Alloy powder spraying system and zinc-aluminum-magnesium coating process based on alloy powder spraying system

Abstract

The invention belongs to the technical field of hot dip coating, and relates to an alloyed powder spraying system and a zinc-aluminum-magnesium coating process based on the alloyed powder spraying system.The alloyed powder spraying system comprises the following steps that 1, alloyed powder is dried for standby application, when the alloyed powder is prepared, high-magnesium-content zinc-aluminum-magnesium alloy is molten in a zinc-aluminum-magnesium pot to form hot dip molten liquid, and the hot dip molten liquid is cooled to the room temperature; the hot-dip coating is waited for use during hot-dip coating; 2, the strip steel is fed into a zinc-aluminum-magnesium pot to be subjected to hot dipping, so that a high-magnesium-content zinc-aluminum-magnesium coating is formed on the surface of the strip steel, and air knife treatment is conducted; and 3, the standby alloy powder in the step 1 is adopted as a cooling agent, alloy powder spraying is conducted on the surfaces of the two sides of the strip steel subjected to hot dipping at the same time through an alloy powder spraying system, a high-magnesium-content zinc-aluminum-magnesium coating is cooled and serves as a nucleation for solidification of a zinc-aluminum-magnesium coating alloy, and the high-magnesium-content zinc-aluminum-magnesium coating alloy is obtained. And cooling control over the solidification process of the high-magnesium-content zinc-aluminum-magnesium coating is achieved by adjusting parameters of the alloy powder.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-dip coating and relates to an alloy powder spraying system and a zinc-aluminum-magnesium coating process based on the alloy powder spraying system. Background Art

[0002] Because zinc-aluminum-magnesium coating products have excellent corrosion resistance and fracture protection functions, zinc-aluminum-magnesium coating products have gradually been widely used in recent years. With the increase in the application of zinc-aluminum-magnesium related products, the requirements for their corrosion resistance and fracture protection functions have become higher, and the demand for new zinc-aluminum-magnesium products has become more urgent, that is, the demand for 19 aluminum 6 magnesium zinc-aluminum-magnesium products has gradually increased. In general, although the existing zinc-aluminum-magnesium products have corrosion resistance and fracture protection functions, their corrosion resistance still needs to be improved, and they are increasingly unable to meet the increasing requirements. At the same time, the fracture protection capacity of thick plates is insufficient, and local corrosion problems often occur during the use of thick plates, which cannot achieve the original intention of using zinc-aluminum-magnesium coating products.

[0003] In the production process of zinc-aluminum-magnesium products, controlling the solidification process of zinc-aluminum-magnesium coating products is a very important part of the process. Controlling the solidification process means controlling the cooling method. There are many cooling methods, and air cooling is the main one. Mist cooling is used in some scenarios, but air cooling has an upper limit on cooling intensity. In some scenarios such as thick strip cooling, air cooling cannot meet the cooling intensity requirements. Mist cooling causes oxidation problems due to the presence of water, especially in the production of zinc-aluminum-magnesium products with high magnesium content such as 19 aluminum 6 magnesium, which is more likely to cause oxidation problems.

[0004] In addition, if the existing process for producing zinc-aluminum-magnesium products of 11 aluminum-3 magnesium or 6 aluminum-3 magnesium is directly adopted, that is, 19 aluminum-6 magnesium zinc-aluminum-magnesium coated products are directly produced on existing equipment, it may have surface quality problems such as black spots, segregation and oxidation. Studies have shown that the coating solidification stage of the production of 19 aluminum-6 magnesium zinc-aluminum-magnesium coated products needs to be reasonably segmented to reasonably control the coating composition and grain size, and the reasonable segmented control of the coating solidification stage of the 19 aluminum-6 magnesium zinc-aluminum-magnesium coated products requires that its post-plating cooling device has the ability to flexibly adjust the cooling intensity. In response to these technical difficulties, the present invention proposes a zinc-aluminum-magnesium coating process and an alloy powder spraying system based on an alloy powder spraying system. Summary of the invention

[0005] In view of this, an object of the present invention is to provide an alloy powder spraying system and a zinc-aluminum-magnesium coating process based on the alloy powder spraying system to solve the technical problems raised in the background technology.

