High-speed low-temperature spraying gun with fuel premixing structure and system of high-speed low-temperature spraying gun

Abstract

The invention discloses a high-speed low-temperature spraying gun with a fuel premixing structure and a system of the high-speed low-temperature spraying gun, and belongs to the technical field of material surface modification and coating. The spray gun comprises a powder feeding needle, the powder feeding needle is sleeved with a pre-premixing air distribution unit I and a pre-premixing air distribution unit II, the end of the powder feeding needle penetrates through a premixing common porous catalytic ceramic plate and is communicated with a combustion chamber, and a premixing interlayer is arranged between the pre-premixing air distribution unit II and the premixing common porous catalytic ceramic plate; a fuel gas channel and a powder feeding needle-compressed air channel are arranged in the pre-premixing air distribution unit I, and the powder feeding needle-compressed air channel is arranged on the periphery of the powder feeding needle; an air and gas inlet and a compressed air channel are arranged outside the pre-premixing air distribution unit I; the compressed air channel is communicated with the air inlet, the powder feeding needle-compressed air channel, the premixing interlayer and the outer wall of the combustion chamber; and the fuel gas channel is communicated with the fuel gas inlet and the premixing interlayer. The spray gun can keep flame flow stable, reduce the temperature of particles and inhibit oxidation and decomposition of the particles.

Description

Technical Field

[0001] The invention belongs to the technical field of material surface modification and coating, and in particular relates to a high-speed low-temperature spraying gun with a fuel premixing structure and a system thereof. Background Art

[0002] High-velocity Oxygen-Fuel (HVOF) is an advanced coating technology. As a traditional thermal spraying process, HVOF has the advantages of fast particle speed, dense coating structure, and high deposition efficiency. However, when the spray powder is heated by the high-temperature flame flow, the particles such as titanium alloy are severely oxidized at high temperature, and oxide inclusions are easily generated on the surface of the particles, resulting in a reduced service life of titanium alloy coatings and mechanical properties that need to be improved. At the same time, due to the large heat input during the spraying process of HVOF, the substrate is easily deformed during the spraying of thin-walled substrates, which limits the use of HVOF technology on related materials.

[0003] Existing supersonic flame spray guns usually install a mixing chamber outside the combustion chamber, and inject cooling gas into the mixing chamber to reduce the temperature of the flame flow; or axially send cooling gas to the inlet of the combustion chamber to cool the flame flow. Although these two methods can reduce the spraying temperature to a certain extent, for axial powder delivery, the former particles will overheat in the high-temperature combustion chamber and cannot effectively inhibit the oxidation and decomposition of the particles; while the latter has a narrow adjustment range without affecting combustion, and the temperature control range is limited, and the degree of oxidation inhibition for easily oxidized particles to be sprayed is limited.

[0004] Chinese patent application CN116103601A discloses a high-speed low-temperature spray gun and its system for cooling the flame flow in the combustion chamber. The gun adopts a non-premixing method, and separately introduces compressed air and propane into the combustion chamber to form a form in which the gas is not fully mixed and burned in the inlet section and fully burned in the combustion section, ensuring that the speed and flame flow temperature of the powder to be sprayed are low when it just enters the combustion chamber, so as not to cause excessive temperature rise, inhibiting the oxidation and decomposition of particles, and being able to solve the problem that the existing gun cannot effectively inhibit the oxidation of particles. However, the gun has the problem of unstable combustion when in use, and requires continuous ignition to maintain combustion. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a high-speed low-temperature spray gun and a system thereof with a fuel premixing structure to solve the problem that the existing spray guns cannot maintain stable combustion.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention discloses a high-speed low-temperature spray gun with a fuel premixing structure, characterized in that it includes a powder feeding needle, the outer sleeve of the powder feeding needle is provided with a premixing air distribution unit I and a premixing air distribution unit II, a premixing common porous catalytic ceramic plate is provided in the combustion chamber, the end of the powder feeding needle is penetrated by the premixing common porous catalytic ceramic plate and is connected to the combustion chamber, and a premixing interlayer is provided between the premixing air distribution unit II and the premixing common porous catalytic ceramic plate;

[0008] A gas channel and a powder feeding needle-compressed air channel are provided inside the pre-premixing air distribution unit I, and the powder feeding needle-compressed air channel is arranged outside the powder feeding needle; an air inlet and a gas inlet are provided at the end of the spray gun shell, and a compressed air channel is provided inside, one end of the compressed air channel is connected to the air inlet, and the other end is respectively connected to the powder feeding needle-compressed air channel, the premixing interlayer, the outer wall of the combustion chamber and the outer wall of the nozzle; one end of the gas channel is connected to the gas inlet, and the other end is connected to the premixing interlayer.

[0009] Preferably, a plurality of through holes II for the premixed gas to pass through are provided on the premixed common porous catalytic ceramic plate.

[0010] Further preferably, the thickness of the premixed common porous catalytic ceramic plate is 70% to 95% of the distance from the inlet of the premixed interlayer to the outlet of the premixed common porous catalytic ceramic plate.

[0011] Preferably, the premixed common porous catalytic ceramic plate is a silicon carbide ceramic plate.

[0012] Preferably, a matching nozzle sleeve is connected to the outside of the nozzle.

[0013] Further preferably, the nozzle is a straight-through nozzle or a Laval nozzle, and the corresponding nozzle sleeve is a straight-through nozzle sleeve or a Laval nozzle sleeve.

