Material powder nozzle for a laser cladding device, laser cladding device, and method for laser cladding

Abstract

The invention relates to a material powder nozzle (1) for a laser cladding device. Powder channels (3) through which a mixture of material powder and transport gas can flow each have a channel longitudinal center axis (2) which includes an associated elevation angle (α) of greater than 0° and less than 90° with a nozzle outlet plane (A) of the material powder nozzle (1), said nozzle outlet plane lying in a horizontal origin plane (Z) of a nozzle coordinate system (r|z|φ). Each channel longitudinal center axis (2) also includes, with a horizontal radial axis (r) of the nozzle coordinate system (r|z|φ), an associated azimuth angle (β) which lies in the nozzle outlet plane (A) and which is greater than 0° and less than 90°. The invention also relates to a laser cladding device comprising the material powder nozzle (1) and to a method for laser cladding, wherein a powder density profile (28) deviating from a Gaussian-like powder density profile (300) is produced in the powder focal plane (P) by means of the mixture of material powder and transport gas flowing out of the powder channels (3).

Description

[0001] MATERIAL POWDER NOZZLE FOR A LASER CLADDING DEVICE, LASER CLADDING DEVICE AND METHOD FOR LASER CLADDING WELDING

[0002] The present invention relates to a material powder nozzle for a laser cladding device and to a laser cladding device having such a material powder nozzle. Furthermore, the invention relates to a method for laser cladding in which a laser cladding device having the material powder nozzle is used.

[0003] In laser cladding processes—for example, LMD (Laser Metal Deposition), DMD (Direct Metal Deposition), DED (Direct Energy Deposition), high-speed laser cladding (HS-LMD), extreme high-speed laser cladding (EHLA), generative laser cladding, etc.—a welding material in the form of a material powder is blown into a process zone at or just above the surface of a workpiece using a transport gas jet. The material powder or the welding material and / or the surface of the workpiece are melted within the process zone using a laser welding beam. This creates a fused-metallurgical bond between the workpiece and the welding material.Conventional laser cladding processes are known from the state of the art, for example from DE 10 2011 100 456 B4 or from DE 102018 130 798 A1.

[0004] To achieve homogeneous energy distribution and a high-quality joining result, a laser welding beam with a round beam cross-section is used, for example, a single-spot laser beam or a 2-in-1 fiber laser beam, each with a top-hat laser intensity profile. Using a conventional material powder nozzle 100, as schematically shown in Fig. 10, the material powder is introduced into the process zone 200 (for example, onto a workpiece surface) at a single point, resulting in a Gaussian-like powder density profile 300 that does not match the top-hat laser intensity profile 400 of the laser welding beam. This is because in the area of ​​a powder accumulation 500 in the center of the powder density profile 300, the process zone 200 is more heavily shaded than in the edge region 600 of the powder density profile 300.The powder density profile 300 results from a positional arrangement of powder channels of the conventional material powder nozzle 100, wherein the respective channel longitudinal center axis 700 of the powder channels lie in a respective plane spanned by a radius of the conventional material powder nozzle 100 and a horizontal axis x of the conventional material powder nozzle 100, whereby the channel longitudinal center axes 700 intersect each other and the horizontal axis x at a single, common point 800. During laser material deposition welding, only a small amount of laser radiation penetrates to the workpiece surface due to the centrally heavily shaded process zone 200, whereby the workpiece is insufficiently heated in the process zone, which leads to bonding errors and / or delamination of the layer structure.

[0005] To counteract this problem, powder channels with a larger inner diameter can be used than previously. However, this requires a higher transport gas volume flow in order to maintain the flight time of the material powder particles in the process or interaction zone compared to conventional powder channels with a smaller inner diameter, and thus to keep the temperature of the material powder particles required to create the fused metallurgical bond constant. This is inefficient both in terms of the increased transport gas consumption and the amount of energy required to carry out the laser cladding. Furthermore, the entire workpiece or a large portion of the workpiece can be heated using a heating device other than the laser welding beam to promote the formation of the fused metallurgical bond.However, this means that a particularly large amount of energy is required to carry out the laser cladding.

[0006] The object of the invention is to create a solution to produce a particularly stable and reliable connection between a workpiece and a welding material by means of laser cladding with the lowest possible energy consumption.

