A material conveying device

Abstract

The present invention relates to a material conveying device. The material conveying device for a material processing device according to the present invention has a material conveying channel which, during operation of the material conveying device, has an output end facing a processing position, and is characterized in that the material conveying device has at least one microchannel.

Description

Specific embodiments

[0001] The present invention relates to a material conveying device. In particular, the present invention relates to a material conveying device for a material processing method, for example, for conveying a filler material.

[0002] The material processing method can be, for example, a laser material processing method. In many laser material processing methods (such as cutting, welding, surfacing, soldering), the actual material or filler material must be conveyed to the processing position in order to provide the filler material or to influence the process by means of a gas. These methods include, for example, laser welding (hard welding and soft welding), plastic welding, metal material welding, application of layers made of metal, ceramic or plastic, generation of structures made of metal, plastic or ceramic, laser beam cutting, laser beam curing, laser beam alloying, laser beam dispersion, naming the most important structures. However, it is not absolutely necessary to use a laser beam in the material processing method; another example of a material processing method can be arc welding.

[0003] For example, in generative manufacturing, such materials must be conveyed. Here and hereinafter, the terms "material" and "filler material" will be used synonymously and in each case specify the material that is conveyed or must be conveyed to the processing position. The material can be supplied in solid, liquid or gaseous form. In solid form, it is mainly wire or powder.

[0004] Material processing devices for performing material processing methods are known. They can have at least one energy generating device, such as a laser for connecting a cooling medium and a protective gas, and a conducting device for these media, and also have a conveying device for conveying the material to the processing position. Such a device usually has a processing head, which has a nozzle-type geometry on the side facing the processing position. Usually, since an inert gas can be conveyed to the processing position through the nozzle-type geometry of the processing head, this part of the processing head is also called an inert gas nozzle. Material processing devices in which the material is conveyed from the side are also known. However, due to its size, such an arrangement is rather cumbersome near the processing position. In addition, such an arrangement is asymmetric, so that if the conveying direction changes following the contour of the workpiece, rotation of the processing head becomes necessary. The processing head has a material conveying device, an optical system for beam guiding and shaping, possibly also a cooling device and an inert gas feeding device. Otherwise, the process depends on the direction.

[0005] If the material is conveyed centrally, for example, with respect to the longitudinal axis of the processing head, the laser beam (if any) must be split such that the central axis becomes or remains free for feeding the material. The material must be conveyed to the processing location, i.e., the location where the laser beam impinges on the substrate. Usually, the individual processing heads have the shape of a nozzle, and the conveyed material as well as the laser beam and any protective gas and any cooling medium to be conveyed are guided through the processing head. These components must be embodied and the laser beam must be conducted such that the beam guidance is not impaired, in particular, such that the beam is either occluded or not occluded. From German Patent DE102007018400B4, an optical system and a corresponding processing head are known by means of which the material can be axially guided to the processing location while the laser beam is split into an annular form and can be coaxially guided to the processing location.

[0006] During this laser material processing, the material conveying device heats up due to scattered radiation from the optical system, thermal radiation from the processing, and reflected laser radiation. If laser material processing is also to be carried out at locations on the workpiece that are difficult to access, the nozzle must be correspondingly small. The limited available space in the processing head usually allows for axial material conveyance without direct cooling. The heating up of the material conveying device leads to process interruptions due to system failures. In this way, it is not possible to achieve longer processing times or use higher laser powers, for example, as required to increase the application rate. For example, when the laser power is less than 1000 W and the processing time is greater than 15 minutes, the material conveying device overheats.

[0007] Now, the process of laser surfacing is interrupted at regular intervals and the cooling time is observed to avoid damage to the material conveying device and / or overheating of the material conveying device and related problems in material conveyance. Alternatively, the operating distance between the material output opening and the processing plane can be increased; however, this results in less precise guidance of the filler material to the weld pool and thus in process instability. For example, for wire materials with a diameter of less than approximately 0.8 mm, it is not desirable to increase the operating distance because the precise guidance and positioning of the material relative to the weld pool can no longer be guaranteed.

