Metal powder deposition nozzle

Abstract

The invention relates to a metal powder deposition nozzle comprising an outer body and an inner body assembled coaxially with the outer body such that a frustoconical section of the inner body is seated inside a frustoconical wall of the outer body. A passage is formed between the frustoconical section and the frustoconical wall for the passage of a metal powder flow. An annular channel is formed between a cylindrical outer surface of the inner body and a cylindrical inner surface of a flange of the outer body, wherein the annular channel fluidly communicates the flow distribution channels with the passage. A separation distance in a radial direction between the cylindrical outer surface of the inner body and the cylindrical inner surface of the flange of the outer body is greater than a diameter of each of the flow distribution channels.

Description

Technical Field

[0001] This invention relates generally to laser metal deposition technology.

[0002] The purpose of this invention is to provide a metal powder deposition nozzle for a laser head that improves the performance of the laser metal deposition process.

[0003] In particular, the present invention provides a metal powder deposition nozzle that reduces metal powder clogging and is easy to clean and maintain. Background Technology

[0004] Laser metal deposition is an additive manufacturing technique in which metal objects are built on a substrate. A specific application of additive manufacturing is laser cladding, in which a metal layer is applied to an existing part to strengthen, modify, or repair the surface of the metal component.

[0005] During laser metal deposition, metal powder is ejected through a nozzle connected to a laser head using a carrier gas, and the laser beam melts the metal powder to create a molten pool on an existing surface. The molten powder combines with the base material in the molten pool, thereby additively forming a new layer or object.

[0006] In conventional nozzles, such as Figure 5A In the nozzle shown, powder flows through the powder flow distribution channel 14 and through the gap 15 between the outer conical portion 16 and the inner conical portion 17 of the nozzle. Because these channels are small and typically have triangular corners and recessed areas, powder blockages 18 easily form at the corners, thus obstructing the powder flow. This alters the linear trajectory of the particles and reduces the powder flow velocity; therefore, the flow becomes turbulent within the gap 15, as... Figure 5A As indicated by the wavy arrow in the image.

[0007] For the reasons mentioned above, and as Figure 5B As indicated, the shape of the metal powder cone 19 discharged from the nozzle is uneven, and a large number of particles are emitted from the cone, such as by... Figure 5B As indicated by the wavy arrow in the diagram. As a result, the metal powder particles cannot properly converge at the apex of the cone, and therefore, the molten pool 20 cannot be accurately formed throughout the manufacturing process. Consequently, the laser deposition process is inefficient because a large amount of metal particles are wasted, and the process quality is not as expected.

[0008] In addition, laser head maintenance is often time-consuming due to the complexity of disassembling the nozzle to clean the powder, mainly because of the formation of metal powder deposits and the difficulty in disassembling the two parts of the nozzle because a vacuum is often formed between them.

[0009] Furthermore, since the nozzle determines the powder focus that should correspond to the laser spot size, it is usually necessary to replace the nozzle to change the powder focus and thus the processing area. However, conventional nozzle designs are not typically conceived for simple nozzle replacement.

[0010] Therefore, a metal powder deposition nozzle that addresses the aforementioned shortcomings is needed. Summary of the Invention

[0011] The present invention is defined in the appended independent claims and satisfactorily solves the above-mentioned disadvantages of the prior art by providing a metal powder deposition nozzle adapted to be coupled to a laser head to be used in a laser metal deposition process.

[0012] The nozzle includes an outer portion formed as an integral body, the outer portion having a truncated conical wall and a peripheral flange extending around a wider portion of the truncated conical wall. The flange has a cylindrical inner surface coaxial with the nozzle axis.

[0013] The nozzle also includes an internal portion formed as an integral body, which has: a cylindrical section defining a cylindrical outer surface, a truncated conical section, and an internal axial conduit for guiding the laser beam through the inner body. The inner body and outer body are coaxially assembled such that the truncated conical section is positioned inside the truncated conical wall of the outer body, and a passage is formed between the truncated conical section and the truncated conical wall for the passage of a metal powder flow formed by metal powder and carrier gas. The metal powder flows through the passage and converges toward the laser beam at the nozzle outlet.

[0014] The inner body has multiple individual powder flow distribution channels, preferably six channels, which are preferably arc-shaped and circumferentially arranged around the axis of the nozzle. Each of these flow distribution channels is arc-shaped around the axis of the nozzle.

