Safety protection method and device for an additive manufacturing facility

Abstract

A method for providing safety protection in an additive manufacturing apparatus (21) for forming a three-dimensional article by successively fusing parts of a powder bed (5) corresponding to successive cross-sections of the three-dimensional article in a closable chamber (20), the method comprising the steps of: providing a position detection device connected to a control unit (65), the position detection device being configured to detect whether a foreign object is located within the closable chamber (20), the foreign object being a part of a body or a tool;and upon detection that a foreign object is located within the closable chamber (20), switching off at least one device associated with the additive manufacturing device (21) via the control unit (65), or providing energy to a powder suction device (35) via the control unit (65).;

Description

BACKGROUNDTechnical FieldVarious embodiments of the present invention relate to a method and apparatus for providing safety protection in an additive manufacturing facility.Prior ArtFree-form fabrication or additive manufacturing is a method of forming three-dimensional articles by successively fusing selected portions of powder layers applied to a work table.An additive manufacturing apparatus may include a work table on which the three-dimensional article is to be formed, a powder dispenser arranged to deposit a thin layer of powder on the work table for forming a powder bed, an energy beam for supplying energy to the powder, wherein fusion of the powder occurs, elements for controlling the energy output by the energy beam for forming a cross section of the three-dimensional article by fusion of parts of the powder bed over the powder bed, and a control computer in which information regarding successive cross sections of the three-dimensional article is stored. A three-dimensional article is formed by successive melts of successive cross-sections of powder layers successively laid out by the powder dispenser.An additive manufacturing apparatus includes, among other things, a jet source, a powder distributor, and other mechanically movable parts that, when not protected, may be detrimental to an operator or service personnel. One way to ensure that the machine is safe to operate with it is to manually shut off the power supply to the additive manufacturing apparatus. A problem with a completely dead device is that non-harmful devices do not operate either, which may be annoying and / or problematic in some situations. Another problem is that it can be forgotten that the power switch is to be turned off.Additive manufacturing may also require safe powder handling and recirculation of unused powder material, that is, only certain types of powder suction devices may be used which do not expose the powder to any form of igniting agent. Safe powder handling may also involve ensuring that the recirculated powder is clean of any extraneous contaminants which may destroy the result of the three-dimensional article being manufactured, which in turn may cause a safety problem where the finished article concludes. Recirculated powder may be unsolidified or uncombined powder material from a prior process that is reused in a later process. Such recirculated powder may be mixed with virgin powder.Apparatuses and methods of the generic type are known from documents DE 10 2011 009 624 A1 and DE 10 2007 018 601 A1. Further prior art relating to the technological background is described in the documents U.S. Pat. No. 3,882,477 A and US 2006 / 0 065 860 A1.BRIEF SUMMARYAgainst this background, it is an object of the invention to provide methods and apparatuses for safety protection in an additive manufacturing apparatus which reduce or eliminate the aforementioned safety problems.The invention is defined by the subjects of the appended claims.According to embodiments of the invention, there is provided a method of providing safety protection in an additive manufacturing apparatus for forming a three-dimensional article by successively fusing portions of a powder bed corresponding to successive cross-sections of the three-dimensional article in a closable chamber. The method comprises the steps of providing a position detection device connected to a control unit, wherein the position detection device is configured to detect whether a foreign object is located within the closable chamber; and upon detection that a foreign object is located within the closable chamber, switching off at least one device associated with the additive manufacturing apparatus via the control unit.At least one advantage of at least these embodiments is that harmful devices such as radiation source and powder distributor can be automatically eliminated, for example, when attempting to enter the closable chamber with a foreign object or object, namely a part of the body or a tool.Foreign objects or foreign objects means everything introduced from outside the closable chamber into the interior of the closable chamber.Position detection means is means capable of detecting whether a foreign object is inside or outside the closable chamber.The at least one device belonging to the additive manufacturing device that is turned off may be a mechanically movable part, a power source, a light emitting source, a laser source, an electron control source, more specifically, any device belonging to the additive manufacturing device that may be harmful to a human in operation.According to further embodiments of the invention, there is provided a further method of providing safety