EP3585541A1

EP3585541A1 - Device and method for an additive manufacture

Info

Publication number: EP3585541A1
Application number: EP18719452.7A
Authority: EP
Inventors: Markus KOGL-HOLLACHER; Christian Staudenmaier; Thibault BAUTZE; Daniel REGULIN; Heinz-Ingo Schneider; Henning Hanebuth
Original assignee: Siemens AG; Precitec GmbH and Co KG
Current assignee: Siemens AG; Precitec GmbH and Co KG
Priority date: 2017-03-31
Filing date: 2018-04-03
Publication date: 2020-01-01
Also published as: US20200038954A1; JP2020530525A; US11691215B2; JP6972165B2; CN110869149A; CN110869149B; WO2018178387A1

Abstract

The invention relates to a device (100) for an additive manufacture. The device (100) comprises a laser device (110) for machining material using a laser beam (112), said laser device (110) being designed to deflect the laser beam (112) onto a machining region of a workpiece (10); at least one supply device (130) for a supply material, said supply device being designed to supply the supply material to the machining region; and an interferometer (140) which is designed to measure a distance to the workpiece (10) by means of an optical measuring beam (142).

Description

DEVICE AND METHOD FOR ADDITIVE MANUFACTURE

The present disclosure relates to an apparatus and a method for additive production. In particular, the present disclosure relates to an apparatus and method for Laser Metal Deposition (LMD).

Background Art Laser Metal Deposition (LMD or Cladding) uses a laser beam and feed material to apply material to a workpiece. The laser beam generates a molten bath on a surface of the workpiece. Through a nozzle metal powder or wire is introduced. It creates welded together material areas that result in structures on existing workpieces or new structures.

It is known to produce coatings and three-dimensional layer structures by means of laser deposition welding. Meanwhile, even more complex three-dimensional components are manufactured by means of laser deposition welding. The laser cladding requires a precise setting of a variety of process parameters, where only in a small range of process parameters around a working point a satisfactory production can take place. Accordingly, there is currently a great interest in suitably setting the process parameters in laser deposition welding.

For process control and process control, measurement techniques can be used to investigate, for example, the welded or applied material area, the emissions from the interaction zone or the molten bath and its geometry. Known methods, such as camera-based methods for melt pool geometry analysis or pyrometer-based methods for temperature measurement, are based on secondary emissions from the interaction process and can give no or only very limited information about an absolute geometry. However, the indication of the height and / or the complete geometry of the additive-produced component or of the additively produced weld bead is valuable information for indicating the machining quality and / or for the process control. For example, DE 10 2014 219 656 A1 discloses a method for producing and / or repairing components such as gas turbine components, for example runners or guide vanes, in which subtractive and additive method steps are combined in a hybrid method. By online monitoring using the pyrometer mentioned above, process parameters such as contours, temperature, material and / or surface condition can be checked and controlled.

Disclosure of the invention

It is an object of the present disclosure to provide an apparatus and method for additive manufacturing that provides improved process control, particularly process control and / or process control. In particular, it is an object of the present invention to determine a topography of a welded material area on a workpiece or a generated structure. Furthermore, it is also an object of the invention to provide an improved method and an improved production device for laser cladding, wherein a reliable production, in particular of three-dimensional components is made possible. This object is solved by the subject matter of the independent claims and the aspects of this invention. Advantageous embodiments of the invention are specified in the subclaims.

In one aspect, an additive manufacturing apparatus is provided. The device comprises a laser device for processing materials by means of a laser beam, such as a laser processing head, the laser device is adapted to direct the laser beam to a processing area of a workpiece, at least one feed material feeder adapted to feed the feed material To supply processing area, and an interferometer unit, which is adapted to measure by means of at least one optical measuring beam, a surface of the workpiece, such as a distance to the workpiece, or between the device and the workpiece surface, and / or a topography of the workpiece surface , According to other embodiments, a method for additive manufacturing is specified. The method includes directing a laser beam at a processing area of a workpiece, feeding a feed material to the processing area, and measuring a surface of the workpiece, such as measuring a distance to the workpiece and / or a topography of the workpiece surface, using an interferometer unit.

According to preferred embodiments, the at least one optical measuring beam may be provided statically with respect to the laser beam. Alternatively, the at least one optical measuring beam may be dynamically, i. be movable, provided with respect to the laser beam. In other words, the optical measuring beam can execute a predetermined scanning movement or shut down a scanning figure. The interferometer unit may comprise an interferometer for providing a reference beam and the optical measuring beam. Furthermore, the interferometer unit may comprise an evaluation unit for evaluating the data acquired by the interferometer. In particular, the interferometer unit may comprise an interferometer, which is set up to allow movements of the optical measuring beam, in particular linear or rotary movements, individually or in combination. The scanning movement performed by the measuring beam can thus have a circular or linear or also the shape of an 8. The linear scanning movement can be parallel to a machining direction or have an angle thereto. The optical measuring beam can be guided in the flow and / or in the wake and / or through a molten bath. Two or more optical measuring beams can be moved independently or independently of each other. In one example, two or more measurement beams may together comprise a rotating motion, e.g. around the beam axis of the laser beam in the machine direction.

For example, two optical measuring beams can be used, one in the forward and one in the wake. For this purpose, the optical measuring beam can be split into two sub-beams, which can be guided simultaneously in the forward and in the wake. The partial beams can be provided movably.

The at least one optical measuring beam may comprise one or more of the following wavelengths: 1550 nm, 1310 nm, 1080 nm, 1030 nm and 830 nm. These wavelengths may a central wavelength of an associated wavelength range of the optical measuring beam.

In preferred embodiments, the interferometer unit may be configured to determine a position of the surface of the workpiece and / or a topography of the surface of the workpiece on the basis of the distance measurement.

Furthermore, the interferometer unit can be set up to measure a distance to the machining area and / or a distance to a region of the workpiece that lies adjacent to the machining area.

The interferometer may comprise a coherence interferometer or a short-coherence interferometer.

The interferometer can be set up to couple the at least one optical measuring beam into a beam path of the laser device. The interferometer may also comprise a beam path for the optical measuring beam separated from the beam path of the laser device.

In one embodiment, the at least one feeder may be configured to supply a powder or a wire as feed material.

