Conveying device for powdered construction material

Abstract

The invention relates to a conveying device (40) for a device (1) for additive manufacturing of a construction material (13, 13 ', 15) into at least one component (2) by selectively at least partially solidifying the construction material (13) in powder form. The conveying device (40) has a chain-driven conveyor (50), preferably a chain conveyor (50), for conveying the building material (13 ') in the device (1), the conveyor having at least one gear (51). At least one inter-tooth region (52) between two adjacent teeth (57, 57 ') of the gear (51) comprises an avoidance space (54, 54') for the powdered construction material (13 '). The invention further relates to a device (1) for additive manufacturing of at least one component (2) and to a method for additive manufacturing of at least one component (2).

Description

Technical Field

[0001] The present invention relates to a conveying device for additively manufacturing at least one component from a powdered building material by selectively at least partially solidifying the powdered building material, a device for additive manufacturing having a conveying device, and a method for additively manufacturing at least one component. Background Art

[0002] Additive manufacturing processes are becoming increasingly important in the production of prototypes and also in series production. Generally speaking, an "additive manufacturing process" should be understood as a manufacturing process in which a manufactured product is built up by depositing materials, also called building materials, usually based on digital 3D design data. The manufactured product is usually and will be referred to below as a component. In this case, the construction is usually, but not necessarily, carried out layer by layer. As a synonym for additive manufacturing, the term "3D printing" is also often used. The production of models, samples and prototypes using additive manufacturing processes is often referred to as "rapid prototyping", the production of molds is called "rapid tooling", and the flexible production of series components is called "rapid manufacturing".

[0003] A key aspect of additive manufacturing processes based on powdered materials ("powder-based") is the selective solidification of the powdered building material. This solidification can often be achieved by irradiation with radiation energy (e.g., electromagnetic radiation, particularly light and / or heat radiation), but also, where appropriate, with particle radiation (e.g., electron radiation). Examples of additive manufacturing processes that utilize radiation include "selective laser sintering" or "selective laser melting." Thin layers of a typically powdered building material are repeatedly applied one above the other. Within each layer, spatially limited irradiation is applied to a location that, after fabrication, should constitute the component to be produced. This selective solidification occurs by partially or completely melting the powder particles of the building material at that location by means of the energy introduced locally by the radiation. During cooling, these powder particles subsequently solidify together to form a solid. In most cases, the energy beam is directed along a solidification path across the building field, and the remelting or solidification of the material in the respective layer occurs correspondingly in the form of "weld paths" or "weld beads," so that ultimately, a plurality of these (component) layers formed by these weld paths are present in the component.

[0004] Typically, to produce a component, a larger volume of powdered building material than is actually required for component production is initially provided in the processing chamber. In particular, but not exclusively, when applying the building material layer by layer, a reserve can be provided in the respective material layers to avoid a shortage of building material in the component layer. To enable the reuse of excess, i.e., unused, building material, additive manufacturing machines are known in which the excess building material is collected in a first container located near the build site and then transferred by means of a transport device to a larger, second collection container, which is typically located further away from the build site.

[0005] Known transport devices, such as screw conveyors, can suffer from the disadvantage that excess build material is relatively slow to be removed from the heat-affected zone of the additive manufacturing machine. This can lead to heat-related damage and severe powder degradation, particularly for plastic-based build materials, which negatively impacts recycling rates. Frictional heat generated during operation of the screw conveyor can also reduce powder quality. During operation, build material can stick to the screw, reducing the conveying capacity of the screw conveyor.

[0006] In transport systems with chain conveyors, powdered build material often adheres to the sprockets or chains, becoming compacted at least where the chain meshes with the sprockets. This can result in difficult-to-remove buildup, such as particles of build material, which at least partially solidify under pressure and / or heat, forming agglomerates. This can cause the chain to jump during operation, which can lead to downtime or failure of the transport system. This problem is prevalent in chain conveyors used to transport powdered build material in additive manufacturing machines, regardless of the direction the build material is transported within the machine or the location of the chain conveyor within the machine. Summary of the Invention

[0007] The object of the present invention is to provide a conveying device for the additive production of components from powdered building material, a device having a conveying device, and a method for the additive production of components, by means of which at least some of the above-mentioned disadvantages can be reduced or avoided.

[0008] This object is achieved by a conveying device according to claim 1 , a device according to claim 13 and a method according to claim 15 .

[0009] The conveying device according to the invention is designed to operate in an apparatus for additively manufacturing a three-dimensional component from a powdered building material by selectively at least partially solidifying the building material. The conveying device is designed to cooperate with other components of the apparatus (hereinafter referred to as additive manufacturing apparatus or AM machine for short) during the additive production of the corresponding component. The conveying device is structurally adapted to the conditions in the processing chamber of the AM machine during the additive manufacturing process. The conveying device can preferably be reversibly integrated into the AM machine. Preferably, the conveying device can be designed as a removable machine component for charging the AM machine.

[0010] The conveyor device is designed to convey powdered build material within the AM machine, particularly when installed therein. Conveying powdered build material means transporting the build material within the AM machine, particularly between two or more different locations. In this description, powdered build material is synonymous with powder.

[0011] According to one embodiment of the present invention, the conveying device can be designed, in particular can be installed in an AM machine, so that powder is transported in the direction of the build field of the AM machine. In particular, the conveying device can be designed and / or can be installed so that (fresh) powder is fed to an application device of the AM machine by means of the conveying device, which applies the powder to the build field in the processing chamber of the AM machine during additive manufacturing. Thus, the conveying device can be designed and / or can be installed so that powdered building material is transported to the processing location in the AM machine by means of the conveying device. Correspondingly, the conveying device can be integrated into the process of applying the building material to the build field of the AM machine.

[0012] According to one embodiment, the conveying device is alternatively or additionally designed, in particular capable of being installed in the AM machine, such that building material can be transported away from the building field of the AM machine. In particular, the conveying device can be designed and / or capable of being installed in such a way that unused or excess powder is diverted away from the direct vicinity of the building field. Unused or excess building material is understood in particular to be that part of the powder on the building field that is not used to form a component. When powder is applied layer by layer to the building field, unused or excess building material corresponds in particular to the part of the powder that is not used to build the powder layer of the corresponding application process. In this case, the unused building material (also called material residue) can be diverted as a reserve or surplus in front of the coater of the AM machine and discharged from the building field at the end of the application process. Alternatively, or preferably in addition, unused build material that was applied to the build field during the (first) powder application and was not cured during the subsequent irradiation process can be removed from the build field (as unused build material) during the subsequent (second) powder application and / or by the movement of the AM machine's coater, in particular by the coater. Furthermore, it is possible, for example, that during the application process, some build material (e.g., due to an error) is not applied to the build field, but rather is applied to the immediate vicinity of the build field, whereby such build material is also referred to as unused build material. Accordingly, the conveyor device can be designed and / or mounted such that unused powder, in particular uncured powder, is removed from the build field of the AM machine by means of the conveyor device. Preferably, the conveyor device can be designed and / or mounted in the (direct) vicinity of the build field, so that powder removed from the build field, for example, after the application process and / or by the coater as it moves over the build field, can be removed from the build field by the conveyor device.

[0013] In order to transport powder in the AM machine, the conveying device has at least one chain-driven conveyor. The chain-driven conveyor includes at least one, preferably several chains, in particular roller chains. In addition, the chain-driven conveyor includes at least one, preferably several, gears. The corresponding gears are preferably implemented as sprockets. During operation of the conveying device, the gears, in particular the sprockets, engage with the associated chains. The chain-driven conveyor preferably has at least one conveying element that acts in conjunction with the chain and is used to move the building material. In addition, the chain-driven conveyor preferably includes a controllable drive device, such as an electric motor, in order to move at least one chain to transport the building material. The chain-driven conveyor can preferably be implemented as a chain conveyor.

[0014] According to the invention, at least one inter-tooth region of a gear (preferably a sprocket) comprises a clearance space for powdered building material between two adjacent teeth or two teeth arranged side by side at a distance in the circumferential direction of the gear. Preferably, the clearance space can be formed by at least a portion of the inter-tooth region of the gear itself. An inter-tooth region is a region of the gear located between two adjacent or consecutive teeth. In particular, an inter-tooth region can be a (material) region of the gear located between two facing tooth flanks of two adjacent teeth and / or between two tooth roots of two adjacent teeth.

[0015] The escape space is particularly designed so that the chain meshing with the gear is spaced apart from the material body of the inter-tooth region in the region of the escape space. This means that the chain meshing preferably does not directly contact the inter-tooth region in the escape space.

[0016] The escape space is particularly designed so that the chain meshing with the gear is spaced apart from the powdery building material present in the escape space. This means that the meshing chain preferably does not directly contact the powdery building material present in the escape space.

[0017] The escape space is preferably designed to guide powdered building material that strikes the escape space during operation away from the interdental area and / or to temporarily accommodate the building material therein. Contact between the powder and the escape space can occur during operation of the conveyor device and / or during operation of an AM machine having a conveyor device, i.e., by powder being flung toward or spilling onto the escape space. Accordingly, the escape space can preferably be designed such that powder that strikes the escape space is guided away from the escape space by gravity, in particular by sliding down.

[0018] Advantageously, the conveying device according to the present invention can be used to achieve the fastest possible transport of build material within the AM machine, for example, compared to known screw conveyors. This has the advantage of reducing powder aging, particularly during the introduction of powder into the heat-affected zone and / or during the removal of powder. This can have a positive impact on the material properties of fresh (i.e., still to be processed) build material. Furthermore, by rapidly removing excess build material from the heat-affected zone, powder recovery can be improved.

[0019] Furthermore, the clearance space can advantageously reduce the critical areas of the gears susceptible to powder adhesion compared to known gears. Critical areas are, in particular, those surface areas of the gears that are subject to tension and / or pressure from the chain during operation of the conveyor system. In known devices, during operation, powder accumulation and subsequent compaction by the chain can lead to large, difficult-to-remove adhesions on the gears, particularly in the chain contact area of ​​the gears, which can be located between the teeth. The chain contact area corresponds to the contact zone between the gear and the chain meshing with it. The chain contact area is the portion of the gear surface that is directly contacted by the chain during operation of the conveyor system. Advantageously, the clearance space within the inter-tooth area (as the critical area) can minimize the surface area of ​​the gears where adhesions are likely to occur. This can at least reduce unwanted adhesions on the gears compared to known gears, which can have a beneficial effect on the proper functioning of the chain and the trouble-free operation of the conveyor system. By reducing the accumulation and adhesion of powder on the gears, it can also be achieved that less adhesions form on the chain.

[0020] An apparatus for additive manufacturing of at least one component according to the present invention comprises a feed device for feeding powdered build material into a processing chamber, an irradiation device for selectively at least partially solidifying the powdered build material by irradiation with at least one energy beam, and at least one conveyor device according to the present invention. The AM machine may preferably have two or more individually controllable conveyor devices. Preferably, the two conveyor devices may be arranged on opposite sides of a build container of the AM machine.