[0014] Preferably, the end of the powder feeding needle is connected with a powder feeding needle fixing device, and the powder feeding needle and the powder feeding needle fixing device are both fixed to the middle of the rear section of the spray gun housing, and both have powder-cooling gas channels for the powder to be sprayed and the cooling gas to pass through.

[0015] Preferably, the combustion chamber consists of a contraction section, a combustion section and an inlet section. The contraction section is connected to the nozzle, and the inlet section is connected to the premixed common porous catalytic ceramic plate. A cooling gas distribution ring is provided on the side of the combustion section body close to the contraction section, and a cooling gas injection port and an ignition port are provided on the combustion section body on the opposite side of the cooling gas distribution ring.

[0016] Further preferably, the length l1 of the center line of the cooling gas injection port from the contraction section is 1 / 10 to 1 / 5 of the length l2 of the combustion section.

[0017] Preferably, cooling gas flow grooves are provided on the combustion chamber body and inside the cooling gas distribution ring, and a plurality of cooling gas flow inlets are provided on the cooling gas flow grooves. The cooling gas flow inlets, the interior of the combustion chamber and the cooling gas injection port are connected.

[0018] Further preferably, the number of cooling air flow inlets is 2n, n≥4, and the 2n cooling air flow inlets are arranged around the cooling air flow groove with the axial direction of the cooling gas injection port as the symmetry axis; the number of cooling air flow inlets on one side of the cooling gas injection port is n.

[0019] Preferably, the cross-sectional area S1 of the cooling air flow groove is more than 8 times the sum of the cooling air inlet opening areas S2.

[0020] Preferably, the aperture of the i-th hole on the axial side of the cooling gas injection port is the aperture of the first hole next to the axial side of the cooling gas injection port.

[0021] The second aspect of the present invention discloses a system containing the above-mentioned high-speed low-temperature spray gun, including a control module, a gas module, a heating module, a powder delivery module and the above-mentioned high-speed low-temperature spray gun, the control module and the high-speed low-temperature spray gun are respectively connected to the gas module, the heating module and the powder delivery module, and the gas module is respectively connected to the heating module and the powder delivery module.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a high-speed low-temperature spray gun with a fuel premixing structure. 1) Compared with the existing non-premixing spray gun using propane cooling, part of the compressed air of the high-speed low-temperature spray gun enters the powder feeding needle-compressed air channel outside the powder feeding needle, which can cool the powder feeding needle, prevent backfire, avoid burning of the powder feeding needle, and mix with the powder feeding gas to reduce particle oxidation, prevent overheating, and increase the protection of the powder feeding needle to a greater extent. 2) Compared with the existing non-premixing spray gun, another part of the compressed air of the high-speed low-temperature spray gun is secondary diverted at the curved compressed air channel, and part of the compressed air enters the premixing interlayer opened between the premixing air distribution unit II and the premixing common porous catalytic ceramic plate, and is fully premixed with the fuel gas. Through premixing, the premixing common porous catalytic ceramic plate can more fully play a heating role, thereby making the premixing structure spray gun easier to ignite, the gas pressure process window is significantly increased, the flame flow is more continuously and stably output, and a stable Mach cone in the blue flame flow is presented at the spray gun outlet. The remaining compressed air flows out of the spray gun along the combustion chamber and the outer wall of the nozzle, acting as a cooling circuit to suppress overheating of the spray gun. Tests have shown that when using this high-speed low-temperature spray gun for spraying, the temperature is stable at 700-900K during the first ignition and at around 850K during the second ignition. The flame flow is stable and can reduce the particle temperature, effectively suppressing the oxidation and decomposition of particles during the spraying process.

[0024] Furthermore, the premixed common porous catalytic ceramic plate is a silicon carbide ceramic plate, and its thickness h2 is 70%-95% of the distance h1 from the inlet of the premixed interlayer to the outlet of the premixed common porous catalytic ceramic plate, which can ensure that the fuel gas and compressed air are fully premixed in the premixed interlayer to maintain flame stability.

[0025] Furthermore, the high-speed low-temperature spray gun can use two sets of nozzles and nozzle sleeves, namely a straight-through nozzle and a straight-through nozzle sleeve, a Laval nozzle and a Laval nozzle sleeve, to provide different process conditions and meet different spraying requirements.

[0026] Furthermore, a powder feeding needle fixing device added to the end of the powder feeding needle can ensure stable powder feeding.

[0027] Furthermore, a cooling gas distribution ring is provided on one side of the combustion section body close to the contraction section, and a cooling gas injection port is provided on the combustion section body on the opposite side of the cooling gas distribution ring, which can radially deliver the cooling gas into the combustion chamber, so that the particles can be timely cooled at a point where the temperature rises significantly, thereby further suppressing the oxidative decomposition of the powder to be sprayed while maintaining stable combustion.

[0028] Furthermore, the length l1 of the center line of the cooling gas injection port from the contraction section is 1 / 10 to 1 / 5 of the length l2 of the combustion section. The limited distance allows the powder to cool the flame flow in time at the position where the temperature rises most significantly.

[0029] Furthermore, the number of the cooling air inflow holes is at least 8, so that the flame flow can be cooled evenly.

