A water-free double-taper premixed coaxial powder feeding device and a method of using the same

Abstract

The application provides a water-free double-taper premix coaxial powder feeding device and a use method thereof, and belongs to the technical field of plasma spraying, to solve the problem of pressure loss and heat energy dissipation caused by cross flow generated by the existing powder feeding device. The application provides a water-free double-taper premix coaxial powder feeding device, a premix groove is arranged as an annular groove surrounding a powder feeding ring, and is used for premixing powder and carrier gas; a powder feeding channel is connected with the powder feeding cavity and the premix groove, and is used for feeding the premixed powder into the powder feeding cavity and mixing with the jet flow; in the jet flow direction, the inlet of the powder feeding channel is located at the rear side of the outlet, so that the included angle between the powder feeding channel and the jet flow direction is less than 90 degrees. The application greatly reduces the cross of the powder carrier gas flow and the plasma jet flow, reduces the fluid motion stability interference of the carrier gas on the plasma jet flow, and improves the spraying quality; the flow discontinuity of the powder can be avoided, and the powder of different sizes, different densities, metals, ceramics and composite materials can be adapted.

Description

Technical Field

[0001] This invention relates to the field of plasma spraying technology, and in particular to a water-free, dual-tapered premixed coaxial powder feeding device and its usage method. Background Technology

[0002] The powder feeding pipe in plasma spraying is one of the key components of plasma spraying equipment. It is used to transport powder material into the plasma jet, thereby achieving coating preparation. The powder feeding pipe connects the powder feeder and the plasma spray gun, and its main function is to transport powder into the plasma jet via powder feeding gas. Depending on the powder feeding method, the powder feeding pipe can be divided into internal powder feeding pipes and external powder feeding pipes.

[0003] Internal powder feeding refers to powder being fed into the plasma jet through a powder feeding orifice inside the spray gun via a powder feeding gas. This orifice is typically located within the nozzle compression channel, approximately 2mm-6mm from the nozzle exit face. External powder feeding refers to powder being fed into the plasma jet from outside the spray gun via a powder feeding gas. This method usually involves installing a powder feeding device outside the spray gun, introducing the powder outside the plasma jet.

[0004] Regardless of whether the powder is fed internally or externally, the powder delivery pipes used in commercial plasma spraying currently form a 90° angle with the plasma jet, which is a typical crossflow in fluid dynamics. Crossflow mainly has the following problems: Fluid flows can be perpendicular or intersecting, resulting in relative motion between fluid molecules. High velocities in these intersecting flows can lead to turbulence. In turbulent flow, fluctuating velocities and vortex motion further exacerbate viscous dissipation. Small vortices in turbulence constantly break up and reform, converting large-scale kinetic energy into small-scale thermal energy, which is ultimately lost through heat conduction. Furthermore, at the inlet, outlet, and bends of intersecting flows, the fluid velocity and direction change drastically, causing localized pressure losses. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a water-free, double-cone premixed coaxial powder feeding device and its usage method, thereby solving the problems of pressure loss and heat dissipation caused by cross-flow during powder feeding in existing powder feeding devices.

[0006] The specific details of the invention are as follows: In a first aspect, the present invention proposes a water-free, double-cone premixing coaxial powder feeding device, which includes a powder feeding ring coaxially arranged with the spray gun nozzle, the powder feeding ring including a powder feeding chamber, a powder feeding channel and a premixing groove; The powder feeding chamber is connected to the nozzle and is used to feed powder to the jet ejected from the nozzle; the premixing tank is an annular groove surrounding the powder feeding ring and is used to premix the powder and carrier gas. The powder feeding channel connects the powder feeding chamber and the premixing tank, and is used to feed the premixed powder into the powder feeding chamber for mixing with the jet. In the jet direction, the inlet of the powder feeding channel is located behind the outlet, so that the angle between the powder feeding channel and the jet direction is less than 90°.

[0007] Optionally, the powder feeding chamber includes a first conical cavity and a second conical cavity; The first conical cavity and the second conical cavity are connected to the nozzle in sequence. The diameter of the first conical cavity and the second conical cavity gradually increases along the jet direction to reduce the heating effect of the jet on the powder feeding ring.

[0008] Optionally, the premixing tank is arranged around the outside of the first conical cavity; the angle between the powder feeding channel and the jet direction is not greater than 25°.

