WO2020093038A1

WO2020093038A1 - System for purging air

Info

Publication number: WO2020093038A1
Application number: PCT/US2019/059635
Authority: WO
Inventors: Russell V. HUGHES
Original assignee: Hughes Russell V
Priority date: 2018-11-02
Filing date: 2019-11-04
Publication date: 2020-05-07

Abstract

A system for purging air includes a chamber having an exhaust port, a purge gas feed-in system configured to provide a purge gas into the chamber, and a bag system including at least one bag inside the chamber. A gas is filled into the bag system to inflate same so that air in the chamber is discharged through the exhaust port prior to the purge gas feed-in system providing the purge gas into the chamber.

Description

SYSTEM FOR PURGING AIR

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority from US Provisional Patent Application

62/754,810, filed November 2, 2018. The entire disclosure of this prior application is

incorporated herein by reference.

BACKGROUND

[0002] The technique of additive manufacturing or wire arc additive manufacturing (WAAM) creates metal parts from individual layers of metal stacked on top of each other. A first layer is deposited on a base and each additional layer is deposited on the previous layer in varying shapes and layouts to form a three dimensional metal part. This additive manufacturing process must occur in an environment that is non-reactive and non-contaminating to the part being fabricated. For example, a chamber in which the additive manufacturing process occurs may initially be purged of undesirable gases including air by being filled with a non-reactive or inert gas such as argon in a manner whereby the argon displaces all the other gasses in the chamber down to negligible amounts, after which a much smaller amount of argon is then continuously fed into and flows through the chamber throughout the additive manufacturing process. Further discussion herein refers to argon as the desired gas, but it will be understood that other non reactive or insert gasses maybe appropriate for use according to the present disclosure.

[0003] Wire arc additive manufacturing (WAAM) consists of additively manufacturing a part using a controlled welding process where the weld is typically positioned through a Computer Numerically Controlled (CNC) program. This can be done in a number of configurations in either an open or closed environment. If the weld is exposed to oxygen or contaminants in the air, then the quality of the weld will be poor and the part will not be usable for critical applications. To address this problem in an open environment, a shielding gas is used to prevent contamination of the weld. Use of a shield gas can have varied results and may present many difficulties based on machine geometry or exposure to an environmental change such as a draft.

[0004] Performing the welding operation in a closed chamber prevents many of the challenges that occur in the open environment. Before welding can begin, however, the chamber must be purged of air. This is typically done by introducing an inert gas such as argon in a number of locations to displace the air in the chamber. The air is driven out of the sealed chamber, leaking through a small port typically in the roof of the enclosure. An oxygen sensor is used to monitor the level of oxygen. Welding begins when a low enough oxygen level has been reached. One major drawback to this problem is that filling the chamber can take an excessive amount of time. A small 1 to 2 cubic meter chamber can take 3 to 4 hours to purge.

[0005] Conventional methods approach the problem by simply purging a chamber with a steady flow of purge gas. In the case that the purge gas is heavier than air, the purge gas will settle in the bottom of the chamber and gradually displace the air though a vent in the top of the chamber. This conventional approach can be inefficient in the time it takes to purge the chamber and in the amount of purge gas needed. Air turbulence within the chamber tends to cause mixing of the air with the purge gas as it is introduced. The mixture can be resolved over time by letting the purge gas settle. In a large chamber, it can take many days to purge the volume of contaminating air. Alternatively, the mixture can be allowed to escape from the chamber through the vent with the effect of significant volumes of purge gas being released along with the purged air, e.g., the amount of purge gas required may be several times the volume of the chamber, which is not cost efficient. The approach disclosed herein seeks to provide an improved air purging system and method to rapidly purge a chamber of air without excessive waste of the purge gas.

Summary

[0006] A system for purging air is disclosed herein that includes a chamber providing an enclosed three dimensional workspace having a workspace volume, an airbag system including at least one airbag within the chamber which is configured to selectably take on an inflated or deflated state, and a purge gas feed-in system configured to provide a purge gas into the workspace. In the system for purging air, the workspace volume is reduced by an airbag volume of the at least one airbag in the inflated state.

[0007] A second aspect of the system for purging air further includes an exhaust port provided with the chamber and configured to selectably allow a flow of gas within the workspace to exit the workspace. A transition from the deflated state to the inflated state of the at least one airbag within the workspace forces gas present in the workspace to exit the workspace through the exhaust port. [0008] According to a third aspect of the system for purging air, the purge gas feed-in system provides the purge gas into the workspace simultaneously with the at least one airbag being in the inflated state within the workspace.