[0030] Furthermore, the cross-sectional area of ​​the cooling air flow groove is more than 8 times the area of ​​the cooling air inlet hole, so that the cooling air flow rate and pressure flowing into each cooling air inlet hole are approximately the same, thereby improving the stability of the flame flow and preventing the powder beam to be sprayed from being blown off and causing adhesion to the combustion chamber.

[0031] Furthermore, by limiting the diameter of the i-th hole in the cooling gas inflow hole close to the cooling gas injection port, it is possible to ensure that the flow rate of each hole is equal.

[0032] The present invention also discloses a system of a high-speed, low-temperature spray gun containing a fuel premixing structure, wherein a heating module is used to heat a gas module, so that the flow rate of the gas is accelerated, thereby ensuring the stability of ignition and combustion; the heating module is used to heat the high-speed, low-temperature spray gun, so that the gas ignition environment is maintained above 80°C, thereby ensuring that the high-speed, low-temperature spray gun has stable ignition performance in the premixed state; during the operation of the high-speed, low-temperature spray gun, the fuel gas is heated to above 60°C, thereby ensuring stable combustion and being able to adjust the spray temperature over a larger range, thereby effectively inhibiting oxidation and decomposition of the powder to be sprayed during the spraying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of a high-speed low-temperature spray gun with a fuel premixing structure provided by the present invention;

[0034] Figure 2 A schematic diagram of a fuel premixing structure provided by the present invention;

[0035] Figure 3 A schematic diagram of the structure of the premixed common porous catalytic ceramic plate provided by the present invention;

[0036] Figure 4 A schematic diagram of the structure of the powder feeding needle provided by the present invention;

[0037] Figure 5 A schematic diagram of the structure of the powder feeding needle fixing device provided by the present invention;

[0038] Figure 6 A schematic diagram of the structure of the combustion chamber provided by the present invention;

[0039] Figure 7 for Figure 6 Sectional view of the AA plane;

[0040] Figure 8 It is a partial enlarged view of the cooling air flow groove;

[0041] Fig. 9 A schematic diagram of the structure of a straight-through nozzle and a straight-through nozzle sleeve, a Laval nozzle and a Laval nozzle sleeve provided by the present invention;

[0042] Fig.10 A schematic structural diagram of a spray system of a high-speed low-temperature spray gun containing a fuel premixing structure provided by the present invention.

[0043] Among them: 1-nozzle sleeve; 2-nozzle; 3-fixing ring; 4-cooling gas distribution ring; 5-combustion chamber; 51-contraction section; 52-combustion section; 53-inlet section; 6-premixing common porous catalytic ceramic plate; 7-1-premixing front air distribution unit I; 7-2-premixing front air distribution unit II; 8-1-spray gun front shell; 8-2-premixing structure spray gun rear shell; 9-1-powder delivery needle; 9-2-powder delivery needle fixing device; 10-cooling gas flow groove; 11-cooling gas flow inlet; 12-cooling gas injection port; 13-ignition port; 14-premixing interlayer. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] The present invention provides a high-speed low-temperature spray gun with a fuel premixing structure, such as Figure 1 As shown, it includes a powder delivery needle 9-1, a fuel premixing structure, a combustion chamber 5 and a nozzle 2. The powder delivery needle 9-1 is inserted into the fuel premixing structure. The fuel premixing structure, the combustion chamber 5 and the nozzle 2 are connected in sequence from powder delivery to spraying direction.

[0047] The fuel premixing structure is used to provide a gas path and premix the incoming compressed air and fuel gas. Figure 2 As shown, from the powder delivery to the spraying direction, the fuel premixing structure includes a premixing air distribution unit I7-1, a premixing air distribution unit II7-2 and a premixing common porous catalytic ceramic plate 6. The premixing air distribution unit I7-1 and the premixing air distribution unit II7-2 are sleeved on the outside of the powder delivery needle 9-1. The powder delivery needle 9-1 coaxially penetrates the premixing air distribution unit I7-1, the premixing air distribution unit II7-2 and the premixing common porous catalytic ceramic plate 6 in sequence, and is connected to the combustion chamber 5. A premixing interlayer 14 is provided between the premixing air distribution unit II7-2 and the premixing common porous catalytic ceramic plate 6, and the premixing interlayer 14 is used to premix compressed air and fuel gas. A fuel gas channel and a powder delivery needle-compressed air channel are provided inside the premixing air distribution unit I7-1. The powder delivery needle-compressed air channel is provided on the periphery of the powder delivery needle 9-1 for cooling the powder delivery needle 9-1. The pre-premix air distribution unit Ⅰ7-1 is externally connected to the premix structure spray gun rear shell 8-2. An air inlet and a gas inlet are provided at the end of the premix structure spray gun rear shell 8-2, and a curved compressed air channel is provided inside. One end of the curved compressed air channel is connected to the air inlet, and the other end is respectively connected to the powder feeding needle-compressed air channel, the premix interlayer 14, the outer wall of the combustion chamber 5 and the outer wall of the nozzle 2, wherein the outer wall of the combustion chamber 5 is connected to the compressed air channel of the outer wall of the nozzle 2. One end of the gas channel is connected to the gas inlet, and the other end is connected to the premix interlayer 14. Figure 3 As shown, the premixed common porous catalytic ceramic plate 6 is connected to the combustion chamber 5, and a through hole I for the powder to be sprayed is provided at the center of the premixed common porous catalytic ceramic plate 6, and a plurality of through holes II for the premixed gas to pass through are provided around the through hole I, and the thickness h2 of the premixed common porous catalytic ceramic plate 6 is 70% to 95% of the distance h1 from the entrance of the premixed interlayer 14 to the exit of the premixed common porous catalytic ceramic plate 6, and this distance can ensure that the fuel gas and the compressed air are fully premixed in the premixed interlayer 14 to maintain flame stability. The premixed common porous catalytic ceramic plate 6 is preferably a silicon carbide ceramic plate.