The at least one feeding device may be selected from a group consisting of a ring jet powder nozzle, a multi-jet powder nozzle, and an off-axis powder nozzle.

In a further embodiment, the at least one optical measuring beam and the laser beam may be coaxial or substantially coaxial. Alternatively or additionally, however, the optical measuring beam may also be inclined relative to the laser beam or with respect to an optical axis of the laser device. The interferometer may be configured to statically provide the at least optical measuring beam with respect to the laser beam. Alternatively or additionally, the interferometer may be arranged to provide the optical measuring beam movable with respect to the laser beam.

In another embodiment, a controller may be provided to control the laser device and / or the at least one delivery device based on the distance measured by the interferometer unit. For example, the controller may be configured to select at least one process input selected from the direction of movement of the apparatus with respect to the workpiece, moving speed with respect to the workpiece, powder flow rate, powder amount, powder composition, powder feed direction, wire feed direction, wire feed speed, working distance, process gas composition, process gas pressure, laser focus diameter, optical position Axis, laser focus position, laser pulse width and laser power.

The device according to the invention can be or comprise a laser deposition welding head.

The device according to the invention can be set up for a method for laser metal deposition (LMD) or cladding. The method according to the invention may comprise a method for laser metal deposition (LMD) or cladding. The device can be set up to determine at least one physical size of the production process from the distance measurement during additive deposition, ie, during laser deposition welding, such as a position and / or topography of the workpiece surface and / or a geometric size of a weld bead manufactured during the process (Also referred to as a component) and / or a derived therefrom size and / or a height of a coated layer and / or a size derived therefrom. Alternatively, one or more additional physical quantities can be detected, such as a laser power and / or a dimension of the laser focus and / or a Feed rate of a feed material and / or a material flow of the feed material and / or a dimension or a diameter of a resulting during the process melt pool and / or a temperature of the molten bath and / or derived from one or more of the aforementioned sizes size. For this purpose, corresponding detection means may be provided.

The at least one physical variable can be recorded or determined continuously or at intervals of at most 100 milliseconds, preferably at most 20 milliseconds and expediently at most 5 milliseconds, advantageously at the same time intervals.

The apparatus may be further configured to adjust at least one additive manufacturing process parameter, such as the at least one particular or sensed physical quantity and / or its history, such as, for example, as shown in FIG. a focus position and / or a laser power.

The at least one process parameter can be adjusted such that deviations from a model of the processing area or the weld bead and / or from a model of the additive manufacturing process are kept below a maximum threshold and / or minimized, preferably by means of a control method. For this purpose, the device may comprise a control and / or regulating device which is set up to set the at least one process parameter such that deviations from the model are kept below a maximum threshold and are preferably minimized.

According to a further aspect of the invention, a method for the additive laser deposition welding of a component by means of a laser is provided, comprising: detecting at least one physical variable of the welding process during laser deposition welding, and setting at least one process parameter of the method depending on the at least one detected physical variable; / or its course. Additive laser cladding in the context of the present application expediently additive manufacturing of preferably three-dimensional structures by means Laser deposition welding understood. The term of the welding process is expediently understood to mean the process of laser deposition welding.

By means of the method according to the invention, a component can also be manufactured precisely in the event of a change in the physical parameters of laser deposition welding caused by drift or other disturbing influences. The deviations from the desired shape of the component can be kept low in the method according to the invention. By means of the adaptation of process parameters on the basis of the value or the course of the physical quantities, a high production quality and a high degree of process reliability can consequently be achieved.

In particular, three-dimensional layer structures and components can also be produced by means of laser deposition welding by means of the method according to the invention, in that a multiplicity of process parameters for realizing the desired component geometry can be set accurately. By means of the method according to the invention, additive manufacturing of even more complex components with the reliability required for industrial application can therefore be easily implemented.

In the method according to the invention, the physical size is preferably at least one geometric size of the component manufactured during the welding process and / or a size derived therefrom and / or a height of a layer applied during laser deposition welding and / or a variable derived therefrom. In the method according to the invention, the at least one geometric variable is particularly preferably a height of the component or of the layer in the direction of a beam direction of the laser used for laser buildup welding and striking the component. It is expedient to use a machining head for laser deposition welding. Advantageously, this machining head allows a distance measurement of the machining head to the component, suitably by means of coherence tomography. In this way, the distance of the machining head from the component can be measured without contact. Advantageously, from the distance of the machining head from the component, the height of the component in the direction of the machining head to easily determine if the position of the machining head to a reference position, such as a point on a side facing away from the machining head of the component or a location of a substrate which rests on this side of the component is known. Appropriately, the Fabrication device configured to detect the relative position of the machining head to such a reference position.

In the context of this invention, the term "height of the component" is preferably understood to mean the height of the component currently reached at the location of the material application during laser deposition welding. As is known per se in 3D printing, the component is preferably manufactured in layers in the method according to the invention for additive laser deposition welding By applying several layers in succession, a CAM model (CAM = Computer Aided Manufacturing) is preferably generated by means of a CAD model of the component, which provides for production of successive layers of the component by means of laser deposition welding , In this embodiment of the invention, therefore, the current height of the component is determined by the already achieved in previous manufacturing steps height of the component and by the height of the currently manufactured layer. Consequently, according to the invention, depending on the embodiment of the method according to the invention, the current height of the component or alternatively or additionally and likewise preferably the height of the layer currently applied can be used as the at least one physical variable.

In the method according to the invention, in an advantageous development of the invention for laser buildup welding, a feed device, in particular a powder conveyor, is used for a welding material and the at least one physical variable is at least one feed stream or material flow of the welding material and / or one feed speed of the feed device and / or a derived from one or more of the aforementioned sizes size. Appropriately, in the method according to the invention for additive laser deposition welding, a machining head is used, wherein the feeding device is ideally accommodated in the machining head. Advantageously, the material flow or the feed speed of the feeder or a derived quantity in the processing head itself can be determined so that no detection means, such as sensors, have to be used outside the processing head. Consequently, the method according to the invention can also be carried out robustly and reliably in harsh environmental conditions typical of laser deposition welding. Suitably, in the method according to the invention, the at least one physical quantity is at least one power of the laser and / or a dimension of a focus of the laser and / or a variable derived from one or more of the aforementioned magnitudes. Preferably, in a development of the method according to the invention, the laser cladding welding with a molten bath and the at least one physical size is at least one dimension of the molten bath and / or a temperature of the molten bath and / or a size derived therefrom. Suitably, the molten bath with a camera, in particular a CCD camera, detected and determined by means of image processing, the at least one dimension of the molten bath. It is also possible to use a machining head for the laser buildup welding and the at least one size to be a distance of the machining head from the component and / or a variable derived therefrom. Advantageously, the dimension of the molten bath is related to the temperature of the molten bath such that a greater temperature of the molten bath requires a greater dimension of the molten bath. Consequently, the at least one dimension of the molten bath is a measure of the temperature of the molten bath.