[0008] It is known to provide welding torches for arc welding processes with water cooling. However, the dimensions of the water cooling require an outer diameter of approximately 25 mm or more, which does not allow the water cooling to be integrated into a miniaturized processing head with axial material conveyance; that is, they require a substantial enlargement of the processing head, which greatly reduces its accessibility, which is disadvantageous. Using conventional manufacturing methods, a feed nozzle with an outer diameter of 8 mm or less cannot integrate water cooling.

[0009] According to German patent application DE102016006247A1, a device for a laser heater for melting filaments is known. The laser heater has a pressure head, an axial hole for passing through the filaments, and at least one hole and an external thread, and an optically transparent nozzle body having a groove, a path folding ring mirror, a nozzle, and an internal thread. At least one laser having the same or different electromagnetic wavelengths and possibly having power control is guided through the hole in the filament by the path folding ring mirror, and the infrared radiation caused by the melting of the filament is guided to at least one infrared sensor through the path folding ring mirror and the hole.

[0010] According to German patent application DE102017215841A1, a powder nozzle in a machine for processing workpieces is known, and / or a powder nozzle in a machine for manufacturing a mold by selectively curing a material powder at a specific position by means of a laser beam to form a coherent region. The powder nozzle includes a substantially rotationally symmetric base body having an axial through hole for a laser beam, and fastening means for releasably fastening the powder nozzle to the laser processing head of the machine. The powder nozzle has means for cooling it.

[0011] From US Patent US6396025B1, a powder application nozzle for laser welding applications is known, which has a nozzle tip with a plurality of discharge ports for focusing the discharged powder jets. A nozzle head with a plurality of ports distributes a plurality of discharge jets, including powder discharge ports and at least one focusing gas discharge port radially spaced from the powder discharge ports for distributing powder jets and gas jets. Powder flows from a powder source through a powder channel to discharge the powder jets. Focusing gas flows through a focusing gas channel angled with respect to the powder channel to discharge the focusing gas jets.

[0012] The object of the present invention is to disclose a material delivery device for performing a laser material processing method, which minimizes the said disadvantages of the prior art. Another object is to disclose a manufacturing method for such a material delivery device.

[0013] The material delivery device according to the present invention is for a material processing device. The material delivery device has a feed channel, and during operation of the material delivery device, the output end of the feed channel faces the processing position; it is characterized in that the material delivery device has at least one microchannel, and the at least one microchannel has a wall thickness of less than 0.5 mm, preferably less than 0.3 mm, and particularly preferably less than 0.2 mm at least at one position, and the at least one microchannel is connected to a coolant supply source.

[0014] Some terms will be explained below:

[0015] In this document, a material conveying device used in a material processing device is understood to be a device that can convey materials to a processing position on a substrate. In particular, the material conveying device can be used in a material processing device that uses a laser material processing method.

[0016] Material processing devices for performing material processing methods are well-known. They can have at least one energy generating device, such as a laser, as well as ports for connecting cooling media and protective gases, and conduction devices for these media and the light beam. In addition, there is a conveying device for conveying materials to the processing position. Such devices usually have a processing head that has an inert gas nozzle on the side facing the processing position. Material processing devices in which the material is conveyed from the side are also known. In such a lateral transfer, the transfer axis has an angle greater than 0° and less than 90° with respect to the axis of the beam guide. However, due to its size, this arrangement is rather cumbersome in the vicinity of the processing position. In addition, this arrangement is asymmetrical, so that if the conveying direction changes following the contour of the workpiece, the rotation of the processing head becomes necessary. The processing head has a material conveying device, an optical system for beam guiding and shaping, possibly also a cooling device, and an inert gas feeding device. Otherwise, the process depends on the direction.

[0017] If the material is conveyed centrally, for example, axially with respect to the longitudinal axis of the processing head, the laser beam (if any) must be split so that the central axis becomes free for material conveyance. The material must be conveyed to the processing position, that is, the position where the laser beam irradiates the substrate. Usually, each processing head has the shape of a nozzle. For example, for an inert gas nozzle, the conveyed material, as well as the laser beam and any protective gas and any cooling medium to be supplied, are guided through the processing head, in particular the inert gas nozzle. These components must be embodied, and the laser beam must be conducted so that the beam conduction is not weakened, in particular, so that the beam is either blocked or not blocked.