[0015] An annular chamber is formed between the cylindrical outer surface of the inner body and the cylindrical inner surface of the flange of the outer body, such that the cross-sectional view of the annular chamber taken in a plane including the axis of the nozzle has a rectangular region. This configuration of the annular chamber facilitates powder flow without reducing its velocity, thus enabling laminar flow of the metal powder rather than turbulent flow.

[0016] This annular chamber connects the flow distribution channel and the passageway, allowing metal powder supplied by the feeder to be introduced into the nozzle. The powder first circulates through a separate powder flow distribution channel, then through the annular chamber, and from the annular chamber through the passageway until the metal powder exits the nozzle through the nozzle outlet. In other words, the annular chamber is positioned upstream of the gap between the inner and outer bodies.

[0017] The radial separation distance between the cylindrical outer surface of the inner body and the cylindrical inner surface of the flange of the outer body is greater than the diameter of each flow distribution channel in the flow distribution channel. This means that the annular chamber expands or enlarges the cross-sectional area through which the metal powder flows.

[0018] The annular chamber has no triangular corners or recessed areas, which avoids the formation of metal powder blockage.

[0019] Preferably, the outer surface of the truncated conical section of the inner body and the inner surface of the outer body are substantially smooth curved surfaces, that is, no ridges or grooves are formed on these surfaces, so that the cross-sectional area of ​​the passage cut at the plane orthogonal to the axis of the nozzle is constant and has an annular shape.

[0020] The inner body also has a flange, and the nozzle is configured such that when the inner and outer bodies are operatively assembled together, the flange of the inner body overlaps with the flange of the outer body for attaching the two bodies. Typically, the two flanges are provided with drilled holes for attaching the two bodies, for example, by means of screws.

[0021] The contact surface between the two flanges is chamfered. To form this chamfer, the flange of the outer body has a tapered annular surface, and the flange of the inner body also has an annular tapered surface that is complementary to the tapered surface of the outer body. Therefore, when the two bodies are assembled together, the two tapered surfaces overlap, thereby defining a tapered contact surface between the two flanges toward the nozzle outlet.

[0022] The gap between the chamfered inner body and the outer body is connected to the annular chamber, or in other words, the gap between the chamfered inner body and the outer body extends from the annular chamber.

[0023] As described above, the chamfer between the two flanges prevents a vacuum from forming between the inner and outer bodies, which in turn facilitates disassembly of the inner and outer bodies. In this way, the maintenance and cleaning of the nozzle are greatly simplified. Attached Figure Description

[0024] To complete the description and to provide a better understanding of the invention, a set of accompanying drawings is provided. These drawings form an integral part of the description and illustrate embodiments of the invention, which should not be construed as limiting the scope of the invention, but are merely examples of how the invention can be practiced. The drawings include the following figures:

[0025] Figure 1 illustrates a preferred embodiment of the nozzle according to the present invention. Figure 1A It is a front view. Figure 1B It is a plan view taken from below. Figure 1C It is a top-down plan, and Figure 1D Is Figure 1AThe cross-sectional view taken at plane AA.

[0026] Figure 2 A cross-sectional view of the nozzle from the previous figure is shown, with the two nozzle bodies disassembled.

[0027] Figure 3 A three-dimensional cross-sectional view of the same nozzle is shown.

[0028] Figure 4 It shows the relationship with Figure 3 A similar illustration, but in this one, the two nozzle bodies are disassembled.

[0029] Figure 5 Figure 5A The image shows enlarged details of a conventional design for a metal powder distribution chamber according to the prior art, where the turbulent trajectory of the metal powder is indicated by arrows. Figure 5B It is from Figure 5A An illustration of a cone of metal powder formed by jetting powder from a nozzle, where the arrow indicates the direction of the powder ejected from the nozzle. Figure 5A The particle dispersion is caused by the turbulent flow of particles in the nozzle.

[0030] Figure 6 Figure 6A The image shows enlarged details of the metal powder distribution chamber according to the invention, wherein the laminar and uniform trajectory of the metal powder is indicated by arrows. Figure 6B It is from Figure 6A An illustration of a metal powder cone formed by jetting powder from a nozzle, where the arrows indicate the formation of a clean powder cone without particle dispersion. Detailed Implementation

[0031] The accompanying drawings illustrate a preferred embodiment of a coaxial nozzle 1 for metal powder deposition according to the present invention, the coaxial nozzle 1 comprising an outer integral body 2 having a truncated conical wall 2a and a peripheral flange 2b having a cylindrical inner surface 4 coaxial with the nozzle axis X, and a tapered annular surface 5 continuous with the inner surface 4.