[0048] The powder delivery needle 9-1 is used to deliver the powder to be sprayed into the combustion chamber 5. Figure 4 and Figure 5 As shown, the end of the powder feeding needle 9-1 is connected with a powder feeding needle fixing device 9-2, and the powder feeding needle fixing device 9-2 can fix the powder feeding needle 9-1 to the middle of the rear shell 8-2 of the premixing structure spray gun. The powder feeding needle 9-1 and the powder feeding needle fixing device 9-2 are both provided with a powder-cooling gas channel for the powder to be sprayed and the cooling gas to pass through. The diameter of the powder-cooling gas channel is 0.2 to 0.6 times the diameter d2 of the gas channel (i.e., the fuel gas channel and the powder feeding needle-compressed air channel), which can increase the speed at which the powder to be sprayed and the cooling gas enter the combustion chamber 5.

[0049] The combustion chamber 5 is used for the complete combustion of the powder to be sprayed. Figure 6 As shown, the combustion chamber 5 is composed of a contraction section 51, a combustion section 52 and an inlet section 53. The contraction section 51 is connected to the nozzle 2, and the inlet section 53 is connected to the premixing common porous catalytic ceramic plate 6. The combustion chamber 5 is externally connected to a spray gun front housing 8-1, and the spray gun front housing 8-1 is connected to a premixing structure spray gun rear housing 8-2. Figure 7 and Figure 8 As shown, a cooling gas distribution ring 4 is provided on one side of the combustion section 52 body close to the contraction section 51, and a cooling gas injection port 12 and an ignition port 13 are provided on the combustion section 52 body on the opposite side of the cooling gas distribution ring 4. The length l1 of the center line of the cooling gas injection port 12 from the contraction section 51 is 1 / 10 to 1 / 5 of the length l2 of the combustion section 52. This distance can ensure that the flame flow is cooled in time at the position where the temperature of the powder to be sprayed rises most significantly. The ignition port 13 is connected to the spark plug. A cooling gas flow groove 10 is provided on the combustion chamber 5 body and inside the cooling gas distribution ring 4. A plurality of cooling gas flow inlets 11 are provided on the cooling gas flow groove 10. The cooling gas flow inlet 11 and the inside of the combustion chamber 5 are connected with the cooling gas injection port 12. Preferably, the total number of cooling gas flow inlets 11 is 2n, n≥4, and the 2n cooling gas flow inlets 11 are all arranged around the cooling gas flow groove 10 with the axial direction where the cooling gas injection port 12 is located as the symmetric axis. The cross-sectional area S1 of the cooling gas flow groove 10 is more than 8 times the sum of the areas S2 of the cooling gas inlet openings 11. This arrangement can ensure that the cooling gas flow rate and pressure flowing into each cooling gas inlet 11 are approximately the same, thereby improving the stability of the flame flow and preventing the powder beam from being blown off and causing adhesion to the combustion chamber 5. The number of cooling gas inlets 11 on one side of the cooling gas injection port 12 is n, where n≥4. The aperture of the i-th hole on the axial side of the cooling gas injection port 12 is the aperture of the first hole next to the axial side of the cooling gas injection port 12. It can ensure that the flow rate of each hole is equal.

[0050] The nozzle 2 is used to control the flow rate and speed of the powder to be sprayed. The nozzle 2 is externally connected to a matching nozzle sleeve 1. Preferably, the nozzle 2 is a straight nozzle or a Laval nozzle, and the corresponding nozzle sleeve 1 is a straight nozzle sleeve or a Laval nozzle sleeve. The design of the two sets of nozzles 2 and nozzle sleeve 1 can provide different process conditions and meet different spraying requirements. Fig. 9 As shown, when conventional spraying process is adopted, straight-through nozzle and straight-through nozzle sleeve can be used together ( Fig. 9 A and B); when spraying materials that require higher powder flight speed, a Laval nozzle and a Laval nozzle sleeve with a contraction and expansion section can be used ( Fig. 9 C and D). The nozzle sleeve 1 is fixed to the front shell 8-1 of the spray gun via a fixing ring 3.

[0051] The working principle of the high-speed low-temperature spray gun with fuel premixing structure is as follows:

[0052] Compressed air is introduced into the air inlet of the rear shell 2 of the premixing structure spray gun, and gas is introduced into the gas inlet. A part of the compressed air enters the powder delivery needle-compressed air channel from the compressed air channel, flows along the outer wall of the powder delivery needle 9-1, and then passes through the premixing common porous catalytic ceramic plate 6 into the combustion chamber 5. In this process, the compressed air flows along the outer wall of the powder delivery needle 9-1, which can prevent backfire and prevent the powder delivery needle 9-1 from being burned during the spraying process. At the same time, it can be mixed with the powder delivery cooling air when entering the combustion chamber 5 to reduce the oxidation of the powder to be sprayed and prevent overheating. Another part of the compressed air enters the premixing front air distribution unit II 7-2 from the compressed air channel for secondary diversion. A part of the compressed air in the premixing front air distribution unit II 7-2 flows out of the spray gun along the outer wall of the combustion chamber 5 and the outer wall of the nozzle 2, which acts as a cooling circuit to suppress overheating of the spray gun, and the other part enters the premixing interlayer 14 to mix with the gas. At the same time, the gas at the gas inlet enters the gas channel in the premixing front air distribution unit I 7-1, flows into the premixing interlayer 14, and mixes with the compressed air. At the same time, the powder to be sprayed and cooling gas are introduced into the powder feeding inlet, and the cooling gas feeds the powder to be sprayed into the combustion chamber 5 through the powder feeding needle 9-1 and the powder feeding fixture 9-2.