[0018] The term laser material processing method should be understood in its broadest sense, including all material processing methods, such as using a laser beam to cut, weld, build-up weld, or solder. A laser beam is an electromagnetic wave with high intensity, usually with a very small frequency range, strong beam focusing ability, and large coherence length. The material can be fed in solid or liquid form or as a gas. In solid form, the material is usually in wire or powder form.

[0019] In this document, the term material conveying channel means a channel through which materials can be conveyed to the processing position. The material conveying channel can have any cross-section, including an annular cross-section.

[0020] The term light channel in this document particularly refers to a channel through which a laser beam can be conducted to the processing position. The light channel can have any cross-section, including an annular cross-section.

[0021] The processing position is the position on the substrate where processing is carried out. The processing position can be punctiform or an area.

[0022] In this context, a microchannel is understood to be a tubular channel with a very small cross-section, for example 10 -2 mm 2 . The microchannels can be partially or fully annular, elliptical, polygonal, helical or straight. The present disclosure also uses a plurality of microchannels, including various unconnected microchannels as well as different windings of various interconnected microchannels or helical microchannels. The microchannels can be embodied as double-walled channels, for example in the form of a channel within a channel and / or a helical channel.

[0023] As a general rule, it should be noted that within the framework of this document, the indefinite numbers "one", "two", etc. should generally not be understood to mean "exactly one", "exactly two", etc., but rather the indefinite article. A statement using the expressions "one...", "two...", etc. should be understood to mean "at least one...", "at least two...", etc., unless it is clear from the corresponding context that only "exactly one", "exactly two", etc. can be inferred. If an independent claim mentions "at least one", this does not mean that the "one...", "two...", etc. mentioned in the dependent claims necessarily mean exactly one, exactly two, etc.

[0024] Within the framework of this patent application, the expression "in particular" is always understood to introduce optional, preferred features. This expression should not be understood as "i.e.".

[0025] In a preferred embodiment, at least at one position, the wall thickness of the at least one microchannel is less than 0.5 mm, preferably less than 0.3 mm, and particularly preferably less than 0.2 mm. The microchannel is bounded by a wall. This wall can form the boundary to the outside of the material delivery device or to another channel. This other channel can be an additional microchannel, a material delivery channel or an optical channel. It can also be an additional winding of a helical microchannel.

[0026] The low wall thickness of the microchannel allows the material delivery device to have very small structural dimensions, which still allows for example temperature regulation.

[0027] The at least one microchannel is also connected to a coolant source. The application can be for example a pump with a temperature controller so that for effective temperature control, a temperature control medium, such as water or heat transfer oil, can be conveyed through the at least one microchannel at a defined temperature and a defined volume flow rate and / or pressure.

[0028] In a particularly preferred embodiment, the at least one microchannel has an integrated support. The support can cause or increase turbulence in the temperature control medium flowing through the microchannel, thus ensuring optimized heat transfer. In addition, the support can also contribute to providing mechanical stability of the microchannel and the material delivery device.

[0029] It has been shown that it is particularly effective if at least one microchannel for cooling ensures a forward flow of the temperature control medium and a return flow of the temperature control medium. This ensures the effectiveness of the temperature control of the material delivery device.

[0030] In another advantageous embodiment, the material delivery device has a threaded area for receiving and fixing the nozzle head in place, and the microchannel passes through the material delivery device at least except for the threaded area. By increasing the area of the material delivery device through which the microchannel passes, the temperature control of the material delivery device is optimized. Due to the provision of the thread, the nozzle tip, which is often subject to wear, can be easily replaced.

[0031] In another advantageous embodiment, a measurement sensor is provided in at least one microchannel. The microchannel is not only used for passing the temperature control medium, but also for introducing the measurement sensor. Such a measurement sensor can be, for example, a temperature sensor for monitoring the material delivery temperature, an optical fiber for recording the welding pool temperature and / or for process control, a sensor for distance measurement, such as an optical fiber tomography for OCT (optical coherence tomography, an imaging method for receiving two-dimensional and three-dimensional images with micron resolution from scattering materials), or a measurement sensor for monitoring the material delivery. By introducing such a measurement sensor, the process parameters can be monitored very close to the site of interest inside the material delivery device and / or close to the processing site without significantly changing the size of the material delivery device.

