A powder feeding system for a laser metal deposition system

Abstract

Powder feed system (1) for a laser metal deposition system, the system comprising: a first hopper (2) designed to supply a first stream of transport gas and metal powder via a first hose (3), a second hopper (4) designed to supply a second stream of transport gas and metal powder through a second hose (5), a combining device (10) to which the first and second hoses (3, 5) are fluidically connected, the combining device (10) being arranged to introduce the first and second streams into a third hose (11), at least one refill hopper (6, 8) for supplying metal powder to the first and second hoppers (2, 4), a first line (7) which fluidically connects the at least one refill funnel (6, 8) to the first funnel (2), a second line (9) which fluidically connects the at least one refill funnel (6, 8) to the second funnel (2), and wherein a cross-sectional area of ​​the inner passage of a portion (7a, 9a) of the first and second conduits (7, 9) adjacent to the refill funnel (6, 8) is smaller than a cross-sectional area of ​​the inner passage of a portion (7b, 9b) of the first and second conduits (7, 9) adjacent to the first and second funnels (2, 4), respectively.

Description

[0001] This application claims priority from European patent application EP 25382524.4, filed on May 23, 2025. The entire disclosure of European patent application EP 25382524.4 is hereby incorporated by reference. TECHNICAL FIELD

[0002] The present invention relates to powder feeding systems for laser metal deposition manufacturing processes.

[0003] An object of the invention is to provide a powder feeding system suitable for high-rate production, which is capable of providing a constant and continuous supply of large volumes of metal powder.

[0004] The use of the invention is particularly advantageous in the manufacture or treatment of components for the automotive industry. STATE OF THE ART

[0005] Laser cladding, or LMD, is a direct-energy deposition (DED) process that uses a laser source to generate a concentrated laser beam that is focused onto the surface of a substrate (workpiece), creating a molten pool on the substrate. Material in the form of powder or wires is injected through one or more dispensing nozzles and into the focused laser beam. When the added material is powder, such as metal or ceramic powder, the injected powder strikes the laser beam and is absorbed and integrated into the molten pool, depositing it on the surface of the substrate.

[0006] Powder particles injected into the laser beam are drawn from a feed system through cylindrical inlets to the feed nozzles. Existing powder feeders use mechanical structures to deliver a metered powder flow. Typically, the powder is drawn from a powder reservoir by the action of a rotating wheel driven by a motor. Such feed systems must maintain a constant pressure (e.g., max. 1.5 bar) within their reservoirs or hoppers to avoid fluctuations in the powder flow, which can provoke powder feeding at an inconsistent rate. For laser beam welding, it is important to ensure that the powder is fed efficiently and consistently into the gas-powder stream at the powder feed nozzles to guarantee high-quality parts.

[0007] However, the reservoirs or hoppers of existing powder feeders have a limited capacity to store powder (hopper volumes generally range from 0.7 to 5 liters). Since they must maintain a constant pressure within very specific margins, laser welding must be stopped every time the hoppers are empty and need to be refilled. This refilling process can occur every few hours depending on the hopper volume and the deposition rate, making the manufacturing process inefficient and potentially causing discontinuities in the resulting part.

[0008] Some solutions have attempted to overcome this problem by providing additional powder feeders with their corresponding hoppers, connected in parallel to the respective laser coating system, and interposing switches, valves, or similar devices to control which powder feeder feeds the deposition nozzle. In this way, the system has a main powder feeder and a backup powder feeder, operating when other powder feeders have emptied their hoppers.

[0009] European patent application EP-4,295,977 A1 describes a powder supply system comprising a powder supply device connectable to a laser metal deposition device, the powder supply device comprising a supply hopper for storing powder, a first powder outlet through which the powder is to be supplied to the laser metal deposition device, and a first powder inlet. The system includes a refill hopper for storing additional powder and a second powder outlet fluidly connected to the first powder inlet through which the additional powder is provided to the supply hopper. The refill hopper is arranged above the powder supply device.The system additionally comprises: a pressure generating device for generating an operating pressure level within the feed hopper; a controller for operating the pressure generating device to generate a pressure level within the refill hopper that is substantially equal to the operating pressure level in the feed hopper, so that additional powder can flow from the refill hopper to the feed hopper by gravity.