Suitably, in the method according to the invention, the at least one process parameter is the position and / or the time profile of the position of the focus of the laser relative to the component and / or a variable derived therefrom. By means of the position and / or the time profile of the focus of the laser, an application rate and / or a spatial application profile during laser deposition welding can be influenced easily. For example, in the case of laser cladding, there is a tendency for the welding material to be reinforced or spatially heterogeneously deposited on the component when the focus of the laser is accelerated and the focus of the laser is slowed down. Consequently, by means of the method according to the invention, a height of a layer applied or a certain degree of divorce in a certain area of the component can be tailored to a certain extent, i. Accurately targeting a predetermined geometric model of the component to be manufactured.

Suitably, in the method according to the invention, the at least one size is continuously, ie continuously, or at intervals of at most 100 milliseconds, preferably at most 20 milliseconds and expediently at most 5 milliseconds, advantageously at the same time intervals. In this way, in the method according to the invention, a sufficiently continuous feedback of the at least one variable is ensured for the laser deposition welding, so that the at least one process parameter can be set sufficiently fast.

In an advantageous development of the invention, in the method, the at least one process parameter is set such that deviations from a model of the component and / or laser cladding are kept below a maximum threshold and / or minimized, preferably by means of a control method. Consequently, by means of the method according to the invention, the component can be geometrically manufactured with high precision. Particularly preferably, the component is manufactured in layers in the inventive method. Suitably, the at least one process parameter is set such that the current height of the component corresponds to the current height of the component provided in a process model of the method according to the invention. Alternatively or additionally, and also particularly preferably, the height of the currently produced layer is determined from the model of laser deposition welding, for example a CAM model of laser deposition welding, and the height of the layer currently produced is kept within predetermined limits, ie almost constant.

Preferably, in the method according to the invention, a control is undertaken in which the at least one physical variable forms a controlled variable and the at least one process parameter forms a manipulated variable. In the method according to the invention, the physical variable is expediently the current height of the component and / or the height of a layer currently applied during laser deposition welding.

In a further aspect, a production device for additive laser cladding of a component is specified by means of a laser and is set up in particular for carrying out a method according to the invention for additive laser deposition welding as described above. The production device according to the invention comprises at least one detection means for detecting at least one physical variable of the welding process and at least one adjusting means for the position of at least one process parameter from the at least one detected physical quantity and / or its course. The dependence of the position of the at least one process parameter on the detected at least one variable is expediently controlled by means of a control device of the production device according to the invention.

In an advantageous development of the invention, the production device has a machining head for laser buildup welding and a distance detection device which is designed to measure the distance of the machining head from the component and / or which has a coherence tomograph or is optically connected to such a coherence tomograph. In this way, the distance of the machining head from the component can be measured without contact. Advantageously, the height of the component in the direction of the machining head can be easily determined from the distance of the machining head from the component, as far as the position of the machining head to a reference position as already described above for the method according to the invention is known. Suitably, the manufacturing device is set up to detect the relative position of the machining head to such a reference position.

The production device according to the invention preferably comprises a supply device for supplying powdered welding material for laser cladding, and at least one detecting means for detecting the supply speed and / or the material flow of the welding material. Suitably, the material flow is detected as a volume flow and / or mass flow. In particular, the volume flow can be easily detected with imaging agents. In an advantageous development of the invention, the manufacturing device comprises at least one detection means for detecting at least one dimension of a laser deposition welding bath and / or at least one detection means for detecting the temperature of the molten bath and / or at least one detection means for detecting the power of the laser. Advantageously, the power of the laser is an internal variable, which can be detected, for example, via a preferably present control device of the production device, in particular in the form of a PC or CNC controller. Suitably, the detection means for detecting the temperature of the molten bath comprises Detection means for detecting at least one dimension of the molten bath. Because the dimension of the molten bath depends on the temperature of the molten bath in such a way that a higher temperature of the molten bath causes a higher dimension of the molten bath. Preferably, the detection means for detecting the at least one dimension comprises at least one CCD camera which detects an image of the molten bath. The dimension can now be determined, for example by means of a preferably provided evaluation device, so that the temperature can be determined therefrom, for example by means of previously determined calibration data. Suitably, in the manufacturing device according to the invention, the at least one setting means comprises at least one adjusting means for setting the position of the focus of the laser or its course and / or at least one adjusting means for setting the power of the laser. As already described above, it is particularly easy to influence the spatial material separation by accelerating the focus of the laser. Preferably, the adjusting means is a movable relative to the component, such as within a plane or three-dimensionally movable, processing head of the manufacturing device.

Expediently, the production device according to the invention comprises a control and / or regulating device which is set up to set the at least one process parameter such that deviations from a model of the component or a process model for laser cladding are kept below a maximum threshold and are preferably minimized. Consequently, in this development of the invention, at least part of the intended geometric shape of the component forms a controlled variable of the method according to the invention.

Preferably, the manufacturing device comprises a control in which the at least one physical variable forms a controlled variable and the at least one process parameter forms a manipulated variable. It goes without saying that aspects of the embodiments can be arbitrarily combined with each other. Preferred, optional embodiments and particular aspects The disclosure will be apparent from the dependent claims, the drawings and the present description.

The invention provides monitoring and / or control of additive manufacturing by means of laser beams and a feed material (also referred to as "feed material" or "filler material"). The sensor principle used is interferometry for distance measurement, such as optical short-coherence interferometry. The interferometry can be used, for example, in the course of the process for determining the position of the surface to be processed and / or in the wake for measuring the resulting topography of the applied material.