[0053] Before the sprayed powder, cooling gas, mixed fuel gas and compressed air enter the combustion chamber 5, a spark plug is connected through the ignition port 13 for ignition to heat the premixed common porous catalytic ceramic plate 6, and the premixed common porous catalytic ceramic plate 6 is heated to the gas ignition temperature.

[0054] After the fuel gas and compressed air are fully premixed in the premixing interlayer 14, they are preheated by the premixing common porous catalytic ceramic plate 6, and then enter the combustion chamber 5 to be ignited and continuously heat the powder to be sprayed, so that the powder to be sprayed reaches a semi-molten state. At the same time, cooling gas is injected into the cooling gas injection port 12, and the cooling gas enters the combustion chamber 5 through the cooling gas inlet 11 for cooling. Through the continuous input of fuel gas, compressed air and cooling gas, the semi-molten powder particles are sprayed out from the nozzle 2 while being heated to achieve spraying.

[0055] The present invention provides a system comprising the high-speed low-temperature spray gun, such as Fig.10 As shown, it includes a control module, a gas module, a heating module, a powder feeding module and the aforementioned high-speed low-temperature spray gun.

[0056] The control cabinet module is used to control the pressure of the gas, the flow rate of the powder to be sprayed and the position of the high-speed low-temperature spraying gun. The control cabinet module includes a control cabinet and a mechanical arm connected by pipelines, and the control cabinet can control the position of the high-speed low-temperature spraying gun through the mechanical arm.

[0057] The gas module is used to deliver compressed air, cooling gas and fuel gas to the high-speed low-temperature spray gun. The gas module includes fuel gas, cooling gas and compressed air. The compressed air, cooling gas and fuel gas are respectively connected to the control cabinet module and the high-speed low-temperature spray gun through pipelines, and compressed air, cooling gas or fuel gas is delivered to the high-speed low-temperature spray gun under the control of the control cabinet module. The cooling gas is connected to the powder delivery module through a pipeline, and the cooling gas is input to the powder delivery module under the control of the control cabinet module.

[0058] The heating module is used to preheat the high-speed low-temperature spray gun before ignition. The heating module includes a gas heater, which is respectively connected to the control cabinet module, the gas module and the high-speed low-temperature spray gun through pipelines.

[0059] The powder feeding module is used to feed the powder to be sprayed to the high-speed low-temperature spray gun. The powder feeding module includes a powder feeder. The powder feeder is respectively connected to the control cabinet module, the gas module and the high-speed low-temperature spray gun through pipelines.

[0060] The working principle of the above system including the high-speed low-temperature spray gun is as follows:

[0061] Under the parameter control of the control cabinet, compressed air, cooling gas and fuel gas are respectively input into the air inlet, cooling gas injection port 12 and fuel gas inlet of the high-speed low-temperature spray gun, the cooling gas and the powder to be sprayed in the powder feeder are fed into the powder feeding inlet of the high-speed low-temperature spray gun, the fuel gas is heated by the fuel gas heater, the position of the high-speed low-temperature spray gun is adjusted by the movement of the robotic arm, and it impacts the surface of the substrate to form a coating.

[0062] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0063] Example 1

[0064] A high-speed low-temperature spray gun with a fuel premixing structure comprises a powder feeding needle 9-1, a fuel premixing structure, a combustion chamber 5 and a Laval nozzle, wherein the Laval nozzle is externally connected to a Laval nozzle sleeve.

[0065] The fuel premixing structure includes a premixing air distribution unit Ⅰ7-1, a premixing air distribution unit Ⅱ7-2 and a silicon carbide ceramic plate from the powder delivery to the spraying direction. The premixing air distribution unit Ⅰ7-1 and the premixing air distribution unit Ⅱ7-2 are sleeved on the outside of the powder delivery needle 9-1 made of 304 stainless steel. The powder delivery needle 9-1 coaxially penetrates the premixing air distribution unit Ⅰ7-1, the premixing air distribution unit Ⅱ7-2 and the silicon carbide ceramic plate in sequence and is connected to the combustion chamber 5. The premixing air distribution unit Ⅰ7-1 and the premixing air distribution unit Ⅱ7-2 are both made of aluminum alloy 6061 material, and a premixing interlayer 14 is provided between the premixing air distribution unit Ⅱ7-2 and the silicon carbide ceramic plate. The premixing air distribution unit Ⅰ7-1 is provided with a propane channel and a powder delivery needle-compressed air channel inside, and is externally connected to the rear shell 8-2 of the premixing structure spray gun made of aluminum alloy 6061 material. The rear shell 8-2 of the premixed structure spray gun is provided with an air inlet and a propane inlet at the end, and a curved compressed air channel is provided inside. One end of the compressed air channel is connected to the air inlet, and the other end is respectively connected to the powder delivery needle-compressed air channel, the premixed interlayer 14, the outer wall of the combustion chamber 5 and the outer wall of the nozzle 2. One end of the propane channel is connected to the propane inlet, and the other end is connected to the premixed interlayer 14. The silicon carbide ceramic plate is connected to the combustion chamber 5, and a through hole I is provided at the center of the silicon carbide ceramic plate for the powder to be sprayed to pass through, and a number of through holes II are provided around the through hole I. The thickness h2 of the silicon carbide ceramic plate is 8.5 mm, and the distance h1 at the outlet is 10 mm.