[0032] The nozzle 1 also includes an inner integral body 3, which has: a truncated conical section 3a, a cylindrical section 3b, a flange 3c projecting radially from the cylindrical section 3b, and an internal axial conduit 6 for conducting a laser beam. The cylindrical section 3b has a cylindrical outer surface 13.

[0033] In addition, the flange 3c of the inner body 3 has several powder flow distribution channels 7 arranged circumferentially around the nozzle axis X, such as... Figure 1C and Figure 3As better illustrated in the diagram. Each of these flow distribution channels 7 has a circumferential arc shape, and in this exemplary embodiment, there are six flow distribution channels 7, such that each channel 7 is an arc of a 60° circular sector.

[0034] Flange 3c has a tapered annular surface 8 at its bottom base 9 that is complementary to the tapered surface 5 of the outer body 2. In a sense, the tapered annular surface 8 and the tapered surface 5 have the same tilt angle and orientation relative to the axis X. Therefore, when the inner body 3 and the outer body 2 are operatively assembled together, the two tapered annular surfaces 5 and 8 overlap, as shown, for example, in... Figure 1D As shown, this is configured with a chamfer 21, which facilitates the disassembly of the two bodies. For example, in... Figure 1D As can be observed, the gap between the inner body and the outer body at chamfer 21 is connected to the annular chamber 12, or in other words, the gap between the inner body and the outer body at chamfer 21 extends from the annular chamber 12.

[0035] The flow distribution channel 7 is located between the tapering annular surface 8 of the inner body 3 and the cylindrical section 3b.

[0036] Inner body 3 and outer body 2, for example, in Figure 1D The coaxial assembly shown is such that the truncated conical section 3a of the inner body 3 is positioned inside the truncated conical wall 2a of the outer body 2. A passage 10 is formed in the gap between the truncated conical section and the truncated conical wall for the passage of a flow of metal powder, that is, the metal powder is transported by a carrier gas in a known manner.

[0037] The outer surface of the truncated conical section 3a of the inner body and the inner surface of the truncated conical wall 2a of the outer body are substantially smooth curved surfaces, such that any cross-sectional area of ​​the passage 10 taken at a plane orthogonal to the nozzle axis X has an annular shape.

[0038] Preferably, the outer surface of the truncated conical section 3a of the inner body and the inner surface of the truncated conical wall 2a of the outer body have a highly polished and bright finish to facilitate the circulation of powder flow.

[0039] The flange 3c of the inner body 3 is positioned on top of the flange 2b of the outer part 2, and the two flanges are provided with drill holes 11, 11' for attaching the two bodies, for example by means of screws (not shown), and the drill holes 11, 11' are also used for attaching a nozzle to a laser head (not shown).

[0040] An annular chamber 12 is formed between the outer cylindrical surface 13 of the cylindrical section 3b of the inner part 3 and the inner cylindrical surface 4 of the flange 2b of the outer body 2. The annular chamber 12 is in fluid communication with all flow distribution channels 7 and passage 10.

[0041] The separation distance in the radial direction relative to the axis X between the cylindrical outer surface 13 of the inner body 3 and the cylindrical inner surface 4 of the flange 2b of the outer body 2 is constant and greater than the width of each flow distribution channel in the flow distribution channel 7, such as in, for example, in Figure 1D This can be noticed in the text.

[0042] In this way, the annular chamber 12, located directly downstream of the flow distribution channel 7, increases the cross-sectional area through which the metal powder flows compared to the sum of all cross-sectional areas of the flow distribution channel 7. The configuration of the annular chamber 12 as a straight passageway, without sharp triangular corners or recessed areas, avoids the formation of obstacles caused by metal powder blockage.

[0043] This advantage of the invention lies in Figure 6A As shown in the figure, it can be observed that the metal powder flows laminarly through the annular chamber 12 and the passage 10 (indicated by the straight arrows in the figure), and as a result, the cone 19 formed by the particles ejected from the nozzle ( Figure 6B The area is well-defined, and a large number of sprayed particles converge or concentrate at the molten pool 20. Therefore, with Figure 5A and Figure 5B Compared to the existing technology processes illustrated in the figure, the nozzle of the present invention provides a highly efficient and accurate laser deposition process throughout the entire manufacturing process.