protection in an additive manufacturing apparatus for forming a three-dimensional article by successively fusing portions of a powder bed corresponding to successive cross-sections of the three-dimensional article in a closable chamber. The method comprises the steps of: providing a position detection device connected to a control unit, the position detection device being configured to detect whether a foreign object is located within the closable chamber; and upon detection that a foreign object is located within the closable chamber, providing energy to a powder suction device.At least one advantage of this embodiment is that the risk of a certified powder suction device for cleaning areas of reusable powder other than the sealable chamber being reduced.This implies that in case powder is wasted on the floor, for example, this powder cannot be collected by the same powder suction means as that intended to collect the powder inside the closable chamber. That is, clean powder can only be collected from one location by a first suction device for further use. Dirty powder from areas other than the closable chamber, which is not to be mixed with the clean powder, has to be collected by other means, for example a second powder suction device.In this regard, the inventive method automatically ensures that the closable chamber area is safe to work therein, but also reduces the risk of mixing clean and dirty powder.In an exemplary embodiment of the present invention, the position detection device is an electromagnetic radiation curtain provided at an opening of the closable chamber. The electromagnetic curtain may comprise at least one electromagnetic radiation source and at least one electromagnetic radiation sensor.The electromagnetic radiation source may be a laser source, an infrared source or a visible light source. The advantage of an electromagnetic curtain as a position detection device is that it represents a favorable, well known and reliable solution. The number of electromagnetic sources and detectors can be chosen arbitrarily. An advantage of a large number is that the dimension or even the structure of the object can be recognized.In another exemplary embodiment of the present invention, the position detection device may be a measurement arm or a robot arm capable of detecting the position in space.The robot arm or the measuring arm may operate in cooperation with the electromagnetic radiation curtain or without aid of the electromagnetic radiation curtain.In another exemplary embodiment, the method further comprises the step of providing a hose from the powder suction device to the robot arm.An advantage of this embodiment is that the likelihood of personal injuries and mixing of powder is reduced even further, since powder handling can be carried out without the aid of a human.In another exemplary embodiment of the present invention, the closable chamber is a vacuum chamber. By enclosing the powder bed in a vacuum chamber, an electron beam can be used as a source for fusing parts in the powder bed.In another exemplary embodiment of the present invention, the object is a nozzle of the powder suction device. That is, once the nozzle enters the closable chamber, one or more of the devices associated with the additive manufacturing apparatus are turned off while power is provided to the powder suction device.In another exemplary embodiment of the present invention, the method further comprises the step of turning on the powder suction device by pressing a switch. That is, the powder suction device needs to be actively turned on, and this can be performed only when a foreign object such as a nozzle of the powder suction device enters the closable chamber.In another exemplary embodiment of the present invention, the electromagnetic radiation source is a laser source, infrared source, or a visible light source. That is, any electromagnetic radiation source and a corresponding sensor sensitive to the electromagnetic radiation used may be used as a position detection sensor. The number of radiation sources and corresponding sensors can be arbitrarily selected from one to as many as fittable into the available space.In another exemplary embodiment of the present invention, the device is an electron beam and / or laser beam and / or powder distributor and / or vacuum pump and / or gas supply and / or work table. Disconnecting one or more of the aforementioned devices greatly enhances the service and operation of the additive manufacturing apparatus.In another exemplary embodiment of the present invention, the powder suction device is an external unit with respect to the closable chamber. That is, any suitable powder suction means may be used. The energy to the powder suction device may depend on the presence of a foreign object in the closable chamber.Another object of the present invention is to provide a safety guard in an additive manufacturing apparatus which reduces or eliminates the aforementioned safety problems.Embodiments of the invention also relate to a safety guard in an additive manufacturing apparatus for forming a three-dimensional article by successively fusing portions of a powder bed corresponding to successive cross-sections of the three-dimensional article in a closable chamber. The safety protection device comprises: a position detection device connected to a control unit, wherein the position detection device is configured to detect whether a foreign object is located within the closable chamber; and a switch for turning off at least one device associated with additive manufacturing apparatus, wherein the switch is controlled