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

[0007] An alloy powder spraying system, comprising a uniform device for spraying alloy powder on a steel strip, the uniform device comprising an air cavity for passing through the steel strip and uniform powder spraying wind boxes symmetrically arranged on both sides of the steel strip and connected to the air cavity;

[0008] The uniform powder spraying bellows comprises a bellows body, wherein the bellows body has a partition plate 2 which divides the bellows body into a plurality of sub-bellows units in a vertical direction;

[0009] The sub-bellows units at the lowest end and the middle part are provided with multi-layer uniform tubes arranged parallel to the steel strip to transport alloy powder to the corresponding sub-bellows units, and partitions one and three are arranged oppositely and connected to the inner wall of the sub-bellows unit on the outer side to divide the corresponding sub-bellows unit into upper and lower parts in the vertical direction, and the sub-bellows units at the lowest end and the middle part are provided with a bellows outlet connected to the wind cavity on the side close to the steel strip, and a re-uniform air inlet is provided on the side away from the steel strip, and the sub-bellows units in the middle part are also provided with an alloy powder return air inlet connected to the wind cavity on the side close to the steel strip, and an alloy powder outlet is also provided on the side away from the steel strip, and the bellows outlet, the re-uniform air inlet and the outlet of the multi-layer uniform tube are all arranged in the upper part, and the alloy powder return air inlet and the alloy powder outlet are both arranged in the lower part;

[0010] An alloy powder return air port connected to the air cavity is provided on the side of the sub-wind box unit located at the uppermost end close to the steel strip, and an alloy powder outlet is provided on the side away from the steel strip.

[0011] Furthermore, a re-air uniformity porous plate is provided in the upper part, with two ends respectively connected to the inner wall of the sub-wind box unit and the multi-layer uniform tube, and the re-air uniformity porous plate is arranged above the outlet of the multi-layer uniform tube.

[0012] Furthermore, the multi-layer uniform tube includes a first-layer uniform tube, a second-layer uniform tube and a third-layer uniform tube arranged in sequence from the inside to the outside, both ends of the second-layer uniform tube and the third-layer uniform tube are closed, one end of the first-layer uniform tube is closed, and the other end is connected to the alloy powder conveying branch pipe;

[0013] A first distribution port is provided on the outer side of the first layer of equal distribution pipe, a second distribution port is provided on the outer side of the second layer of equal distribution pipe, and a third distribution port is provided on the outer side of the third layer of equal distribution pipe, and the first distribution port and the second distribution port are staggered by 40-60° on the circumference, the second distribution port and the third distribution port are staggered by 40-60° on the circumference, and the third distribution port is arranged at the upper part of the sub-bellows unit to connect to the wind cavity through the bellows outlet.

[0014] Furthermore, the first distribution port, the second distribution port and the third distribution port are provided in plurality and arranged along the width direction of the steel strip, and the wind box outlet and the alloy powder return air port are both long strip air ports arranged along the width direction of the steel strip.

[0015] Furthermore, each alloy powder conveying branch pipe connected to the multi-layer uniform pipe is connected to an alloy powder conveying branch pipe arranged along the vertical direction of the wind box body, and the alloy powder conveying branch pipe is connected to the alloy powder conveying inlet pipe.

[0016] Furthermore, the alloy powder spraying system also includes an alloy powder storage tank, an alloy powder conveying device, a recycling device and a connecting device 1. The alloy powder storage tank, the alloy powder conveying device, the recycling device, the connecting device 1 and the alloy powder conveying inlet pipe are connected in sequence to convey the alloy powder in the alloy powder storage tank to the multi-layer uniform tube, and the alloy powder is sprayed on both sides of the strip through the bellows outlet.