[0009] According to a fourth aspect of the system for purging air, the system further includes an oxygen sensor provided with the exhaust port to sense an oxygen level in a gas flow exiting the exhaust port and a bag retraction system configured to retract the bag to a deflated state when the oxygen level detected by the oxygen sensor is below a predetermined threshold amount.

[0010] According to a fifth aspect of the system for purging air, the at least one airbag includes an outlet valve configured to allow gas within the at least one airbag into the workspace, and the purge gas feed-in system is configured to fill the at least one airbag with the purge gas.

[0011] According to a sixth aspect of the system for purging air, the at least one airbag is shaped to conform to the workspace.

[0012] According to a seventh aspect of the system for purging air, the at least one airbag includes a plurality of airbags.

[0013] According to an eighth aspect of the system for purging air, the system further includes a second airbag configured to be inflated by gas present within the workspace and wherein the inflation of the first airbag within the workspace forces gas present within the workspace into the second airbag.

[0014] According to a ninth aspect of the system for purging air, the chamber includes a hinged chamber door on at least one side surface thereof, the chamber door having a concave surface extending into the workspace, and wherein the airbag is disposed within a void provided by the concave surface of the door.

Brief Description of the Drawings

[0015] Fig. 1 shows a sectional view of a manufacturing chamber with a system for purging air including an airbag system with an airbag in an undeployed state;

[0016] Fig. 2 shows a sectional view of the manufacturing chamber of Fig. 1 with the airbag in a filled/deployed state; [0017] Figure 3 shows sectional view of a manufacturing chamber with a system for purging air according to another exemplary approach in which the airbag system includes complementary airbags both in the inflated state;

[0018] Fig. 4 shows a plan view of a conventional large manufacturing chamber;

[0019] Fig. 5 shows a plan view of a large manufacturing chamber according to another exemplary approach, in which the manufacturing chamber has concave doors; and

[0020] Fig. 6 shows a close up view of the manufacturing chamber of Fig. 5 in which the concave doors are in a closed state.

Detailed Description

[0021] Fig. 1 depicts a system for purging air 10 including CNC machine 12 having a manufacturing chamber 14, an airbag system 16, a purge gas feed-in system 18, and a controller 20 such as an electronic control unit (ECU) which is programmed for operating of the airbag system 16 and the purge gas feed system 18. Such a CNC machine 12 is of the type that is typically used in additive manufacturing, welding, and similar applications. The manufacturing chamber 14 provides an operational workspace 22 which is a three dimensional space in which a workpiece is operated on and/or produced. The manufacturing chamber 14 typically includes access doors or ports for loading/unloading machine components, equipment, and workpieces. These doors or ports may be closed during operation of the CNC machine 12 to prevent the inflow of air into the manufacturing chamber 14. In some applications, the chamber 14 may be airtight during operation. In one approach, the chamber may include inflow and outflow valves to control the internal pressure of the manufacturing chamber 14 during operation of the CNC machine 12, and such valves would also be controlled by the controller.

[0022] In many welding and additive manufacturing applications, the manufacturing chamber 14 needs to be purged of air / oxygen prior to the start of the welding or manufacturing process.

The purging of oxygen can be accomplished by providing a purge gas to the chamber 14.

Common examples purge gasses are inert and include Helium and Argon. In the case of Argon, which is typically 40% heavier than air, the chamber purging can be accomplished by filling the chamber 14 with the purge gas and allowing oxygen containing air to exit out of a chamber exhaust port 24 positioned near the top of the manufacturing chamber 14. [0023] The exhaust port 24 can include an associated oxygen sensor 26 for detecting an oxygen level of an air or gas flow exiting the exhaust port 24. The exhaust port 24 includes an opening and closing mechanism such as a valve to open and close the exhaust port 24 as necessary. In one approach, the operation of the oxygen sensor 26 and exhaust port 24 is handled manually. In another approach, the opening and closing mechanism is an electro-mechanical mechanism controlled by the ECU 20 and configured to receive an input of oxygen level of the gas flow from the oxygen sensor 26 and configured to close the exhaust port 24 when the oxygen level reaches a predetermined threshold value.