[0009] Optionally, the device further includes a mounting member surrounding the powder feeding ring, the mounting member being used to coaxially mount the powder feeding ring to the nozzle, the mounting member including a mounting groove, a seal and a fastener; The mounting groove is provided corresponding to the nozzle to radially limit the powder feeding ring; The sealing element is disposed between the powder feeding ring and the nozzle to seal the contact surface between the powder feeding ring and the nozzle; The fastener is located on the outside of the powder feeding ring to limit the powder feeding ring in the axial direction.

[0010] Optionally, the device further includes a powder feeding pipe connected to the premixing tank for feeding carrier gas and powder into the premixing tank; the mounting component is also provided with a connecting channel, the two ends of which are respectively connected to the powder feeding pipe and the premixing tank for feeding the powder from the powder feeding pipe into the premixing tank.

[0011] Optionally, the slope of the second conical cavity is greater than the slope of the first conical cavity.

[0012] Optionally, the slope angle of the first conical cavity is 4°-8°; the slope angle of the second conical cavity is 25°-35°.

[0013] Secondly, this invention proposes a method for using a water-cooled, dual-cone premixed coaxial powder feeding device, comprising the following steps: S1: Pour the powder to be sprayed into the carrier gas powder feeder; S2: Install the waterless, double-cone premixed coaxial powder feeding device at the nozzle of the plasma generator; S3: Adjust the carrier gas flow rate to 1.25-2.5 L / min; S4: Turn on the plasma generator and carrier gas powder feeding device, and add powder into the plasma jet for plasma spraying through the waterless double-cone coaxial powder feeding device. The powder feeding rate is 10-30 g / min.

[0014] Optionally, the surface temperature of the water-free, double-tapered, coaxial powder feeding device is below 250°C.

[0015] Optionally, the powder may be powder of different sizes, densities, and materials.

[0016] Compared with the prior art, the present invention has the following advantages: This invention provides a water-free, dual-tapered premixed coaxial powder feeding device and its usage method. The device features a coaxial powder feeding ring parallel to the plasma jet direction, significantly reducing the cross-flow between the powder carrier gas and the plasma jet, improving powder heating, minimizing interference from the carrier gas on the fluid motion stability of the plasma jet, ensuring uniform powder entry into the central region of the jet, and improving coating quality. The premixing tank thoroughly mixes the carrier gas and powder before they enter the plasma jet through the powder feeding ring, effectively preventing discontinuous powder flow and adapting to metal, ceramic, and composite powders of different sizes and densities. The premixing tank design ensures thorough mixing of the powder and carrier gas before entry into the jet, enhancing conveying stability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This shows a cross-sectional structural schematic diagram of the water-free, double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention; Figure 2 A cross-sectional structural schematic diagram of the powder feeding ring of the waterless double-tapered premixing coaxial powder feeding device provided in an embodiment of the present invention is shown. Figure 3 This is a side view of the powder feeding ring of the water-free, double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention. Figure 4 A cross-sectional structural schematic diagram of the mounting component of the waterless double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention is shown.

[0019] The accompanying figure is labeled as follows: 1. Mounting component; 11. Mounting groove; 12. Seal; 13. Fastener; 14. Connecting channel; 2. Powder feeding pipe; 4. Powder feeding ring; 41. First conical cavity; 42. Second conical cavity; 43. Powder feeding channel; 44. Premixing tank; 5. Nozzle. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0021] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0022] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0023] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Before providing a detailed description of the water-free, double-cone premixed coaxial powder feeding device and its usage method provided by this invention, it is necessary to explain the relevant technologies as follows: The powder feeding pipe in plasma spraying is one of the key components of plasma spraying equipment. It is used to transport powder material into the plasma jet, thereby achieving coating preparation. The powder feeding pipe connects the powder feeder and the plasma spray gun, and its main function is to transport powder into the plasma jet via powder feeding gas. Depending on the powder feeding method, the powder feeding pipe can be divided into internal powder feeding pipes and external powder feeding pipes.