by the control unit and is activated when the position detection device detects that a foreign object is located within the closable chamber.In another embodiment of the invention, the safety device further comprises a powder suction device which is controlled by a control unit such that the powder suction device receives energy only when the position detection device detects that a foreign object is located within the closable chamber.In another exemplary embodiment, the detection device is an electromagnetic radiation curtain provided at an opening of the closable chamber, wherein the electromagnetic curtain comprises at least one electromagnetic radiation source and at least one electromagnetic sensor.In another exemplary embodiment, the sealable chamber is a vacuum chamber.In another exemplary embodiment, the position detection device may include a measurement arm or a robot arm capable of detecting the position in space, wherein the foreign object is a nozzle of the powder suction device provided on the robot arm.In another exemplary embodiment, the electromagnetic radiation source is a laser source, infrared source, or visible light source.In a further exemplary embodiment, the device is an electron beam and / or laser beam and / or powder distributor and / or vacuum pump and / or gas supply and / or work table.Further embodiments of the invention relate to a safety guard in an additive manufacturing apparatus for forming a three-dimensional article by successively fusing portions of a powder bed corresponding to successive cross-sections of the three-dimensional article in a closable chamber. The safety guard comprises: a position detection device connected to a control unit, the position detection device being configured to detect whether a foreign object is located within the closable chamber; and a powder suction device configured such that the control unit provides energy to the powder suction device only when the position detection device detects that a foreign object is located within the closable chamber.In certain embodiments, in which the position detection device is an electromagnetic radiation curtain provided at an opening of the closable chamber, this electromagnetic curtain comprises at least one electromagnetic radiation source and at least one electromagnetic radiation sensor. In at least one such embodiment, the at least one electromagnetic radiation sensors are positioned adjacent and spaced relative to each other substantially along an entirety of a first side of the opening; each of the at least one electromagnetic radiation sensors is positioned adjacent and relatively spaced relative to each other along substantially an entirety of a second side of the opening, the second side being disposed opposite the first side relative to the opening; and each of the at least one electromagnetic radiation sensors is configured to receive, based at least in part on its relative position, an emission from a corresponding one of the at least one electromagnetic sources, wherein transmission and reception of the emission defines the electromagnetic radiation curtain via the opening.More or less, the same advantages of the exemplary embodiment of the method apply to the exemplary embodiments of the devices.BRIEF DESCRIPTION OF SOME VIEWS OF THE DRAWINGSThe invention will be further described below in a non-limiting manner with reference to the accompanying drawings. Some reference numerals are used to identify corresponding similar parts throughout the several figures of the drawings: FIG. 1 illustrates a first exemplary embodiment of a device according to the present invention; FIG. 2 shows, in a schematic view, an exemplary embodiment of a device for producing a three-dimensional product, in which device the inventive method and the inventive apparatus can be used; FIG. 3 illustrates a second exemplary embodiment of a device according to the present invention; FIG. 4 illustrates a third exemplary embodiment of a device according to the present invention; and FIG. 5 illustrates an exemplary embodiment of a flow chart of an inventive method according to the present invention.DETAILED DESCRIPTION OF VARIOUS EMBODIMENTSVarious embodiments will be described in detail below with reference to the accompanying drawings, in which some, but not all, embodiments of the present invention are shown. Indeed, the various embodiments of the present invention may be expressed in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, the embodiments are provided so that this disclosure satisfies legal requirements.In order to facilitate understanding of the invention, a number of terms are defined below. Terms defined herein have meanings generally understood by a person of ordinary skill in the art in the relevant fields of the present invention.Terms such as "a", "an" and "the", etc. are not intended to refer to only a single entity, but include the general class for which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but the use thereof does not limit the invention except as set forth in the claims.The term "three-dimensional structures" and the like as used herein generally refer to intended or truly manufactured three-dimensional configurations (e.g., of structure, material, or materials) intended to be used for a particular purpose. Such structures or the like can be constructed, for example, using a three-dimensional CAD system.The term "electron beam" as used herein in various embodiments refers to any charged particle beam. The charged particle beam sources may include an electron gun, a linear accelerator, etc.Figure 2 illustrates an