[0032] Alternatively or additionally, a filler material influencing device can be provided in at least one microchannel. Such an influencing device can be, for example, a device for preheating the filler material, such as an induction preheating unit. By preheating the material to be delivered, for example, the application rate of the material (such as the filler material) can be increased. By introducing the material influencing device into the microchannel, it is possible to approach the filler material influencing device, for example, very close to the material delivery channel, especially very close to the processing position, so that the filler material can be influenced in a targeted and highly precise manner.

[0033] It has been proven to be advantageous if the manufacturing method of the material conveying device comes from the method category of additive manufacturing. "Additive manufacturing" denotes a process in which, based on digital 3D construction data, components are built up layer by layer by deposition of materials. The term "3D printing" is often used today as a synonym for additive manufacturing. However, "additive manufacturing" better describes that the method is significantly different from conventional abrasive manufacturing methods. Instead of, for example, milling a workpiece from a solid block, additive manufacturing forms components layer by layer from materials that are available, for example, in the form of fine powders or thin wires. These materials can be different types of metals, plastics, and composite materials. By having the material conveying device build the structure layer by layer, geometries, especially microchannels, can be produced that cannot be produced at all or can only be produced in large quantities by conventional manufacturing methods.

[0034] A particularly advantageous technique for the manufacturing method has proven to be the laser powder bed fusion (LPBF) technique. With this technique, the material to be processed is applied as a powder in a thin layer on a substrate. By laser irradiation, the powder material is locally completely melted and, after solidification, forms a rigid material layer. Subsequently, the substrate is lowered by an amount equal to the layer thickness and the powder is reapplied. This cycle is repeated until all layers have been remelted. The finished component is cleaned from the excess powder and processed or used directly as required. For all materials, the typical layer thickness for forming the component is between 15 and 500 μm. The data for guiding the laser beam is generated from a 3D CAD body by software. In a first calculation step, the component is divided into individual layers. In a second calculation step, a path to be traced by the laser beam is created for each layer. To avoid contamination of the material by oxygen, the method is typically carried out in an inert gas atmosphere with argon or nitrogen. Components manufactured with LPBF are characterized by a high relative density of 99%. In this way, it is ensured that the mechanical properties of the produced components largely correspond to those of the base material.

[0035] It should be clearly pointed out that all the indicated numerical values should not be understood as exact values, but that in the case of not departing from the described aspects of the present invention, the actual values can be higher or lower on an engineering scale.

[0036] From the accompanying drawings, from the dependent claims, and from the examples of the preferred embodiments given below, other advantages, features, and useful further improvements of the present invention will become clear. Description of the Drawings

[0037] Figure 1 Shows the processing head of the material processing device;

[0038] Figure 2 Is a three-dimensional schematic view of the material conveying device according to the present invention;

[0039] Figure 3 Is a longitudinal sectional view of an embodiment of the material conveying device according to the present invention;

[0040] Figure 4 is a longitudinal sectional view of another embodiment of the material conveying device according to the present invention;

[0041] Figure 5 is an enlarged cross-sectional view of the material conveying device according to the present invention.

[0042] Figure 1 shows the processing head 200 of the material processing device. The processing head 200 has a material conveying device 100 according to the present invention, and the material conveying device 100 has a material conveying channel 110. The material conveying device according to the present invention used in the material processing device has a material conveying channel 100, and the material conveying channel 100 has an output end 111 facing the processing position during the operation of the material conveying device 100. Through the material conveying device 100, materials can be conveyed to the processing position on the substrate. The material processing device is used to perform a material processing method, such as a laser welding method. The processing head 200 has a guiding device for the laser beam. The guiding device has a deflection unit 215 for the laser beam, such as a mirror and / or a prism, a focusing lens 210, and an inert gas nozzle 230 having an inert gas channel 235. Through the inert gas channel 235, the inert gas is conveyed to the processing position. The inert gas respectively prevents the scaling of the hot substrate or the supplied material during processing by temporarily making the processing position not in contact with oxygen. In the shown embodiment, the material is conveyed axially to the processing position at the center, for example, relative to the longitudinal axis of the processing head 200. For this purpose, if one or more laser beams are used, the laser beams must be split so that the central axis becomes or remains free for material conveyance. To achieve this, all components in the processing head must be embodied, that is, especially the material conveying device 100, and the laser beam must be conducted in the optical channel 220 (shown in the laser beam ring 220 in the embodiment) so that the beam guiding is not impaired, especially so that the beam is not blocked. The material conveying channel 110 has a replaceable material nozzle (not shown) at its end opposite to the processing position. The material nozzle can be screwed into the material conveying channel 110, for example. During operation, due to the thermal load received by this end of the material conveying channel 110 during the operation of the processing head 200, wear occurs at the end of the material conveying channel 110 opposite to the processing position. When the wear exceeds the critical limit, the replaceable material nozzle can be easily replaced. The material can be conveyed in solid, liquid or gas form. In solid form, it is usually in wire or powder form. For example, if the conveyed material has the form of a wire, the wear will cause an increase in the diameter of the material conveying channel 110 at the output end 111, thereby reducing the accuracy of wire guiding.