[0024] The manufacturing chamber 14 can include a purge gas feed-in system 18 configured to provide a purge gas into the chamber workspace 22. Purge gas such as argon introduced into the chamber workspace 22 from the purge gas feed-in system 18 will eventually force the less dense oxygen containing air out of the chamber 14 through the chamber exhaust port 24 positioned near the top of the chamber 14. The amount of time required for such a purge can be dependent on the inflow rate of the purge gas from the purge gas feed-in system 18 and the degree to which the purge gas and the oxygen containing air are allowed to mix due to any turbulence caused by the in-flowing purge gas or by other actions. The purge gas feed-in system 18 can include a plurality of purge gas feed-in tubes with outlet ports along the tubes disposed along the bottom of the chamber workspace 22. The purge gas feed-in system 18 further includes a purge gas supply which supplies the purge gas to the tubes and one or more control valves to control the rate of purge gas inflow from the supply to the tubes.

[0025] An airbag system 16 can be provided with the chamber to assist with the air purging of the manufacturing chamber workspace 22. The airbag system 16 may include one or more airbags 28a, b that can be inflated within the chamber workspace 22. The airbag(s) 28a, b of the airbag system 16 can be inflated with air or gas from outside of the chamber through a fill port 30 to assume an inflated state within the chamber workspace (see Fig. 2). Upon inflation of the airbag 28a, b, the volume of the chamber workspace 22 may be reduced by the volume of the airbag 28a, b and inflation of the airbag 28a, b may force some of the air/oxygen in the chamber 14 to be discharged through the exhaust port 24. The reduction in volume of the chamber workspace 22 reduces the amount of oxygen containing air that must be purged from the workspace 22 using the purge gas. While the airbag 28a, b is in an inflated state, the purge gas feed-in system 18 can introduce purge gas into the reduced volume of the chamber workspace 22. Due to the smaller volume to be purged, the time required to purge the workspace 22 can be greatly reduced. Also, the smaller volume to be purged also results in less possibility of purge gas mixing with the oxygen containing air being purged due to turbulence generated when the purge gas is introduced into the chamber 14, and further reduces the required amount of purge gas.

[0026] In one approach, the airbag system 16 includes a filling port 30 for the airbag to rapidly fill the airbag 28a, b with air or gas from outside of the chamber. For example, the filling port 30 can be fitted with a valve and attached to an air pump, compressed air tank, etc. to rapidly fill the airbag 28a, b inside the chamber. As the airbag 28a, b expands due to inflation within the chamber workspace 22, existing air within the chamber workspace 22 is forced out of the chamber exhaust port. 24

[0027] The airbag system 16 further includes an airbag exhaust port 32. The airbag exhaust port 32 can include an opening and closing mechanism such as a valve for allowing air or gas present within the airbag 28a, b to exit the airbag. In one approach, the purge gas feed-in system 18 introduces purge gas into the chamber workspace 22 with sufficient pressure to collapse the airbag 28a, b by forcing air or gas out of the airbag 28a, b through the airbag exhaust port 32. In such an approach, the chamber exhaust port 24 would be closed to allow for sufficient purge gas pressure to collapse the airbag 28a, b.

[0028] The chamber workspace 22 will typically include internal objects or obstacles 34 to the inflation of the airbag 28a, b, e.g., CNC machine components that performs a WAAM operation, such that completely filling the workspace 22 volume with the volume of the airbag 28a, b would not be possible. With such a chamber 14, the airbag 28a, b can be specifically designed to accommodate common internal obstacles 34 within the chamber. Similarly, the airbag system 16 can include a collection of cooperating airbags 28a, b that inflate to fill different portions of the workspace 22 of the chamber 14.

[0029] The airbag system 16 may further include a retraction system 36 to assist with the deflation and retraction of the airbag 28a, b. For example, the retraction system 36 retracts the airbag 28a, b during the time of manufacturing within the chamber 14 to prevent the airbags 28a, b from interfering with the manufacturing process. The retraction system 36 can be a manual device such as straps or ties that can be manipulated from outside of the chamber 14 by an operator. In another approach, the retraction system 36 can be a mechanical system of straps and ties within the chamber 14 that is operated remotely and/or autonomously, e.g., by the ECU 20. In either approach, the retraction system 36 is operable without opening the chamber 14 to avoid the introduction of oxygen containing air.