embodiment of a free form fabrication or additive manufacturing apparatus 21 in which the inventive method and apparatus according to the present invention may be implemented.This apparatus 21 comprises an electron beam gun 6; deflection coils 7; two powder containers 4, 14; a build platform 2; a build tank 10; a powder distributor 28; a powder bed 5; and a vacuum chamber 20.The vacuum chamber 20 is capable of maintaining a vacuum environment using a vacuum system, which system may comprise a turbomolecular pump, a scroll pump, an ion pump, or one or more valves well known to those skilled in the art and therefore need no further explanation in this context. The vacuum system is controlled by a control unit 8.The electron beam gun 6 generates an electron beam used for melting or fusing powder material provided on the build platform 2. At least a part of the electron beam gun 6 can be provided in the vacuum chamber. The control unit 8 may be used for controlling and directing the electron beam emitted by the electron beam gun 6. At least one focusing coil, not shown, at least one deflection coil 7, an optional coil, not shown, for astigmatism correction, and an electron beam power supply, not shown, may be electrically connected to the control unit 8. In an exemplary embodiment of the invention, the electron beam gun 6 generates a beamable electron beam having an accelerating voltage between about 15 to 60 kV and having a beam conduction in the range of 3 to 10 kW. The pressure in the vacuum chamber may be 10-3 mbar or less when the three-dimensional article is constructed by fusing the powder layer with the electron beam.The powder containers 4, 14 comprise the powder material to be provided on the build platform 2 in the build tank 10. The powder material may be, for example, pure metals or metal alloys, such as titanium, titanium alloys, aluminum, aluminum alloys, stainless steel, Co-Cr alloys, nickel-based superalloys, etc.The powder distributor 28 is arranged to deposit a thin layer of powder material on the build platform 2. During a working sequence, the build platform 2 is successively lowered with respect to a fixed point in the vacuum chamber. In order to enable this movement, the construction platform 2 is configured to be movable in the vertical direction, in particular in the direction indicated by the arrow P, in one embodiment of the invention. That is, the build platform 2 starts in a starting position in which a first layer of powder material of a required thickness is deposited. Means for lowering the build platform 2 can be, for example, a servo machine with a gear, adjusting screws, etc.An electron beam can be directed over this build platform 2, which causes the first powder layer to fuse in selected areas to form a first cross-section of the three-dimensional article. The beam is directed via the build platform 2 by instructions from the control unit 8. In the control unit 8, instructions are stored as to how the electron beam must be controlled for each layer of the three-dimensional article.After a first layer is completed, more specifically, the fusion of the powder material for manufacturing a first layer of the three-dimensional article, a second powder layer is provided on the build platform 2. The second powder layer is preferably dispersed in the same manner as in the preceding layer. However, alternative methods may also be present in the same additive manufacturing machine for distributing powder on the work table. For example, a first layer may be provided by a first powder distributor 28 and a second layer may be provided by another powder distributor. The shape of the powder distributor is automatically changed according to the instructions of the control unit 8. A powder distributor 28 in the form of a single rake system, more specifically, in which a rake receives powder falling from both a left powder container 4 and a right powder container 14, such a rake can change shape.After the second layer of powder is dispensed onto the build platform, the energy beam is directed over the work table causing the second layer of powder to fuse in selected areas to form a second cross-section of the three-dimensional article. Fused portions of the second layer may be joined to fused portions of the first layer. The fused areas of the first and second layers may be fused together not only by melting the powder in the uppermost layer, but also by re-melting at least a portion of the thickness of a layer located directly below the uppermost layer.In the case where an electron beam is used, it is necessary to take into account the charge distribution produced in the powder when the electrons are incident on the powder bed 5. The invention is based at least in part on the fact that the charge distribution density depends on the following parameters: beam current, electron velocity (which is determined by the acceleration voltage), beam scanning velocity, powder material and electrical conductivity of the powder, more precisely, primarily the electrical conductivity between the powder grains. The latter is in turn a function of several parameters, such as temperature, degree of sintering and powder grain size / size distribution.Thus, for a given powder, more precisely a powder of a particular material having a particular grain size distribution, and a given acceleration voltage, it is possible to influence the charge distribution by varying the beam current (and thus the beam power) and the beam scanning speed.FIG. 1 schematically illustrates an additive manufacturing apparatus 21 with the inventive safety protection device.The