[0043] Figure 2is a three-dimensional schematic view of a material conveying device 100 according to the present invention. The material conveying device 100 has a continuous material conveying channel 110 through which materials are conveyed to a processing position. In addition, the material conveying device 100 has a medium connection port 130. Through these medium connection ports 130, for example, a cooling medium, such as water, can be introduced into and discharged from the material conveying device 100. The medium connection ports 130 are located at the ends of the material conveying device 100, and during the operation of the processing head 200, the material conveying device 100 faces the processing position. In addition, the material conveying device 100 has a connection port 120 for a material nozzle (not shown), and during the operation of the processing head 200, this connection port 120 is arranged to be screwed into the end of the material conveying device 100 facing the processing position. In addition, as can be seen in the figure, there is a connecting member 150 to which the material conveying device 100 is attached. For manufacturing reasons, the material conveying device 100 has a two-part structure. The material conveying device 100 is manufactured by an additive manufacturing method. If the size of the part to be manufactured in the additive manufacturing equipment is limited, the material conveying device 100 can be manufactured in two or more components and can be assembled to operate at one or more connecting members 150. The material conveying device 100 can also be manufactured integrally, but a corresponding additive manufacturing equipment needs to be available.

[0044] Figure 3 is a longitudinal sectional view of an embodiment of the material conveying device 100 according to the present invention. As Figure 2 shown, the medium connection port 130 and the connection port 120 for the material nozzle can be seen. For the sake of clear display, the display of the threads is omitted in this figure. The material conveying device 100 has a continuous material conveying channel 110. In addition, the material conveying device 100 has several medium channels 131 which are operably connected to the medium connection port 130. For example, a cooling medium, such as water, can be introduced into the medium channels 131 through the medium port 130. The medium channels 131 are implemented as microchannels 131, that is, tubular channels with a very small cross-section, such as 10 -2 mm 2。The microchannel 131 can be partially or fully annular, elliptical, polygonal, helical or even straight. Several microchannels 131 can include various microchannels 131 that are not interconnected and various interconnected microchannels 131 or different windings of helical microchannels 131. The microchannel 131 can also be embodied as a double-wall channel, such as a channel-in-channel and / or a helical channel. The microchannel 131 is bounded by walls. The walls can form the boundary to the outside of the material delivery device 100 or to another channel. This other channel can be an additional microchannel 131, a material delivery channel 110 or an optical channel 220. The additional microchannel 131 can also be an additional winding of the helical microchannel 131. Each microchannel 131 can have a wall thickness that is less than 0.5 mm, preferably less than 0.3 mm, and particularly preferably less than 0.2 mm at least at one location. The low wall thickness of the microchannel 131 allows the material delivery device 100 to have a very small structural size, and thus, in any case, allows for, for example, temperature regulation. Except at least for the threaded area for screwing the material nozzle (not shown in the figure) into place, the microchannel 131 passes through the material delivery device 100. By increasing the area of the material delivery device 100 through which the microchannel 131 passes, the temperature control of the material delivery device 100 is optimized. A measurement sensor can also be introduced into one or more microchannels 131 of the material delivery device 100 close to the material delivery channel 110. Such a measurement sensor can be, for example, a temperature sensor for monitoring the temperature of the material delivery, an optical fiber for recording the welding pool temperature and / or for process control, a sensor for distance measurement, such as an optical fiber tomography for OCT (optical coherence tomography, an imaging method for receiving two-dimensional and three-dimensional images with micron resolution from scattering materials) or a measurement sensor for monitoring the material delivery. By introducing such a measurement sensor, the process parameters can be monitored very close to the site of interest inside the material delivery device 100 and / or close to the processing site without significantly changing the size of the material delivery device 100.