[0007] This object is achieved by the subject matter of the independent patent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description and the figures. Features, advantages and possible embodiments that are set out in the description for one of the subject matter of the independent claims are to be regarded, across categories and embodiments, at least analogously as features, advantages and possible embodiments of the respective subject matter of the other independent claims and of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims. According to the invention, a material powder nozzle for a laser deposition welding device and a laser deposition welding device having the material powder nozzle are proposed. Furthermore, a method for laser deposition welding using the laser deposition welding device is proposed.For the description of the material powder nozzle, reference is made to a nozzle coordinate system (r|z|cp) of the material powder nozzle. For the sake of simplicity, it is assumed here that an origin plane (Z plane) of the nozzle coordinate system is arranged horizontally for an observer. The nozzle coordinate system and the material powder nozzle are fixed to one another, so that when the material powder nozzle is rotated, its nozzle coordinate system rotates uniformly. References such as "vertical," "horizontal," etc., refer to the origin plane, which is referred to below as the horizontal origin plane. The nozzle coordinate system is, for example, a cylindrical coordinate system, particularly when the material powder nozzle has a cylindrical shape and / or when powder channels of the material nozzle are arranged along specific circles, as described below.

[0008] The material powder nozzle has a vertical nozzle longitudinal center axis that coincides with a vertical axis of the nozzle coordinate system, whereby a nozzle outlet plane of the material powder nozzle and the horizontal origin plane of the nozzle coordinate system coincide. A nozzle inlet plane of the material powder nozzle is spaced from the nozzle outlet plane in the Z direction by a material powder nozzle height, whereas a powder focus plane of the material powder nozzle is spaced from the nozzle outlet plane or from the horizontal origin plane in the opposite Z direction by a powder focal length. Furthermore, the material powder nozzle has two or more powder channels, each of which can be flowed through by a material powder-transport gas mixture whose transport gas component comprises, for example, helium, argon, nitrogen, or a gas mixture. The material powder-transport gas mixture flowing through the powder channels can also be referred to as a powder gas jet.In particular, the material powder nozzle has three or more powder channels, for example, six, seven, or eight, up to 20 or more. Accordingly, the material powder nozzle is designed as a multi-jet nozzle. Each powder channel is, for example, 10 mm long or longer along its longitudinal center axis and has a flow-through inner diameter of, for example, 0.5 mm to 5 mm.

[0009] A respective outlet opening of the respective powder channel lies in the nozzle outlet plane, and a respective inlet opening of the respective powder channel lies in the nozzle inlet plane. A completely straight longitudinal channel center axis runs through an outlet opening center point of the outlet opening and through an inlet opening center point of the inlet opening, which encloses an elevation angle with the nozzle outlet plane that is greater than 0° and less than 90°. In addition, the longitudinal channel center axis encloses an azimuth angle with a horizontal radial axis of the nozzle coordinate system that lies in the nozzle outlet plane, which is greater than 0° and less than 90°, in particular a maximum of 60°. The radial axis lies in the horizontal origin plane and intersects the vertical or Z-axis of the nozzle coordinate system. Therefore, the radial axis and a radius of the material powder nozzle coincide.

[0010] The powder channels can be rigidly arranged in a support body of the material powder nozzle made of hard metal, glass, or copper, for example as a respective through-opening that completely penetrates the support body along the respective channel's longitudinal center axis, or as a respective tube and / or hose element made of hard metal, glass, or copper, the ends of which are fixed to the support body. This makes the material powder nozzle robust against laser reflections from laser deposition welding and has particularly few movable components that can be worn away by powder contamination. Alternatively, an adjustment mechanism can be provided that is designed to adjust a positional orientation of the respective powder channel, in particular its azimuth and / or elevation angle.This enables flexible adaptation of a powder focus diameter and powder density distribution to a change in a laser beam spot diameter and a laser beam profile without having to change the material powder nozzle, which would require unproductive downtime of the laser cladding device. The channel longitudinal center axes of the powder channels can each enclose the same azimuth and / or elevation angle, i.e., they can be arranged similarly in a geometric sense. This means that if one channel longitudinal center axis were rotated around the vertical axis into the other of the channel longitudinal center axes, the two channel longitudinal center axes would coincide. Alternatively, it is envisaged that the channel longitudinal center axes each enclose an individual azimuth and / or elevation angle.

[0011] In the laser cladding process, a laser cladding device is used, whereby a welding material in the form of material powder is fed into a transport gas jet by means of a powder feed unit, creating a material powder-transport gas mixture that is introduced into the respective powder channel through the respective inlet opening, flows through it, and is blown out of the powder channel through the associated outlet opening. Furthermore, it is conceivable for the respective powder channel to have a further inlet opening in addition to the inlet and outlet openings. During laser cladding, only transport gas is introduced into the powder channel through one of the inlet openings, and only material powder is introduced through the other of the inlet openings, so that the material powder-transport gas mixture is prepared directly in the powder channel.It can be provided that two or more different welding materials are introduced into the process zone at the same time, whereby the respective welding materials are fed to the process zone in a pure form through the respective assigned powder channels.