[0010] In some applications, it may be desirable to feed and combine two or more streams of metal powder from two or more hoppers into a single hose fluidly coupled to the nozzle of a laser head, thereby delivering a large amount of metal powder to the laser head. However, when two or more streams of metal powder are combined into a single hose, the pressure of the two or more streams adds up, creating overpressure in the hoppers of the powder feeder(s) to such an extent that powder from the refill hopper cannot flow to the powder feeder by gravity because the pressure in the hoppers of the powder feeder(s) is greater than the pressure in the refill hopper. DESCRIPTION OF THE INVENTION

[0011] The invention is defined in the appended independent claim and satisfactorily counteracts the above-described disadvantage of the prior art by providing a powder feeding system for a laser metal deposition system, the system comprising: a powder feeder provided with a first hopper adapted to feed a first stream of transport gas and metal powder through a first hose, and a second hopper adapted to feed a second stream of transport gas and metal powder through a second hose.

[0012] The system comprises a combiner to which the first and second hoses are fluidly connected, wherein the combiner is configured to introduce the first and second streams into a third hose. The third hose is coupled to the nozzle of a laser head either directly or through a powder splitter. Due to the connection of the first and second hoses at the combiner, pressures in the first and second hoses are added to each other, thereby creating an overpressure in the first and second hoppers.

[0013] The system further comprises: at least one refill hopper for supplying metal powder to the first and second hoppers, a first conduit fluidly connecting the at least one refill hopper to the first hopper, and a second conduit fluidly connecting the at least one refill hopper to the second hopper.

[0014] According to one aspect of the invention, the cross-sectional area of ​​the internal passage of a portion of the first and second conduits adjacent to the refill hopper is smaller than a cross-sectional area of ​​the internal passage of a portion of the first and second conduits adjacent to the first and second hoppers of the powder feeder, respectively, to increase the pressure in the portion of the first and second conduits adjacent to the refill hopper, thereby compensating for the overpressure created in the hoppers caused by the addition of the first and second flows at the combiner.

[0015] The refill hopper is arranged above the first and second hoppers of the powder feeder so that metal powder can flow by gravity (or by its own weight) from the refill hopper to the hoppers of the powder feeder when pressures are equalized, that is, when the internal pressure in the refill hopper is equal to or slightly greater than the individual pressure in each hopper of the feed system.

[0016] Preferably, a first and a second valve are installed on the first and second conduits, respectively, for controlling the flow through the first and second conduits. The portions of the first and second conduits adjacent to the refill hopper extend at least partially from the outlet of the refill hopper to the first and second valves, and the portions of the first and second conduits adjacent to the first and second hoppers of the powder feeder extend at least partially from the first and second valves to the inlet of the first and second hoppers of the powder feeder.

[0017] The system further comprises a pressure generating device for independently pressurizing the hoppers of the powder feeder and the refill hopper.

[0018] The system includes a controller configured to operate the pressure generating device. The controller is configured to control the pressure generating device such that the pressure in the refill hopper is greater than the pressure in the first and second hoppers of the powder feed device.

[0019] The system further comprises first and second flow meters fluidly connected to the first and second conduits for measuring the flow of powder flowing through the first and second conduits, respectively.

[0020] The first and second flow meters are arranged adjacent to the first and second valves, respectively, and wherein the cross-sectional area of ​​a portion of the first and second conduits passing through the first and second valves and the first and second flow meters is substantially constant, larger than the portion of the first and second conduits adjacent to the refill hopper, and smaller than a cross-sectional area of ​​the internal passage of a portion of the first and second conduits adjacent to the first and second hoppers of the powder feeder, respectively.

[0021] The combining device may be implemented as a "T" or "Y" shaped connector having first and second inlets fluidically coupled to the first and second tubes, respectively, and an outlet fluidically coupled to the first and second inlets and to the third tube.