[0066] The end of the powder feeding needle 9-1 is connected to the powder feeding needle fixing device 9-2. Both the powder feeding needle 9-1 and the powder feeding needle fixing device 9-2 are provided with powder-nitrogen channels. The diameter of the powder-nitrogen channel is 4 mm, and the diameters of the propane channel and the powder feeding needle-compressed air channel are both 7 mm.

[0067] The combustion chamber 5 made of 304 stainless steel material consists of a contraction section 51, a combustion section 52 and an inlet section 53. The contraction section 51 is connected to the nozzle 2, and the inlet section 53 is connected to the silicon carbide ceramic plate. The combustion chamber 5 is externally connected to a spray gun front shell 8-1 made of aluminum alloy 6061 material. The spray gun front shell 8-1 is connected to the premixing structure spray gun rear shell 8-2. The spray gun front shell 8-1 is fixed to the Laval nozzle sleeve by a fixing ring 3. A cooling nitrogen distribution ring is provided on the side of the combustion section 52 body close to the contraction section 51, and a cooling nitrogen injection port and an ignition port 13 are provided on the combustion section 52 body on the opposite side of the cooling nitrogen distribution ring. The length l1 of the cooling nitrogen injection port from the center line of the contraction section 51 is 4 mm, and the length of the combustion section 52 is 36 mm. The ignition port 13 is connected to the spark plug. The combustion chamber 5 body and the cooling nitrogen distribution ring are both provided with cooling nitrogen flow grooves. The cooling nitrogen flow grooves are symmetrically arranged along the axis of the cooling nitrogen injection port. There are 8 cooling nitrogen flow inlets around the circle. The cooling nitrogen flow inlets, the combustion chamber 5 and the cooling nitrogen injection port are connected. The cross-sectional area of ​​the cooling nitrogen flow groove is 36mm 2 The number of cooling nitrogen gas inlets on one side of the cooling nitrogen gas injection port is 6, and the apertures of the cooling nitrogen gas inlets are 1 mm, 1.03 mm, 1.07 mm, 1.12 mm, 1.19 mm and 1.24 mm, respectively.

[0068] The high-speed low-temperature spray gun comprises two sets of nozzles 2 and nozzle sleeves 1, namely a straight nozzle and a straight nozzle sleeve, a Laval nozzle and a Laval nozzle sleeve. The nozzle sleeve 1 is fixed to the front shell 8-1 of the spray gun by a fixing ring 3.

[0069] A system including the above-mentioned high-speed low-temperature spray gun includes a control cabinet, a mechanical arm, compressed air, cooling nitrogen, liquefied propane, a propane heater, a powder feeder and a high-speed low-temperature spray gun. The mechanical arm, compressed air, cooling nitrogen, liquefied propane, a propane heater, and a powder feeder are respectively connected to the control cabinet and the high-speed low-temperature spray gun. The cooling nitrogen is connected to the powder feeder. Each gas channel in the control cabinet is connected to a solenoid valve and a proportional valve to adjust the gas pressure parameters, and the circuit is connected to connect the high-voltage package and the spark plug for ignition. At the same time, a gas detection system is installed inside the control cabinet. The control cabinet inputs compressed air into the air inlet of the high-speed low-temperature spray gun through parameter control, inputs cooling nitrogen into the nitrogen inlet, heats the liquefied propane through the propane heater, and the temperature of the vaporized propane after heating is about 40°C, and then inputs propane into the propane inlet, and the cooling nitrogen and the powder to be sprayed in the powder feeder are sent to the powder feeding inlet of the high-speed low-temperature spray gun, and the position of the high-speed low-temperature spray gun is adjusted by the movement of the mechanical arm to hit the surface of the substrate to form a coating.

[0070] The system including the high-speed low-temperature spray gun was used to conduct the test:

[0071] 1. When the cooling nitrogen is not injected and the gun is only ignited without powder delivery, the temperature at the outlet of the Laval nozzle gun at 50mm is measured to be 1381.2℃, and the temperature at the outlet of the high-speed low-temperature spray gun at 93.5mm is measured to be 1100℃, and the high-speed low-temperature flame can burn stably and continuously.

[0072] 2. Without injecting cooling nitrogen, the system including the high-speed low-temperature spray gun was used to conduct the test, and the TC4 powder with a particle size of 15-53 μm was used to conduct the deposition test on the TC4 substrate. The parameters were propane pressure 0.448 MPa, compressed air 0.489 MPa, powder feeding gas flow 25 L / min, spraying distance 200 mm, spray gun moving speed 800 mm / s, coating thickness 200 μm, propane heater preheating temperature 38 ° C. The average porosity of the coating was measured to be 1.218%, the average hardness of the coating was 247.13 HV, and the bonding strength was 50.65 MPa.