The present invention thus provides an online (or in-situ) sensor technology for the exact measurement of the process result in the form of a geometry measurement, whereby an improved process control, in particular an improved process control and / or process control can be achieved.

Brief description of the drawings

Embodiments of the disclosure are shown in the figures and will be described in more detail below. Show it:

1 shows a schematic representation of an apparatus for additive production with a static optical measuring beam according to embodiments of the present disclosure, FIG. 2 shows a schematic representation of an apparatus for additive production with a spatially movable optical measuring beam according to embodiments of the present disclosure,

FIGS. 3A and B show a schematic representation of an apparatus or a beam path for additive manufacturing with a static optical measuring beam according to an embodiment of the present disclosure, 4A and B show a schematic representation of a device or a beam path for additive manufacturing with a spatially movable optical measuring beam according to embodiments of the present disclosure, Figures 5A and B is a schematic representation of a device or a beam path for additive manufacturing with a static optical measuring beam according to further embodiments of the present disclosure,

FIGS. 6A and B show a schematic illustration of an apparatus or a beam path for additive production with a spatially movable optical measuring beam according to further embodiments of the present disclosure,

FIG. 7 shows a schematic illustration of an apparatus for additive production according to still further embodiments of the present disclosure, and

FIG. 8 is a flowchart of an additive manufacturing process according to embodiments of the present disclosure.

FIGS. 9A to 9C are schematic illustrations for possible guides of the optical measuring beam, and FIG. 9D is a graphical representation of a measurement by means of an optical measuring beam executing a linear scanning movement in the lead and tail of the laser beam.

Figure 10 shows an inventive method for 3D printing of a component schematically in a schematic sketch.

Figure 11 shows a part of a manufacturing device according to the invention for 3D printing of the component according to the method of Figure 10 schematically in longitudinal section. FIG. 12 shows a part of the production device according to the invention according to FIG. 11 for 3D printing of the component according to the method according to FIG. 10, schematically in longitudinal section. Figure 13 shows a detail of the inventive manufacturing device according to Figures 11 and 12 for 3D printing of the component according to the method of Figure 10 schematically in longitudinal section. Embodiments of the disclosure

In the following, unless otherwise stated, the same reference numerals are used for the same and equivalent elements. Figure 1 shows a schematic representation of an apparatus 100 for additive manufacturing or a manufacturing device for additive laser cladding with a static optical measuring beam according to embodiments of the present disclosure. The device 100 may be a laser deposition welding head. The additive manufacturing apparatus 100 includes a laser apparatus 110 for processing materials by a laser beam 112 (eg, a laser machining head), the laser apparatus 110 configured to direct the laser beam 112 at a processing area of a workpiece 10, at least one feeder 130 for a feed material adapted to supply the feed material to the processing area, and an interferometer unit having an interferometer 140 arranged to measure a distance to the workpiece 10 by means of an optical measuring beam. The device 100 may be movable along a machining direction 20 according to embodiments. The machining direction 20 may be a direction of movement of the device 100 with respect to the workpiece 10. In particular, the processing direction can be a horizontal direction.

In accordance with the present invention, an interferometer, such as a short-coherence interferometer, is used for distance measurement. The interferometry can be used, for example, in the lead-in of an LMD process for determining the position of the surface of the workpiece to be processed and / or in the wake for measuring the resulting topography of the applied material. Thus, an on-line sensor technology is provided for the exact measurement of the process result in the form of a geometry measurement, whereby improved process control and / or process control can be achieved.

As exemplified in FIG. 1, the interferometer 140 may be configured to provide the optical measuring beam substantially statically with respect to the laser beam 112. However, the present disclosure is not limited to this, and the interferometer 140 may be configured to dynamically, i. movable to provide with respect to the laser beam 112, as shown for example in Figures 2, 4A, 4B, 6A, 6B and 7.

The apparatus 100 may be used in accordance with laser metal deposition (LMD) embodiments in which the laser beam 112 and the feed material are employed to apply material to the workpiece 10. As shown in FIG. 1, the laser beam 112 generates a molten pool 14 on a surface of the workpiece 10. By means of the feeder 130, such as a nozzle 132, the feed material, which may be, for example, a metal powder, is introduced into the molten bath 14. The result is welded together material areas, the structures, such as a weld bead 12, resulting in existing workpieces. Likewise, the device 100 can be used for so-called high-speed cladding, in which no molten bath is produced, but the molten powder hits the workpiece surface and is deposited thereon.

The apparatus 100, and in particular the laser apparatus 110, may include focusing optics 120 for focusing the laser beam 112 onto the workpiece 10. The focusing optics 120 defines an optical axis. The focusing optics 120 may be, for example, a fixed focal length or variable focal length (zoom) optical system. The focusing optics 120 may include at least one imaging optical element defining the optical axis. By way of example, a divergent laser light beam emerging from an optical fiber of the laser device 110 is converted by means of a collimator optics into a parallel laser light bundle, which is focused onto the workpiece 10 by a focusing lens. The interferometer unit is configured to measure a distance to the workpiece 10, for example with respect to a reference point defined by the interferometer 140, by means of the optical measuring beam, which may be a laser beam. The interferometer 140 may be a coherence interferometer, and more particularly a short-coherence interferometer. The distance measurement by means of an interferometer is known and will not be explained in detail. In particular, the interferometer 140 may be configured to measure a change in distance while the device 100 is being moved along the machining direction 20 and / or while the measuring beam is moving on the surface of the workpiece. As a result, for example, a topography measurement can take place.

According to embodiments that may be combined with other embodiments described herein, the interferometer unit is configured to measure a distance to the processing area. For example, a post-topography survey may be performed to determine the geometry of the area machined by the device, such as an application weld bead. The topography measurement can be used according to embodiments for error detection and / or regulation of one or more process input variables. The process inputs may be e.g. a powder flow, a wire feed, a process speed, a laser power, a working distance, etc.

In some embodiments, the interferometer unit may be configured to measure a distance to an area of the workpiece 10 that is adjacent to the processing area. The area may be an unprocessed surface of the workpiece 10. For example, a topography measurement in the feed (for example a z-position of the workpiece surface) can be used as a reference measurement and / or for process control.