three-dimensional article may be manufactured within the closable chamber 20 by successively fusing portions of a powder bed whose portions correspond to successive cross-sections of the three-dimensional article, as previously described in connection with Figure 2. The closable chamber 20 includes a door 30. when the door is closed, a vacuum may be provided within the closable chamber. The vacuum may be achieved by one or more vacuum pumps, not shown, connected to the closable chamber.The safety protection device comprises a position detection device which is connected to a control unit 65 for detecting whether an foreign object is located within the closable chamber. In Fig. 1, the position detecting means is in the form of electromagnetic emitting means 50, 52, 54, 56, 68, 60 and electromagnetic sensors 70, 72, 74, 76, 78, 80. The sensors 70, 72, 74, 76, 78, 80 are connected to the control unit 65. The control unit registers whether each sensor receives the electromagnetic radiation emitted by the emitting devices 50, 52, 54, 56, 68, 60.The safety protection device further comprises a switch, not shown, for turning off at least one device belonging to the additive manufacturing apparatus 21 controlled by the control unit 65 when the position detection device 50, 52, 54, 56, 68, 60, 70, 72, 74, 76, 78, 80 detects that the foreign object is located within the closable chamber. A foreign object may be detected when one or more sensors 70, 72, 74, 76, 78, 80 do not receive electromagnetic radiation emitted by the emitting devices 50, 52, 54, 56, 68, 60, because the foreign object breaks the electromagnetic connection between the emitting devices 50, 52, 54, 56, 68, 60 and the sensor 70, 72, 74, 76, 78, 80. The foreign object is any part of the body or a tool. The tool can be, for example, a nozzle 40 of a powder suction device 35.The number of emitters in FIG. 3 is 6 as an example, however, any number of emitters and corresponding number of sensors may be used. Of course, using only one sensor in a wide opening would increase the risk that an object located in the closable chamber will not be detected. If a larger number of sensors and emitters are used that are close to each other, the sensors and emitters can be used to determine the size and shape of the foreign object that breaks the electromagnetic connection between the emitter 50, 52, 54, 56, 68, 60 and the sensor 70, 72, 74, 76, 78, 80.If at least one electromagnetic connection between the emission device 50, 52, 54, 56, 68, 60 and the sensor 70, 72, 74, 76, 78, 80 is broken, the control unit 65 receives a signal that the sensor(s) does not receive the signal of the emitter(s). The control unit 65 then separates at least one device associated with the additive manufacturing apparatus 21, for example an electron beam gun 6, a powder distribution system or any other mechanically moving member mounted inside or outside the closable chamber 20. The control unit also turns on the energy to the powder suction device 35 when at least one electromagnetic connection between the emitter 50, 52, 54, 56, 68, 60 and the sensor 70, 72, 74, 76, 78, 80 is broken.It requires a foreign object detected within the closable chamber 20 to supply power to the powder suction device, and the means for controlling this is the control unit 65. the powder suction device is useless as long as there is no foreign object within the closable chamber. The foreign object may be, for example, the nozzle 40 provided on a hose 37 connected to the powder suction device 35. This foreign object may also be a tool, any part of the human body or any other part which is moved from outside the closable chamber into the closable chamber.The actual turning on of the powder suction device may be performed by a turn-on switch 39 provided on the powder suction device 35 or in the vicinity of the nozzle 40. That is, it may require two events to turn on the powder suction device, first, it may be necessary for a foreign object to be located within the closable chamber 20 and, second, for a switch 39 to be activated (turned on).4 FIG. shows another exemplary embodiment of a position detection device. Here, the position detection device may be a robot arm or a measurement arm 90 (see also 3) having a first rotation axis 34 and a second rotation axis 32. A first arm 38 is provided between the first axis of rotation 34 and the second axis of rotation. A second arm 39 is provided with its first end on the second rotation axis. A second and second arm may include a gripping device 33. The powder suction hose 37 or powder suction nozzle 40 can be attached to the gripping device 33. The measurement arm can be made by Baces3D.In one embodiment, the distance between the powder suction device 35 and the additive manufacturing apparatus 21 is fixed. A first angle of the first arm 38 relative to a predetermined position and a second angle of the second arm 39 relative to the first arm 38 determines the position of the gripping device 33 (see also 3). Now, assuming that the gripping means grips the powder suction means at a predetermined position, the position of the nozzle can be determined from the first and second angles. There are a set of first and second angles for which the nozzle 40 can be said to be within the closable chamber 20, assuming that the gripping means 33 grips the hose 37 at a predetermined position, from which predetermined position the distance of the nozzle 40 is known. Once the gripping device 33 of the robot arm or measurement arm 90 or any tool attached to the gripping device is located within the closable chamber 20, the