[0017] Furthermore, the alloy powder spraying system further comprises a recirculating negative pressure device 1, a connecting device 2, a drying and cooling device, a recirculating negative pressure device 2, a connecting device 3, a filtering device, an alloy powder recovery device and an alloy powder processing device;

[0018] The alloy powder outlet in the alloy powder spraying system is connected to the connection device 2 and the connection device 3 respectively, and the connection device 2, the recycling negative pressure device 1, the drying and cooling device and the recycling device are connected in sequence to directly recycle the alloy powder-containing mixed fluid in the wind chamber through drying and cooling, and the connection device 3, the recycling negative pressure device 2, the filtering device and the drying and cooling device are connected in sequence, and the filtering device is also connected with the alloy powder recovery device, the alloy powder processing device and the alloy powder storage tank in sequence, so that the alloy powder-containing mixed fluid is filtered and dried and cooled through the filtering device for recycling, and the large-particle alloy powder obtained after filtration is processed by the alloy powder recovery device and the alloy powder processing device and then sent to the alloy powder storage tank for storage.

[0019] Furthermore, the alloy powder-containing mixed fluid in the alloy powder spraying system is recycled by the first recycling negative pressure device at a ratio of 70-100%, and recycled by the second recycling negative pressure device at a ratio of 0-30%.

[0020] Furthermore, two uniform powder spraying bellows arranged on both sides of the steel strip are staggered from each other in the vertical direction.

[0021] A zinc-aluminum-magnesium coating process based on an alloy powder spraying system comprises the following steps:

[0022] Step 1. Dry the alloy powder for later use. While preparing the alloy powder, melt the high-magnesium zinc-aluminum-magnesium alloy in a zinc-aluminum-magnesium pot to form a hot-dip plating melt to be used when hot-dip plating is in progress;

[0023] Step 2. feeding the steel strip into a zinc-aluminum-magnesium pot for hot-dip plating to form a high-magnesium zinc-aluminum-magnesium coating on the surface of the steel strip, and performing an air knife treatment on the high-magnesium zinc-aluminum-magnesium coating;

[0024] Step 3. Use the alloy powder reserved in step 1 as a coolant, and use the alloy powder spraying system to simultaneously spray the alloy powder on both sides of the strip after hot dip coating, so as to cool the high-magnesium-containing zinc-aluminum-magnesium coating and serve as a nucleus for the solidification of the zinc-aluminum-magnesium coating alloy.

[0025] Furthermore, the composition of the alloy powder is preferably the same as that of the high-magnesium-content zinc-aluminum-magnesium alloy powder in the zinc-aluminum-magnesium pot.

[0026] Furthermore, the method also includes step 4: sequentially air cooling, water cooling, skin pass and straightening the strip steel coated with alloy powder, and rolling it into a high magnesium-zinc-aluminum-magnesium content product.

[0027] Furthermore, the high magnesium-zinc-aluminum-magnesium alloy is preferably 19 aluminum 6 magnesium zinc aluminum magnesium.

[0028] Furthermore, the alloy powder has a particle size of 5-20 μm, and the moisture content is controlled below 0.1 wt % after drying.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention uses an alloy powder spraying system for the production of zinc-aluminum-magnesium coatings to solve the requirement of high-strength and flexibly adjustable cooling intensity in the production of high-magnesium zinc-aluminum-magnesium coating products such as 19 aluminum 6 magnesium, that is, the alloy powder is used as a coolant to greatly enhance the cooling intensity, and the cooling rate can be increased to 200°C / s, which is much higher than the existing air cooling intensity. The cooling intensity can also be flexibly adjusted by adjusting the alloy powder spraying parameters. The high-strength cooling effectively solves the problems of oxidation and local segregation, and improves the uniformity and quality of the coating. Secondly, the present invention solves the problems of black spots, segregation and oxidation in the production process of high-magnesium zinc-aluminum-magnesium coating products such as 19 aluminum 6 magnesium, that is, the alloy powder acts as a coating solidification nucleus, greatly increasing the nucleation density, thereby greatly improving the surface density and smoothness, effectively solving the surface quality problems such as black spots and segregation in the production process of high-magnesium zinc-aluminum-magnesium products.