[0026] Internal powder feeding refers to powder being fed into the plasma jet through a powder feeding orifice inside the spray gun via a powder feeding gas. This orifice is typically located within the nozzle compression channel, approximately 2mm-6mm from the nozzle exit face. External powder feeding refers to powder being fed into the plasma jet from outside the spray gun via a powder feeding gas. This method usually involves installing a powder feeding device outside the spray gun, introducing the powder outside the plasma jet.

[0027] Regardless of whether the powder is fed internally or externally, the powder delivery pipes used in commercial plasma spraying currently form a 90° angle with the plasma jet, which is a typical crossflow in fluid dynamics. Crossflow mainly has the following problems: Fluid flows can be perpendicular or intersecting, resulting in relative motion between fluid molecules. High velocities in these intersecting flows can lead to turbulence. In turbulent flow, fluctuating velocities and vortex motion further exacerbate viscous dissipation. Small vortices in turbulence constantly break up and reform, converting large-scale kinetic energy into small-scale thermal energy, which is ultimately lost through heat conduction. Furthermore, at the inlet, outlet, and bends of intersecting flows, the fluid velocity and direction change drastically, causing localized pressure losses.

[0028] To enable those skilled in the art to better understand the present invention, the following embodiments will be used to provide a detailed description of the water-free, double-cone premixed coaxial powder feeding device and its usage method.

[0029] Firstly, Figure 1 This shows a cross-sectional structural schematic diagram of the water-free, double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention; Figure 2 A cross-sectional structural schematic diagram of the powder feeding ring of the waterless double-tapered premixing coaxial powder feeding device provided in an embodiment of the present invention is shown. Figure 3 This is a side view of the powder feeding ring of the water-free, double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention. Figure 4 This diagram shows a cross-sectional view of the mounting component of the waterless, double-tapered premixed coaxial powder feeding device provided in an embodiment of the present invention; as shown. Figure 1-4 As shown, the present invention proposes a water-free, double-cone premixing coaxial powder feeding device, including a powder feeding ring 4 coaxially arranged with the spray gun nozzle 5. The powder feeding ring 4 includes a powder feeding chamber, a powder feeding water-free, double-cone premixing coaxial powder feeding device channel 43, and a premixing groove 44. The powder feeding chamber is connected to the nozzle 5 of the plasma spray gun and is used to feed powder to the jet sprayed from the nozzle 5; the premixing tank 44 is an annular groove surrounding the powder feeding ring 4 and is used to premix the powder and carrier gas. The powder feeding channel 43 connects the powder feeding chamber and the premixing tank 44, and is used to feed the premixed powder into the powder feeding chamber for mixing with the jet. In the jet direction, the inlet of the powder feeding channel 43 is located behind the outlet, so that the angle between the powder feeding channel 43 and the jet direction is less than 90°.

[0030] The nozzle 5 is the nozzle 5 of an existing plasma spray gun, used to emit a high-temperature plasma jet to melt the powder to be sprayed and then uniformly spray it onto the material surface.

[0031] like Figure 1 As shown, the powder feeding ring 4 can be made of stainless steel and coaxially mounted on the nozzle 5 so that the axis of the powder feeding ring 4 is aligned with the nozzle 5. The powder feeding chamber is the cavity in which the powder feeding ring 4 connects to the nozzle 5 on the axis, and is used to feed the premixed powder into the jet ejected from the nozzle 5; The premixing tank 44 is a hollow annular tank with the nozzle 5 as the center, and is located outside the powder feeding chamber. It is used to uniformly disperse the powder in the annular premixing tank 44 and then feed the powder into the powder feeding chamber through the powder feeding channels 43 that are uniformly distributed on the premixing tank 44. By connecting the premixing tank 44 of the powder feeding ring 4 to the powder feeding pipe 2, the powder can be fed into the jet ejected from the nozzle 5 through the powder feeding ring 4. Using this technical solution, by setting the powder feeding ring 4 and the nozzle 5 coaxially, the nozzle ejects the plasma jet perpendicularly, and the plasma jet is parallel to the axis of the powder feeding ring 4. Furthermore, the intersection angle between the powder feeding channel 43 and the plasma jet is less than 90°. This non-perpendicular cross-feeding greatly reduces the cross-flow between the powder carrier gas and the plasma jet, improves the powder heating effect, reduces the interference of the carrier gas on the fluid motion stability of the plasma jet, ensures that the powder uniformly enters the central region of the jet, and improves the coating quality. Among them, the powder feeding ring 4 with premixing function allows the powder entering the premixing tank 44 through the annular groove structure of the premixing tank 44. Under the action of the carrier gas, the carrier gas and the powder are fully mixed and uniform. Then, the powder enters the plasma jet through the powder feeding channel 43 of the powder feeding ring 4. This can basically avoid the phenomenon of discontinuous powder flow and adapt to metal, ceramic and composite powders of different sizes and densities. The design of the premixing tank 44 ensures that the powder and the carrier gas are fully mixed before entering the jet, which improves the conveying stability. In some implementations, such as Figure 1As shown, the powder feeding chamber includes a first conical cavity 41 and a second conical cavity 42. The first conical cavity 41 is the first cavity of the powder feeding ring 4 that connects to the nozzle 5 on its axis. The second conical cavity 42 is the second cavity on the other side of the first conical cavity 41 away from the nozzle 5. The diameter of the first conical cavity 41 gradually increases along the jet direction of the nozzle 5, i.e., the axial direction of the powder feeding ring 4, to gradually reduce the heating effect of the jet on the powder feeding ring after the jet is ejected from the nozzle 5. Furthermore, the slope of the second conical cavity 41 is greater than that of the first conical cavity, resulting in a gentler radius expansion of the small slope, allowing for gradual cooling. After the gradual cooling, the large slope provides a buffering effect.