[0022] In a preferred embodiment, there is a single refill hopper for supplying powder to two or more hoppers of the feeding system.

[0023] In an alternative embodiment, the system comprises a first and a second refill hopper, such that the first line fluidly connects the first refill hopper to the first hopper of the powder feeder and the second line fluidly connects the second refill hopper to the second hopper of the powder feeder.

[0024] The invention also relates to a laser metal deposition system comprising: a laser head including a nozzle; and the powder delivery system defined above. The third hose is fluidly coupled to the nozzle for delivering metal powder to the laser head. Preferably, the third hose is fluidly coupled to the nozzle by a powder splitter, which divides the powder flowing through the third hose into two or more individual streams, which are fed into the nozzle of the laser head. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To complete the description and better understand the invention, a set of 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 merely as examples of how the invention may be carried out. The drawings include the following figures: Fig. 1 and Fig. 2 show schematic representations of the powder feeding system of the invention with two individual refill hoppers in the case of Fig. 1 and with a single refill hopper for two feed hoppers in the case of Fig. 2. Fig. Figure 3 shows a schematic representation of a line connecting a refill hopper to a hopper of a powder feeder comprising a valve and a flow meter. Fig. Figure 4 shows a schematic representation of a splitter device used in the embodiment of Fig. 2 is used. BRIEF DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

[0026] Fig. Figure 1 shows a preferred embodiment of a powder feeding system (1) according to the invention, comprising: a powder feeding device (21) provided with a first hopper (2) designed to feed a first stream of transport gas and metal powder through a first hose (3), and a second hopper (4) designed to feed a second stream of transport gas and metal powder through a second hose (5).

[0027] The system (1) further includes: a first refill hopper (6) for supplying metal powder to the first hopper (2) of the powder feeder (21) through a first line (7) and a second refill hopper (8) for supplying metal powder to the second hopper (4) of the powder feeder (21) through a second line (9). As shown in Fig. 1, the first and second refill hoppers (6, 8) are arranged above the first and second hoppers (2, 4) of the powder feeders (21), respectively, so that when pressures in a refill hopper and the corresponding hopper of the powder feeder are equalized, powder can flow by gravity from the refill hopper to the corresponding hopper of the powder feeder.

[0028] Conventionally, each hopper (2, 4) consists of a powder container (19, 20), a stirrer (26, 27) for stirring powder in the corresponding powder container (19, 20) and a disc-like dispenser (28, 29).

[0029] The hoppers (2, 4) of the powder feeder (21) are installed in a cabinet (23) which encloses electrical and mechanical components necessary to manage the powder feed process in a known manner.

[0030] The first and second refill hoppers (6, 8) have a much larger capacity for storing metal powder than the feed hoppers (19, 20). For example, the capacity of the conventional hoppers (2, 4) can range from 0.7 to 5 liters, whereas the capacity of the refill hopper (6, 8) can have a volume selected to store 30 kg to 400 kg of powder, or even more.

[0031] The system (1) comprises a combining device (10) to which the first and second hoses (3, 5) are fluidically connected. The combining device (10) is configured to introduce the first and second streams flowing through the first and second hoses (3, 5) into a third hose (11), which in turn is fluidically coupled to a powder splitter (24) to supply metal powder to the nozzle (12) of a laser head (13) through two or more inlets (12a, 12b).

[0032] The powder splitter (24) has a common line (24a) coupled to the third hose (11) and two outlets (24b, 24c) so that the metal flow coming from the third line is divided at the powder splitter (24) and fed to the inlets (12a, 12b) of the nozzle (12) through hoses (30, 31), respectively.

[0033] The combining device can be implemented as a "T" or "Y" shaped connector with a first and a second inlet fluidically coupled to the first and second hoses (3, 5) respectively, and an outlet fluidically coupled to the first and second inlets and to the third hose (11).