[0031] 2. The present invention designs an alloy powder spraying system for high-Mg-Zn-Al-Mg coatings, realizes temperature and moisture control through a drying and cooling device, greatly reduces temperature accumulation and alloy powder agglomeration, realizes alloy powder recycling and recovery through reasonable proportion control of two recycling negative pressure absorption devices, and realizes alloy powder replenishment by conveying alloy powder through an alloy powder conveying device;

[0032] Secondly, the present invention provides a specific structure of a uniform powder spraying bellows, which uses a main pipe, a branch pipe to a branch pipe to distribute alloy powder particles to preliminarily achieve uniform distribution of airflow containing alloy powder, and divides the bellows into multiple sub-bellows units internally, thereby transforming the problem of solving a large space airflow distribution problem into solving a single outlet small space airflow distribution problem. The small area can ensure more uniform mixing, and it is easy to achieve standardized amplification; the uniformity of distribution of the airflow containing alloy powder along the width of the strip is improved by arranging multiple layers of uniform pipes in a staggered manner, thereby improving the uniformity of powder spraying of the uniform powder spraying bellows; and the problem of alloy powder redistribution is achieved by re-uniform wind and re-mixing, thereby further improving the uniformity of alloy powder distribution;

[0033] The present invention adopts a structure in which multiple pairs of alloy powder spraying outlets (bellows outlets) and alloy powder return air outlets are arranged in pairs to realize a multi-layer vortex structure flow field and form an air cushion. At the same time, the bellows for uniform powder spraying on both sides of the steel strip are slightly staggered to avoid the influence between multiple alloy powder-containing fluid inlets and outlets, making it easier to stabilize the steel strip and achieve uniform and stable airflow.

[0034] 3. The present invention mainly adjusts the quality of the alloy powder and supplements it with the gas intensity to achieve adjustable cooling intensity, thereby improving the cooling adaptability of products with different thicknesses such as 19 aluminum 6 magnesium and high magnesium-zinc aluminum-magnesium coatings, and achieving an adjustable and controllable cooling speed of 50-200℃ / s to meet diversified production needs.

[0035] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0037] Figure 1 It is a process flow chart of a zinc-aluminum-magnesium coating process based on an alloy powder spraying system in an embodiment;

[0038] Figure 2 This is a structural schematic diagram of an alloy powder spraying system in an embodiment;

[0039] Figure 3 It is a structural schematic diagram of a uniform device in an embodiment;

[0040] Figure 4 It is a structural schematic diagram of a uniform powder spraying bellows in the embodiment;

[0041] Figure 5 It is a side view of the uniform powder spraying bellows in the embodiment;

[0042] Figure 6 It is a schematic structural diagram of the upper bellows outlet and the alloy powder return air outlet of the sub-bellows unit located in the middle part in the embodiment;

[0043] Figure 7 Schematic diagram of the structure of a multi-layer uniform tube in an embodiment;

[0044] Figure 8 Schematic diagram of the flow field of the uniform powder spraying bellows in the embodiment.

[0045] Figure markings: 1-multi-layer uniform tube, 2-bellows outlet, 3-partition one, 4-alloy powder return air outlet, 5-partition two, 6-re-air uniform porous plate, 7-bellows body, 8-re-air uniform inlet, 9-alloy powder outlet, 10-partition three, 11-alloy powder conveying branch pipe, 12-alloy powder conveying branch pipe, 13-alloy powder conveying inlet pipe, 14-wind chamber, 1-1-first layer uniform distribution pipe, 1-2-second layer uniform distribution pipe, 1-3-third layer uniform distribution pipe, 1-1-1-first distribution port, 1-2-1-second distribution port, 1-3-1-third distribution port. DETAILED DESCRIPTION

[0046] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0047] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0048] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0049] See also Figure 1 , which is a zinc-aluminum-magnesium coating process based on an alloy powder spraying system, specifically comprising the following steps:

[0050] Step 1. Preparation:

[0051] First, alloy powder with a particle size in the range of 5-25 μm is selected. The composition of the alloy powder is preferably the same as the zinc-aluminum-magnesium alloy melted in the zinc-aluminum-magnesium pot. The alloy powder is dried to remove moisture from the alloy powder to obtain alloy powder that meets the moisture requirements. The dried alloy powder is placed in an alloy powder storage tank and waits for use.