[0012] By means of the laser deposition welding device, a laser welding beam is generated which in particular has a wavelength range of 0.8 pm to 2 pm and a beam quality of

[0013] 4 mm ■ mrad to 50 mm ■ mrad. A 2-in-1 fiber optic cable laser or a single-core fiber laser can be used. The laser welding beam is focused onto a process zone by means of laser optics, with the powder focal plane, the process zone and the surface of the workpiece being arranged so as to coincide with one another. A focus diameter on the powder focal plane or on the workpiece surface is, for example, 0.3 mm to 20 mm. In particular, it is provided that the process zone or powder focal plane and the material powder nozzle are spaced apart from one another by a constant powder focal length during the laser deposition process. The material powder-transport gas mixture flowing out of the powder channels and into the process zone is heated by the laser welding beam immediately above the process zone, whereby a material powder portion of the material powder-transport gas mixture is heated.The heated material powder then impacts the workpiece in a partially molten state. Specifically, the laser welding beam is directed along the nozzle's longitudinal center axis through a material-free laser passage of the material powder nozzle.

[0014] Due to the azimuthal alignment of the powder channels of the material powder nozzle, the material powder-transport gas mixture flowing out of the powder channels generates a powder density profile in the powder focal plane or process zone that deviates from a Gaussian-like powder density profile. For example, for a laser welding beam that exhibits a top-hat laser intensity profile in the powder focal plane, a top-hat powder density profile is generated in the powder focal plane. Alternatively or additionally, for a laser welding beam that exhibits an annular laser intensity profile in the powder focal plane, a concave powder density profile is generated for the laser welding beam in the powder focal plane.

[0015] This results in more uniform shading of the workpiece surface, improving the molten metallurgical bond between the weld metal applied to the workpiece and the workpiece. This results in a more uniform application of the weld metal across a cross-section of the process zone due to a more consistent powder density. The powder density profile and the laser intensity profile are better coordinated than before.

[0016] According to a possible further development of the material powder nozzle, two of the channel longitudinal center axes intersect in the powder focus plane away from the nozzle longitudinal center axis or vertical axis. In other words: the two powder channels whose channel longitudinal center axes intersect in the powder focus plane form a powder channel pair, with the powder channels of the powder channel pair enclosing opposite azimuth angles. The magnitude of one of the azimuth angles and the magnitude of the other azimuth angle are the same, but the two azimuth angles have different signs. Two or more such powder channel pairs can be provided. In particular, a further channel longitudinal center axes is provided, which is skew relative to the channel longitudinal center axes intersecting in the powder focus plane. This enables a particularly advantageous adjustment of the powder density profile without swirl in the powder gas jet.

[0017] In a further possible embodiment, an outer nozzle circle located in the powder focus plane and an inner nozzle circle located in the powder focus plane are specified, the circle centers of which coincide on the nozzle longitudinal center axis or vertical axis, wherein the outer nozzle circle has a larger radius than the inner nozzle circle. Two or more of the powder channels form an outer channel group, in which the respective longitudinal center axis of the powder channels belonging to the outer channel group and the powder focus plane form a respective outer intersection point. The outer intersection points are equidistant from one another along at least one partial circular arc of the outer nozzle circle. Two or more outer channel groups can be provided, which are equidistant from one another, in particular along the outer nozzle circle.Alternatively or additionally, two or more of the powder channels form an inner channel group, in which the respective longitudinal center axis of the powder channels belonging to the inner channel group and the powder focal plane form a respective inner intersection point, wherein the inner intersection points are equidistant from one another along at least one partial arc of the inner circle of the orifice. Two or more inner channel groups can be provided, which are equidistant from one another, in particular along the inner circle of the orifice. In this way, a large powder jet spot is generated in the process zone or on the powder focal plane during laser material deposition. Advantageously, only small powder channel inner diameters are required for this, and an almost pure material powder is introduced into a process zone center (towards which the powder channels of the inner channel group are directed) orinto an outer process zone ring (toward which the powder channels of the outer channel group are directed). This prevents unwanted mixing of the welding materials.

[0018] In order to make it particularly easy to connect the powder feeder to the powder channels, a further possible embodiment provides that the inlet openings are arranged along an inlet opening circle located in the nozzle inlet plane, the circle center and the nozzle longitudinal center axis or vertical axis coincide, wherein the inlet openings are equidistant from one another along the entire inlet opening circle.

[0019] According to a further possible embodiment, in addition to the powder channels, which - as described above - are arranged with an azimuth angle of 0° (exclusive) to 90° (exclusive), the material powder nozzle has one or two or more further powder channels, wherein their respective channel longitudinal center axis encloses an azimuth angle of exactly 0° with the radial axis. In other words, the channel longitudinal center axis of the respective further powder channel lies in the plane spanned by the vertical axis and the radial axis of the nozzle coordinate system. Thus, a portion of the material powder-transport gas mixture flowing through the at least one further powder channel can be directed precisely into the center of the process zone. This results in an even more uniform top-hat powder density profile in the process zone or on the powder focus plane.