The sensor system of the present disclosure is based on interferometry, such as short-coherence interferometry. For this purpose, a measuring beam off-axis is statically or movably provided by the interferometer. Alternatively, the measurement beam provided by the interferometer is coupled into the optical beam path of the processing laser and superimposed coaxially or almost coaxially in the interaction zone statically or movably. In some embodiments, the interferometer 140 may include a beam path for the optical measuring beam separate from the beam path of the laser device 110. In some embodiments, the interferometer 140 may be configured to tilt the optical measuring beam with respect to the optical axis of the laser device 110 to the workpiece 10. By way of example, the interferometer 140 may comprise an off-axis beam path for the optical measuring beam separated from the beam path of the laser device 110, wherein an oblique incidence of the optical measuring beam may take place, for example, in the wake. A measurement of the height of the build-up weld bead can take place, wherein the interferometer 140 can be statically positioned in the wake. In further embodiments, a topography can be measured, for example by means of a 1D or 2D oscillation in the wake. According to further embodiments, the interferometer 140 may be configured to couple the optical measuring beam into a beam path of the laser device 110. The optical measuring beam may be substantially coaxial with the laser beam 112. In some embodiments, the at least one feeder 130 is configured to dispense a powder jet as a feed.

The distance measurement can be effected by the interferometer unit by means of a static or movable optical measuring beam, such as for example by means of a measuring beam rotating around the machining laser or the laser beam 112 or deflected arbitrarily with respect to an optical axis of the laser device. In this way, a measurement of the height of the build-up weld bead can take place, it being possible for the interferometer or the optical measuring beam to be statically positioned in the wake (unidirectionally, for example, along the machining direction 20). In further embodiments, a measurement in the lead and / or tail, for example, the base material and / or order height done (eg statically positioned, uni-directional along the machining direction 20). Alternatively, the topography can be measured (eg rotating with scanner, multi-directional). Optionally, a measurement of the powder density may be made ("disturbance" of the optical measurement signal by the powder flow.) According to embodiments that may be combined with other embodiments described herein, the apparatus 100 further includes a controller configured to operate the laser device 110 and / or. or the at least one delivery device 130 based to control and / or regulate at the distance measured by the interferometer. The control can be based on an interferometry carried out in the forerun and / or after-run. Typically, process control and / or process control may be based on the distance measured by the interferometer. For example, a machining speed, a laser power, a laser focus, and / or operating parameters of the feeder, such as a powder flow or a wire feed, may be controlled based on the interferometry. Alternatively or additionally, the interferometry may be performed for quality control of the area machined by the device, such as a build-up weld bead.

According to embodiments that may be combined with other embodiments described herein, the at least one feed device 130 is selected from a group consisting of a ring jet powder nozzle, a multi-jet powder nozzle, and an off-axis powder nozzle. An off-axis powder nozzle 132 (also referred to as a "side powder nozzle") is shown by way of example in Figure 1. The off-axis powder nozzle 132 is a lightweight, simple and robust system that is particularly easy to access, even with poorly accessible welding positions distinguished.

FIG. 2 shows a schematic representation of an additive manufacturing apparatus 200 having a movable optical measuring beam according to embodiments of the present disclosure, such as a rotating optical measuring beam. In some embodiments, the interferometer 140 may be configured to movably or dynamically provide the optical measuring beam with respect to the laser beam 112. In particular, the interferometer 140 may be configured to rotate the optical measuring beam about the laser beam 112. The optical measuring beam may scan a two-dimensional contour, such as a circular contour, on the workpiece 10. As a result, a topography measurement, for example, the hardfacing bead can take place. The apparatus 200, and in particular the interferometer 140, may include a drive 210 that is configured to move or scan the optical measuring beam over the workpiece. Typically, the interferometer 140 includes one or more optical elements, such as lenses, mirrors or wedge plates, which deflect the optical measuring beam to direct it to the workpiece 10. At least one optical element of the one or more optical elements may be movable to move or scan the optical measuring beam over the workpiece 10. Alternatively, the drive may be a mechanical drive, eg, a rotary drive, that moves the interferometer 140 to move or scan the optical measuring beam over the workpiece 10.

FIGS. 3A and B show a schematic representation of an apparatus 300 or a beam path for additive fabrication with a static optical measurement beam 142 according to embodiments of the present disclosure. The apparatus 300 includes a ring jet powder nozzle 330. In particular, the ring jet powder nozzle 330 may be configured to dispense a powder jet as a feed material. The optical measuring beam 142 may be substantially coaxial or inclined with respect to the laser beam 112. The powder jet 134 may be directed to a first point or first area outside the annular jet powder nozzle 330, which may be at or above the processing area of the workpiece. The laser beam 112 may be directed to a second point (e.g., a focal point) or second area outside of the torch jet nozzle 330, which may be at the processing area.

The first point and the second point may overlap or may be mutually objectionable. As shown in the example of FIG. 3B, the first point or first area may be located about 20 mm outside (eg below) an exit of the annular jet powder nozzle 330 and / or an exit of the focusing optic 120. The second point or second area may be located about 23.5 mm outside (eg, below) the exit of the annular jet powder nozzle 330 and / or the exit of the focusing optics 120. The numbers are merely exemplary and are not intended to limit the embodiment illustrated in FIG. 3B. The first point and the second point can be arranged vertically one above the other be. The optical measuring beam 142 may be directed to a point or area of the workpiece that is horizontally offset from the first point and / or second point.

4A and B show a schematic representation of a device 400 or a beam path for additive manufacturing with a movable, e.g. rotating optical measuring beam according to embodiments of the present disclosure.

The apparatus 400 comprises the annular jet powder nozzle 330 as described with reference to FIGS. 3A and B. FIG. The optical measuring beam is dynamic, i. locally movable. In particular, the optical measuring beam can rotate about the laser beam 112 and / or the optical axis of the focusing optics 120. The optical measuring beam may scan a two-dimensional contour 242, such as a circular contour, on the workpiece 10. As a result, a topography measurement, for example, the hardfacing bead can take place. The optical measuring beam 142 may be substantially coaxial or inclined with respect to the laser beam 112.

FIGS. 5A and B show a schematic illustration of a device 500 or a beam path for additive manufacturing with a static optical measuring beam 142 according to further embodiments of the present disclosure.