[0021] The corresponding conveying devices can have different functions in the AM machine. For example, a first conveying device can be designed to transport (fresh) powder to the processing location in the AM machine, while a second conveying device can be designed to guide excess powder away from the AM machine's build field.

[0022] A method according to the invention for additive manufacturing of at least one component, preferably a plurality of components, comprises at least the following steps which are repeated:

[0023] In one step, a powdered build material is introduced into the processing chamber of an AM machine, in particular by applying the build material layer by layer onto a build field. In a further step, the build material is selectively irradiated with at least one energy beam in order to selectively, at least partially, cure the build material to form a component layer. Partial curing of the previously applied build material of the powder layer is preferably performed by selectively irradiating the powder layer with the energy beam at locations corresponding to the cross-section of the component to be produced.

[0024] In a next step, the building material is conveyed into the AM machine using a conveyor device, in particular a conveyor device according to the present invention. The conveyor device comprises at least one chain-driven conveyor, preferably a chain conveyor, having at least one gear, preferably a sprocket, wherein at least one inter-tooth region of the gear, between two adjacent teeth of the gear, comprises an escape space for powdered building material. The method is preferably performed such that powder that comes into contact with the escape space is directed away from the inter-tooth region through the escape space and / or is temporarily contained therein. The method is preferably performed in an apparatus according to the present invention for additive manufacturing.

[0025] Furthermore, in the method, it can be provided that excess building material, in particular excess building material of the corresponding powder layer, is transferred to an intermediate container of the conveying device. Excess building material can be transported from the intermediate container to an overflow container assigned to the conveying device by means of the conveying device.

[0026] Advantageously, the AM machine, production method, and conveyor device according to the present invention are based on the same inventive concept. This inventive concept consists of a conveyor device for an AM machine, comprising a chain-driven conveyor having at least one gear, wherein at least one inter-tooth region of the gear comprises a clearance space for powdered building material. Consequently, this AM machine and production method also achieve the advantages described with respect to the conveyor device.

[0027] Other particularly advantageous designs and improvements of the present invention are revealed in the dependent claims and the subsequent description, wherein the independent claim of one claim category can also be improved similarly to the dependent claims and embodiments of another claim category, and in particular, individual features of different embodiments or variants can also be combined into new embodiments or variants.

[0028] The conveying device can be used in different AM machines, regardless of the operating principle. For a better understanding, the present invention is described below with the help of an AM machine and a production method, but not limited thereto, in which a powdered building material is applied layer by layer to a building field and then selectively solidified. Correspondingly, in an AM machine or a production method, several material application planes or material layers can be built up in sequence in the building field. The building material can be a polymer-based powder. However, the present invention is not limited thereto, but also includes other powdered building materials. For example, metal powder, ceramic powder, filler or mixed powder, sand and mixtures of different materials can be used.

[0029] To produce a component, the building material of each previously applied material layer is cured by irradiating the building material with at least one energy beam generated by an irradiation unit. This refers to a photon or particle energy beam, such as a light beam or electron beam. In principle, the AM machine can also have multiple irradiation devices, which can be controlled in coordination with control data. Furthermore, the energy beam can consist of multiple superimposed beams. Preferably, each layer of the building material is selectively cured by selectively irradiating locations corresponding to the cross-section of the component to be produced.

[0030] The AM machine preferably comprises a removable build container or an exchangeable frame for accommodating the build material. Preferably, the build container can form a build field, in particular an area of ​​the build container located inside the opening. The AM machine preferably has a coater for applying the build material layer by layer to the build field. The coater is preferably part of the feed device. The AM machine preferably has other components that are generally known in additive manufacturing devices and are therefore not described in detail. This particularly relates to a control device that controls all components of the AM machine to produce a component, in particular according to the described production method. Preferably, the control device of the AM machine can be designed to also control the operation of the conveying device.

[0031] As previously mentioned, the additive manufacturing apparatus includes at least one conveyor device. The conveyor device is preferably designed, and in particular, arranged in the processing chamber of the AM machine, so as to remove unused or excess build material from the build field in the processing chamber of the AM machine. The unused or excess build material may include at least build material that was not used to build the powder layer during the (corresponding) application process, and / or may include at least build material that was applied to the build field during the (first) powder application process, was not cured during the subsequent irradiation process, and was discharged from the build field during the subsequent (second) powder application process and / or by movement of the AM machine's coater.

[0032] Preferably, excess build material can be transported from an intermediate container of the conveyor device to an overflow container assigned to the conveyor device by means of a conveyor device. The intermediate container is designed to accommodate at least the material residues of a single coating process. The intermediate container is preferably arranged in the direct vicinity of the build field. Preferably, the intermediate container can be directly adjacent to or connected to the build container. The intermediate container can extend along the entire side of the build field, for example along the entire longitudinal or transverse section of the build field. In particular, the intermediate container can be arranged such that the upper side or upper edge of the intermediate container is flush with the current working plane of the AM machine or slightly below this working plane (in the vertical direction).

[0033] Accordingly, a preferred production method can provide for (fresh) powder to be applied layer by layer on the build field, wherein excess building material, in particular excess building material of the respective powder layer, is transferred to an intermediate container of a conveyor device, and the excess building material is transferred from the intermediate container to an overflow container, also called a receiving container, by means of the conveyor device. To apply the powder layer to the build field, a coater can be guided over the build field as a movable crossbeam at a distance corresponding to the predetermined layer thickness, thereby advancing a portion of powder and substantially consuming it. At the end of the respective application process, the excess building material introduced in front of the coater can be discharged from the build container and transferred to an intermediate container in an adjacent area of ​​the build field.

[0034] While conveyor systems are generally designed for transporting powdered building material in AM machines, advantageous developments of these systems will be described with reference to conveyor systems for removing excess powder, but are not limited thereto. DE 10 2017 126 665 A1 discloses a conveyor system that, while not specifically a chain-driven conveyor, nonetheless achieves a similar purpose. Reference is made to the aforementioned patent application, the contents of which are hereby incorporated into the present application.

[0035] In principle, an AM machine can have two or more conveyor devices. The corresponding conveyor device can preferably be arranged in the direct vicinity of the build field, for example, directly adjacent to the build field. Depending on the working mode of the coater, that is, whether the layers are built only in one working direction or in two opposite directions, the AM machine can include one or two conveyor devices. If two conveyor devices are provided, they are preferably each located behind the build container in the working direction of the coater. The present invention is described below with reference to an AM machine with only one conveyor device, so in principle, the arrangement of several conveyor devices should also be covered in this sense.

[0036] The chain-driven conveyor of the conveying device can preferably have two, in particular four, sprockets. Preferably, during operation, each of the two sprockets meshes with an endless chain. The present invention is described below with the aid of a roller chain (as a chain) and a sprocket (as a gear), but is not limited thereto. In principle, other types of chains can also be used, such as chains in which the sleeve meshes with the teeth of the sprocket, chains with offset structures, sealed chains, etc. The advantageous improvements described with the aid of a single sprocket can be applied in the same way to multiple sprockets. It should be pointed out that the conveying device can in principle also have different sprockets, in particular with regard to the design of the avoidance space. For example, in addition to the sprocket according to the invention, the conveying device can also additionally have at least one conventional gear, i.e. a gear without a special inter-tooth area, for example, if this gear is rarely or not at all affected by the powder during operation due to positional factors.

[0037] The corresponding sprocket (as a gear) can preferably have two or more spaced-apart, preferably different, escape spaces for impinging powdered building material. Preferably, a separate escape space can be formed between each of two adjacent teeth of the sprocket. Preferably, a separate escape space can be arranged in each inter-tooth region of the sprocket. The present invention will be described below using the aforementioned sprocket, but is not limited thereto. The different escape spaces of the same sprocket can have different designs.

[0038] The escape space for impinging powdered building material can include a relief in the interdental area. It is possible for the escape space to be implemented as a relief. The relief can preferably be formed by a material recess in the material body of the interdental area. Different reliefs can be formed in the respective interdental areas.

[0039] According to one embodiment of the present invention, the corresponding relief space can have a lowering surface designed to guide or direct building material away from the inter-tooth region of the sprocket. In particular, the lowering surface can guide powder away from at least certain areas of the inter-tooth region. The lowering surface can preferably be formed by a relief portion within the inter-tooth region. Preferably, the lowering surface can be formed from the material of the inter-tooth region itself. Accordingly, the lowering surface can be a portion of the inter-tooth region.

[0040] The respective sliding surfaces are preferably designed so that powder that strikes them slides down them due to gravity, thereby being drawn away from the inter-tooth area. Thus, in this embodiment, the respective sliding surfaces can form a "sloping bottom" that provides a clearance for the powder. The individual sliding surfaces can preferably be separated from each other by the teeth of the sprocket. Preferably, a single sliding surface can be formed between all adjacent teeth. The sliding surfaces of the same sprocket can, in principle, be designed differently.

[0041] Preferably, the corresponding lower runner surface can be formed by the tooth gap bottom surface between two adjacent teeth of the sprocket (as a gear). Depending on the design, the corresponding lower runner surface can completely connect two adjacent teeth to each other. This means that the lower runner surface can extend from one tooth to the adjacent tooth along the longitudinal extension of the tooth gap bottom surface (the longitudinal extension of the tooth gap bottom surface has a circumferential direction, i.e., orthogonal to the radius of the sprocket).

[0042] The tooth gap bottom is generally understood to be the (material) area of ​​the sprocket that connects two teeth arranged side by side. The tooth gap bottom is the material area of ​​the sprocket that connects two opposite tooth flanks of two adjacent teeth to each other, in particular without transition.

[0043] The corresponding tooth groove bottom surface of the sprocket preferably includes an upper side surface that points away from the sprocket midpoint. The upper side surface of the tooth groove bottom surface can preferably be aligned substantially parallel to the rotation axis of the sprocket. Preferably, the (same) tooth groove bottom surface can have an upper side surface of the tooth groove bottom surface that is substantially parallel to the rotation axis of the sprocket and at least one lower lower surface.

[0044] Preferably, to form a lower sliding surface between two adjacent teeth, the corresponding sprocket (as a gear) can have a material cross-section that tapers toward the corresponding tooth gap bottom surface. In particular, the material cross-section of the sprocket can decrease radially outward in the direction of the side surface of the corresponding tooth gap bottom surface. For example, the material cross-section can taper radially outward, preferably toward the side surface of the tooth gap bottom surface, starting from the midpoint of the sprocket or from another point radially spaced from the center of the sprocket.

[0045] The inter-tooth region can, in particular, include a relief portion in the tooth groove bottom surface, so that a lower sliding surface can be formed by means of the relief portion. Particularly preferably, the inter-tooth region can include a tooth groove bottom surface having an upper side surface of the tooth groove bottom surface and an adjacent lower sliding surface. This means that by forming the relief portion, the width and / or area of ​​the tooth groove bottom surface, in particular the side surface of the tooth groove bottom surface, can be reduced to a certain extent (compared to the original tooth groove bottom surface). In principle, at least a portion of the tooth groove bottom surface can also be formed by the lower sliding surface.