control unit 65 switches off at least one device 6 belonging to the additive manufacturing apparatus. The control unit 65 also turns on the power supply to the powder suction device 35 when the gripping device 33 of the robot arm or measurement arm 90 or any tool (such as the nozzle 40 of the powder suction device 35) attached to the gripping device is located within the closable chamber 20.Fig. 3 is a combination of the embodiments in Figs. 1 and 4. In 3, a robot arm or measurement arm 90 and electromagnetic emitters and sensors are used as position detecting means. The determination of the position of the gripping device 33 or of any tool attached to the gripping device can be determined in the same way as disclosed in connection with 4. The functionality of the electromagnetic emitting and sensing devices is identical to that disclosed in connection with 1. In FIG. 3, the power supply to a predetermined number of devices 60 belonging to the additive manufacturing apparatus 21 may be turned off when at least one of the electromagnetic sensors 70, 72, 74, 76, 78, 80 does not receive electromagnetic radiation of the corresponding emitters 50, 52, 54, 56, 68, 60. In contrast, in order to provide energy to the powder suction device 35, it not only requires that at least one of the sensors does not receive electromagnetic radiation from the corresponding emitters. It also requires that the gripping device or a predetermined part of the robot or measurement arm is determined to be located within the lockable chamber based on the position of the measurement or robot arm. This embodiment has the advantage that the powder suction device cannot be operated in a "wrong" area, in order to thereby make it possible to collect, for example, dirty powder from the ground. In Figure 3, the gripping device or any tool attached to the gripping device, such as the hose of the powder suction device, must be identified within the closable chamber in order to provide energy to the powder suction device. The actual activation of the powder suction device can take place automatically, more precisely as soon as the nozzle is determined to be located within the closable chamber. Another alternative for turning on the powder suction device is to press a switch on. The switch-on will, however, be active only when the nozzle is determined to be within the closable chamber.FIG. 5 schematically illustrates an exemplary embodiment of a flow chart of an inventive method for providing safety protection in an additive manufacturing apparatus according to the present invention.In a first step 502, a position detection device is provided, which is connected to a control unit for detecting whether a foreign object is located within the closable chamber. The position detection device may be a robot arm or measurement arm and / or at least one electromagnetic sensor device and corresponding electromagnetic emitting device, as disclosed above.It is then determined whether a foreign object is located within the closable chamber 20. The question to be answered in box 504 is any foreign object within the closable chamber? If the answer is NO, this question is reasserted within a predetermined time interval. The time window may be in a range of microseconds. If the answer is YES, a foreign object is located within the closable chamber 20, the method proceeds to the second step 506. In the second step 506, at least one device of the additive manufacturing apparatus is turned off. When this step has been performed, the method proceeds to the third step 508. In the third step 508, energy is supplied to the powder suction device.In an alternative embodiment of the method, the at least one device belonging to the additive manufacturing device is switched off when at least one of the sensors 70, 72, 74, 76, 78, 80 does not receive electromagnetic radiation emitted by the corresponding emitters 50, 52, 54, 56, 68, 60. The energy is provided to the powder suction device when the gripping device or any predetermined part of the measurement arm or robot arm or a tool attached to the gripping arm is determined to be within the closable chamber 20.In a further alternative embodiment of the method, this at least one device belonging to the additive manufacturing device is switched off, for example when the gripping device of the robot arm or measurement arm or a tool attached to the gripping arm is determined to be located within the closable chamber 20. The power is supplied to the powder suction device when the gripping device of the robot arm or measurement arm or a tool attached to the gripping arm is determined to be located inside the closable chamber 20.The invention is not limited to the embodiments described above, and adaptations are possible within the scope of the following claims. Such adjustments may be, for example, using a source of energy beams other than the example electron beam, such as a laser beam. Materials other than metal powder may be used, such as polymer powder or ceramics powder. Indeed, one skilled in the art might be able to use the information in the preceding text to modify various embodiments of the invention into ways that are not described literally but are nevertheless encompassed by the appended claims, as they achieve substantially the same functions to achieve substantially the same results. Therefore, it is to be understood that the invention is not limited to the specific embodiments disclosed and that the modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are used herein, they are used in a generic or descriptive sense only and not for purposes of limitation.