The apparatus 500 includes a multi-jet powder nozzle 530. The multi-jet powder nozzle 530 may include at least two powder nozzles 532 configured to supply a respective powder jet to the processing area on the workpiece. Typically, the multi-jet powder nozzle 530 includes four powder nozzles 532 arranged at an angle to one another.

As shown in FIG. 5B, the powder jets 134 of the at least two powder nozzles 532 may be directed to a first point or first area outside of the multi-jet powder nozzle 530, which may be at or above the processing area of the workpiece. The laser beam 112 may be directed to a second point (eg, a focal point) or a second area outside of the multi-jet powder nozzle 530, which may be at the processing area can. The optical measuring beam 142 may be substantially coaxial or inclined with respect to the laser beam 112.

The first point and the second point may overlap, or may be spaced apart. As shown in the example of Figure 5B, the first point or first region may be located about 14 mm outside (e.g., below) an exit of the multi-jet powder nozzle 530 and / or an exit of the focusing optic 120. The second point or second area may be disposed about 0.8 mm further, that is about 14.8 mm, outside (e.g., below) the exit of the multi-jet powder nozzle 530 and / or the exit of the focusing optics 120. The numbers are merely exemplary and are not intended to limit the embodiment shown in FIG. 5B. The first point and the second point may be arranged vertically one above the other. The optical measuring beam 142 may be directed to a point or area of the workpiece that is horizontally offset from the first point and / or second point.

FIGS. 6A and B show a schematic representation of an apparatus 600 or of a beam path for additive production with a rotating optical measuring beam according to further embodiments of the present disclosure. The apparatus 600 includes the multi-jet powder nozzle 530 as described with reference to FIGS. 5A and B. The optical measuring beam is dynamic, i. locally movable. For example, the optical measuring beam can be rotated about the laser beam 112 and / or the optical axis of the focusing optical system 120 or can be radiated in a deflected manner in this regard. The optical measuring beam may scan a two-dimensional contour, such as a circular contour, on the workpiece 10. As a result, a topography measurement, for example, the hardfacing bead can take place. The optical measuring beam 142 may be substantially coaxial or inclined with respect to the laser beam 112.

FIG. 7 shows a schematic illustration of an apparatus 700 for additive manufacturing according to still further embodiments of the present disclosure. The device 700 may be configured for wire plating. According to embodiments that may be combined with other embodiments described herein, the at least one feeder 730 is configured to dispense a wire 731 as a feed material. The wire 731 may be, for example, a metal wire.

The optical measuring beam 742 may be provided off-axis or substantially coaxial with the laser beam. With an off-axis measuring beam provided in a separate optical path (e.g., oblique incidence in the wake), a topography measurement may be performed, for example, with a 1D or 2D oscillation in the wake. In the beam-coaxial configuration, a measurement of the height of the build-up weld bead may be made and the interferometer 740 may be statically positioned in the wake (uni-directionally, for example, along the machining direction). In addition, in the case of a dynamic or movable configuration, a topography can be measured, for example, using at least two rotatably mounted wedge plates 744 (multi-directional). Here, the optical measuring beam 742 is split by the two wedge plates 744 into two partial beams. As a result, it is possible, for example, to move one of the partial beams in the forerun and in the wake, so that the topography is detected simultaneously in both areas.

FIG. 8 shows a flowchart of a method 800 for additive production according to embodiments of the present disclosure. The method may be implemented using the additive manufacturing apparatus described herein.

The method includes, in step 810, directing a laser beam onto a processing area of a workpiece and feeding a feed material to the processing area. The method further comprises, in step 820, measuring a distance to the workpiece using an interferometer unit comprising an interferometer.

FIG. 9A shows a linear scan figure 144 of the optical measuring beam 142. Here, the optical measuring beam 142 between a position in the forward and a position in the wake, ie parallel to the machining direction, reciprocated and can thereby detect the geometry or the profile of the weld bead 12. The measurement result of this linear scanning movement 144 is shown in FIG. 9B: FIG. 9B shows a height profile of FIG Weld bead 12 along the processing direction shortly before and shortly after the processing point or the laser beam 112. FIGS. 9C and 9D show alternative scanning movements 144: In FIG. 9C, the optical measuring beam 142 is guided in a circle around the processing point or the laser beam 112, for example. sequentially) in the pre- and post-run. In FIG. 9D, two optical measuring beams are guided together along a circular figure around the processing point or the laser beam 112, so that it is possible to measure simultaneously in the forward and the after-run. In addition, a lateral topography of the weld bead 12 along the scan figure can be detected. The scanning figure or scanning movement 144 can be carried along in the machining direction.

In the embodiments of the present invention, the optical measuring beam (s) 142 may have at least one of the following central wavelengths: 1550 nm, 1310 nm, 1080 nm, 1030 nm and 830 nm. The additional laser deposition welding method 1010 shown in FIG a 3D printing process, with which a weld bead or a component 1020 is manufactured by means of laser deposition welding with a laser 1030 of a device according to the invention for additive manufacturing or manufacturing device 1035 shown in FIGS. 11 and 12.

In the method, an intended component height is derived from a CAD model of the component 1020 and, using a CAM model for manufacturing the component 1020, a layer height 1040 for applying a layer is determined by means of laser deposition welding. The layer height 1040 forms a controlled variable of the method 1010 according to the invention.