[0030] One exemplary approach of an air purging process of a manufacturing chamber 14 including an airbag system 16 and purge gas feed-in system 18 will now be described. Initially, a latch provided with the airbag retraction system 36 is released to allow the airbags 28a, b, in a deflated state, to extend into the chamber workspace 22, the chamber exhaust port 24 is opened, the airbag system exhaust port 32 is closed, and air or gas is rapidly forced into the airbags 28a, b of the air bag system 16 through the fill port 30 thereby inflating the airbags 28a, b inside of the chamber workspace 22. The volume of air or gas within the chamber workspace 22 is rapidly replaced by the volume of air or gas within the airbags 28a, b, but the two volumes are separated by the airbags 28a, b such that they do not mix with each other. The air or gas of the chamber workspace 22 exits the workspace through the chamber exhaust port 24 as the airbags 28a, b inflate.

[0031] Depending on the design and shape of the airbags 28a, b and the amount and size of any internal obstacles 34 within the chamber workspace 22, the workspace volume can be reduced by more than 50 percent. The shape of the airbags 28a, b can be configured to occupy any space within the workspace not blocked by internal obstacles 34. These open spaces within the workspace 22 are considered an easy-to-purge volume of the chamber 14 which are overtaken by the inflation of the airbags 28a, b. The remaining volume of the workspace 22 around internal obstacles 34 in the workspace are considered a difficult-to-purge volume and will be purged by the introduction of purge gas from the purge gas feed-in system 18. One or more airbags 28 a, b can be included with the air-bag system 16 to adequately encompass the easy-to-purge volume.

[0032] The purge gas feed-in system 18 may be operated to introduce purge gas into the chamber workspace 22 simultaneously while the airbags 28a, b are maintained in the inflated state. Due to the inflated state of the airbags 28a, b, the workspace volume is reduced by the size of the easy-to-purge volume to only the difficult-to-purge volume. This significantly smaller volume can then be rapidly and efficiently purged by the introduced purge gas.

[0033] The chamber exhaust port 24 is maintained in an open state as the purge gas is initially introduced into the chamber workspace 22. The oxygen sensor 26 provided with the exhaust port 24 can provide output signals to track the oxygen level of the gas flow exiting the exhaust port 24 from the chamber workspace 22. The exhaust port 24 can be closed once the oxygen level indicated by the oxygen sensor 26 reaches a desired predetermined level. It should be appreciated that mixing of the purge gas and the air within the workspace 22 can occur due to turbulence cause by the introduction of the purge gas. Therefore, any single instantaneous reading of the oxygen sensor 26 might not accurately reflect the actual oxygen level within the chamber 14. Accordingly, in one approach, the exhaust port 24 can be partially closed or repeatedly closed and then opened over time until the final predetermined oxygen level is reached. Similarly, the introduction of the purge gas into the chamber 14 can be reduced or stopped during the purging process to allow time for the gases within the chamber workspace 22 to settle and separate.

[0034] Once the final predetermined oxygen level is achieved. The airbag system 16 can open the airbag exhaust port 32 to allow air within the airbags 28a, b to exit the airbags 28a, b to the exterior of the chamber 14. With the chamber exhaust port 24 closed the introduction of purge gas from the purge gas feed-in system 18 increases the pressure within the workspace 22. This increased pressure within the workspace 22 along with the opening of the airbag exhaust port 32 allows for the airbags 28a, b to deflate and collapse with the air exiting the airbags 28a, b to the exterior of the chamber 14. As the airbags 28a, b deflate and gas from within the airbags 28a, b is discharged out of the airbag exhaust port 32 to the exterior of the chamber 14, purge gas fills the workspace 22 volume previously occupied by the airbag volume.

[0035] Once the airbags 28a, b are fully deflated, the collapsed airbags 28a, b can be retraced by the airbag retraction system 36. In one approach, the retraction system 36 can include straps, ties, latches, etc. to secure the collapsed airbag. As depicted, in Fig. 1, the airbag system 16 including the retraction system 36 is fitted to the upper portion of the chamber 14. The retraction system 36 retracts and secures the deflated airbags 28a, b away from the workspace 22 of the chamber 14.

[0036] Once the airbags 28a, b are fully deflated and retracted, the purge process can continue as necessary until a desired, predetermined appropriate oxygen level is reached. As explained above, the chamber exhaust port 24 can be opened and closed as necessary and the introduction of the purge gas can be altered or stopped as necessary to allow for the settling of the gasses within the purge chamber 14. When the final predetermined appropriate oxygen level is reached, the chamber exhaust port 24 can be closed, the introduction of the purge gas can be stopped, and the manufacturing process can proceed. However, in some manufacturing processes, the introduction of purge gas may continue through some or all of the time of the manufacturing process. Similarly, the chamber exhaust port 24 may be opened as necessary during the manufacturing process to allow for adjustment of the internal pressure of the chamber 14 to an appropriate level.