[0020] In a further possible embodiment, a total of the powder channels of the material powder nozzle has up to six different types of powder channels: A respective powder channel of the first type is shaped like a straight or oblique prism having a polygonal base area. A respective powder channel of the second type is shaped like a straight or oblique cylinder having an oval base area. A respective powder channel of the third type is shaped like a truncated pyramid having a polygonal base area, wherein the powder channel of the third type is designed to converge from the nozzle inlet plane towards the nozzle outlet plane. A respective powder channel of the fourth type is shaped like a truncated pyramid having a polygonal base area, wherein the powder channel of the fourth type is designed to diverge from the nozzle inlet plane towards the nozzle outlet plane.A respective powder channel of the fifth type is shaped like a truncated cone having an oval base area, wherein the powder channel of the fifth type is designed to converge from the nozzle inlet plane towards the nozzle outlet plane. A respective powder channel of the sixth type is shaped like a truncated cone having an oval base area, wherein the powder channel of the sixth type is designed to diverge from the nozzle inlet plane towards the nozzle outlet plane. The base area of ​​one or more of the powder channels of the first, third and / or fourth type is, for example, rectangular, in particular square. Other polygons, in particular those that deviate from a rectangle, are also conceivable as the base area of ​​the corresponding powder channel. The base area of ​​one or more of the powder channels of the second, fifth and / or sixth type is, for example, circular.Ovals that deviate from a circle, especially ellipses, are also conceivable as the base area of ​​the corresponding powder channel. By designing the appropriate geometry of the powder channels, the powder density distribution can be further influenced.

[0021] Further advantages, features, and details of the invention can be derived from the following description of possible embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective specified combination, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] The drawing shows

[0023] Fig. 1 shows a nozzle coordinate system of a material powder nozzle of a laser welding device, wherein a channel longitudinal center axis of a powder channel of the material powder nozzle is shown in isolation,

[0024] Fig. 2 is a perspective view of the material powder nozzle,

[0025] Fig. 3 is a schematic view of the material powder nozzle along its longitudinal center axis, with only the channel longitudinal center axes and the inlet and outlet openings of the powder channels being shown,

[0026] Fig. 4 is a view of the material powder nozzle cut along a section plane IV-IV (see Fig. 3),

[0027] Fig. 5 is a schematic view of the material powder nozzle, which has powder channel pairs with two powder channels each (Fig. 5a), as well as a schematic view of the material powder nozzle along its nozzle longitudinal center axis, whereby only the channel longitudinal center axes and inlet and outlet opening centers of the powder channels are shown (Fig. 5b),

[0028] Fig. 6 is a schematic view of the material powder nozzle along its nozzle longitudinal center axis, wherein only the channel longitudinal center axes and outlet orifice centers of the powder channels are shown, and wherein an outer channel group is formed by three powder channels and an inner channel group is formed by three further powder channels,

[0029] Fig. 7 is a schematic view of the material powder nozzle along its nozzle longitudinal center axis, wherein only the channel longitudinal center axes and outlet orifice centers of the powder channels are shown, and wherein two outer channel groups are arranged along an orifice outer circle,

[0030] Fig. 8 is a schematic view of the material powder nozzle, the powder channels of which are arranged in such a way that a top-hat powder density profile is obtained on a powder focus plane during a laser welding process, and

[0031] Fig. 9 is a schematic view of the material powder nozzle, whose powder channels are arranged in such a way that a concave powder density profile results on the powder focus plane during the laser welding process.

[0032] The drawing shows further in

[0033] Fig. 10 is a schematic view of a conventional material powder nozzle used to produce a Gaussian-like powder density distribution in a conventional laser welding process.

[0034] With reference to Figs. 1 to 9, a material powder nozzle 1, a laser welding device (not shown) having the material powder nozzle 1, and a method for laser cladding are explained in a joint description below. Identical and functionally equivalent elements are provided with the same reference numerals in Figs. 1-9.

[0035] Fig. 1 shows a nozzle coordinate system r|z|cp of the material powder nozzle 1, designed as a cylindrical coordinate system, which has two or more powder channels 3. A channel longitudinal center axis 2 of one of the powder channels 3 of the material powder nozzle 1 is shown in isolation. A radial axis r lies in a horizontal origin plane Z of the nozzle coordinate system, wherein the radial axis r and a vertical axis z of the nozzle coordinate system intersect each other perpendicularly at the origin of the nozzle coordinate system, which lies in the horizontal origin plane Z. With respect to the origin, the position of each point within the nozzle coordinate system is uniquely defined by means of a horizontal coordinate (along the radial axis r), a vertical coordinate (along the vertical axis z), and a position angle (p). The following applies to the further description:

[0036] - A vertical nozzle longitudinal center axis 4 of the material powder nozzle 1 and the vertical axis z coincide.

[0037] - A nozzle outlet plane A of the material powder nozzle 1 and the horizontal origin plane Z coincide.