[0046] Advantageously, if the sprocket has a sliding surface, the most trouble-free and reliable operation of the conveying device can be achieved in a simple and at the same time effective manner. The tooth groove bottom surface is usually a critical area of ​​the sprocket where powder easily accumulates and adheres. Advantageously, due to the gradually tapering material area or material cross-section, the area of ​​the corresponding tooth groove bottom surface, in particular the area of ​​the side surface on the tooth groove bottom surface, can be designed to be relatively small compared to traditional sprockets. As a result, the area of ​​the tooth groove bottom surface can be as small as possible for potential adhesion or accumulation. Preferably, the powder that hits the sliding surface can be drawn off the sliding surface as completely as possible by gravity and / or due to the rotational movement of the sprocket, thereby avoiding a larger accumulation of powder. Another advantage can be that the sliding surface adjacent to the side surface of the (reduced) tooth groove bottom surface can also support the drawing off of powder from the side surface of the tooth groove bottom surface.

[0047] In order to form a corresponding lower runner, the sprocket of the conveying device (as a gear) can have one or more of the elements described below, wherein a combination of these elements in the same gear is also possible.

[0048] The sprocket can have at least one downwardly directed surface as a downwardly directed surface, wherein the downwardly directed surface originates from the tooth gap bottom surface. Preferably, the downwardly directed surface can have its origin in the tooth gap bottom surface and / or can contact the tooth gap bottom surface. In particular, the downwardly directed surface can be (directly) connected to the upper side surface of the tooth gap bottom surface. Preferably, the downwardly directed surface is formed by a (material) region of the sprocket that extends radially or obliquely radially inward from the tooth gap bottom surface, in particular from the upper side surface of the tooth gap bottom surface, i.e., in the direction of the rotation axis of the sprocket.

[0049] Preferably, a (corresponding) glide plane can have two or more (sub-)regions as a glide surface, wherein the individual (sub-)regions are designed differently, in particular geometrically. These (sub-)regions can, for example, be radially adjacent to one another, i.e., form different "radial segments" of the glide surface.

[0050] Preferably, the sliding plane can be arranged obliquely to the tooth longitudinal extension of the adjacent tooth. For example, the sliding plane can form an inclined surface with respect to the tooth longitudinal extension. The tooth longitudinal extension is understood to be the longest extension of the tooth in the radial direction.

[0051] Preferably, the gliding plane is arranged obliquely relative to the longitudinal extension of the tooth, particularly with respect to its longitudinal extension. The angle of inclination relative to the longitudinal extension of the associated tooth can be, for example, at least 30°, preferably at least 40°, preferably at least 45°, particularly preferably at least 50°, in particular 60° or more. The gliding plane can have a constant angle of inclination relative to its longitudinal extension. It may also be possible for the gliding plane to have different angles of inclination relative to its longitudinal extension.

[0052] The term "downward sliding plane" or its longitudinal extension is understood to mean the longest extension of the downward sliding plane, starting from the tooth gap base, preferably the upper side surface of the tooth gap base, in the direction of the sprocket's axis of rotation, i.e., in the radial or obliquely radial direction. For example, the sprocket can have a material cross-section in the region of the downward sliding plane in the form of a right-angled trapezoid. In this case, the short base of the trapezoid can form the upper side surface of the tooth gap base, with the oblique side (not perpendicular to the base) forming the downward sliding plane.

[0053] Alternatively or additionally, the sprocket (as a gear) can have at least two downwardly directed planes as downwardly directed planes, starting from the same tooth gap bottom surface. These downwardly directed planes are arranged obliquely to the longitudinal extension of the tooth on opposite sides of the sprocket, each forming a specific angle with respect to the longitudinal extension of the tooth. Accordingly, the two downwardly directed planes each form a specific (and possibly different) angle with respect to the longitudinal extension of the tooth.

[0054] In this embodiment, the inter-tooth region comprises two independent lowering planes or lowering surfaces, which together form the clearance space. The two lowering planes can directly contact each other, forming the upper side surfaces of the tooth gap bottom surface. The material thickness of the tooth gap bottom surface (at least in certain areas) can be several times lower than the material thickness of the tooth, particularly in the area of ​​the tooth root.

[0055] However, it is also possible in principle for the two lowering planes to extend on both sides of the tooth gap base (without forming the upper side of the tooth gap base itself). For example, the sprocket can have a material cross-section in the form of an isosceles trapezoid in the area between the teeth. In this case, the short base of the trapezoid can form the tooth gap base, in particular the upper side of the tooth gap base, wherein each oblique side forms a lowering plane.

[0056] Preferably, the (inner) angle between the respective rundown plane and the longitudinal extension of the tooth (i.e., in the radial direction of the gear or in the direction perpendicular to the axis of rotation of the sprocket) can be at least 15°, preferably at least 30°, preferably at least 45°, and / or at most 75°, preferably at most 65°, particularly preferably at most 60°. In principle, as will be explained below, the inclination angle of the rundown plane in the inter-tooth region can also vary in the radial direction (with respect to the direction perpendicular to the axis of rotation of the sprocket), for example, in steps or continuously (in the form of an arc).

[0057] Therefore, the gear can have at least one curved, preferably concave, sliding surface as a sliding surface, starting from the tooth gap bottom surface, in particular from the upper side of the tooth gap bottom surface. Preferably, the sliding surface can be designed to be concave at least in sections along its longitudinal extension. Alternatively or additionally, the sliding surface can have a curved, in particular concave surface in a transverse extension, which is orthogonal to the longitudinal extension of the sliding surface. The ratio of the radius of curvature of the (concave) sliding surface in the direction of the (radial) longitudinal extension and / or transverse extension to the gear radius can be at least 1:8, preferably at least 1:4, particularly preferably 1:2 and / or at most 8:1, preferably at most 4:1, particularly preferably 2:1.

[0058] Preferably, the curvature and / or slope of the sliding plane can be compatible with or adapted to other structural parameters of the gear. For example, the height of the sliding plane in the radial direction (i.e., the direction perpendicular to the axis of rotation) can be affected by the specific curvature or specific slope of the sliding plane and the thickness of the gear. In the case of determining geometric conditions, such as when the slope on a specific radial section needs to be achieved according to a certain curvature radius, a certain parameter can even be indirectly determined by other parameters. For example, if two parameters (thickness and curvature or slope) are determined, the third parameter (height) can be automatically given. In other words, when the sliding plane has a specific height in the extension direction of the gear and when the gear has a specific thickness, the curvature or slope of the sliding plane can only be set within a certain range.

[0059] Preferably, the free end of the sliding surface or the sliding plane (pointing to the outer edge of the sprocket) is as steep as possible. The height of the sliding surface and / or the curvature and / or the slope of the sliding surface and / or the thickness of the gear can be selected so that the free end of the sliding surface is as steep as possible.

[0060] As previously mentioned, the gliding plane can have at least two different inclination angles along its longitudinal extension. That is, the gliding plane has at least two radial sections in the radial direction, which are differently inclined relative to the radial direction of the gear. Preferably, a certain section of the gliding plane, including its free end, is designed to have a steeper inclination along its longitudinal extension than other sections. This can be achieved, for example, by having the section including the free end of the gliding plane have a greater inclination angle along its longitudinal extension relative to the gear's axis of rotation than the other sections of the gliding plane.

[0061] In the case of a concave curvature, a steep lowering end is achieved with a relatively large radius of curvature and a relatively small gear thickness.

[0062] Furthermore, other non-linear and / or non-circular (arc-shaped) glide planes (in the longitudinal extension as well as in the transverse extension, i.e., in the circumferential direction) are possible. For example, parabolic, elliptical, hyperbolic, and / or exponential glide planes can be implemented. Curved, non-circular glide planes can be compatible with or adapted to other structural parameters of the sprocket, similar to the glide planes already disclosed herein.

[0063] In particular, in the case of non-circular, curved gliding planes, another structural parameter can be the distance between a certain position on the gear (e.g. the tooth end and / or the gear center) and the (virtual) origin of the gliding plane of the curved surface. The origin of a (virtual) curved surface in three-dimensional space is generally understood to be a point that is located at the minimum of the surface in three-dimensional space. Conversely, the gliding plane of a curved surface can be defined or described by a sub-region of such a curved surface in three-dimensional space. In this case, it can also be determined (together) by the position of the origin relative to the gear: which part of the (virtual) curved surface defines the real gliding plane. In particular, the direction of the surface of the gliding plane in the radial direction of the gear can also be defined by the position of the origin of the curved surface in the radial and axial (along the axis of rotation) direction of the gear.

[0064] In the (imaginary) three-dimensional representation, the origin of the gliding plane can in particular also lie outside the gear volume.

[0065] Preferably, in the case of a concavely curved gliding surface, the origin is arranged such that the radially inner end of the gliding surface is as steep as possible (i.e., the slope is as steep as possible in the radially inner region relative to the gear radius). A steep gliding surface end can be achieved when the distance between a location on the gear (e.g., a tooth end and / or gear center) and the origin of the gliding surface is small. In particular, as will be described later with reference to the embodiments in the accompanying drawings, it is advantageous if the origin of the parabola, ellipse, hyperbola, and / or exponential function (used to define the gliding surface) is arranged lower than the height of the gliding surface (i.e., the origin is lower in the radial direction than the end of the gliding surface), thereby making the gliding surface as steep as possible at the end of the gliding surface.

[0066] For the sake of completeness, it should be noted that even in the case of an inter-tooth region with two downwardly directed surfaces (directed toward opposite sides of the gear), it is possible for at least one downwardly directed surface (or both) to have a curvature. For example, the material cross-section of the gear in the inter-tooth region can be designed to be biconcave and / or biconvex to form the downwardly directed surface. The curvature of the two downwardly directed surfaces can be different, for example according to the above-described embodiments and combinations thereof.

[0067] In principle, the corresponding gliding plane can also be only partially curved and / or partially inclined, regardless of the other design of the inter-tooth area. This means that the gliding plane can have different radial sections, which are differently inclined or differently curved in the radial direction.

[0068] Furthermore, the upper side surfaces of the corresponding tooth gap bottom surfaces (pointing away from the center point of the gear wheel) can be designed to be concave at least in sections, regardless of the other design of the inter-tooth region.

[0069] The sliding surface or the sliding plane can be realized, for example, in the form of an arched recess in the material body of the sprocket. Preferably, the sliding surface or the sliding plane can each be designed to be bag-shaped. Preferably, at least one bag-shaped structure can extend in the direction of the center point of the sprocket in the form of a tongue starting from the bottom surface of the tooth groove, in particular from the side surface of the bottom surface of the tooth groove. Preferably, the bag-shaped structure can be arc-shaped or form a semicircle on the end side, that is, in the direction pointing to the center point of the sprocket. The arc-shaped bag-shaped structure or the semicircular bag-shaped structure can be realized according to the above-mentioned embodiments or their combinations. Here, as mentioned above, not only a straight line design of the sliding plane in the transverse extension (that is, in the circumferential direction of the gear) is feasible, but also an arc-shaped design, wherein different shapes can also be selected in the circumferential direction in sections or by sector. In other words, the entire three-dimensional surface of the sliding plane can be optimized for the corresponding application situation.