[0034] The first and second lines (7, 9) are in Fig. 3 is shown in more detail. The first line (7) has a first valve (14) for controlling the flow through the first line and a first flow meter (15) for measuring the flow through the first line. The first flow meter (15) is located downstream and adjacent to the first valve (14).

[0035] Similarly, the second line (9) has a second valve (16) for controlling the flow through the second line and a second flow meter (25) for measuring the flow through the second line. The second flow meter (25) is located downstream and adjacent to the second valve (16).

[0036] A first section (7a) of the first line (7), adjacent to the first refill funnel (6), extends from the outlet (6a) of the first refill funnel (6) to the first valve (14). A second section (7c) of the first line (7), adjacent to the first funnel (2), extends from the first flow meter (15) to the first funnel (2), in particular from the first flow meter (15) to the container (19) of the first funnel (2).

[0037] The cross-sectional area of ​​the inner passage of the first section (7a) is smaller than the cross-sectional area of ​​the inner passage of the second section (7c) in order to increase the pressure at the first section (7a) and to compensate for an overpressure at the first funnel (2) caused by its connection to the second hose (5) by the combiner (10).

[0038] Preferably, the first conduit (7) is a cylindrical tube, so that the diameter of the first section (7a) is smaller than the diameter of the second section (7c).

[0039] Similarly, a first portion (9a) of the second conduit (9), adjacent to the second refill funnel (8), extends from the outlet (8a) of the second refill funnel (8) to the second valve (16). A second portion (9c) of the second conduit (9), adjacent to the second funnel (4), extends from the second flow meter (25) to the second funnel (4), in particular to the container (20) of the second funnel (4). The cross-sectional area of ​​the inner passage of the first portion (9a) is smaller than the cross-sectional area of ​​the inner passage of the second portion (9c).

[0040] Preferably, the second conduit (9) is also a cylindrical tube, so that the diameter of the first section (9a) is smaller than the diameter of the second section (9c).

[0041] The system (1) comprises a pressure generating device (not shown) for independently pressurizing the first and second hoppers (2, 4) of the powder feed devices (21) and the refill hoppers (6, 8), and a controller (not shown) for controlling the operation of the pressure generating device.

[0042] As in Fig. 3, the cross-sectional area of ​​a third section (7b) of the first conduit (7), which runs internally through the first valve (14), through the second flowmeter (15) and through the connection (17) between the first valve (14) and the second flowmeter (15), is substantially constant, larger than the first section (7a) and smaller than the second section (7c).

[0043] Similarly, the cross-sectional area of ​​a third section (9b) of the second conduit (9), which passes internally through the second valve (16), through the second flowmeter (25) and through the connection (22) between the second valve (16) and the second flowmeter (25), is substantially constant, larger than the first section (9a) and smaller than the second section (9c).

[0044] In the alternative embodiment of Fig. 2, there is a single refill hopper (6) for supplying metal powder to two hoppers (2, 4) of the powder feed device (21), in particular through the first line (7) to the first hopper (2) of the powder feed device (21) and through the second line (9) to the second hopper (4) of the powder feed device (21). The outlet (6a) of the refill hopper (6) is provided with a flow divider (18), for example the one shown in Fig. 4, which consists of a Y-shaped conductor with a common branch (18a) coupled to the outlet (6a) of a refill hopper (6), and two branches (18b, 18c) such that one branch (18b) is coupled to the first conduit (7) and the other branch (18c) is coupled to the second conduit (9). The cross-sectional area of ​​the internal passages of the branches (18b, 18c) is larger than the cross-sectional area of ​​the internal passage of the common branch (18a) to prevent metal powder from clogging.

[0045] A laser metal deposition system according to the invention as described in the Fig. 1 and Fig.2, comprising: a laser head (13) including a nozzle (12), and the powder supply system (1) previously defined in any embodiment, wherein the third hose (11) is fluidly coupled to a powder splitter (24) for supplying metal powder to the nozzle (12) of the laser head (13).