[0037] While only one oxygen sensor 26 is depicted, it should be apparent that the oxygen sensor 26 may be a set of oxygen sensors distributed throughout chamber workspace and chamber exhaust port. A set of oxygen sensors distributed throughout the chamber workspace and chamber exhaust port could detect regional pockets of oxygen. Thus, the above described purging process could include detecting oxygen levels from the set of oxygen sensors and continuing the purge process until each sensor of the set of sensors outputs an acceptable predetermined level.

[0038] Alternatives to the above-described purging process can also be effective. In one alternative approach, rather than inflating and deflating the airbags 28a, b a single time, the airbags 28a, b can be repeatedly inflated and deflated. The repeated inflation and deflation of the airbags 28a, b has the effect of pumping the volume of the chamber workspace 22. This pumping effect can be combined with the simultaneous introduction of purge gas from the purge gas feed- in system 18. The pumping effect caused by the repeated inflation and deflation of the airbags 28a, b may reduce the time necessary to purge the chamber workspace 22 as indicated by the oxygen level reaching a predetermined final appropriate level as sensed by the oxygen sensor 26.

[0039] In yet another alternative approach, rather than filling the airbags 28a, b with a standard air mixture, the airbags 28a, b can be filled with the purge gas, which may also be provided by the purge gas feed-in system 18. In such an approach, the airbags 28a, b would begin in a deflated state with as small an air volume as possible. The purge gas is then introduced into the deflated airbags 28a, b allowing the airbags 28a, b to inflate within the chamber workspace 22, and the thus inflated airbags 28a, b will have an extremely high concentration of the purge gas therein. Once inflated, this volume of purge gas contained in the airbags 28a, b is located within the chamber workspace 22 and displaces much of the air previously therein. In this approach, the airbags 28a, b includes an outlet 38 to exhaust the purge gas within airbags 28a, b into the chamber workspace 22 rather than to the exterior of the chamber 14 as described in the earlier exemplary approach. The retraction system 36 is operable to retract the airbags 28a, b to a deflated state. As the airbags 28a, b are retracted by the retraction system 36 causing them to deflate, the purge gas present within the airbags 28a, b is forced out through the outlet 38 into the chamber workspace 22, and in a manner that generates as little turbulence as possible within the chamber workspace.

[0040] In yet another exemplary approach, the airbag system 16 can include multiple

complimentary airbags 28a, b, 29a, b. These complimentary airbags 28a, b 29a, b are each configured to occupy the same internal volume of the chamber workspace 22. However, only one of the complimentary airbags 28a, b, 29a, b can be fully inflated within the workspace at a given time. Further, inflation and deflation of the complimentary airbags 28a, b 29a, b may be controlled such that the inflation of one set of the complimentary airbags 28a, b has the effect of deflating the opposing complimentary airbags 29a, b, and vice versa. In addition to inflating inside of the chamber workspace 22, complimentary airbags can also inflate to the exterior of the chamber workspace. That is, as one set of the complimentary airbags 28a, b inflates inside of the workspace, the volume of the opposing airbags 29a, b is shifted to the exterior of the workspace. In such an approach, recovery and preservation of the purge gas can be achieved.

[0041] Continuing on with this exemplary approach, the purging process described above can be conducted with one of the sets of complimentary airbags 28a, b. However, at the conclusion of the manufacturing process with both sets of complimentary airbags 28a, b, 29a, b in the deflated state, one set of the complimentary airbags 28a, b can be filled with air to inflate the airbags in the inside of the workspace 22 while the exhaust port 24 is closed to force the purge gas present within the workspace 22 into the opposing set of complimentary airbag 29a, b, which would then inflate to the exterior of the workspace. This has the effect of recovering and preserving the purge gas into the second set of complimentary airbags 29a, b in a pure or near pure state for reuse in a later manufacturing process. Upon the next purging process, the purge gas present in the second set of complimentary airbags 29a, b inflated to the exterior of the chamber 14 can be used as a source for introducing purge gas into the workspace 22.