[0073] Example 2

[0074] A high-speed low-temperature spray gun with a fuel premixing structure comprises a powder feeding needle 9-1, a fuel premixing structure, a combustion chamber 5 and a straight-through nozzle, wherein the straight-through nozzle is externally connected to a straight-through nozzle sleeve.

[0075] The fuel premixing structure includes a premixing air distribution unit Ⅰ7-1, a premixing air distribution unit Ⅱ7-2 and a silicon carbide ceramic plate from the powder delivery to the spraying direction. The premixing air distribution unit Ⅰ7-1 and the premixing air distribution unit Ⅱ7-2 are sleeved on the outside of the powder delivery needle 9-1 made of 304 stainless steel. The powder delivery needle 9-1 coaxially penetrates the premixing air distribution unit Ⅰ7-1, the premixing air distribution unit Ⅱ7-2 and the silicon carbide ceramic plate in sequence and is connected to the combustion chamber 5. The premixing air distribution unit Ⅰ7-1 and the premixing air distribution unit Ⅱ7-2 are both made of aluminum alloy 6061 material, and a premixing interlayer 14 is provided between the premixing air distribution unit Ⅱ7-2 and the silicon carbide ceramic plate. The premixing air distribution unit Ⅰ7-1 is provided with a propane channel and a powder delivery needle-compressed air channel inside, and is externally connected to the rear shell 8-2 of the premixing structure spray gun made of aluminum alloy 6061 material. The rear shell 8-2 of the premixed structure spray gun is provided with an air inlet and a propane inlet at the end, and a curved compressed air channel is provided inside. One end of the compressed air channel is connected to the air inlet, and the other end is respectively connected to the powder delivery needle-compressed air channel, the premixed interlayer 14, the outer wall of the combustion chamber 5 and the outer wall of the nozzle 2. One end of the propane channel is connected to the propane inlet, and the other end is connected to the premixed interlayer 14. The silicon carbide ceramic plate is connected to the combustion chamber 5, and a through hole I is provided at the center of the silicon carbide ceramic plate for the powder to be sprayed to pass through, and a number of through holes II are provided around the through hole I. The thickness h2 of the silicon carbide ceramic plate is 9 mm, and the distance h1 at the outlet is 10 mm.

[0076] The end of the powder feeding needle 9-1 is connected to the powder feeding needle fixing device 9-2. Powder-nitrogen channels are provided inside the powder feeding needle 9-1 and the powder feeding needle fixing device 9-2. The diameter of the powder-nitrogen channel is 4 mm, and the diameters of the propane channel and the powder feeding needle-compressed air channel are both 10 mm.

[0077] The combustion chamber 5 made of 304 stainless steel material consists of a contraction section 51, a combustion section 52 and an inlet section 53. The contraction section 51 is connected to the nozzle 2, and the inlet section 53 is connected to the silicon carbide ceramic plate. The combustion chamber 5 is externally connected to a spray gun front shell 8-1 made of aluminum alloy 6061 material. The spray gun front shell 8-1 is connected to the premixing structure spray gun rear shell 8-2. The spray gun front shell 8-1 is fixed to the straight nozzle sleeve by a fixing ring 3. A cooling nitrogen distribution ring is provided on the side of the combustion section 52 body close to the contraction section 51, and a cooling nitrogen injection port and an ignition port 13 are provided on the combustion section 52 body on the opposite side of the cooling nitrogen distribution ring. The length of the cooling nitrogen injection port center line from the contraction section 51 is 6 mm, and the length of the combustion section 52 is 36 mm. The ignition port 13 is connected to the spark plug. The combustion chamber 5 body and the cooling nitrogen distribution ring are both provided with cooling nitrogen flow grooves. The cooling nitrogen flow grooves are symmetrical with the axial direction of the cooling nitrogen injection port. There are 10 cooling nitrogen flow inlets around the circle. The cooling nitrogen flow inlets, the combustion chamber 5 and the cooling nitrogen injection port are connected. The cross-sectional area of ​​the cooling nitrogen flow groove is 36mm 2 The number of cooling nitrogen gas inlets on one side of the cooling nitrogen gas injection port is 5, and the apertures of the cooling nitrogen gas inlets are 1 mm, 1.03 mm, 1.07 mm, 1.12 mm and 1.19 mm, respectively.

[0078] The high-speed low-temperature spray gun comprises two sets of nozzles 2 and nozzle sleeves 1, namely a straight nozzle and a straight nozzle sleeve, a Laval nozzle and a Laval nozzle sleeve. The nozzle sleeve 1 is fixed to the front shell 8-1 of the spray gun by a fixing ring 3.

[0079] A system including the above-mentioned high-speed low-temperature spray gun includes a control cabinet, a mechanical arm, compressed air, cooling nitrogen, liquefied propane, a propane heater, a powder feeder and a high-speed low-temperature spray gun. The mechanical arm, compressed air, cooling nitrogen, liquefied propane, a propane heater, and a powder feeder are respectively connected to the control cabinet and the high-speed low-temperature spray gun. The cooling nitrogen is connected to the powder feeder. Each gas channel in the control cabinet is connected to a solenoid valve and a proportional valve to adjust the gas pressure parameters, and the circuit is connected to connect the high-voltage package and the spark plug for ignition. At the same time, a gas detection system is installed inside the control cabinet. The control cabinet inputs compressed air into the air inlet of the high-speed low-temperature spray gun through parameter control, inputs cooling nitrogen into the nitrogen inlet, heats the liquefied propane through the propane heater, and the temperature of the vaporized propane after heating is about 40°C, and then inputs propane into the propane inlet, and the cooling nitrogen and the powder to be sprayed in the powder feeder are sent to the powder feeding inlet of the high-speed low-temperature spray gun, and the position of the high-speed low-temperature spray gun is adjusted by the movement of the mechanical arm to hit the surface of the substrate to form a coating.