[0070] The sprocket of the conveying device is preferably designed such that the ratio between the radial longitudinal extension of the sliding surface, in particular the sliding surface (measured from the radially inner end of the sliding surface to the tooth gap bottom surface) and the radial longitudinal extension of the associated tooth (tooth longitudinal extension) (measured from the tooth gap bottom surface to the radially outer end of the tooth) is at least approximately 1:2, preferably at least approximately 1:1.5 and / or at most approximately 1:0.25, preferably at most approximately 1:0.5. The associated tooth is preferably the tooth adjacent to the sliding surface.

[0071] The sprocket of the conveying device can be designed such that the ratio between the longitudinal extension of the lower runner, preferably the lower runner plane (measured from the radially inner end of the lower runner plane to the tooth gap bottom surface), and the radius of the wheel body of the gear or sprocket (i.e., the radial distance between the rotation axis of the gear and the tooth gap bottom surface) is at least 1:10, preferably at least 1:5 and / or at most 1:1.5, preferably at most 1:2. Preferably, the ratio between the longitudinal extension of the lower runner or the lower runner plane and the radius of the wheel body of the gear can be approximately 1:3.

[0072] The wheel body is understood to be the base body of the sprocket without the external teeth arranged thereon. The wheel body can preferably have a perfectly circular outer circumference. Preferably, the wheel body is defined by the tooth root circle of the sprocket.

[0073] Advantageously, in a conveying device with the aforementioned sliding surface, the powder that impinges can be led away from the inter-tooth area particularly reliably. In addition, the sliding surface with a large longitudinal extension has the advantage that it can be formed relatively easily in the sprocket, thereby enabling the sprocket to be produced more cheaply.

[0074] According to one embodiment of the invention, the corresponding clearance space for the building material can include a relief in the inter-tooth region, which is designed such that a certain distance is formed between the chain rollers of a chain meshing with the sprocket and the tooth gap bottom surface in the inter-tooth region. In other words, the relief can be designed such that there is no (direct) contact between the meshing chain and the tooth gap bottom surface in the inter-tooth region (in the region of the relief). As previously mentioned, a relief is understood to be a specific material-free space in the material body of the sprocket or a specific material recess in the inter-tooth region of the sprocket.

[0075] The reliefs can preferably be formed in the tooth gap bottom surface itself. This means that the tooth gap bottom surface can be "lowered" at least in sections by the reliefs. Preferably, the reliefs can be used to slightly offset the upper side of the tooth gap bottom surface in the direction of the sprocket center point (relative to the inter-tooth area without such reliefs). Preferably, such reliefs can be designed in combination with the aforementioned lowering surface.

[0076] It is further possible that the clearance space for the building material comprises a relief, which is designed such that a chain meshing with the sprocket, in particular a chain roller meshing with the sprocket, is supported (only) via two contact areas on two teeth lying opposite one another. The relief, preferably the sprocket, can be designed such that a certain distance is formed between the chain roller of the chain meshing with the sprocket and the wheel body of the gear wheel or the sprocket body.

[0077] The sprocket is preferably designed such that the chain meshes with the sprocket exclusively via the teeth, with no (direct) contact between the chain and (the rest of) the sprocket in the area between the teeth, in particular in the area between two adjacent tooth roots. Accordingly, the respective chain roller contacts the gear wheel only via two defined contact areas of the teeth. The relief can extend along the entire longitudinal extent of the area between the teeth.

[0078] The contact area for supporting the chain rollers can preferably be located on the facing tooth flanks of two teeth arranged side by side. The distance between the two contact areas of the opposing teeth is preferably less than the diameter of the chain rollers. In particular, the sprocket is designed so that the relief does not exceed the radius of the involute transition. The gripping conditions of the teeth are preferably taken into account.

[0079] Sprockets with such reliefs generally do not require tooth gap bottoms. This means that individual teeth can be arranged on the wheel body of the sprocket, without there being a direct connection between the tooth flanks of adjacent teeth. Instead, the tooth flanks can abut the wheel body or tooth root. The teeth of the sprocket are arranged quasi-discretely on the wheel body, with a material-free space (as relief) formed between two adjacent teeth, which extends into the wheel body.

[0080] Alternatively or additionally, the sprocket, in particular the relief, can be designed such that the meshing chain, in particular the chain roller, is supported (only) via two contact areas on two teeth lying opposite each other, wherein a certain distance is formed between the chain roller of the chain and the (lowered) tooth gap bottom surface.

[0081] Advantageously, sprockets with such reliefs can effectively prevent unwanted sticking to the sprocket. Due to the reliefs, the chain rests only on the teeth themselves, with no direct contact between the chain and the rest of the sprocket in the area between the teeth during operation of the conveyor system. This prevents any compression of powder that may be present in the area between the teeth. Advantageously, the chain operates stably despite the reliefs in the sprocket.

[0082] It should be noted that it is possible to combine different clearance spaces for powder in the same sprocket. In principle, it is also possible to provide for at least one inter-tooth region to have no clearance space for powder. Furthermore, according to the present invention, the conveying device can have different sprockets, in particular sprockets with different clearance spaces for powder.

[0083] Optionally, it is possible to design the sprocket in such a way that the entire sprocket is shaped so that its outer basic shape (regardless of the clearance space between the teeth) already has a radius of curvature and / or a slope. For example, at least one side of the sprocket can have a radius of curvature and / or a slope in the radial direction, starting from the tooth to the midpoint. In this case, the entire curved and / or inclined (radial) surface of the sprocket can form a sliding surface for the powder that hits it. For example, at least one side of the gear can have a concave surface. In principle, it is also possible that only a specific part or specific section of the sprocket or the sprocket surface has a curvature and / or slope. The curvature can be designed, for example, as a circle (arc), parabola, hyperbola or exponential curve. Combinations of these curvatures are also possible. The teeth can have a different slope or curvature than the rest of the sprocket.

[0084] Optionally, the conveying device can have a scraper for powder, wherein the scraper is assigned to the sprocket. The scraper can be designed to scrape off building material that adheres to the side of the sprocket during operation. Correspondingly, the scraper can be arranged transversely and essentially orthogonally to the longitudinal extension of the teeth. Depending on the design of the sprocket, the scraper can optionally have a curvature that is adapted to the radius of curvature and / or the angle of inclination of the sprocket. In principle, each gear of the conveying device can be assigned a separate scraper. The corresponding scraper can optionally have an elastic scraping element, such as bristles or the like. Advantageously, the scraper can keep the side of the sprocket, in particular the radial area, as free of powder as possible during operation. This can also improve the efficiency of the powder being diverted away via the sliding surface. For example, the scraper can mechanically support the powder from being diverted away from the bag-like sliding surface.

[0085] Optionally, the sprocket can be designed so that the reference area of ​​the respective tooth tip surface pointing away from the sprocket center point corresponds to a maximum of 50%, preferably a maximum of 40%, preferably a maximum of 30%, and in particular a maximum of 20% of the reference area of ​​the tooth base surface. The tooth tip surface can preferably be designed to be planar and can be transverse to the longitudinal extension of the respective tooth, for example, approximately perpendicular. The tooth base surface of the tooth corresponds to the surface that is present in the contact area with the wheel body in a cross section through the tooth root. Advantageously, by reducing the tooth tip surface, for example in two dimensions, the surface pressure between the sprocket and the chain can be increased during operation. This can press powder out of the chain contact area. Alternatively or additionally, it is also possible to reduce the width of the entire gear, for example with respect to the chain, and thus also the width of the teeth, in order to increase the surface pressure.

[0086] As mentioned at the outset, the conveying device can have at least one intermediate container for accommodating the building material. The intermediate container is preferably designed to temporarily accommodate and / or transport the building material, in particular excess building material, in the AM machine.

[0087] The conveying device can preferably be designed such that the chain-driven conveyor, preferably the chain conveyor, acts in a predetermined manner in the intermediate container. In particular, the chain conveyor can act along the longitudinal extension of the intermediate container. The chain-driven conveyor can be arranged at least partially in the intermediate container. The intermediate container is preferably designed in the form of a trough or basin.

[0088] The upper side of the intermediate container, which points upward (opposite to the vertical) when intended for use, may preferably be open. Preferably, the upper side may have an opening for receiving powder along the entire longitudinal extension of the intermediate container. Preferably, transporting the powder (in or out) within the AM machine may include moving the building material within the intermediate container via a chain-driven conveyor. The intermediate container may have an incline, particularly a slope toward the intended location of the powder.

[0089] The intermediate container can preferably be implemented as part of a conveyor device, wherein other components of the conveyor device, in particular a chain-driven conveyor, can be detachably coupled to the intermediate container. Preferably, the conveyor device and the intermediate container form a module that can be reversibly installed in the AM machine.

[0090] The intermediate container is preferably designed to hold unused material residues from at least one coating process, preferably multiple coating processes, i.e., a portion of the material residue accumulated during the entire production process of the component to be produced. The material residue can then be transferred from the intermediate container to an overflow container using a conveyor device, thereby at least partially emptying the intermediate container to accommodate new material residues. The intermediate container can preferably be installed in the AM machine so that it can be coupled to the overflow container for powder transfer. The overflow container is preferably designed to hold excess powder from the entire production process, which includes multiple application processes, until multiple components are completed. The overflow container can be part of the conveyor device or can be part of the AM machine.

[0091] The intermediate container, in particular an intermediate container with a chain-driven conveyor, can preferably extend along (the entire) side of the building container. The intermediate container can have an elongated, particularly flat basic shape, wherein the intermediate container can be arranged relative to the building container such that its longitudinal extension is parallel to the (outer) wall of the building container. Preferably, the intermediate container is arranged such that its longitudinal extension is substantially orthogonal to the working direction or direction of movement of the coating machine.

[0092] The chain-driven conveyor can be realized in different ways, wherein the invention is not limited to a specific design.The chain-driven conveyor can operate continuously or intermittently.

[0093] According to one embodiment, the conveying device can include a chain conveyor extending in the intermediate container along its longitudinal extension. The chain conveyor can preferably have two (traction) chains running continuously in the transport direction or conveying direction, each with an upper section and a lower section. The chain conveyor can preferably be designed in the manner of a scraper conveyor or a trough chain conveyor. Both allow the powdered material residues to be conveyed through the empty return upper chain section to the lower load section. In this way, the depth of the intermediate container can be fully utilized, in particular when the material residues are transferred to the conveying device in a gushing manner. Alternatively, the chain conveyor can also be designed to transport the material residues from both sides, specifically by arranging a horizontal intermediate plate between the upper section and the lower section on a section of the longitudinal extension of the intermediate container, so that the upper section in the area of ​​the intermediate plate also becomes a load section. While scraper conveyors can transport material residues using carriers (conveyor elements) fixed transversely to the conveying direction on the circulating drag chain, trough chain conveyors can be completely immersed in the conveying flow with their drag chain and / or the carriers (conveyor elements) provided thereon. Trough chain conveyors therefore offer a particularly space-saving design.