[0032] This technical solution employs a double-tapered structure to match the nozzle outlet structure of a plasma generator. The entire structure can be made of stainless steel, improving the critical dimension design for controlling the double taper. The tapered structure, with its gradually layered inner diameter along the jet direction, effectively avoids the intense radiation and high temperature at the plasma generator outlet. Furthermore, by reducing the powder's incident angle, it minimizes pressure loss and heat dissipation caused by powder injection, allowing for long-term use without water cooling. The powder feeding ring 4 has a surface temperature not exceeding 250°C, ensuring long-term operation without rusting, burning, softening, or tilting. The powder feeding channel 43 (angle less than 90°) reduces disturbance to the jet, preventing impact on jet morphology. This achieves a water-free design, reducing system complexity and energy consumption. The tapered flared structure reduces the thermal impact of the high-speed jet on the powder feeding ring, minimizing localized overheating. The double-tapered structure forms a buffer zone, further reducing the speed at which heat is conducted to the powder feeding ring body. This improves the device's high-temperature resistance and extends its service life, supporting applications of higher-power spraying processes.

[0033] In some implementations, such as Figure 1 As shown, the premixing tank 44 is a hollow annular tank centered on the nozzle 5 and is located outside the powder feeding chamber. It is used to uniformly disperse the powder in the annular premixing tank 44 and then feed the powder into the powder feeding chamber through the powder feeding channels 43 evenly distributed on the premixing tank 44. The angle between the powder feeding channel 43 and the jet direction of the plasma jet ejected perpendicularly from the nozzle 5 is not greater than 25°, and can be 25°, 23°, 20°, 17° and 15°. The angle between the powder feeding channel 43 and the wall of the first conical cavity 41 is not greater than 30° and the angle between the powder feeding channel 43 and the wall of the first conical cavity 41 is not greater than 50°.

[0034] In some implementations, such as Figure 2As shown, the slope of the second conical cavity 42 is greater than that of the first conical cavity 41; the slope angle of the first conical cavity 41 is 4°-8°, which can be 4°, 5°, 6°, 7° and 8°; the slope angle of the second conical cavity 42 is 25°-35°, which can be 25°, 27°, 30°, 33° and 35°. Using this technical solution, the premixing tank is arranged around the perimeter to enhance the premixing space and mixing efficiency; the small-angle powder feeding further reduces interference with the jet and improves the continuity of powder feeding; the powder is more easily carried by the airflow into the jet core, improving the uniformity and adhesion of the coating; different slopes meet different functional requirements: the small slope radius expands more gradually, allowing for gradual cooling; after gradual cooling, the large slope provides a buffer; the heat transfer path and speed can be effectively controlled; the device's ability to adapt to high-temperature environments is improved, ensuring long-term stable operation.