[0052] While preparing the alloy powder, melt the zinc-aluminum-magnesium alloy corresponding to the high-magnesium zinc-aluminum-magnesium coating product such as 19 aluminum 6 magnesium in the zinc-aluminum-magnesium pot, and stir it thoroughly to form a relatively uniform hot-dip molten liquid in the zinc-aluminum-magnesium pot, waiting for use in hot-dip galvanizing;

[0053] Step 2. Plating:

[0054] The strip steel to be zinc-aluminum-magnesium coated is pickled, annealed and other treatments are carried out, and the soaking temperature after annealing is controlled. The soaking temperature is determined according to the strip steel specifications. The annealed strip steel passes through the rapid cooling section, the equalization section and the furnace nose in sequence. After the rapid cooling section and the equalization section, the temperature of the strip steel entering the zinc-aluminum-magnesium pot needs to be controlled according to the relevant requirements of the high-magnesium zinc-aluminum-magnesium coated products. This temperature needs to be determined according to the melting temperature of the zinc-aluminum-magnesium pot. The strip steel that reaches the controlled temperature enters the zinc-aluminum-magnesium pot and is hot-dip plated in the zinc-aluminum-magnesium pot. Then the strip steel comes out of the zinc-aluminum-magnesium pot and is treated by an air knife. The coating weight is controlled by the air knife, and then it enters the alloy powder spraying system. A variety of methods are used to control the temperature of the strip steel entering the alloy powder spraying system. This temperature needs to be determined according to the composition and specifications of the high-magnesium zinc-aluminum-magnesium alloy.

[0055] Alloy powder spraying: Alloy powder is sprayed onto the strip entering the uniform device through the alloy powder spraying system to achieve cooling control of the solidification process of high-Mg-Zn-Al-Mg (such as 19-Al-6-Mg-Zn-Al-Mg) coating, to achieve high-strength and adjustable-strength cooling intensity requirements in the alloy powder spraying system, and to act as the nucleation for alloy solidification in the zinc-aluminum-magnesium coating, increase the nucleation density, and thus obtain high-Mg-Zn-Aluminum-Mg products with excellent surface quality.

[0056] In general, the alloy powder spraying system is as follows: the prepared alloy powder is stored in the alloy powder storage tank and transported to the inlet of the recirculation device through the alloy powder conveying device for replenishing the alloy powder; wherein the recirculation device is connected to the uniform device for evenly distributing the wind and the alloy powder through the connecting device 1, and the alloy powder is sprayed to the strip through the uniform device to realize the functions of the alloy powder coolant and the nucleation, that is, to realize the solidification process control of the zinc-aluminum-magnesium coating;

[0057] The alloy powder-containing fluid in the uniform device is recycled and utilized through the alloy powder return air port, and is recycled and utilized through the recirculating negative pressure device 1 and the recirculating negative pressure device 2 respectively; wherein the recirculating negative pressure device 1 is connected to the uniform device through the connecting device 2, and is used to realize the recycling of the alloy powder-containing fluid, and the recovered alloy powder-containing fluid passes through the drying and cooling device, and the drying and cooling device is used to control the moisture and temperature of the alloy powder-containing fluid, and the alloy powder-containing fluid after drying and cooling enters the inlet of the recycling device for the next utilization, and the proportion of this part is 70-100%, and this proportion is adjusted by adjusting the power ratio of the recirculating negative pressure device 1 and the recirculating negative pressure device 2;

[0058] At the same time, the recycling negative pressure device 2 is connected to the uniform device through the connecting device 3, and then passes through the filtering device, which is used to filter the large-particle alloy powder, and then is recovered by the alloy powder recovery device in turn. The recovered alloy powder is processed by the alloy powder processing device and placed in the alloy powder storage tank after being qualified. The alloy powder (large-particle alloy powder) larger than 25μm is removed and the alloy powder-containing fluid enters the drying and cooling device, and enters the entrance of the recycling device for next use. The proportion of this part is 0-30%, and this proportion is adjusted by adjusting the power ratio of the recycling negative pressure device 1 and the recycling negative pressure device 2.