[0038] - A nozzle inlet plane E of the material powder nozzle 1 is spaced from the nozzle outlet plane A or horizontal origin plane Z in the Z direction by a material powder nozzle height 5.

[0039] - A powder focus plane P of the material powder nozzle 1 is spaced from the nozzle outlet plane A or horizontal origin plane Z opposite to the Z direction by a powder focal length 6.

[0040] - An outlet opening 7 of the respective powder channel 3 is located in the nozzle outlet plane A.

[0041] - An inlet opening 8 of the respective powder channel 3 is located in the nozzle inlet plane E.

[0042] It can also be seen in Fig. 1 that the completely straight channel longitudinal center axis 2 of the powder channel 3 runs through both an outlet orifice center point 9 of the outlet orifice 7 and an inlet orifice center point 10 of the inlet orifice 8. The channel longitudinal center axis 2 forms an elevation angle α with the nozzle outlet plane A that is greater than 0° and less than 90°. Furthermore, the channel longitudinal center axis 2 forms an azimuth angle β with the radial axis r in the nozzle outlet plane A that is greater than 0° and less than 90°.

[0043] Fig. 2 shows a perspective view of the material powder nozzle 1, in this example with seven powder channels 3, of which not all are provided with the corresponding reference numerals for reasons of clarity. The powder channels 3 are each, for example, 10 mm long or longer and each have a flow-through inner diameter of 2 mm or more.

[0044] The powder channels 3 are in this case rigidly arranged in a carrier body 11 of the material powder nozzle 1 made of hard metal, glass or copper, in that the respective powder channel 3 is designed as a through-opening, for example a bore, which completely penetrates the carrier body 11 along the respective channel longitudinal center axis 2. A variant of the material powder nozzle 1 not shown in the figures has an adjustment mechanism by means of which a positional orientation of the respective powder channel 3, in particular its angles α, β, can be adjusted. The channel longitudinal center axes 2 of the powder channels 3 arranged according to Fig. 2 each enclose the same azimuth angle α and elevation angle β, and are therefore arranged similarly in a geometric sense. This means that if one of the channel longitudinal center axes 2 shown in Fig. 2 were to be rotated about the vertical axis z into another of the channel longitudinal center axes 2, the two channel longitudinal center axes 2 would coincide.

[0045] In the laser material deposition process, the laser material deposition device is used, wherein a welding material in the form of material powder is fed into a transport gas jet by means of a powder feed unit, whereby a material powder-transport gas mixture is generated, which is introduced through the respective inlet opening 8 into the respective powder channel 3, flows through this and is blown out of the powder channel 3 through the associated outlet opening 7, whereby the material powder-transport gas mixture is blown onto the powder focal plane P, specifically into a process zone 12 which lies in the powder focal plane P. By means of the laser material deposition device, a laser welding beam (not shown) is generated which, for example, has a wavelength range of 0.8 pm to 2 pm and a beam quality of 4 mm ■ mrad to 50 mm ■ mrad. A 2-in-1 fiber optic cable laser or a single-core fiber laser can be used.By means of laser optics (not shown), the laser welding beam is focused onto the process zone 12, wherein the powder focal plane P, the process zone 12 and a surface of a workpiece to which the welding material is to be welded are arranged so as to coincide with one another. A focal diameter on the powder focal plane P or on the workpiece surface is, for example, 0.3 mm to 20 mm. The process zone 12 or powder focal plane P and the material powder nozzle 1 are spaced from one another by the constant powder focal length 6 during the laser deposition welding process. The material powder-transport gas mixture flowing out of the powder channels 3 and into the process zone 12 is heated by the laser welding beam immediately above the process zone 12, whereby a material powder portion of the material powder-transport gas mixture is heated. The heated material powder then impacts the workpiece in partially molten form.The laser welding beam runs along the nozzle longitudinal center axis 4 through a material-free laser passage 13 of the material powder nozzle 1.

[0046] Fig. 3 shows a schematic view of the material powder nozzle 1 along its longitudinal nozzle center axis 4, wherein only the channel longitudinal center axes 2 and orifices 7, 8 of the powder channels 3 are shown for the material powder nozzle 1. The azimuth angle ß is shown representatively on one of the powder channels 3 for all of the powder channels 3 or channel longitudinal center axes 2 shown in Fig. 3. It can be seen that the respective channel longitudinal center axis 2 and the radial axis r of the material powder nozzle 1, which arises perpendicularly from the vertical axis z or nozzle longitudinal center axis 4, diverge and together enclose the azimuth angle ß. In the figures, rx represents a rotational image of the radial axis r belonging to the respective powder channel 3, which, like the radial axis r, arises from the vertical axis z or nozzle longitudinal center axis 4.Therefore, the corresponding azimuth angle ß occurs between the image rx of the radial axis r and the associated channel longitudinal center axis 2. It can also be seen in Fig. 3 that the inlet openings 8 are arranged along an inlet opening circle 14 located in the nozzle inlet plane E, the circle center of which and the nozzle longitudinal center axis 4 or vertical axis z coincide, wherein the inlet openings 8 are equidistantly spaced from one another along the entire inlet opening circle 14. Furthermore, the outlet openings 7 are arranged along an outlet opening circle 15 located in the nozzle outlet plane A, the circle center of which and the nozzle longitudinal center axis 4 or vertical axis z coincide, wherein the outlet openings 7 are equidistantly spaced from one another along the entire outlet opening circle 15.