[0035] In some embodiments, such as Figure 1 As shown, the axial length of the second conical cavity 42 can be less than the axial length of the first conical cavity 41. Using this technical solution, the first conical cavity 41 is relatively long, serving as a primary thermal buffer zone to mitigate the impact of the jet on subsequent structures; the second conical cavity 42, although short, has a steep slope, enabling rapid airflow diffusion and reducing localized heat accumulation; this achieves a "slow first, then rapid" heat dispersion strategy, improving heat resistance. The long first conical cavity 41 helps to gradually reduce the jet velocity, forming a stable airflow; the short and steep second conical cavity 42 quickly guides the airflow into the nozzle, maintaining a good flow state; the combination of these two effectively avoids undesirable phenomena such as turbulence and backflow. In some embodiments, such as... Figure 1 As shown, on the axial plane of the first conical cavity 41, the orthographic projection of the premixing tank 44 on this axial plane can be located within the orthographic projection of the first conical cavity 41 on this axial plane, for example, it can be located in the central region of the orthographic projection of the first conical cavity 41 on this axial plane. This causes the premixing tank 44 to be staggered from the second conical cavity 42, thereby avoiding vertical powder feeding. Using this technical solution, the premixing tank and the second conical cavity are arranged in a staggered manner, thereby preventing powder from being fed vertically into the high-speed jet region. This method not only reduces the direct impact of powder on the cavity wall or jet core area, improving conveying stability, but also reduces the thermal load on the second conical cavity 41 region, improving powder feeding stability and coating quality. In some embodiments, such as... Figure 4 As shown, the device also includes a mounting member 1 surrounding the powder feeding ring 4. The mounting member 1 is used to coaxially mount the powder feeding ring 4 to the nozzle 5. The mounting member 1 includes a mounting groove 11, a sealing member 12, and a fastener 13. The mounting groove 11 is provided corresponding to the nozzle 5, so that the nozzle 5 falls in the center of the mounting groove 11, and the powder feeding ring 4 is also installed in the mounting groove 11, and the mounting groove 11 radially limits the powder feeding ring 4. The sealing element 12 is located between the powder feeding ring 4 and the nozzle 5. During installation, the powder feeding ring 4 is installed first, and then the sealing element 12 is installed to seal the contact surface between the powder feeding ring 4 and the nozzle 5. The fastener 13 is located on the outside of the powder feeding ring 4, such as... Figure 1 As shown, the fastener 13 is configured to control the axial tightness of the powder feeding ring 4 by screwing, and to limit the powder feeding ring 4 in the axial direction. This technical solution ensures precise alignment between the powder feeding ring and the nozzle through a coaxial mounting structure; the seal prevents gas leakage or powder spillage, improving safety and reliability; the fastener provides axial locking to prevent displacement caused by vibration, making it suitable for high-frequency industrial operating environments.

[0036] In some implementations, such as Figure 1 As shown, the device also includes a powder feeding pipe 2, which is L-shaped. One end of the powder feeding pipe is connected to a powder feeding device used to provide powder and carrier gas, and the other end is connected to the premixing tank 44. The length of the short side of the L-shape is greater than the radius of the powder feeding ring 4, so as to feed carrier gas and powder into the premixing tank 44. Using this technical solution, the powder feeding is supplied through a dedicated powder feeding pipe 2, improving the stability and controllability of powder supply; it facilitates the adjustment of carrier gas flow rate and powder ratio, achieving precise control of spraying parameters; the structure is simple and reliable, and easy to maintain and replace.

[0037] In some implementations, such as Figure 3 As shown, the mounting component 1 is also provided with a connecting channel 14. The connecting channel 14 is set according to the number and position of the powder feeding pipes 2 and passes through the powder feeding ring 2. The two ends of the connecting channel 14 are respectively connected to the powder feeding pipes 2 and the premixing tank 44, so as to feed the powder from the powder feeding pipes 2 into the premixing tank 44.

[0038] By adopting this technical solution, the integrated channel design simplifies the layout of external pipelines and reduces the risk of leakage; it realizes a lossless transmission path from powder feeding pipe 2 to the premixing tank, improving efficiency; and it enhances the system's integration and compactness, facilitating modular design.