[0045] Alternatively or additionally, a filler material influencing device can be provided in at least one microchannel 131. Such an influencing device can be, for example, a device for preheating the filler material, such as an induction preheating unit. By preheating the material to be delivered, the application rate of the material (such as the filler material) can be increased, for example. By introducing a material influencing device into the microchannel 131, the filler material influencing device can be close to, for example, very close to the material delivery channel 110, especially very close to the processing location, so that the filler material can be influenced in a targeted manner with high precision.

[0046] The material delivery device 100 is manufactured by an additive manufacturing method. By layer-by-layer constructing the material delivery device 100, geometries such as the microchannel 100 described above can be manufactured, which cannot be manufactured at all or can only be manufactured with great effort by traditional manufacturing methods.

[0047] Figure 4 Shows a longitudinal cross - section of another embodiment of the material delivery device 100 according to the present invention. The microchannel 131 has an integrated support 132 or a plurality of such supports 132. The support 132 can ensure turbulence or an increase in turbulence in the temperature - controlled medium flowing through the microchannel 131, thus ensuring optimized heat transfer. In addition, the support 132 can also contribute to the mechanical stability of the microchannel 131 and the material delivery device 100.

[0048] Figure 5 is Figure 4 An enlarged cross - section of the material supply device 100 according to the present invention. In this enlarged portion, the support 132 is more easily visible. The support 132 is applied internally, that is, on the side of the microchannel 131 facing the material delivery channel 110. However, the support 132 can also be arranged at any other position within the microchannel 131.

[0049] The embodiments shown here are merely exemplary and are not intended to be limiting. Alternative embodiments contemplated by those skilled in the art are also included within the scope of the present invention. List of reference numerals:

[0050] 100 Material delivery device

[0051] 110 Material delivery channel

[0052] 111 Output end 120 Connection port for material nozzle 130 Medium connection port

[0053] 131 Medium channel, microchannel

[0054] 132 Support

[0055] 150 Connector

[0056] 200 Processing head

[0057] 210 Focusing lens

[0058] 215 Deflection unit

[0059] 220 Optical channel, laser beam ring

[0060] 230 Inert gas nozzle 235 Inert gas channel

Claims

1. A material conveying device (100) used in a material processing device, the material conveying device (100) having at least one material conveying channel (110), the material conveying channel (110) having an output end (111), the output end (111) facing a processing position during operation of the material conveying device (100), characterized in that, The material delivery device (100) has at least one microchannel (131), the at least one microchannel (131) having a wall thickness of less than 0.5 mm at least at one location, and the at least one microchannel being connected to a coolant supply source.

2. The material conveying device (100) according to claim 1, characterized in that, The material delivery device (100) has a central material delivery channel (110).

3. The material conveying device (100) according to claim 1, characterized in that, The material delivery device (100) has a material delivery channel (110) that is laterally disposed at an angle greater than 0° and less than 90° with respect to the axis of the laser beam guide.

4. The material conveying device (100) according to any one of the above claims, characterized in that, The at least one microchannel (131) has an integrated support (132).

5. The material conveying device (100) according to claim 1, wherein, The at least one microchannel (131) connected to the coolant supply source ensures forward flow of the temperature control medium and return flow of the temperature control medium.

6. The material conveying device (100) according to claim 1, characterized in that, The material delivery device (100) has a threaded area for receiving a nozzle tip and fixing the nozzle tip in place, and the microchannel (131) passes through the material delivery device (100) at least outside the threaded area.

7. The material conveying device (100) according to claim 1, characterized in that, A measurement sensor is provided in at least one microchannel (131).

8. The material conveying device (100) according to claim 1, characterized in that, A material influencing device is provided in at least one microchannel (131).

9. A method for manufacturing the material conveying device (100) according to claim 1, characterized in that, The manufacturing method is from the method category of additive manufacturing methods.

10. The manufacturing method according to claim 9, characterized in that, The manufacturing method uses laser powder bed fusion technology.

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