[0044] The cylindrical outer surface 13 of the inner body 3 is higher than the cylindrical inner surface 5 of the flange 2b of the outer body 2. The annular chamber 12 is located in... Figure 1D The cross-sectional view shown is rectangular in the upper portion and triangular in the lower portion, which is directly connected to passage 10. The annular chamber 12 has two 90° corners in its upper portion, which is directly connected to flow distribution channel 7.

[0045] Preferably, for laser metal deposition (LMD) applications, the truncated conical wall 2a of the outer body and the truncated conical section 3a of the inner body define an angle of approximately 40° relative to the nozzle axis X.

[0046] Alternatively, for ultra-high-speed laser cladding (EHLA) applications, the truncated conical wall 2a of the outer body and the truncated conical section 3a of the inner body are defined at an angle equal to or greater than 45° relative to the nozzle axis X, preferably in the range of 60° to 100°.

Claims

1. A metal powder deposition nozzle (1), comprising: The outer body (2) has a truncated conical wall (2a) and a peripheral flange (2b) having a cylindrical inner surface (4) coaxial with the nozzle axis (X). The inner body (3) has: a cylindrical outer surface (13), a truncated conical section (3a), and an internal axial conduit (6) for conducting laser beams. The inner body (3) and the outer body (2) are coaxially assembled such that the truncated conical section (3a) is placed inside the truncated conical wall (2a) of the outer body (2), and a passage (10) is formed between the truncated conical section (3a) and the truncated conical wall (2a) for the passage of metal powder. The inner body (3) has multiple powder flow distribution channels (7) arranged circumferentially around the nozzle axis (X). An annular chamber (12) is formed between the cylindrical outer surface (13) of the inner body (3) and the cylindrical inner surface (4) of the flange (2b) of the outer body (2), wherein the annular chamber (12) fluidly connects the flow distribution channel (7) and the passage (10), and wherein the radial separation distance between the cylindrical outer surface (13) of the inner body (3) and the cylindrical inner surface (4) of the flange (2b) of the outer body (2) is greater than the diameter of each flow distribution channel in the flow distribution channel (7).

2. The metal powder deposition nozzle according to claim 1, wherein, The outer surface of the truncated conical section of the inner body (3) and the inner surface of the truncated conical wall (2a) of the outer body (2) are substantially smooth curved surfaces, such that the cross-sectional area of ​​the passage (10) cut at a plane orthogonal to the nozzle axis has an annular shape.

3. The metal powder deposition nozzle according to claim 1 or 2, wherein, The cylindrical outer surface (13) of the inner body (3) is higher than the cylindrical inner surface (4) of the flange (2b) of the outer body (2).

4. The metal powder deposition nozzle according to any one of the preceding claims, wherein, The inner body (3) has a flange (3c), and wherein the nozzle (1) is configured such that when the outer body (2) and the inner body (3) are operatively assembled together, the flange (3c) of the inner body overlaps with the flange (2b) of the outer body for attaching the two bodies.

5. The metal powder deposition nozzle according to claim 4, wherein, A portion of the contact surface between the flange (3b) of the inner body and the flange (2b) of the outer body tapers toward the nozzle outlet (14), thereby forming a chamfer (21).

6. The metal powder deposition nozzle according to claim 5, wherein, The gap between the inner body (3) and the outer body (2) at the chamfer (21) extends from the annular chamber (12).

7. The metal powder deposition nozzle according to any one of the preceding claims, wherein, Each flow distribution channel in the flow distribution channel (7) has a circumferential arc shape.

8. The metal powder deposition nozzle according to any one of the preceding claims, wherein, The truncated conical wall (2a) of the outer body (2) and the truncated conical section (3a) of the inner body (3) define an angle of approximately 40° relative to the nozzle axis.

9. The metal powder deposition nozzle according to any one of claims 1 to 5, wherein, The truncated conical wall (2a) of the outer body and the truncated conical section (3a) of the inner body define an angle equal to or greater than 45° relative to the nozzle axis.

10. The metal powder deposition nozzle according to claim 9, wherein, The angle is in the range of 60° to 100°.

11. A laser head suitable for laser metal deposition processes, said laser head comprising a metal powder deposition nozzle as defined in any one of the preceding claims.

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