[0094] A preferred chain conveyor can have four sprockets mounted in pairs on two shafts connected via two endless roller chains. Preferably, all four sprockets can have inter-tooth areas with the aforementioned clearances. During additive manufacturing, the sprockets and chains are regularly exposed to powder, particularly due to excess powder being discharged from the build field. Advantageously, special sprockets can reliably guide even large amounts of powder away from the sprockets, enabling smooth operation. This advantage, combined with the space-saving design of the chain conveyor and its sufficiently high conveying capacity, can have a positive impact on the efficiency of the AM machine.

[0095] In principle, the chain conveyor can also be operated intermittently as a continuous conveyor. This means that it can be put into operation as soon as the residual material has been deposited into an intermediate container after the coating process. Once the intermediate container is completely empty, the conveyor system can be shut down, for example, when there is sufficient time to deposit residual material for the next coating process.

[0096] Chain-driven conveyor, preferably chain conveyor can have one or more conveying elements, and these conveying elements can be moved along its longitudinal extension in the intermediate container, particularly relative to the outlet opening of the intermediate container. Preferably, a plurality of conveying elements (such as conveying plates) for powder can be fixed at the two chains of the chain conveyor at regular intervals. Conveying elements can be designed in the form of carriers, and these carriers are fixed to the two roller chains transversely to the conveying direction. Carrying elements (or slightly higher than the bottom) can be guided on the bottom of the intermediate container to transport powder in the conveying direction, i.e. in the direction of the predetermined location, for example, to the outlet opening. The outlet opening is preferably arranged at one end of the elongated intermediate container. Preferably, one of the two shafts of the chain conveyor can be arranged above the outlet opening.

[0097] According to one embodiment, the conveying device can have a chain-driven conveyor that operates alternately, and this conveyor has at least one conveying element, and this conveying element can move alternately along its longitudinal extension in the intermediate container. The conveyor is not continuously conveyed, but conveyed at a single time interval. Therefore, this conveyor can be suitable for intermittent operation, and is suitable for adjusting its conveying capacity during its operation. The conveyor can have several carrying members, which can move back and forth (as conveying elements) in the conveying direction and in the reverse direction, and these carrying members are arranged laterally in the conveying direction and in a manner that can rotate 90 °. Since these carrying members are all operated on the same path in the conveying direction and in the reverse direction, the space required by this conveyor in the intermediate container is small. Thus, the larger area of ​​the intermediate container can be utilized to accommodate powder.

[0098] The conveyor can have a conveying element that can be moved alternately along its longitudinal extension in the intermediate container. This conveying element can extend horizontally and include slats that protrude downward and are inclined in the conveying direction. These slats extend into the material residue and push it in the conveying direction. In the reverse direction, the slats slide over the powdered material residue. In addition, the slats can be designed to be hollow, for example frame-shaped. Therefore, when the conveying element moves in the reverse direction, the powder can pass through the slats and is not transported. The scraper or slat plate serving as the conveying element only needs to have a low overall height, which means that the overall space of the intermediate container is almost entirely used to accommodate the material residue.

[0099] The conveying system preferably includes a drive unit with a linkage mechanism designed to cause the alternating chain conveyors, in particular the alternatingly movable conveying elements, to advance slowly in the conveying direction and return quickly in the opposite direction. This allows the conveying capacity to be increased by utilizing the inertia of the material residues. This is because in the slow conveying direction, the material residues are fully carried along. Conversely, in the fast opposite direction, the material residues remain largely stationary due to their inertia.

[0100] Alternatively or additionally, the drive of the conveyor system can include a linkage mechanism designed to lower the alternating chain conveyor, in particular the alternatingly movable conveyor element, in the conveying direction and raise it in the opposite direction. The slats thus immerse themselves in the material residue in the conveying direction, enabling efficient transport of the material residue. Conversely, in the opposite direction, the slats are lifted from the material residue to prevent it from being displaced. This results in a more uniform motion profile for the conveyor element while maintaining the same efficiency, thereby reducing wear.

[0101] In principle, it is also possible to combine the above-described conveying principles in a conveying device.

[0102] If the intermediate container is designed to be flat, the build container can be removed from the AM machine by passing it underneath the intermediate container without the overflow container obstructing this removal. This makes it possible to guide the build container through a protective airlock before removal and to position the overflow container in a location in the machine that is more easily accessible to the operator. While the placement of the protective airlock makes the machine more cost-effective to operate, the newly designed overflow container at least makes the machine more convenient to operate.

[0103] The conveying device is preferably capable of being mounted or installed in the AM machine so that at least part of the conveying device, in particular the intermediate container, can be moved between a working position and a maintenance position. For example, the conveying device can be designed to be pivotable and / or displaceable. For example, the building container of the AM machine can be removed from the AM machine in the direction of the working position of the intermediate container. During the machine's idle time, that is, outside the production process, the conveying device, in particular the intermediate container, can be moved from the working position to a maintenance position, for example upwards into a gap in the processing chamber. This creates (additional) space for removing the building container. As a result, the dimensions of the conveying device and / or the intermediate container can be designed to be larger than in a rigid conveying device.

[0104] The AM machine can include a temperature gate for generating a temperature difference in the conveying device, in particular between the intermediate container and the associated overflow container. Suitable devices for use as a temperature gate include, for example, a narrowing of the channel cross section or a belt-like curtain in the transport path between the intermediate container and the overflow container. This can reduce the temperature increase of the outer periphery of the build container and the adjacent intermediate container.

[0105] Advantageously, the temperature gate can achieve a difference between the average maximum temperature of the powder in the intermediate container and the overflow container of at least 30° C., preferably at least 50° C., more preferably at least 100° C., particularly preferably at least 200° C. The relatively low temperature of the powder in the overflow container can have a favorable effect on the recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] The present invention will be described in more detail below by way of example with reference to the accompanying drawings. In the various figures, identical components are designated by identical reference numerals. The figures are generally not drawn to scale. The figures show:

[0107] Figure 1 A schematic, partially sectional view of an exemplary embodiment of a device for additive manufacturing is shown;

[0108] Figure 2 A perspective view showing parts of an apparatus for additive manufacturing having two conveying devices according to the present invention;

[0109] Figure 3 Shown Figure 2 Perspective views and partial schematic diagrams of various parts of the conveying equipment in;

[0110] Figure 4 Shown Figure 3 A perspective view of a portion of a chain conveyor of a conveying device;

[0111] Figures 5 to 7 Shows different views of a sprocket according to the invention;

[0112] Figure 8 A schematic diagram showing a portion of a sprocket according to the present invention;

[0113] Figures 9 to 11 A schematic diagram of a portion of a sprocket according to the present invention is shown. DETAILED DESCRIPTION

[0114] exist Figure 1Schematically depicting an apparatus 1 for additive manufacturing, or an AM machine for producing a component 2, is a selective laser sintering or laser melting apparatus 1, although the present invention is not limited to selective laser sintering or laser melting apparatuses. The apparatus 1 is hereinafter referred to as a laser sintering apparatus 1, without limiting its generality.

[0115] The laser sintering device 1 has a process chamber 3 or process chamber 3 with a chamber wall 4, in which the manufacturing process essentially takes place. An upwardly open build container 5, or simply container 5, with container walls 6 is provided in the process chamber 3. The top opening of the container 5 forms the current working plane 7 in each case. The area of ​​the working plane 7 located within the opening of the container 5 can be used to build the object 2 and is therefore referred to as the build field 8.

[0116] Container 5 has a base plate 11 that is movable in a vertical direction V and is arranged on a carrier 10. This base plate 11 closes container 5 downward and thus forms its bottom. Base plate 11 can be formed integrally with carrier 10, but it can also be a plate formed separately from carrier 10 and fastened to carrier 10 or simply supported thereon. Depending on the specific build material (i.e., for example, the powder used) and the type of manufacturing process, a build platform 12 can be mounted on base plate 11 as a build support, on which object 2 is built. However, in principle, object 2 can also be built on base plate 11 itself, in which case the base plate forms the build support.

[0117] The basic construction of the object 2 is carried out as follows: first, a layer of building material 13 is applied to the building platform 12; then, as explained below, the building material 13 is selectively cured at points that are to form parts of the object 2 to be manufactured using a laser beam 22 as an energy beam; then, the substrate 11 and therefore the building platform 12 are lowered by means of the carrier 10, and a new layer of building material 13 is applied and selectively cured, and so on. Figure 1 The figure shows an object 2 being built on a building platform 12 in a container 5 in an intermediate state, below the working plane 7. The object already has several solidified layers, which are surrounded by a still unsolidified building material 13. Different powders or mixtures of different powders can be used as building material 13. Even in Figure 1 While only a single component 2 is shown, it is possible and generally common to produce multiple objects simultaneously in the process chamber 3 or container 5. To this end, the building material is scanned layer by layer by an energy beam at locations corresponding to the cross-section of the object in each layer.

[0118] Fresh building material 15 is arranged in a storage container 14 of the laser sintering device 1. The building material can be applied in the form of thin layers in the working plane 7 or in the building field 8 by means of a coater 16 that can be moved in the horizontal direction H. Optionally, an additional radiation heating device 17 is provided in the process chamber 3 for heating the applied building material 13.

[0119] For selective curing, the laser sintering device 1 has an irradiation device 20, or more specifically, an exposure device 20 with a laser 21. The laser 21 generates a laser beam 22 or energy beam 22, which is deflected by a deflection device 23 or scanner 23 so as to scan the layer to be selectively cured in each case along an exposure path or track (hatching) provided according to the exposure strategy and selectively introduce energy. Furthermore, the laser beam 22 is focused onto the working plane 7 in a suitable manner by a focusing device 24. The irradiation device 20 is located outside the process chamber 3, and the laser beam 22 is guided into the process chamber 3 via an incoupling window 25 arranged in the chamber wall 4 at the top of the process chamber 3.

[0120] The irradiation device 20 may, for example, include not one but a plurality of lasers 21. Preferably, they may be gas or solid-state lasers or any other type of laser, such as laser diodes, in particular VCSELs (Vertical Cavity Surface Emitting Lasers) or VECSELs (Vertical External Cavity Surface Emitting Lasers) or arrays of these lasers. Particularly preferably, one or more CO and / or CO2 lasers may be used within the scope of the present invention.

[0121] The laser sintering device 1 further comprises a sensor assembly 18, which is suitable for detecting the process radiation emitted when the laser beam 22 impinges on the building material 13 in the working plane 7. The sensor assembly 18 operates in a spatially resolved manner, i.e., it is able to detect an emission image of the respective layer. The sensor assembly 18 can comprise an image sensor or a camera 18. Alternatively or in addition, it is possible to also use one or more sensors to detect optical and / or thermal process radiation, for example, a photodiode that detects the electromagnetic radiation emitted by the molten pool under the incident laser beam, or a temperature sensor that detects the emitted thermal radiation (so-called molten pool monitoring). The signals detected by the sensor assembly 18 can be transmitted as a process chamber sensor data set or layer image to a control device 30 of the laser sintering device 1.

[0122] The laser sintering apparatus 1 includes a control device 30, which is also used to operate the various components of the laser sintering apparatus 1 for overall control of the additive manufacturing process. The control device 30 includes a control unit 29, which operates the components of the irradiation device 20, namely, in this case, the laser 21, the deflection device 23, and the focusing device 24, and transmits corresponding irradiation control data BS to these components.