[0039] Secondly, this invention proposes a method for using a water-cooled, dual-cone premixed coaxial powder feeding device, comprising the following steps: S1: Pour the powder to be sprayed into the carrier gas powder feeder; S2: Install the waterless, double-cone premixed coaxial powder feeding device at nozzle 5 of the plasma generator; S3: Adjust the carrier gas flow rate to 1.25-2.5 L / min; S4: Turn on the plasma generator and carrier gas powder feeding device, and add powder into the plasma jet for plasma spraying through the waterless double-cone coaxial powder feeding device. The powder feeding rate is 10-30 g / min.

[0040] By adopting this technical solution, controlling the carrier gas flow rate and powder feeding rate helps to obtain a stable spraying effect; it is simple to operate and suitable for industrial mass production applications.

[0041] In some embodiments, the surface temperature of the waterless double-cone coaxial powder feeding device is below 250°C.

[0042] By adopting this technical solution, the heat transfer from the plasma jet to the powder feeding ring 4 is reduced through the double-tapered structure and the small included angle design of the powder feeding channel 43. The heat generated by the powder feeding ring 4 and the mixing of powder with the plasma jet is also reduced. Therefore, the surface temperature of the powder feeding ring 4 is low, which supports water-free design and saves cooling resources; it reduces the dependence on external cooling systems and reduces equipment complexity; it is safer and suitable for temperature-sensitive working environments.

[0043] In some embodiments, the powder may be powder of different sizes, densities, and materials.

[0044] By adopting this technical solution, the powder is fully premixed through the premixing tank 44, which can effectively avoid the problems of discontinuity and clogging when powders of different materials, densities and sizes are fed. This greatly improves the versatility and adaptability of the device, meets the spraying needs of multiple industries and materials (such as metals, ceramics, composite materials, etc.), and helps to expand the scope of market applications and enhance product competitiveness.

[0045] Example 1 like Figure 1-4 As shown, a water-free, dual-cone premixed coaxial powder feeding device includes a powder feeding ring 4 coaxially arranged with the spray gun nozzle 5. The powder feeding ring 4 includes a first conical cavity 41, a second conical cavity 42, a powder feeding channel 43, and a premixing groove 44. The slope angle of the first conical cavity 41 is 6°, and the slope angle of the second conical cavity 42 is 30°. The first conical cavity 41 and the second conical cavity 42 are sequentially connected to the nozzle 5. The apertures of the first conical cavity 41 and the second conical cavity 42 gradually increase along the jet direction to reduce the heating effect of the jet on the powder feeding ring 4. The premixing tank 44 is configured as an annular groove surrounding the powder feeding ring 4 to premix the powder and the carrier gas. The powder feeding channel 43 connects the second conical cavity 42 and the premixing tank 44, and is used to feed the premixed powder into the second conical cavity 42 to mix with the jet. In this embodiment, the water-free, double-tapered premixed coaxial powder feeding device is used to spray a high-temperature protective coating onto engine blades. The powder is zirconium oxide, and the carrier gas is argon.

[0046] In this embodiment, the premixing tank 44 is arranged around the outside of the first conical cavity 41; the powder feeding channel 43 has an angle of 25° with the jet direction.

[0047] In this embodiment, the device further includes a mounting member 1 surrounding the powder feeding ring 4. The mounting member 1 is used to coaxially mount the powder feeding ring 4 to the nozzle 5. The mounting member 1 includes a mounting groove 11, a sealing member 12, and a fastener 13. The mounting groove 11 is provided corresponding to the nozzle 5 to limit the powder feeding ring 4 radially. The sealing member 12 is provided between the powder feeding ring 4 and the nozzle 5 to seal the contact surface between the powder feeding ring 4 and the nozzle 5. The fastener 13 is provided on the outside of the powder feeding ring 4 to limit the powder feeding ring 4 axially.

[0048] In this embodiment, the device further includes a powder feeding pipe 2, which is connected to the premixing tank 44 and is used to feed carrier gas and powder into the premixing tank 44.

[0049] In this embodiment, the mounting component 1 is further provided with a connecting channel 14, the two ends of which are respectively connected to the powder feeding pipe 2 and the premixing tank 44, so as to feed the powder from the powder feeding pipe 2 into the premixing tank 44.

[0050] In this embodiment, the powder feeding ring 4 and the mounting component 1 are made of stainless steel, and the mounting component 1 is installed to the nozzle 5 by bolts.