This controlled variable is transmitted to a controller 1050, which determines from the intended layer height 1040 a set of process parameters 1060 for laser deposition welding, which serve as manipulated variables of the method 1010 according to the invention. The process parameters 1060 include in the illustrated embodiment, a power of a light 1065 of the laser 1030 and a position of a focus of the laser 1030 and a material flow of a powdered welding material 1070 through a nozzle 1080 of a process head 1090 of the inventive manufacturing device 1035th With this set of process parameters 1060, the component 1020 is welded by laser deposition welding 1095. Laser deposition welding 1095 results in an actual height 1096 of the layer, which is determined by the distance of the nozzle 1080 of the process head 1090 from the component 1020. This determination is carried out by means of an optical coherence tomograph 1097, by means of which a measuring light 2100 of a light source 2110 of the coherence tomograph is coupled into the beam path 2115 of the laser 1030 which is used to manufacture the component 1020 in the process head 1090. In this case, the light of the laser 1030 and the measuring light 2100 are brought together by means of a partially transmissive mirror 2117 in the direction downstream of the light 1065 of the laser 1030 to the nozzle 1080 and separated from the nozzle 1080 upstream of the light 1065 of the laser 1030. The light of the laser 1030 and the measuring light 2100 do not coincide spectrally, so that the measuring light 2100 can be evaluated largely undisturbed by portions of the light of the laser 1030. Reflections of the measuring light 2100 of the light source 21 lO occurring in the case of laser cladding pass back into the beam path 2115 in the process head 1090. In the process head 1090, the reflections are coupled out and interferometrically compared with the measuring light 2100 of the light source 2110 originally fed into the process head 1090. From this comparison, the distance is obtained. The coherence tomograph 1097 and the optical beam path 2115 contained in the process head 1090, including the optical elements located in the beam path 2115, cooperatively form a distance sensor. This distance sensor is known per se and known for other than the welding processes described here, namely for laser welding, as an in-process depth meter of the company Precitec GmbH and described in the document DE10 102014 011 569 AI.

The use of this distance sensor requires a filtering of the obtained Ab Stands signals: Because in contrast to the already known use of the distance sensor described above in laser welding process requires the use of the distance sensor for laser cladding a consideration of the influence of powdered welding material 1070, which from the nozzle 1080th out and deposited on the device 1020 and which blocks a portion of the optical signal of the proximity sensor. Because this welding material 1070 absorbs a large part of the measuring light 2100 of the light source 2110 of the coherence tomograph 1097. The filtering of the distance signals therefore ensures the robustness of the method according to the invention.

For filtering, all the acquired distance values are initially recorded along a time window, in the present case 20 milliseconds, in further, not specifically illustrated exemplary embodiments, 4 milliseconds. Subsequently, from these detected distance values, a filter value is determined which is applied to temporally subsequent time windows of the same duration of 20 milliseconds (or 4 milliseconds in further embodiments). When the laser 1030 is turned off, only one-sided scattering occurs, so that here a maximum filter is used, which filters out the largest measured distance values as a measure of the actual distance. If an analysis of the measured distance values in a time window shows that two-sided scattering occurs, then the distance value which combines most of the measured data, that is, is used. The measured data are subjected to filtering according to the highest frequency value in the distribution of the distance values, ie a "mode filter." This filtering takes into account the fact that the distance value with the highest density of measured data reliably indicates the distance to the molten bath.

From the distance thus obtained, the actual height 1096 of the layer applied by laser deposition welding is obtained.

In the method according to the invention, in addition, further physical quantities of the laser deposition welding can be detected: Thus, in addition, the temperature of a molten bath 2140 formed during laser buildup welding can be determined. For this purpose, the molten bath 2140 is observed, for example, with a CCD camera 2150 of the production facility 1035. To observe the molten bath 2140, a portion of the light passing from the molten bath 2140 through the nozzle 1080 into the optical path 2115 of the processing head 1090 is coupled out with a partially transmissive mirror 2145 and imaged onto the CCD camera 2150. The CCD camera 2150 is connected to an evaluation device 2155 of the production device 1035. The evaluation device 2155 evaluates, via an algorithm, the image of the molten bath 2140 recorded with the CCD camera 2150 and determines a mean diameter of the molten bath 2140. The evaluation device 2155 contains Calibration data, by means of which from the average diameter of the molten bath 2140 is closed to the temperature of the molten bath 2140.

The CCD camera 2150 and the evaluation device 2155 can be handled in one piece in the processing head 1090, i. together with the machining head 1090 can be handled in one piece, so that the machining head 1090 with its housing (not shown in FIGS. 11, 12 and 13) reliably protects the CCD camera 2150 and the evaluation device 2155 from the harsh process conditions prevailing during laser deposition welding. In addition, a constant held flow of material of the powdered welding material 1070 can be detected by the nozzle 1080. The material flow is kept constant as it has a long delay time which limits the benefit of fast process feedback. A powder sensor 2160 in a powder feed line 2165 in the processing head 1090 observes the current material flow of the welding material 1070 and detects it as a volume flow. The detection of the volumetric flow makes it possible to adapt the production process due to changes in the volumetric flow of the welding material 1070 by setting the process parameters 1060. The powder sensor 2160 used in the exemplary embodiment shown is an optical flow meter which determines the proportion of the area of the cross-section of a powdered welding material 1070 Output of a powder conveyor (not detailed in the drawing) determined. The powder conveyor is arranged in the processing head 1090 for feeding the nozzle 1080 with welding material 1070, so that the welding material 1070 reaches the nozzle 1080 in a manner known per se for laser deposition welding and can be applied to the component 1020. A quadratic function of the volume flow is proportional to the proportion of the area occupied by the powdered welding material 1070 of the cross section of the output of the powder conveyor. The volume flow of the welding material 1070 is taken into account by the controller 1050 in order to correctly realize the intended geometry of the component 1020 during laser buildup welding 1095.

In the illustrated embodiment, the controller 1050 is implemented as a PC system. Alternatively or additionally, the controller 1050 can be used in further embodiments, which in the Incidentally correspond to the illustrated embodiment, be designed as a CNC controller. Additional external hardware and software control devices are dispensable in this further embodiment. Process sensors are connected directly to the CNC controller via a fast bus interface.

Depending on the above-noted sensed physical quantities, ie, the actual height 1096 of the layer, the temperature of the molten bath 2140, and / or the volumetric flow of the weld material 1070, the controller 1050 determines an adjusted set of process parameters 1060 for laser deposition welding 1095. The process parameters become such adapted that geometric deviations of the manufactured by laser deposition welding 1095 component 1020 are minimized so that at most deviations occur below a specified tolerance threshold. Accordingly, the component 1020 is manufactured reliably and sturdily. According to embodiments that may be combined with other embodiments described herein, the feed material is a powder or a wire. The method may in particular be a method for laser metal deposition (LMD).