[0047] Fig. 4 shows a view of the material powder nozzle 1, cut along a sectional plane IV-IV (see Fig. 3), wherein the respective positions of the powder channels 3 and their orifices 7, 8 are particularly clearly visible. Furthermore, Fig. 4 shows that, in this example, the powder channels 3 are each shaped according to a right circular cylinder. This means that the respective powder channel 3 is rotationally symmetrical within the carrier body 11, wherein the orifices 7, 8 located in planes A, E appear as ellipses when viewing the material powder nozzle 1 opposite the Z-axis.

[0048] It is further conceivable for the material powder nozzle 1 to have a powder channel 3 shaped like a straight or oblique prism. Alternatively or additionally, the material powder nozzle can have a further powder channel 3 shaped like a straight or oblique cylinder having an oval base area that deviates from a circular disk. A supplementarily or alternatively provided powder channel 3 is shaped like a truncated pyramid, wherein this powder channel is designed to converge from the nozzle inlet plane E in the direction of the nozzle outlet plane A. Again alternatively or additionally, the material powder nozzle 1 can comprise a powder channel 3 shaped like a truncated pyramid, wherein this powder channel is designed to diverge from the nozzle inlet plane E in the direction of the nozzle outlet plane A.Furthermore, a further powder channel 3 can be provided, which is shaped according to a truncated cone and is designed to converge from the nozzle inlet plane E in the direction of the nozzle outlet plane A. Additionally or alternatively, a further powder channel 3 is shaped according to a truncated cone, which is designed to diverge from the nozzle inlet plane E in the direction of the nozzle outlet plane A. It should be understood that a total of the powder channels 3 of the material powder nozzle 1 consists of one or more of the above-mentioned types of powder channels 3.

[0049] Starting from the nozzle inlet plane E, a flange portion 16 of the material powder nozzle 1 can be connected to the carrier body 11 in the Z direction, by means of which the material powder nozzle 1 and a nozzle flange of the laser cladding device for laser cladding can be connected or are connected to one another. The flange portion 16 has, for example, first channel extensions 17 that communicate fluidically with the inlet openings 8 and by means of which the powder conveying unit and the powder channels 3 are coupled to one another. Starting from the nozzle outlet plane A, a nozzle end body 18 of the material powder nozzle 1 can be connected to the carrier body 11 in the opposite direction to the Z direction, said nozzle end body having second channel extensions 19 that communicate with the outlet openings 7. The carrier body 11, the flange portion 16, and the nozzle end body 18 are integrally connected to one another, in this case formed integrally with one another.

[0050] Fig. 5a shows a schematic view of the material powder nozzle 1, which has a powder channel pair 20 or more—in this case, three—powder channel pairs 20, each with two powder channels 3. The two channel longitudinal center axes 2 of the respective powder channel pair 20 intersect each other away from the nozzle longitudinal center axis 4, as can be seen in Fig. 5a. The powder channel pairs 20 can be of identical design, i.e., see Fig. 5a, be geometrically similar. In this case, the powder channels 3 or channel longitudinal center axes 2 of the powder channel pair 20 form an opposite azimuth angle ß with respect to one another. a , ßb, where the azimuth angles ß a , ßb are equal in amount (|ß a | = |ßb|), but have different signs (ß a= -ßb). This can be seen particularly well in Fig. 5b, which shows a schematic view of the material powder nozzle 1 along its nozzle longitudinal center axis 4, wherein only the channel longitudinal center axes 2 and the orifice centers 9, 10 of the powder channels 3 or powder channel pairs 20 are shown.