[0042] In yet another approach, a gas recovery system (not shown) can be provided in association with the chamber 14 and the exhaust port 24. At the conclusion of a manufacturing process with the chamber filled with the purge gas, the chamber exhaust port 24 can be opened to the gas recover system. The airbags 28a, b could then be filled with air and inflated into the chamber workspace 22 thereby forcing the purge gas out of the exhaust port 24 into the gas recover system. The gas recovery system would then preserve the gas in a pure or near pure state for reuse in a later manufacturing process.

[0043] With all of the above-described approaches, the amount of time and the quantity of purge gas required to purge the chamber can be significantly reduced in comparison to conventionally known approaches. This desirably results in several advantages, e.g., lower operating costs and greater throughput.

[0044] While the above-described approaches address manufacturing of workpieces of limited size, it should be appreciated that the same type of system could be adapted to larger workpieces that require a larger size manufacturing chamber.

[0045] A larger manufacturing chamber 40 necessary for manufacturing larger workpieces, would also require operational space 42 within the chamber walls 44. For example, large workpieces might need operators, robots, cranes, equipment, etc, for loading and unloading into the chamber 40. These operators and equipment need operational access space 42 to operate within the chamber walls but outside of a printing envelope 46. Such operational access space 42 can greatly increase the volume of air which must be purged from the chamber 40 prior to the start of the manufacturing process.

[0046] As an example, a larger manufacturing chamber 40 can have a four foot by eight foot printing envelope 46. However, such a larger chamber 40 can also require a two foot wide operational access space 42 around the entire printing envelope 46 but within the chamber walls 44. The entire printing envelope 46 along with the operational access space 42 would be enclosed within the chamber walls 44. In a conventional larger manufacturing chamber 40, there would be an access door 48 along at least one wall of the chamber. This may be a typical door 48 supported by a hinge 50 opening outward from the operational access space and provided with a gas seal 52 on an inner side of the door. In a closed state of the door 54, the chamber 40 would be seal from outside air. With this type of chamber walls 44 and access door 54, the full volume of the chamber including both the printing envelope 46 and the operational access space 42 would need to be purged with purge gas prior to the manufacturing process. This larger volume would correspondingly require very large amounts of purge gas and considerable amounts of time to reach the desired oxygen level.

[0047] According to another exemplary approach, an improved large manufacturing chamber 60 can be achieved with one or more concave doors 62 provided along the outer perimeter of the chamber 44. These concave doors 62 can be hinged 64 along one vertical edge thereof to upright supports 66 of the chamber provided at each corner. The doors 66 can be configured to open outwardly away from the printing envelop 46. With the hinges at one end, the doors 62 open wide to allow for wide access to the printing envelope. The depiction in Fig. 5 shows a large manufacturing chamber 60 with a plurality of concave doors 62, with some of the doors in an open state 68 and some in a closed state 70.

[0048] When closed, the concave portions of the doors 62 occupy much the space associated with the operational access area 42 surrounding the printing envelope 46. The concave portion of each door 62 can be formed in an angular manner with roughly three vertical faces. A first vertical face 72 near the door hinges 64 extends inward from the hinges toward the printing envelope 44 and would abut or nearly abut an opposing first vertical face of an adjacent door when the doors are in the closed position (See Fig. 6). The second vertical face 74 of the concave portion of the door would extend roughly parallel to the printing envelope 46, and the third vertical face 76 would extend outward from the printing envelope 46 toward the exterior wall 44 of the chamber. The angle 78 between the second vertical face 74 and the third vertical face 76 would allow for door swing space 80 between adjacent doors.

[0049] The concave portions of the doors 62 provide a void 82 that can be filled with an airbag system 16 of the same type as the airbag system described above, e.g., including the same input and exhaust ports and gas recovery system as necessary. It should be appreciated that the airbag system included with the doors would be in addition to any airbag system provided elsewhere in the manufacturing chamber such as within the printing envelope.

[0050] Many components considered for 3D printing can be very lengthy but not particularly wide or tall, for example the wing spar of an aircraft which is much like a girder or beam. Such a part could be printed inside a chamber resembling a tunnel. Deploying a long tubular airbag system such as that described herein into this tubular chamber would massively decrease the purge volume that must initially be brought down to a low level of oxygen/air (typically lOppm of oxygen). In such a long tubular chamber, the manufacturing process may be initiated after only an initial purge from the airbag device. Given the size of the workpiece to be manufactured and given the corresponding long time it takes to manufacture same, the portion of the chamber in which manufacturing begins could be at a sufficient oxygen level. The full purge process can continue simultaneously with the start of the manufacturing process. That is, the manufacturing process can continue so long as the portion of the workpiece that is being completed is in an area of the chamber that has the proper oxygen level. This simultaneous purging process can reduce the time it takes to manufacture the workpiece given that the process can begin prior to the complete purge of the chamber.