[0123] The control unit 29 also controls the radiation heating device 17 by means of suitable heating control data HS, controls the coater 16 by means of coating control data ST, and controls the movement of the carrier 10 by means of carrier control data TS, thereby controlling the layer thickness.

[0124] The control device 30 is connected here, for example, via a bus 33 or another data connection, to a terminal 32 having a display etc. Via this terminal 32 an operator can control the control device 30 and thus the entire laser sintering device 1 , for example by transmitting process control data PS.

[0125] The laser sintering device 1 has a purely schematically illustrated conveyor device 40, which is arranged in an intermediate container 41, also schematically illustrated. The intermediate container 41, together with the conveyor device 40, is arranged in the direct vicinity of the build area 8 and, there, contacts the container wall 6 of the build container 5 from the outside. The conveyor device 40 or the intermediate container 41 can be arranged flush with the working plane 7 or slightly below it. Contrary to the exemplary illustration in this figure, the conveyor device 40 could also be assigned to the opposite (left-hand) container wall 6.

[0126] During operation of the laser sintering device 1, the coater 16 distributes fresh building material over the building field 8, starting, for example, from the container wall 6 on the left in the figure, to the container wall 6 on the right. At the end of the application process, the coater 16 pushes excess building material (e.g., introduced as a reserve in front of the coater 16) through the container wall 6 on the right in the figure into the intermediate container 41. The intermediate container 41 extends along the entire side of the building container 5, here along the entire right chamber wall 6 shown in the cross-section.

[0127] The intermediate container 41 extends in the process chamber 3 with its longitudinal extension parallel to the right container wall 6 and cooperates with a purely schematically illustrated receiving container 42 in order to deposit excess powder 13 ′ discharged from the building container 5 by the coating machine 16 into the receiving container 42. Unlike the schematic representation in this figure, the receiving container 42 can be spaced further apart from the building field 8.

[0128] Figure 2The figure shows a perspective view of the parts of the laser sintering device 1 related to the present invention. The building container 5 of the laser sintering device 1 is provided with a conveying device 40 on each of the two opposite sides 5'. Since the structures of the conveying devices 40 are similar, only the conveying device 40 on the right side of this figure will be described in more detail below. The conveying device 40 has a basin-shaped intermediate container 41, wherein some components of the conveying device 40 are arranged inside the intermediate container 41 and other components are arranged outside the intermediate container. The intermediate container 41 is designed in this figure to have a longitudinal extension LE along its longitudinal extension LE. FE The majority of the upper side is open upwards (except for the housing 45). Via this open upper side (which preferably faces the coating machine of the AM machine during operation), excess powder can enter the intermediate container 41 by gravity.

[0129] The conveying device 40 has its longitudinal extension LE FE (This longitudinal extension corresponds to the longitudinal extension LE of the intermediate container 41 FE ) extends along the short side 5 ' of the building container 5 and protrudes on both sides. The intermediate container 41 directly (laterally) contacts the building container 5, wherein the upwardly pointing upper edge 41 ' of the intermediate container 41 is arranged slightly below the opening of the building container 5.

[0130] A chain conveyor 50 is arranged in the intermediate container 41 , wherein the longitudinal extension of the chain conveyor 50 corresponds to the longitudinal extension LE of the intermediate container 41 FE .

[0131] To move the chain conveyor 50, the conveying device 40 includes a controllable drive 40', which is arranged on a housing 45 in an end region of the conveying device 40. The housing 45 closes the intermediate container 41 at one end and contains, for example, drive components of the chain conveyor 50, in particular the shaft of the chain conveyor 50. The housing 45 forms a downwardly pointing, funnel-shaped housing region that is provided for conveying excess powder discharged by the chain conveyor 50 from an outlet opening (not visible) of the intermediate container 41 via a connecting pipe 44 into an overflow container 42. The overflow container 42 or receiving container 42 is a component of the laser sintering device 1.

[0132] exist Figure 3 middle, Figure 2 The parts of the conveying device 40 in FIG. 4 are shown in perspective and partially schematically enlarged. In the elongated intermediate container 41 , the chain conveyor 50 is arranged so that the longitudinal extension of the chain conveyor 50 corresponds to the longitudinal extension LE of the intermediate container 41 FE or the longitudinal extension LE of the conveying device 40 FEThe chain conveyor 50 comprises two endlessly circulating parallel roller chains 63, 63'. The roller chains 63, 63' are each meshed with two sprockets (as gears), wherein the two sprockets are arranged on a common shaft 68. The shafts 68 are each arranged at opposite ends of the intermediate container 41. Figure 3 Only one shaft 68 is visible, wherein the second shaft is arranged in the housing 45 and can be rotated by the drive 40 ′. The chain conveyor 50 is designed so that at least the roller chains 63, 63 ′ and the conveyor plate 43 located on the roller chains are arranged inside the intermediate container 41, i.e. do not protrude beyond the upper edge 41 ′.

[0133] Between the two roller chains 63, 63', a conveying plate 43 is installed at regular intervals as a conveying element 43. The conveying plate 43 has a basic rectangular shape in the cross-sectional view and can be designed as an angle plate with an L-shaped profile. During operation, the (bottom) conveying plate 43 for transporting excess powder 13' in the intermediate container 41 can be guided on the base plate 46 of the intermediate container 41 in the direction of movement BR. The direction of movement BR preferably corresponds to the conveying direction of the powder 13'. The powder 13' is shown purely schematically in this figure. For example, the narrow side of one edge of the conveying plate 43 can be placed flat on the base plate 46, wherein the powder 13' in front of the corresponding conveying plate 43 is pushed on the base plate 46 according to the direction of movement BR. Correspondingly, the chain conveyor 50 has a load section at the bottom in this figure.

[0134] In the housing 45, the powder 13' can be discharged from the intermediate container 41 via an outlet opening (not shown), thereby leaving the conveying device 40. Preferably, the second shaft of the chain conveyor 50 is mounted above the outlet opening and / or behind the outlet opening with respect to the direction of movement BR. After the second shaft is reversed, the conveying plate 43 is returned upwards to the opposite end of the intermediate container 41 against the direction of movement BR by two roller chains 63, 63'.

[0135] exist Figure 4 Shown in detail Figure 3A portion of a chain conveyor 50 is shown in FIG. The remaining components of the conveying system are not depicted. Two sprockets 51 can be seen, arranged on shaft 68. The sprockets 51 can, for example, be fixedly connected to shaft 68. It is also possible for the sprockets 51 to be implemented as part of shaft 68. Furthermore, it can be seen that each conveyor plate 43 (as conveying element 43) forms an L-shaped profile. A guide plate 67 is arranged between the lower portion of the front roller chain 63' (serving as the load section) and the upper portion of the same roller chain 63' in this figure to maintain a specific distance between the upper and lower chain sections during operation. The upper chain section in this figure rests on the guide plate 67 and contacts it via the rollers (not shown) of roller chain 63'. The guide plate 67 can also function to remove any powder buildup on the upper chain section. Both roller chains 63, 63' have outer chain links 69 and connected inner chain links 69'. The rollers of roller chains 63, 63' are not shown here. The two roller chains 63, 63' can be designed as known roller chains in terms of structure. Unlike what is shown in the figure, the roller chains 63, 63' are designed as endless roller chains 63, 63' during operation (in the figure, some chain links are not shown in order to be able to see other parts).

[0136] exist Figure 4 The two sprockets 51 are shown with different sprocket sides 53, 53'. The outward-facing sprocket side 53' (facing away from the other sprocket on the same shaft) has several clearance spaces 54 for powder, which will be described in more detail below. In contrast, in this embodiment, the opposite, inward-facing sprocket side 53 is designed to be flat, i.e., without any clearance spaces. The two sprockets 51 of the corresponding shaft 68 can preferably be designed identically (e.g., only with the sides reversed).

[0137] exist Figure 5 For example, Figure 4 51 in a perspective view, wherein the sprocket side 53 ' with the escape spaces 54, 54 ' for powder is shown here. The opposite sprocket side that is not visible can preferably be flat or planar, for example as Figure 4 It can also be seen that a portion of the sprocket 51 is formed by the shaft 68 .

[0138] The sprocket 51 includes a plurality of teeth 57, 57' arranged regularly distributed around the circumference of the sprocket 51. The area of ​​the sprocket 51 between two adjacent teeth 57, 57' forms an inter-tooth region 52. (To better distinguish between two adjacent teeth 57, 57' and clearance spaces 54, 54' in the present description, different teeth and clearance spaces are arbitrarily assigned slightly different reference numerals 57, 57', 54, 54' in this figure, even though the teeth 57, 57' or clearance spaces 54, 54' are each constructed identically.) In the example shown in this figure, the sprocket 51 has nine separate inter-tooth regions 52, each separated from one another by a tooth 57, 57'. For reasons of perspective and clarity, only one inter-tooth region 52 is labeled in this figure.

[0139] In this figure, the inter-tooth region 52 extends from the lower end of the tooth flank 60 of the first tooth 57 to the starting point of the opposing tooth flank 60 of the adjacent second tooth 57'. In this example, the inter-tooth region 52 includes the tooth gap bottom surface 56 between the two adjacent teeth 57, 57'. Accordingly, the tooth gap bottom surface 56 connects the tooth flank 60 of the first tooth 57 with the facing tooth flank 60 of the second tooth 57'. Unlike the exemplary illustration in this figure, the inter-tooth region 52 and the tooth gap bottom surface 56 may also be designed to have different dimensions.

[0140] A lowering surface 55 is formed as an escape space 54 for the powder by the tooth groove bottom surface 56 between the first tooth 57 and the second tooth 57'. In this example, the lowering surface 55 forms a lowering plane 58 for the powder. The lowering plane 58 starts in or at the tooth groove bottom surface 56, in particular from the upper side surface 56' of the tooth groove bottom surface, and extends in the direction of the axis 68 or in the direction of the sprocket center point 59 ( Figure 6 ).exist Figure 5 As can be seen in the figure, the sliding surface 58 is designed in the shape of a tongue, in particular in the region of the sliding surface 58 that faces the axis 68. It is also shown that the sliding surface 58 extends along the entire longitudinal extension of the tooth gap base 56. This means that the sliding surface 58 extends from the tooth flank 60 of the first tooth 57 to the tooth flank 60 of the adjacent second tooth 57'.

[0141] The lowering plane 58 is formed by a relief in the tooth gap base 56 of the sprocket 51. As a result, the width of the tooth gap base 56 (parallel to the axis 68), in particular the width of the upper side 56' of the tooth gap base, is reduced compared to known sprockets. The relief in the tooth gap base 56 or the lowering plane 58 in the inter-tooth region 52 results in a certain portion of the tooth gap base 56, in particular the upper side 56' thereof, being replaced by a material-free space.