[0051] Fig. 6 shows a schematic view of the material powder nozzle 1 along its longitudinal nozzle center axis 4, wherein only the channel longitudinal center axes 2 and the outlet orifice centers 9 of the powder channels 3 are shown for the material powder nozzle 1. An outer orifice circle 21 located in the powder focus plane P and an inner orifice circle 22 located in the powder focus plane P are specified, the circle centers of which coincide on the nozzle longitudinal center axis 4 and vertical axis z, respectively. The outer orifice circle 21 has a larger radius than the inner orifice circle 22. Two or more of the powder channels 3 - for example, three of the powder channels 3 - form an outer channel group 23, in which the respective channel longitudinal center axis 2 of the powder channels 3 belonging to the outer channel group 23 and the powder focus plane P form a respective outer intersection point 24. The outer intersection points 24 are equidistant from each other along the outer circle of the mouth 21.In addition, according to the present example, an inner channel group 25 is formed by two or more other powder channels 3 - here by three of the other powder channels 3 - in which the respective channel longitudinal center axis 2 of the powder channels 3 belonging to the inner channel group 25 and the powder focal plane P form a respective inner intersection point 26, wherein the inner intersection points 26 are equidistant from one another along the inner circle 22 of the mouth. The respective channel longitudinal center axis 2 belonging to the outer channel group 23 forms a first azimuth angle ß with the radial axis r or its image rx. c wherein the respective channel longitudinal center axis 2 belonging to the inner channel group 25 encloses a second azimuth angle ßd with the radial axis r or its image rx. The azimuth angles ß c , ßd can be equal or have the same magnitude. In this case, the first azimuth angle ß c greater than the second azimuth angle ßd.

[0052] Fig. 7 shows a schematic view of the material powder nozzle 1 along its nozzle longitudinal center axis 4, wherein only the channel longitudinal center axes 2 and outlet orifice centers 9 of the powder channels 3 are shown of the material powder nozzle 1, and wherein two outer channel groups 23 are arranged along the orifice outer circle 21. It can be seen that the two outer channel groups 23 each have three powder channels 3. The respective channel longitudinal center axis 2 belonging to the outer channel group 23 encloses the azimuth angle ß with the radial axis r or its representation rx. It can also be seen that the outer intersection points 24 of the respective outer channel group 23 are evenly spaced from one another along the orifice outer circle 21, and in this case only along a partial arc of the orifice outer circle 21. Furthermore, the outer channel groups 23 are evenly spaced from one another with respect to the entire outer orifice circle 21.

[0053] Fig. 7 further shows that, in addition to the powder channels 3 positioned at the elevation angle α and the azimuth angle β, the material powder nozzle 1 can have a further powder channel whose azimuth angle is 0°. The material powder nozzle 1 can further have two or more such additional powder channels. A channel longitudinal center axis 27 of the respective additional powder channel and the radial axis r or its representation rx coincide.

[0054] Due to the azimuthal alignment of the powder channels 3 of the material powder nozzle 1, the material powder-transport gas mixture flowing out of the powder channels 3 generates a powder density profile 28 (see Fig. 8 and Fig. 9) in the powder focal plane P or process zone 12 that deviates from a Gaussian-like powder density profile 300 (see Fig. 10). Corresponding powder spots 29, together with their associated powder spot centers 30, are shown in Fig. 3 and Fig. 5 to Fig. 9.

[0055] Fig. 8 shows the material powder nozzle 1, the seven powder channels 3 of which are arranged such that, during laser deposition welding, a top-hat powder density profile 31 is generated for the laser welding beam, which has a top-hat laser intensity profile in the powder focal plane P. Fig. 9 shows the material powder nozzle 1, the seven powder channels 3 of which are arranged such that, during laser deposition welding, a concave powder density profile 32 is generated for the laser welding beam, which has an annular laser intensity profile in the powder focal plane P. Although only seven powder channels 3 are shown here, it is to be understood that more or fewer powder channels 3 can be arranged in or on the material powder nozzle 1.

[0056] The material powder nozzle 1, the laser cladding device, and the laser cladding method show a respective possibility of how a particularly stable and reliable connection between a workpiece and a welding material can be produced by means of laser cladding with the lowest possible energy consumption.

[0057]

[0058] 1 material powder nozzle

[0059] 2 Channel longitudinal center axis

[0060] 3 Powder channel

[0061] 4 Nozzle longitudinal center axis

[0062] 5 Material powder nozzle height

[0063] 6 focal length

[0064] 7 Exit orifice

[0065] 8 Entrance mouth

[0066] 9 Outlet center

[0067] 10 Entry mouth center point

[0068] 11 Carrier body

[0069] 12 Process zone

[0070] 13 Laser Passage

[0071] 14 Entrance mouth circle

[0072] 15 Exit mouth circle

[0073] 16 flange portion

[0074] 17 first canal process

[0075] 18 nozzle end bodies

[0076] 19 second canal process

[0077] 20 powder channel pair

[0078] 21 Outer circle of the mouth

[0079] 22 Inner circle of the mouth

[0080] 23 Outer channel group

[0081] 24 Outer intersection point

[0082] 25 inner channel group

[0083] 26 Interior intersection point

[0084] 27 Channel longitudinal center axis

[0085] 28 Powder density profile

[0086] 29 Powder Spot

[0087] 30 Powder spot center

[0088] 31 Top-Hat powder density profile

[0089] 32 concave powder density profile r|z|cp nozzle coordinate system Z horizontal origin plane x horizontal axis z vertical axis