In accordance with the present disclosure, laser based additive manufacturing (powder or wire based) is combined with sensor based interferometry (statically or dynamically deflected) for process monitoring and / or process control based on the measurement of geometrical distances and topgraphs in or around the interaction zone provided between the processing laser and the workpiece. The optical measuring beam can be radiated, for example by a laser deposition welding head through either the powder flow (powder deposition welding) or past the wire static or precise and highly dynamic, so that sequential or parallel measurement tasks can be performed. A measurement task can be a topography measurement in the forerun (z position of the workpiece surface) as a reference measurement or for process control. Another measuring task can be a topography measurement in the wake for determining the geometry of the surfacing bead, for example for Error detection. The measurement results can be used to control process input variables (eg laser power, powder flow, wire feed, process speed).

Claims

claims

A device (100) for additive manufacturing, comprising:

a laser device (110) for material processing by means of a laser beam (112), the laser device (110) being arranged to direct the laser beam (112) to a processing region of a workpiece (10);

at least one feed material feeder (130) configured to supply the feed material to the processing area; and

an interferometer unit having an interferometer (140) arranged to measure a distance to a surface of the workpiece (10) by means of at least one optical measuring beam (142).

2. Device (100) according to claim 1, wherein the interferometer unit is set up to determine, based on the distance measurement, at least one physical variable from the group which has a size of a generated weld bead (12), a height of a generated weld bead (12) Position of a generated weld bead (12), a position of the surface of the workpiece (10) and a topography of the surface of the workpiece (10).

The apparatus (100) of claim 1 or 2, wherein the interferometer unit is arranged to measure a distance to the machining area and / or a distance to a portion of the workpiece (10) adjacent to the machining area.

The apparatus (100) of any one of the preceding claims, wherein the apparatus (100) further comprises detecting means for detecting at least one further physical quantity, the further physical quantity being selected from the supply flow of the feed material, feeding speed of the feeder, laser power, focus diameter of the laser beam (112), dimension of a molten bath and a temperature of the molten bath.

5. Device, in particular according to one of the preceding claims, which is a production device (1035) for the additive laser deposition welding (1095) of a component (1020), comprising detection means (1097) for detecting at least one physical quantity (1096) of the welding process and adjusting means for positioning at least one process parameter (1060) depending on the at least one detected physical quantity (1060) and / or its course,

which preferably comprises a machining head (1090) for laser deposition welding and a distance detection device (10097), which for measuring the distance of the machining head (1090) from the component (1020) is formed and / or which has a coherence tomograph (1097) or is optically connected to such , having.

The apparatus (100) of any one of the preceding claims, further comprising a controller configured to operate the laser device (110) and / or the at least one delivery device (130) based on the distance measured by the interferometer unit and / or based on controlling the at least one specific physical quantity and / or based on the at least one detected physical quantity.

The apparatus (100) of claim 6, wherein the controller is configured to control the laser device (110) and / or the at least one delivery device (130) by controlling at least one process input, the process input being selected from the direction of movement of the device of the workpiece (10), moving speed with respect to the workpiece (10), feeding speed of the feeding device (130), feed flow of the feeding material, powder flow rate, powder amount, powder composition, powder feeding direction, wire feeding direction, wire feeding speed, working distance, process gas composition, process gas pressure, laser focus diameter, optical axis position, Laser focus position, laser pulse width and laser power.

The apparatus (100) of claim 6 or 7, wherein the controller is configured to provide at least one process input such that deviations from and / or minimizes deviations from a model of the processing region or weld bead (12) or the additive manufacturing process are below a maximum threshold become.

9. Device (100) according to one of the preceding claims, wherein the interferometer (140) is a coherence interferometer or a short-coherence interferometer and / or wherein the interferometer (140) is arranged to couple the optical measuring beam (142) into a beam path of the laser device (110), or wherein the interferometer (140) has a beam path for the optical measuring beam (142) separated from the beam path of the laser device (110). includes.

10. Apparatus (100) according to any one of the preceding claims, wherein the interferometer (140) is arranged to statically provide the optical measuring beam (142) with respect to the laser beam (112) and / or

wherein the interferometer (140) is arranged to provide the optical measuring beam (142) movable with respect to the laser beam (112) and / or

wherein the interferometer is arranged to reciprocate the at least one optical measuring beam (142) linearly or in a circular path between a forward position and a post-cursor position.

The device (100) of any one of the preceding claims, wherein at least one central wavelength of a wavelength range of the optical measuring beam (142) is approximately 1550 nm, 1310 nm, 1080 nm, 1030 nm and / or 830 nm.

A device (100) according to any one of the preceding claims, wherein the at least one feed device (130, 730) is arranged to supply a powder or wire (731) as feed material and / or is selected from a group consisting of a ring jet powder nozzle (330), a multi-jet powder nozzle (530), and an off-axis powder nozzle.

The apparatus (100) of any one of the preceding claims, wherein the apparatus (100) is a laser deposition welding head.

14. A method for the additive laser cladding of a component (1020) by means of a laser (1030), wherein during laser deposition welding at least one physical quantity (1096) of the welding process is detected and dependent on the at least one detected physical size (1096) and / or its course at least one process parameter (1060) of the method is provided.

15. The method of claim 1, wherein the physical quantity determines at least one geometric size of the component produced during the welding process and / or a size derived therefrom and / or a height of a layer applied during laser deposition welding and / or a derived quantity.

16. The method according to any one of the preceding claims, wherein for laser deposition welding a supply device (2165), in particular a powder conveyor, is used for a welding material and the at least one physical size at least one feed stream and / or a feed speed of the supply device (2165) and / or is a quantity derived from one or more of the aforementioned quantities and / or in which the at least one physical variable is at least one power of the laser (1030) and / or one dimension of a focus of the laser (1030) and / or one of one or more of the size derived above.

17. The method according to any one of the preceding claims, wherein the laser cladding is carried out with a molten bath (2140) and the at least one physical size at least one dimension of the molten bath (2140) and / or a size derived therefrom and / or in which laser deposition welding Processing head (90) is used and the at least one size is a distance of the machining head (90) from the component (20) and / or a size derived therefrom and / or wherein the at least one process parameter (1060) the position and / or temporal Course of the position of the focus of the laser (1030) relative to the component (1020) and / or a size derived therefrom.

18. The method of claim 1, wherein the at least one process parameter is set such that deviations from a model of the component and / or the laser deposition welding are kept below a maximum threshold and / or minimized , preferably by means of a regulatory procedure.