[0142] By having such a narrow tooth groove bottom surface and side surface 56', the contact surface between the gear 51 and the chain can be advantageously minimized. Figure 5 , a single chain roller 64 of a roller chain is schematically shown, wherein the chain roller 64 meshes with the sprocket 51. The schematic illustration shows that the chain roller 64 in this figure directly contacts the gear 51 or rests on it only in the region of the upper side 56' of the tooth gap bottom surface. In the region of the lower run-down plane 58', the chain roller 64 is spaced apart from the lower run-down plane 58' during operation.

[0143] The lowering plane 58' is inclined with respect to its longitudinal extension to the tooth longitudinal extension LE of the adjacent tooth 57'. ZA This arrangement allows powder that strikes the sliding surface 58' to slide down therefrom by gravity. Furthermore, the slope of the sliding surface 58' can help to divert powder that lies flat on the tooth groove bottom surface 56 or the upper side surface 56' of the tooth groove bottom surface away from it, as long as the chain roller 64 does not lie exactly flat on the corresponding tooth groove bottom surface 56.

[0144] The lowering planes 58, 58' between adjacent teeth 57, 57' are Figure 5 However, it is also possible to arrange different lowering planes 58, 58' or escape spaces 54, 54' at the same sprocket 51.

[0145] exist Figure 6 In another view, a sprocket 51 according to the present invention is shown, for example Figure 5 The sprocket 51 in FIG. It can be seen that the respective inter-tooth region 52 is designed to have the same dimensions (with respect to the longitudinal extension) as the associated tooth gap base 56 in this figure. The tooth gap base 56 connects the opposing tooth flanks 60 of two adjacent teeth 57, 57' to one another. The tooth longitudinal extension LE is schematically shown with the help of the middle tooth 57' in this figure (upper in this figure). ZA , wherein the tooth 57 ′ includes a tooth top 56 ″′ and a tooth root 56 ″. The tooth 57 ′ is connected to the wheel body of the sprocket 51 via the tooth root 56 ″.

[0146] The wheel body (not shown in detail in this figure) refers to the sprocket 51 without the teeth 57, 57' arranged on its outer side. The wheel body has a positive circumference, which is defined by a specific radius R, which is based on the root circle diameter D f The sprocket 51 can preferably be designed such that the longitudinal extension LE1 of the lower runner 55 and the tooth longitudinal extension LE of the associated tooth 57 ′ are aligned. ZA It is also possible to achieve a specific ratio between the longitudinal extension LE1 of the lower runner 55 and the radius R and / or the tooth root diameter D f A specific ratio between.

[0147] The teeth 57, 57' can be relatively large, such as Figure 6 As shown, the longitudinal extension LE ZAcan each be approximately the root diameter D f One fifth of Figure 6 Also shown is the gear midpoint 59 or sprocket midpoint 59 .

[0148] exist Figure 7 shows a section through a sprocket 51 according to the invention. It can be seen that the sprocket side 53' pointing in the viewing direction has a respective escape space 54, 54' or a respective run-down surface 58, 58' for powder between two teeth 57, 57'. The opposite sprocket side 53 has no such escape space 54. Correspondingly, adjoining the upper side 56' on the tooth gap floor is a vertical, flat surface in this figure, which is approximately parallel to the tooth longitudinal extension LE of the associated tooth 57'. ZA Or substantially orthogonal to the axis of rotation of shaft 68 .

[0149] The lower runner surface 55' or lower runner plane 58' is oriented with respect to its longitudinal extension LE1 relative to the tooth longitudinal extension LE of the associated tooth 57'. ZA The lowering surface 55' or the lowering plane 58' is arranged obliquely. The lowering surface 55' or the lowering plane 58' is arranged at a specific angle α relative to the longitudinal extension LE of the tooth. ZA The angle α is schematically shown in this figure with respect to the sprocket side 53 facing away, wherein the corresponding surface is substantially parallel to the tooth longitudinal extension LE ZA In this figure, the down-sliding surface 55' or down-sliding plane 58' forms an oblique, flat down-sliding surface for powder impinging from above. However, in principle, the down-sliding plane does not have to be essentially flat as shown in this figure, but can also be curved, in particular slightly curved, for example, transversely to the radial direction (e.g., concavely), i.e., have a large radius of curvature.

[0150] exist Figure 7 It can be seen that the material cross section MQ of the sprocket 51 in the region between the teeth tapers starting from the axis 68 toward the tooth gap bottom surface upper side 56 ′.

[0151] Figure 9 A portion of a cross section of a sprocket 51 parallel to its axis of rotation is shown, wherein the fragment shown in this figure corresponds to Figure 7 The upper area of ​​the cross section in the foreground (only the lower glide surface with a slightly different design is shown in this figure).

[0152] exist Figure 9 In the figure, HO represents the height of the lower sliding surface 55 in the direction perpendicular to the rotation axis of the gear 51, and LE Rrepresents an axis also perpendicular to the axis of rotation, which intersects the edge between the upper side 56' of the tooth gap bottom surface and the longitudinal extension LE1 of the lower running surface 55, MQ' represents the projected length of the lower running surface 55 or the longitudinal extension LE1 onto an axis parallel to the axis of rotation of the sprocket 51 (MQ' also corresponds to the difference between the material cross section MQ of the sprocket 51 and the width of the upper side 56' of the tooth gap bottom surface), and α represents the difference between the longitudinal extension LE1 and the axis LE R The angle between Figure 7 (The definition of α in the description of the tooth gap is omitted.) In the case of the basic shape of the inter-tooth space described, it is sufficient to determine two of the three structural parameters HO (height), LE1 (longitudinal extension), and α (angle), and the third parameter must be determined accordingly. In the case of a specific width of the side surface 56' on the tooth gap base, two of the structural parameters HO (height), LE1 (longitudinal extension), and α (angle), MQ (material cross section), and / or MQ' (the difference between the material cross section MQ and the width of the side surface 56' on the tooth gap base) can be determined, and the other parameter must be determined accordingly.

[0153] Preferably, it is sufficient that the slope of the longitudinal extension LE1 of the sliding surface 55 satisfies the following: the powder that hits the sliding surface 55 slides down the sliding plane 58, for example by gravity, and can be carried away from the inter-tooth area. This means that the angle α is as small as possible, compatible with other structural parameters, in particular the height HO and / or the material cross section MQ and / or the material cross section MQ'. Although Figure 7 and Figure 9 A single inclination angle α is shown in the figures, but the gliding plane 58 or the gliding surface 55 can have a plurality of different inclination angles. In order to make the free end of the gliding surface 55 as steep as possible, the gliding plane 58 or the gliding surface 55 can be divided into two radial sections 80a, 80b, each of which has a different inclination angle. Figure 9 In the example shown, this alternative variant is indicated by a dashed line which shows the course of the surface of a radially inner section 80b of the lower runner, which connects at a bending point 81 to a radially outer section 80a of the lower runner from the upper side 56' of the tooth groove bottom. In the example shown, this radially outer section 80a again has a RThe inclination angle α is α, and starting from the inflection point, the downward sliding surface 55 has a smaller inclination angle in the inner radial section 80b, that is, the downward sliding surface 55 is steeper here. Therefore, the height of the downward sliding surface 55 in this case is also greater than that of the first embodiment. This makes it easier for powder to slide down or be carried away. However, in principle, the inclination angle in the radially inner section of the downward sliding surface 55 can also be larger, that is, the downward sliding surface 55 is steeper at the side surface 56' on the tooth groove bottom surface and becomes flatter inward, if this is more reasonable in the individual design. However, a steeper radial inner end is generally preferred.

[0154] Figure 10 A portion of a cross section of an alternative sprocket 51 parallel to its axis of rotation is shown, in particular again the upper portion of the cross section, which is at a point between two teeth 57, 57' ( Figure 7 ), that is, cut the sprocket 51 at the position of the lower sliding surface 55. Figure 7 and Figure 9 In contrast, a circular (arc-shaped) gliding plane 58 forms the gliding surface 55 in this figure. The gliding plane 58 in this figure extends in the radial direction as an arc profile 78 with a curvature radius KR. This curvature radius KR determines the curvature or steepness of the gliding plane 58. For comparison, Figure 10 An alternative arc profile 78' with a smaller radius of curvature KR' is shown in dashed lines. Figure 10 It can be seen from the figure that the free end (pointing to the left in this figure) or the end of the sliding surface 55 following the arc profile 78 with a larger curvature radius KR is steeper than the area of ​​the sliding surface 55 following the arc profile 78' with a smaller curvature radius KR'. A steep sliding surface end is advantageous because it makes it easier for the powder that hits the sliding surface 55 to slide down the sliding plane 58. Therefore, it is preferred in most cases to realize a circular (arc-shaped) sliding surface 58 with a curvature radius that is as large as possible (compatible with other structural parameters such as the width of the gear) to form the sliding surface 55. In addition, it is advantageous for the sliding plane 58 to be as high as possible. As shown in FIG. Figure 10 As shown, the height HO corresponding to the larger curvature radius KR is greater than the height HO' corresponding to the smaller curvature radius KR'. The large curvature radius KR and the large height of the lower sliding surface 55 can be compensated by the wide upper side 56' of the tooth groove bottom surface, or be structurally compatible with the wide upper side 56' of the tooth groove bottom surface.

[0155] Figure 11 Another alternative sprocket 51 is shown again somewhere between two teeth 57, 57' ( Figure 7 ) is the upper part of the cross section, that is, the cross section through the lower sliding surface 55 of the sprocket 51 again. Figure 7 、 Figure 9 and Figure 10 Different, in Figure 11 In the embodiment, a curved, but non-circular, gliding surface 58 forms a gliding surface 55. In particular, Figure 11 In the embodiment, the downhill slope 55 is formed by a parabolic downhill slope 58 in the radial direction. Figure 11 A parabolic descent plane 55 is shown in FIG, but other curved, non-circular descent planes are also conceivable, such as a hyperbolic or elliptical descent plane.

[0156] exist Figure 11 In order to illustrate the effect of the precise shape, two two-dimensional parabolic arc contours 79, 79' are drawn alternatively to define the direction of such a parabolic gliding plane, and these two contours each form a gliding surface. The first parabolic arc contour 79 (the contour follows the radial direction) Figure 10 The descending plane depicted in the cross section (by a solid line) is a segment of a (fictitious) parabola starting from a (virtual) origin U located outside the material cross section of the sprocket. An alternative second parabolic arc profile 79 ′, drawn only as a point in this figure, is instead a segment of a (fictitious) parabola starting from a point located on the axis LE R1 The axis is perpendicular to the axis of rotation of the sprocket 51 and is located in the plane corresponding to the sprocket side 53'. That is, the origin U' is closer to the axis LE than the origin U. R .

[0157] from Figure 11 As can be seen from the diagram of FIG, the radially outer free end (free glide surface end) of the glide surface corresponding to the parabolic arc profile 79 (whose origin U is farther from the sprocket) is steeper than the free end of the glide surface corresponding to the parabolic arc profile 79'. A steeper free glide surface end is advantageous because it allows the powder that hits the corresponding sub-region of the glide surface 55 to slide down the glide plane 58 more easily. In other words, it is advantageous to form a curved, non-circular (for example, parabolic, hyperbolic, or elliptical) glide surface so that its origin (compatible with other structural parameters such as the width of the sprocket) is as far away from the axis LE as possible. R Furthermore, it can be advantageous if the origin U is below the axis of rotation of the sprocket 51. This makes it easier for the powder to slide off or be carried away.