[0046] Due to the large capacity of the refill hoppers (6, 8), the plant can operate continuously for long periods of time to produce or treat parts at a high production rate. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 25382524.4

[0001] EP 25382524.4

[0001] EP 4.295.977 A1

[0009]

Claims

[1] Powder feed system (1) for a laser metal deposition system, the system comprising: a first hopper (2) designed to supply a first stream of transport gas and metal powder via a first hose (3), a second hopper (4) designed to supply a second stream of transport gas and metal powder through a second hose (5), a combining device (10) to which the first and second hoses (3, 5) are fluidically connected, the combining device (10) being arranged to introduce the first and second streams into a third hose (11), at least one refill hopper (6, 8) for supplying metal powder to the first and second hoppers (2, 4), a first line (7) which fluidically connects the at least one refill funnel (6, 8) to the first funnel (2), a second line (9) which fluidically connects the at least one refill funnel (6, 8) to the second funnel (2), and wherein a cross-sectional area of ​​the inner passage of a portion (7a, 9a) of the first and second conduits (7, 9) adjacent to the refill funnel (6, 8) is smaller than a cross-sectional area of ​​the inner passage of a portion (7b, 9b) of the first and second conduits (7, 9) adjacent to the first and second funnels (2, 4), respectively. [2] System according to claim 1, comprising a powder feeder (21) provided with the first and second hoppers (2, 4). [3] A system according to claim 1 or 2, wherein the first and second lines (7, 9) each have a first and a second valve (14, 16) for controlling the flow through the first and second lines, and wherein the portions (7a, 9a) of the first and second lines adjacent to the refill funnel (6, 8) extend from the outlet (6a, 8a) of the refill funnel (6, 8) to the first and second valves (14, 16), and wherein the portions (7b, 9b) of the first and second lines adjacent to the first and second funnels (2, 4) extend from the first and second valves (14, 16) to the inlet of the first and second funnels (2, 4). [4] A system according to any one of the preceding claims, further comprising a pressure generating device for independently pressurising the first and second hoppers (2, 4) and the refill hopper (6, 8). [5] The system of claim 4, further comprising a controller for controlling the operation of the pressure generating device, and wherein the controller is configured to control the pressure generating device such that the pressure in the refill hopper (6, 8) is greater than the pressure in the first and second hoppers (2, 4). [6] System according to claim 5, wherein the at least one refill funnel (6, 8) is arranged above the first and second funnels (2, 4). [7] A system according to any one of the preceding claims, further comprising first and second flow meters (15, 17) fluidly connected to the first and second conduits (7, 9) for measuring the flow of powder flowing through the first and second conduits (7, 9), respectively. [8] A system according to claim 7, wherein the first and second flow meters (15, 17) are arranged adjacent to the first and second valves (14, 16), respectively, and wherein the cross-sectional area of ​​a portion of the first and second conduits passing through the first and second valves and the first and second flow meters is substantially constant, larger than the portion of the first and second conduits adjacent to the refill funnel, and smaller than a cross-sectional area of ​​the internal passage of a portion of the first and second conduits adjacent to the first and second funnels (2, 4), respectively. [9] System according to one of the preceding claims, wherein the combining device (10) is a "T" or "Y" shaped connector, having a first and a second inlet fluidically coupled to the first and second hoses (3, 5) respectively, and an outlet fluidically coupled to the third hose (11). [10] System according to one of the preceding claims, comprising a single refill hopper (6) for supplying powder to two or more hoppers (2, 4) of the powder supply device (21). [11] System according to one of claims 1 to 8, comprising a first and a second refill funnel (6, 8), wherein the first line (7) fluidically connects the first refill funnel (6) to the first funnel (2) of the powder feed device (21) and wherein the second line (9) fluidically connects the second refill funnel (8) to the second funnel (4) of the powder feed device (21). [12] A laser metal deposition system comprising: a laser head (13) including a powder splitter (24) and a nozzle (12), and the powder supply system (1) defined in any one of the preceding claims, wherein the third hose (11) is fluidly coupled to the powder splitter (24) to supply metal powder to the nozzle (12) of the laser head (13).

Images