unfused powder, such as inverted to enable at least some of the unfused powder to flow under the influence of gravity from the build assembly.

15. The machine of any one of claims 1 to 14, wherein the cover housing part is movable relative to the basal part by pivoting, such as on a horizontally extending hinge line along which the cover and basal housing parts are connected.

16. The machine of claim 14 or claim 15, wherein the basal housing part may have an upwardly projecting sidewall, and the support device for the build assembly is movably mounted on the sidewall.

17. The machine of claim 16, wherein the support device has a mounting section connected to the sidewall to be rotatable on an axis projecting from the sidewall, and a support section extending from the mounting section on which a build assembly can be secured.

18. The machine of claim 17, wherein the support section has a turntable on which the build plate can be secured, with the turntable section rotatable relative to the support section, such as on an axis substantially perpendicular to the axis projecting from the sidewall.

19. The machine of any one of claims 14 to 18, wherein the support device is rotatable on the axis projecting from the sidewall by depression of a foot pedal of the machine mounted below the container and a drive line acting between the foot pedal and a mounting shaft by which the support device is mounted on the sidewall.

20. The machine of any one of claims 14 to 19, wherein the machine has facility for conducting powder that is recover from the build assembly, into the housing, to a suitable container that is separable from the machine.

21. The machine of any one of claims 14 to 20, wherein the control system is operable to enable a gas-down time, to reach an oxygen content of not more than 5% in a substantially inert or protective atmosphere, of less than about 10 minutes, preferably less than about 5 minutes, such as less than about 3 minutes.

22. The machine of any one of claims 14 to 21, wherein gas-down time is enabled by operation of the low-pressure regulator of the control system that is close to and in communication with the interior of the closed housing by an outlet pipe with an internal diameter enabling a flow rate of the order of 200 litre/minute with a housing internal pressure of about 5 millibar.