Claims

A method of providing safety protection in an additive manufacturing apparatus (21) for forming a three-dimensional article by successively fusing parts of a powder bed (5) corresponding to successive cross-sections of the three-dimensional article in a closable chamber (20), the method comprising the steps of: providing position detection means connected to a control unit (65), the position detection means being configured to detect whether a foreign object is within the closable chamber (20), the foreign object being part of a body or a tool; and upon detection that a foreign object is located within the closable chamber (20), switching off at least one device associated with the additive manufacturing apparatus (21) via the control unit (65), or providing energy to a powder suction device (35) via the control unit (65).The method of claim 1, wherein the position detection device is an electromagnetic radiation curtain provided at an opening of the closable chamber (20), and the electromagnetic curtain includes at least one electromagnetic radiation source and at least one electromagnetic radiation sensor, each of the at least one electromagnetic radiation sensors being configured to receive an emission from a corresponding one of the at least one electromagnetic radiation sensors so as to form the electromagnetic curtain.Method according to claim 1, wherein the position detection device is a measurement arm (90) and / or a robot arm which is capable of determining the position in space.The method of claim 3, wherein: the method further comprises the step of providing a hose (37) of the powder suction device (35) to the robotic arm; and the step of disabling at least one device associated with the additive manufacturing apparatus (21) occurs when the hose (37) enters the closable chamber (20).The method of claim 1, wherein the closable chamber (20) is a vacuum chamber.The method according to claim 1, wherein the foreign object is a nozzle (40) of the powder suction device (35).The method of claim 1, further comprising the step of, upon providing the power to the powder suction device (35), turning on the powder suction device (35) by pressing a mechanical switch.Method according to claim 2, wherein the electromagnetic radiation source is a laser source and / or an infrared source and / or a visible light source.Method according to claim 1, wherein the means associated with the additive manufacturing device (21) is an electron beam and / or a laser beam and / or a powder distributor and / or a vacuum pump and / or a gas supply and / or a work table.The method of claim 1, wherein the powder suction device (35) is an external unit with respect to the closable chamber (20).A safety guard in an additive manufacturing apparatus (21) for forming a three-dimensional article by successively fusing parts of a powder bed (5) corresponding to successive cross-sections of the three-dimensional article in a closable chamber (20), the safety device comprising: position detection means connected to a control unit (65), the position detection means being configured to detect whether a foreign object is located within the closable chamber (20); wherein the foreign object is a part of a body or a tool; and a switch for turning off at least one device associated with the additive manufacturing apparatus (21), wherein the switch is controlled by the control unit (65) and activated when the position detection device detects that the foreign object is inside the closable chamber (20), or wherein the control unit (65) is configured to provide energy to a powder suction device (35) only when the position detection device detects that the foreign object is inside the closable chamber (20).Safety protection device according to claim 11, wherein the position detection device is an electromagnetic radiation curtain provided at an opening of the closable chamber (20), the electromagnetic curtain comprising at least one electromagnetic radiation source and at least one electromagnetic radiation sensor.The safety guard of claim 12, wherein: each of the at least one electromagnetic radiation sensors is positioned adjacent to and relatively spaced apart from each other substantially along an entirety of a first side of the opening; each of the at least one electromagnetic radiation sensors is positioned adjacent to and relatively spaced apart from each other substantially along an entirety of a second side of the opening, the second side being disposed opposite the first side relative to the opening; and each of the at least one electromagnetic radiation sensors is configured to receive an emission from a corresponding one of the at least one electromagnetic radiation sources based at least in part on its relative positioning, wherein the emission emission emission and the emission receipt define the electromagnetic radiation curtain across the opening.Safety protection device according to claim 11, wherein the closable chamber (20) is a vacuum chamber.A safety guard according to claim 11, wherein: the position detection means is a measurement arm (90) and / or robot arm, at least a part of the measurement arm (90) and / or robot arm being configured to determine the position thereof in space; and the foreign object is a nozzle (40) of the powder suction means (35) which is relatively fixed with respect to the robot arm in use.Safety protection device according to claim 12, wherein the electromagnetic radiation source is a laser source and / or an infrared source and / or a visible light source.Safety protection device according to claim 11, wherein the device associated with the additive manufacturing device (21) is an electron beam and / or a laser beam and / or a powder distributor and / or a vacuum pump and / or a gas supply and / or a work table.

Images