[0051] The present disclosure is not limited in its application to the details of construction and to the dispositions of the components set forth in the foregoing description or illustrated in the appended drawings in association with the present illustrative approaches of the disclosure. The present disclosure is capable of other approaches and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purposes of illustration and example, and should not be regarded as limiting.

[0052] As such, those skilled in the art will appreciate that the concepts, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present disclosure. It is important, therefore, that the scope of the claims appended hereto be regarded - interpreted as including such equivalent constructions.

Claims

1. A system for purging air comprising:

a chamber having an exhaust port;

a purge gas feed-in system configured to provide a purge gas into the chamber; and at least one bag inside the chamber, wherein a gas inflates the bag to exhaust air in the chamber through the exhaust port.

2. The system for purging air according to claim 1, wherein the purge gas feed-in system provides the purge gas into the chamber simultaneously with the at least one bag being in an inflated state within the chamber.

3. The system for purging air according to claim 1, further comprising:

an oxygen sensor provided with the exhaust port to sense an oxygen level in a gas flow exiting the exhaust port; and

a bag retraction system configured to retract the bag to a deflated state when the oxygen level detected by the oxygen sensor is below a predetermined threshold amount.

4. The system for purging air according to claim 1, wherein the at least one bag includes an outlet valve configured to allow gas within the bag into the chamber, and wherein a purge gas feed-in system is configured to fill the bag with the purge gas.

5. The system for purging air according to claim 1, wherein the at least one bag is shaped to conform to an interior space of the chamber.

6. The system for purging air according to claim 1, where in the at least one bag includes a plurality of bags.

7. The system for purging air according to claim 1, further comprising a second bag configured to be inflated by gas present within the chamber and wherein the inflation of the first bag within the chamber forces gas present within the chamber into the second bag.

8. The system for purging air according to claim 1, wherein the chamber includes a hinged chamber door on at least one side surface thereof, the chamber door having a concave surface extending into the chamber when the door is in a closed position, and wherein the bag is disposed within a void provided by the concave surface of the door.

9. A system for purging air comprising:

a chamber providing an enclosed three dimensional workspace having a workspace volume; an airbag system including at least one airbag within the chamber which is configured to selectably be in an inflated or deflated state; and

a purge gas feed-in system configured to provide a purge gas into the workspace, wherein the workspace volume is reduced by an airbag volume of the airbag in the inflated state.

10. The system for purging air according to claim 9, further comprising:

an openable and closeable exhaust port provided with the chamber which is configured to selectably allow a flow of gas within the workspace to exit the workspace, wherein a transition from the deflated state to the inflated state of the at least one airbag within the workspace forces gas present in the workspace to exit the workspace through the exhaust port.

11. The system for purging air according to claim 9, wherein the purge gas feed-in system is configured to provide the purge gas into the workspace when the at least one airbag is in the inflated state within the workspace.

12. The system for purging air according to claim 9, further comprising:

an oxygen sensor provided with the exhaust port; and

an airbag retraction system configured to retract the at least one airbag to the deflated state when an oxygen level sensed by the oxygen sensor is below a predetermined threshold amount.

13. The system for purging air according to claim 9, wherein the at least one airbag includes an outlet valve configured to allow gas within the at least one airbag into the workspace, and wherein the purge gas feed-in system is further configured to fill the at least one airbag with the purge gas.

14. The system for purging air according to claim 9, wherein the at least one airbag is shaped to conform to the workspace.

15. The system for purging air according to claim 9, where in the at least one airbag includes a plurality of airbags.

16. The system for purging air according to claim 9, further comprising a second airbag configured to be inflated by gas present within the workspace and wherein the inflation of the first airbag within the workspace forces gas present within the workspace into the second airbag.

17. The system for purging air according to claim 9, wherein the chamber includes a hinged chamber door on at least one side surface thereof, the chamber door having a concave surface which extends into the chamber when the chamber door is in a closed position, and wherein the airbag system is disposed within a void provided by the concave surface of the door.