[0059] The operation of the overall alloy powder spraying system is as follows: the prepared alloy powder is stored in the alloy powder storage tank, and is transported to the inlet of the recycling device through the alloy powder conveying device, and the alloy powder-containing fluid from the branch of the recycling negative pressure device 1 is dried and cooled by the drying and cooling device, and the alloy powder-containing fluid then enters the inlet of the recycling device, and the alloy powder-containing fluid from the branch of the recycling negative pressure device 2 where large particles of alloy powder are removed is dried and cooled by the drying and cooling device, and the alloy powder-containing fluid then enters the inlet of the recycling device; the three-way alloy powder is mixed in the recycling device to form a mixed fluid containing alloy powder for powder spraying on the strip, and passes through the recycling device and the connecting device 1 in turn, and then enters the uniform device, in which the alloy powder-containing mixed fluid is evenly distributed along the width direction of the strip and relatively evenly distributed along the moving direction of the strip, and then the alloy powder is sprayed onto the strip through the air outlet (bellows outlet) of the uniform device, to achieve The alloy powder now acts as a coolant and nucleation function, thereby realizing the solidification process control of the high-Mg-Zn-Al-Mg alloy layer, and then the alloy powder-containing mixed fluid enters the uniform device again through the alloy powder return air port of the uniform device; then the alloy powder-containing mixed fluid with a proportion of 70-100% enters the recycling negative pressure device one through the connecting device two, and then enters the drying and cooling device to control the temperature and moisture of the alloy powder-containing mixed fluid, and then the alloy powder-containing fluid enters the inlet of the recycling device; then the alloy powder-containing mixed fluid with a proportion of 0-30% enters the recycling negative pressure device two through the connecting device three, and then passes through the filtering device, the filtering device is used to filter the large-particle alloy powder, and then is recovered by the alloy powder recovery device in turn, the recovered alloy alloy powder is processed by the alloy powder processing device and then put into the alloy powder storage tank, the alloy powder-containing mixed fluid with the large-particle alloy powder removed enters the drying and cooling device, and enters the inlet of the recycling device.

[0060] Step 4. Subsequent treatment: After the strip is sprayed with alloy powder, it enters the stages of final cooling, skin pass and straightening, and finally becomes a finished coil.

[0061] Specifically, the high magnesium-zinc-aluminum-magnesium content product is preferably a 19-aluminum-6-magnesium-zinc-aluminum-magnesium product, and the alloy powder composition is preferably 19Al6Mg75Zn; the particle size of the alloy powder is preferably 5-20μm, and the moisture content is controlled below 0.1wt%.

[0062] like Figure 2As shown, the alloy powder spraying system is composed of an alloy powder storage tank, an alloy powder conveying device, a recycling device, a connecting device 1, a uniform device, a recycling negative pressure device 1, a connecting device 2, a drying and cooling device, a recycling negative pressure device 2, a connecting device 3, a filtering device, an alloy powder recovery device and an alloy powder processing device. The alloy powder storage tank, the alloy powder conveying device, the recycling device, the connecting device 1 and the uniform device are connected in sequence along the flow direction of the alloy powder mixed fluid, the uniform device, the connecting device 2, the recycling negative pressure device 1, the drying and cooling device and the recycling device are connected in sequence along the flow direction of the alloy powder mixed fluid, the uniform device, the connecting device 3, the recycling negative pressure device 2, the filtering device and the drying and cooling device are connected in sequence along the flow direction of the alloy powder mixed fluid, the filtering device, the alloy powder recovery device, the alloy powder processing device and the alloy powder storage tank are connected in sequence along the alloy powder flow direction. The wind used in the alloy powder spraying system is air or protective gas, preferably protective gas.

[0063] See also Figure 3 to Figure 7 The uniform device in the alloy powder spraying system includes an air cavity 14 for passing through the strip steel and uniform powder spraying bellows symmetrically arranged on both sides of the strip steel and connected to the air cavity 14;

[0064] The uniform powder spraying bellows comprises a bellows body 7, wherein the bellows body 7 has a partition plate 5 which divides the bellows body 7 into a plurality of sub-bellows units in a vertical direction;