[0051] Example 2 A method for using a water-free, dual-cone premixed coaxial powder feeding device includes the following steps: S1: Pour the powder to be sprayed into the carrier gas powder feeder; S2: Install the waterless, double-cone premixed coaxial powder feeding device at nozzle 5 of the plasma generator; S3: Adjust the carrier gas flow rate to 2-2.5 L / min; S4: Turn on the plasma generator and carrier gas powder feeding device, and add powder into the plasma jet for plasma spraying through the waterless double-cone coaxial powder feeding device. The powder feeding rate is 20-25 g / min.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0053] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0054] The above provides a detailed description of the water-free, double-cone premixed coaxial powder feeding device and its usage method provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A water-cooled, double-cone premixed coaxial powder feeding device, characterized in that, It includes a powder feeding ring (4) coaxially arranged with the spray gun nozzle (5), the powder feeding ring (4) including a powder feeding chamber, a powder feeding channel (43) and a premixing tank (44); The powder feeding chamber is connected to the nozzle (5) and is used to feed powder to the jet ejected from the nozzle (5); the premixing tank (44) is configured as an annular groove surrounding the powder feeding ring (4) and is used to premix the powder and carrier gas; the powder feeding chamber includes a first conical cavity (41) and a second conical cavity (42). The first conical cavity (41) and the second conical cavity (42) are connected to the nozzle (5) in sequence. The aperture of the first conical cavity (41) and the second conical cavity (42) gradually increases along the jet direction to reduce the heating effect of the jet on the powder feeding ring (4). The slope of the second conical cavity (42) is greater than the slope of the first conical cavity (41); The slope angle of the first conical cavity (41) is 4°-8°; the slope angle of the second conical cavity (42) is 25°-35°. The powder feeding channel (43) connects the powder feeding chamber and the premixing tank (44) to feed the premixed powder into the powder feeding chamber and mix it with the jet. In the jet direction, the inlet of the powder feeding channel (43) is on the rear side of the outlet; The premixing tank (44) is arranged around the outside of the first conical cavity (41); the angle between the powder feeding channel (43) and the jet direction is no greater than 25°.

2. The water-cooled, double-cone premixed coaxial powder feeding device according to claim 1, characterized in that, The device further includes a mounting member (1) arranged around the powder feeding ring (4), the mounting member (1) being used to coaxially mount the powder feeding ring (4) to the nozzle (5), the mounting member (1) including a mounting groove (11), a seal (12) and a fastener (13). The mounting groove (11) is provided corresponding to the nozzle (5) to radially limit the powder feeding ring (4). The sealing element (12) is disposed between the powder feeding ring (4) and the nozzle (5) to seal the contact surface between the powder feeding ring (4) and the nozzle (5); The fastener (13) is located on the outside of the powder feeding ring (4) to limit the powder feeding ring (4) in the axial direction.

3. The water-cooled, double-tapered premixed coaxial powder feeding device according to claim 2, characterized in that, The device also includes a powder feeding pipe (2), which is connected to the premixing tank (44) for feeding carrier gas and powder into the premixing tank (44); the mounting component (1) is also provided with a connecting channel (14), which is connected to the powder feeding pipe (2) and the premixing tank (44) at both ends for feeding the powder from the powder feeding pipe (2) into the premixing tank (44).

4. A method of using a water-cooled, double-cone premixed coaxial powder feeding device, characterized in that, The method of use is applicable to the water-free, dual-cone premixed coaxial powder feeding device according to any one of claims 1 to 3, and includes the following steps: S1: Pour the powder to be sprayed into the carrier gas powder feeder; S2: Install the waterless, double-cone premixed coaxial powder feeding device at the nozzle of the plasma generator; S3: Adjust the carrier gas flow rate to 1.25-2.5 L / min; S4: Turn on the plasma generator and carrier gas powder feeding device, and add powder into the plasma jet for plasma spraying through the waterless double-cone coaxial powder feeding device. The powder feeding rate is 10-30 g / min.

5. The method of using the water-cooled double-cone premixed coaxial powder feeding device according to claim 4, characterized in that, The surface temperature of the water-free, double-cone, coaxial powder feeding device is below 250°C.

6. The method of using the water-cooled double-cone premixed coaxial powder feeding device according to claim 4, characterized in that, The powder can be of different sizes, densities, and materials.

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