[0090] (p Position angle A Nozzle exit plane

[0091] E Nozzle inlet plane

[0092] P powder focal plane r, r x Radial axis ß, ß a , ßb, ßc, ßd azimuth angle a elevation angle

[0093] 100 conventional material powder nozzle

[0094] 200 process zone

[0095] 300 Gaussian-like powder density profile 400 T op-Hat laser intensity profile

[0096] 500 powder accumulation

[0097] 600 edge area

[0098] 700 Channel longitudinal center axis

Claims

PATENT CLAIMS 1. Material powder nozzle (1) for a laser cladding device, wherein the material powder nozzle (1) comprises: - a vertical nozzle longitudinal center axis (4) which coincides with a vertical axis (z) of a nozzle coordinate system (r|z|cp) of the material powder nozzle (1), - a nozzle exit plane (A) which coincides with a horizontal origin plane (Z) of the nozzle coordinate system (r|z|cp), - a nozzle inlet plane (E) which is spaced from the nozzle outlet plane (A) in the Z direction by a material powder nozzle height (5), - a powder focal plane (P) which is spaced from the nozzle exit plane (A) by a powder focal length (6) in the opposite direction to the Z direction, - powder channels (3) through which a material powder-transport gas mixture can flow, - whose respective outlet opening (7) lies in the nozzle outlet plane (A), - whose respective inlet opening (8) is located in the nozzle inlet plane (E), - the respective channel longitudinal center axis (2) passing through an outlet orifice center point (9) and through an inlet orifice center point (10) - encloses with the nozzle exit plane (A) a respective elevation angle (a) which is greater than 0° and less than 90°, - with a horizontal radial axis (r) of the nozzle coordinate system (r|z|cp) encloses a respective azimuth angle (ß) lying in the nozzle outlet plane (A) which is greater than 0° and less than 90°.

2. Material powder nozzle (1) according to claim 1, characterized in that two of the channel longitudinal center axes (2) intersect in the powder focus plane (P) away from the nozzle longitudinal center axis (4).

3. Material powder nozzle (1) according to claim 1 or 2, characterized in that an outer orifice circle (21) lying in the powder focus plane (P) and an inner orifice circle (22) lying in the powder focus plane (P) are predetermined, the circle centers of which coincide on the nozzle longitudinal center axis (4), wherein the outer orifice circle (21) has a larger radius than the inner orifice circle (22), and wherein - an outer channel group (23) is formed by two or more of the powder channels (3), in which the respective channel longitudinal center axis (2) of the powder channels (3) of the outer channel group (23) and the powder focal plane (P) form a respective outer intersection point (24), wherein the outer intersection points (24) are equidistant from one another along at least one partial circular arc of the orifice outer circle (21), and / or - an inner channel group (25) is formed by two or more of the powder channels (3), in which the respective channel longitudinal center axis (2) of the powder channels (3) of the inner channel group (25) and the powder focal plane (P) form a respective inner intersection point (26), wherein the inner intersection points (26) are equidistant from one another along at least one partial circular arc of the inner circle (22) of the mouth.

4. Material powder nozzle (1) according to one of the preceding claims, characterized in that the inlet openings (8) are arranged along an inlet opening circle (14) lying in the nozzle inlet plane (E), the circle center and the nozzle longitudinal center axis (4) coinciding, wherein the inlet openings (8) are equidistantly spaced from one another along the entire inlet opening circle (14).

5. Material powder nozzle (1) according to one of the preceding claims, characterized in that it has a further powder channel, the channel longitudinal center axis (27) and the radial axis (r) enclose an azimuth angle (ß) of 0° with each other.

6. Material powder nozzle (1) according to one of the preceding claims, characterized in that - one of the powder channels (3) is shaped according to a prism and / or - one of the powder channels (3) is shaped like a cylinder with a base area different from a circular disk, - one of the powder channels (3) is shaped according to a truncated pyramid and / or - one of the powder channels (3) is shaped like a truncated cone.

7. Material powder nozzle (1) according to claim 6, characterized in that the powder channel (3) shaped according to a pyramid or truncated cone is designed to converge or diverge from the nozzle inlet plane (E) in the direction of the nozzle outlet plane (A).

8. Laser cladding device comprising the material powder nozzle (1) designed according to one of the preceding claims.

9. A method for laser cladding by means of a laser cladding device designed according to claim 8, wherein a powder density profile (28) deviating from a Gaussian-like powder density profile (300) is generated in the powder focus plane (P) by means of the material powder-transport gas mixture flowing out of the powder channels (3).

10. Method according to claim 9, characterized in that in the powder focus plane (P) - for a laser welding beam having a top-hat laser intensity profile in the powder focus plane (P), a top-hat powder density profile (31) is generated, and / or - a concave powder density profile (32) is generated for a laser welding beam which has an annular laser intensity profile in the powder focus plane (P).

Images