[0158] exist Figure 8Figure 2 schematically shows a portion of a sprocket 51 according to the present invention. A chain roller 64 of a chain meshing with the sprocket 51 is shown between two adjacent teeth 57, 57'. The inter-tooth region 52 includes a clearance 61, which serves as an escape space 54 for powder. The clearance 61 is designed so that the meshing chain roller 64 is spaced apart from the wheel body 62 of the gear 51 by a distance a. The chain roller 64 is supported on two opposing teeth 57, 57' solely via two contact areas 65, 65', one of which is formed by a tooth 57, 57'. The contact areas 65, 65' are arranged on the respective tooth flanks 60, particularly in the convex sections.

[0159] In the present embodiment, the chain roller 64 rests on the sprocket 51 only via two narrow, elongated contact surfaces 65, 65' in the area of ​​the teeth 57, 57'. In the area of ​​the inter-tooth space 52, in particular between the two contact areas 65, 65', there is no direct contact between the chain roller 64 and (the rest of) the sprocket 51 during operation. In this example, the relief 61 is designed as a material-free space so that an inter-tooth region 52 is formed without a tooth groove bottom surface. The width b of the inter-tooth region 52 is slightly smaller than the outer diameter D of the roller chain 64. The relief 61 in the inter-tooth region 52 makes it possible to space the chain roller 64 placed thereon from the powder 13' present in the inter-tooth region 52.

[0160] Finally, it is pointed out again that the conveying devices described in detail above are only embodiments and can be modified in various ways by a person skilled in the art without departing from the scope of the invention. Thus, for example, the avoidance spaces of the sprockets shown in the corresponding embodiments can be interchanged and / or combined with each other as desired. In addition, it is also possible for the sprockets to each have a lowering surface or a lowering plane in the inter-tooth region and also on the other side, i.e., for example, on the "inner" side (the inner side in each case points to another second sprocket arranged on the same axis in the figures). Similarly, it is also possible for the sprockets to each have a lowering surface or a lowering plane on both sides of the inter-tooth region, so that the side surface on the tooth groove bottom surface is offset more toward the center parallel to the gear rotation axis, so that the powder material can slide down from both sides of the side surface on the tooth groove bottom surface. In addition, the use of the indefinite article "a" or "an" does not exclude that the relevant feature may be present multiple times.

[0161] Reference Signs List

[0162] 1Device for additive manufacturing / laser sintering device

[0163] 2 Components / Objects

[0164] 3 processing room / processing cavity

[0165] 4 cavity wall

[0166] 5. Build Container / Containers

[0167] 5' side

[0168] 6 container wall

[0169] 7 Work Plane

[0170] 8 Build Field

[0171] 10 carriers

[0172] 11 base plate

[0173] 12 Build Platform

[0174] 13.13' Construction Materials

[0175] 14 Storage Containers

[0176] 15 Construction materials in storage containers

[0177] 16 Coating Machine

[0178] 17 Radiant heating device

[0179] 18 sensor components / cameras

[0180] 20 irradiation device / exposure device

[0181] 21 lasers

[0182] 22 laser beams / energy beams

[0183] 23 Deflection device / scanner

[0184] 24 Focusing Equipment

[0185] 25 Coupling Window

[0186] 29 Control Unit

[0187] 30 Control Equipment

[0188] 32 Terminal

[0189] 33 bus

[0190] 40 Conveying equipment

[0191] 40' drive unit

[0192] 41 intermediate container

[0193] 41' top edge

[0194] 42 Overflow container / receiving container

[0195] 43 conveying elements / conveying plates

[0196] 44 connecting pipe

[0197] 45 shell

[0198] 46 bottom plate

[0199] 50 Chain driven conveyor / chain conveyor

[0200] 51 gear / sprocket

[0201] 52 Interdental area

[0202] 53, 53' sprocket side

[0203] 54, 54' avoidance space

[0204] 55, 55' glide surface

[0205] 56 tooth groove bottom surface

[0206] 56' tooth groove bottom surface and side surface

[0207] 56” tooth root

[0208] 56" tooth top

[0209] 57, 57' teeth

[0210] 58, 58' descent plane

[0211] 59 gear midpoint / sprocket midpoint

[0212] 60 tooth surface

[0213] 61 Give way

[0214] 62 wheel body

[0215] 63, 63' chain / roller chain

[0216] 64 chain rollers

[0217] 65, 65' contact area

[0218] 67 guide plate

[0219] 68 axis

[0220] 69 outer link

[0221] 69' inner link

[0222] 78, 78' two-dimensional arc profile

[0223] 79, 79' Two-dimensional parabolic arc profile

[0224] 80a, 80b radial sections

[0225] 81 bending point

[0226] α angle

[0227] a distance

[0228] b width

[0229] BS irradiation control data

[0230] BR Movement Direction

[0231] D Chain roller diameter

[0232] D f Root diameter

[0233] H horizontal direction

[0234] HS Heating Control Data

[0235] HO, HO' height of the glide plane

[0236] KR, KR' curvature radius

[0237] LE1 longitudinal extension

[0238] LE FE longitudinal extension

[0239] LE ZA Tooth longitudinal extension

[0240] LE R LE R1 axis

[0241] MQ, MQ' material cross section

[0242] PS process control data

[0243] R wheel radius

[0244] ST coating control data

[0245] TS carrier control data

[0246] V vertical direction

[0247] U, U' origin.

Claims

1. A conveying device (40) for additively producing at least one component (2) from a building material (13, 13', 15) by selectively at least partially solidifying a powdered building material (13), in, The conveying device (40) for conveying building material (13') in the device (1) has a chain-driven conveyor (50), preferably a chain conveyor (50), which has at least one gear (51), wherein at least one inter-tooth area (52) between two adjacent teeth (57, 57') of the gear (51) includes an escape space (54, 54') for the powdered building material (13').

2. The conveying device according to claim 1, wherein The gear wheel (51) has two or more mutually spaced, preferably different, escape spaces (54, 54') for the building material (13'), and / or The escape space (54, 54') for the building material (13') comprises a relief portion (61) in the interdental area (52).

3. The conveying device according to claim 1 or 2, wherein: The escape space (54, 54') has a lower sliding surface (55, 55') for guiding the building material (13') away from the interdental area (52).

4. The conveying device according to claim 3, wherein: The lower sliding surface (55, 55') is formed by the tooth groove bottom surface (56) between two adjacent teeth (57, 57'), wherein preferably, the lower sliding surface (55, 55') connects the two adjacent teeth (57, 57') to each other.

5. The conveying device according to claim 3 or 4, wherein: In order to form the lower sliding surface (55, 55'), the gear (51) has a material cross section (MQ) which tapers toward the tooth gap bottom surface (56).

6. The conveying device according to any one of claims 3 to 5, wherein: In order to form the lower sliding surface (55, 55'), the gear (51) has one of the following elements: - at least one descending plane (58, 58') starting from the tooth groove bottom surface (56), said descending plane being aligned with the tooth longitudinal extension (LE ZA ) arranged obliquely, - at least one curved, in particular concave, lowering plane (58, 58') starting from the tooth groove bottom surface (56), - at least two, optionally curved, descending planes (58, 58') starting from the same tooth groove bottom surface (56), said descending planes being aligned with the tooth longitudinal extension (LE) at a specific angle to each other ZA ) arranged diagonally.

7. The conveying device according to any one of claims 4 to 6, wherein: The upper side surface (56') of the tooth groove bottom surface (56) pointing in a direction away from the gear center point (59) is designed to be concave at least in sections.

8. The conveying device according to any one of claims 3 to 7, wherein: The longitudinal extension (LE1) of the lower sliding surface (55, 55') is aligned with the longitudinal extension (LE2) of the associated tooth (57, 57') ZA ) is at least 1:2, preferably at least 1:1.5 and / or at most 1:0.25, preferably at most 1:0.5, and / or The ratio between the longitudinal extension (LE1) of the lower sliding surface (55, 55') and the radius (R) of the wheel body (62) of the gear (51) is at least 1:10, preferably at least 1:5 and / or at most 1:1.5, preferably at most 1:

2.

9. The conveying device according to any one of claims 2 to 8, wherein: The relief space (54, 54') for the building material (13') comprises a relief portion (61) which is designed such that a certain distance (a) is formed between a chain roller (64) of a chain (63) meshing with the sprocket (51) and a tooth groove bottom surface (56).

10. The conveying device according to any one of claims 2 to 9, wherein The escape space (54, 54') for the building material (13') comprises a relief portion (61) which is designed in such a way that a chain (63) meshing with the sprocket (51) is supported via two contact areas (65, 65') on two opposite teeth (57, 57'), in particular in such a way that a distance (a) is left between the chain rollers (64) of the chain (63) and the wheel body (62) of the gear (51).

11. The conveying device according to any one of the preceding claims, wherein: The conveying device (40) has a preferably trough-shaped intermediate container (41) for receiving the building material (13'), wherein the chain-driven conveyor (50) acts in the intermediate container (41) and is preferably at least partially arranged therein.

12. The conveying device according to claim 11, wherein The chain-driven conveyor (50) has at least one conveying element (43) which is capable of being conveyed in the intermediate container (41) along its longitudinal extension (LE FE ) are moved, optionally alternately, in particular relative to the outlet opening of the intermediate container (41).

13. A device (1) for additive manufacturing of at least one component (2), comprising a feed device (16) for feeding powdered building material (13, 13', 15) into a processing chamber (3), an irradiation device (20) for selectively at least partially solidifying the building material (13) by irradiation with at least one energy beam (22), and a conveying device (40) according to any of the preceding claims.

14. The device according to claim 13, wherein The conveying device (40) is designed to convey unused building material (13') away from the building area (8) in the processing chamber (3), in particular to convey the building material (13') from an intermediate container (41) of the conveying device (40) into an overflow container (42), and / or wherein the conveying device (40) is at least partially movable between a working position and a maintenance position, and / or The device (1) comprises a temperature gate for generating a temperature difference in the conveying device (40).

15. A method for additive manufacturing of at least one component (2), preferably in an apparatus (1) according to claim 13 or 14, comprising the following steps: - feeding powdered building material (13, 13', 15) into the processing chamber (3), preferably by applying the building material (13) layer by layer onto the building field (8), - irradiating the building material (13) with at least one energy beam (22) in order to selectively at least partially cure the building material (13), - conveying the building material (13') by means of a conveying device (40), said conveying device having a chain-driven conveyor (50), preferably a chain conveyor (50), said conveyor having at least one gear wheel (51), wherein at least one inter-tooth region (52) between two adjacent teeth (57, 57') of said gear wheel (51) comprises an escape space (54, 54') for the powdered building material (13'), - preferably transferring excess building material (13') into an intermediate container (41) of the conveying device (40) and conveying the building material (13') from the intermediate container (41) to an overflow container (42) assigned to the conveying device (40) by means of the conveying device (40).

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