[0080] The system including the high-speed low-temperature spray gun was used to conduct the test:

[0081] 1. When the cooling nitrogen is not injected and the gun is only ignited without powder delivery, the temperature at 80mm from the outlet of the straight-through nozzle gun is measured to be 1350.5℃, and the high-speed and low-temperature flame can burn continuously and stably.

[0082] 2. Without injecting cooling nitrogen, the system including the high-speed low-temperature spray gun was used to test the deposition of nickel-based 718 powder with a particle size of 15-45 μm on the TC4 substrate. The parameters were propane pressure 0.462 MPa, compressed air 0.496 MPa, cooling nitrogen 0.300 MPa, powder feeding gas flow 25 L / min, spraying distance 170 mm, spray gun moving speed 800 mm / s, coating thickness 200 μm, propane heater preheating temperature 37.5 ° C. The average porosity of the coating was measured to be 1.349%, and the average hardness of the coating was 453.8 HV.

[0083] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A high-speed low-temperature spray gun with a fuel premixing structure, characterized in that: The invention comprises a powder delivery needle (9-1), the powder delivery needle (9-1) is provided with a pre-premixing air distribution unit I (7-1) and a pre-premixing air distribution unit II (7-2) on its outer sleeve, a pre-premixing common porous catalytic ceramic plate (6) is provided in a combustion chamber (5), the end of the powder delivery needle (9-1) penetrates the pre-premixing common porous catalytic ceramic plate (6) and is connected to the combustion chamber (5), and a pre-premixing interlayer (14) is provided between the pre-premixing air distribution unit II (7-2) and the pre-premixing common porous catalytic ceramic plate (6); A gas channel and a powder delivery needle-compressed air channel are provided inside the pre-premixing air distribution unit I (7-1), and the powder delivery needle-compressed air channel is arranged outside the powder delivery needle (9-1); an air inlet and a gas inlet are provided at the end of the spray gun shell, and a compressed air channel is provided inside, one end of the compressed air channel is connected to the air inlet, and the other end is respectively connected to the powder delivery needle-compressed air channel, the premixing interlayer (14), the outer wall of the combustion chamber (5) and the outer wall of the nozzle (2); one end of the gas channel is connected to the gas inlet, and the other end is connected to the premixing interlayer (14).

2. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 1, characterized in that: The premixed common porous catalytic ceramic plate (6) is provided with a plurality of through holes II for the premixed gas to pass through.

3. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 2, characterized in that: The thickness of the premixed common porous catalytic ceramic plate (6) is 70% to 95% of the distance from the inlet of the premixed interlayer (14) to the outlet of the premixed common porous catalytic ceramic plate (6).

4. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 1, characterized in that: The nozzle (2) is externally connected to a matching nozzle sleeve (1).

5. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 4, characterized in that: The nozzle (2) is a straight nozzle or a Laval nozzle, and the corresponding nozzle sleeve (1) is a straight nozzle sleeve or a Laval nozzle sleeve.

6. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 1, characterized in that: The end of the powder feeding needle (9-1) is connected to a powder feeding needle fixing device (9-2). The powder feeding needle (9-1) and the powder feeding needle fixing device (9-2) are both fixed to the middle of the rear section of the spray gun housing, and both have a powder-cooling gas channel for the powder to be sprayed and the cooling gas to pass through.

7. A high-speed low-temperature spray gun with a fuel premixing structure according to any one of claims 1 to 6, characterized in that: The combustion chamber (5) is composed of a contraction section (51), a combustion section (52) and an inlet section (53); the contraction section (51) is connected to the nozzle (2); the inlet section (53) is connected to the premixed common porous catalytic ceramic plate (6); a cooling gas distribution ring (4) is provided on the combustion section (52) body on the side close to the contraction section (51); a cooling gas injection port (12) and an ignition port (13) are provided on the combustion section (52) body on the opposite side of the cooling gas distribution ring (4).

8. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 7, characterized in that: The length l1 of the center line of the cooling gas injection port (12) from the contraction section (51) is 1 / 10 to 1 / 5 of the length l2 of the combustion section (52).

9. A high-speed low-temperature spray gun with a fuel premixing structure according to claim 7, characterized in that: A cooling gas flow groove (10) is provided on the combustion chamber (5) body and inside the cooling gas distribution ring (4), and a plurality of cooling gas flow inlets (11) are provided on the cooling gas flow groove (10). The cooling gas flow inlets (11), the interior of the combustion chamber (5) and the cooling gas injection port (12) are connected.

10. A system comprising the high-speed low-temperature spray gun according to any one of claims 1 to 9, characterized in that: It comprises a control module, a gas module, a heating module, a powder delivery module and a high-speed low-temperature spray gun as described in any one of claims 1 to 9, wherein the control module and the high-speed low-temperature spray gun are respectively connected to the gas module, the heating module and the powder delivery module, and the gas module is respectively connected to the heating module and the powder delivery module.

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