[0065] In the sub-bellows units located at the lower end and the middle part, there are multi-layer uniform tubes 1 arranged parallel to the steel strip to transport alloy powder to the corresponding sub-bellows units, and on the outer side of each multi-layer uniform tube 1, there are partitions 1 3 and 10 arranged relatively and connected to the inner wall of the sub-bellows unit to divide the corresponding sub-bellows unit into upper and lower parts in the vertical direction. The sub-bellows units at the lower end and the middle part are provided with a bellows outlet 2 connected to the wind cavity 14 on the side close to the steel strip, and a re-uniform air inlet 8 is provided on the side away from the steel strip. The sub-bellows units in the middle part are also provided with an alloy powder return air inlet 4 connected to the wind cavity on the side close to the steel strip, and an alloy powder outlet 9 is also provided on the side away from the steel strip. The bellows outlet 2, the re-uniform air inlet 8 and the outlet of the multi-layer uniform tube 1 are all arranged in the upper part, and the alloy powder return air inlet 4 and the alloy powder outlet 9 are all arranged in the lower part.

[0066] An alloy powder return air port 4 connected to the air cavity is provided on the side of the uppermost sub-wind box unit close to the steel strip, and an alloy powder outlet 9 is provided on the side away from the steel strip.

[0067] Specifically, the connecting device 1 sequentially connects the alloy powder conveying inlet pipe 13, the alloy powder conveying branch pipe 12 and the alloy powder conveying branch pipe 11 to evenly divide the alloy powder into several parts. Thereafter, the alloy powder conveying branch pipe 11 is connected to the multi-layer uniform pipe 1. The multi-layer uniform pipe 1 is used to achieve uniform distribution of the alloy powder in the width direction. Thereafter, the alloy powder enters the bellows body 7 and is mixed with the re-uniform air entering from the re-uniform air inlet 8 and then is ejected from the bellows outlet to be blown toward the strip.

[0068] The bellows body is divided into a plurality of sub-bellows units by partition 2 5, so as to improve the uniformity of powder spraying. The multi-layer uniform tube 1 and the inner wall of the sub-bellows unit are connected by partition 1 3 and partition 3 10, and the sub-bellows unit located at the lower end and the middle part is divided into upper and lower parts in the vertical direction.

[0069] Furthermore, a re-air-distributing porous plate 6 is provided in the upper portion, with two ends respectively connected to the inner wall of the sub-wind box unit and the multi-layer uniform tube 1, and the re-air-distributing porous plate 6 is arranged above the outlet of the multi-layer uniform tube.

[0070] Furthermore, the multi-layer uniform tube 1 comprises a first-layer uniform tube 1-1, a second-layer uniform tube 1-2 and a third-layer uniform tube 1-3 which are arranged in sequence from the inside to the outside, the second-layer uniform tube 1-2 and the third-layer uniform tube 1-3 are closed at both ends, one end of the first-layer uniform tube 1-1 is closed, and the other end is connected to the alloy powder conveying branch pipe 11 to serve as the inlet of the multi-layer uniform tube 1;

[0071] A first distribution port 1-1-1 is provided on the outer side of the first layer of equal distribution pipe, a second distribution port 1-2-1 is provided on the outer side of the second layer of equal distribution pipe, and a third distribution port 1-3-1 is provided on the outer side of the third layer of equal distribution pipe, and the first distribution port and the second distribution port are staggered by 40-60° on the circumference, the second distribution port and the third distribution port are staggered by 40-60° on the circumference, and the third distribution port is arranged at the upper part of the sub-wind box unit to serve as the outlet of the multi-layer uniform pipe 1, and is connected to the wind cavity 14 through the wind box outlet 2.

[0072] Furthermore, the first distribution port 1-1-1, the second distribution port 1-2-1 and the third distribution port 1-3-1 are provided in plurality and arranged along the width direction of the strip, and the wind box outlet 2 and the alloy powder return air port 4 are both long strip air ports arranged along the width direction of the strip.

[0073] Specifically, the flow field of the uniform powder spraying bellows is as follows: Figure 8As shown, the bellows outlet 2 of the lowermost sub-bellows unit sprays out a fluid containing alloy powder, which enters the corresponding sub-bellows unit from the alloy powder return air port 4 of the sub-bellows unit located above it, and flows out of the bellows from the alloy powder outlet 9 of the sub-bellows unit, and the bellows outlet of the sub-bellows unit sprays out a mixed fluid containing alloy powder, which enters the corresponding sub-bellows unit from the alloy powder return air port 4 of the sub-bellows unit located above it, and flows out of the bellows unit from the alloy powder air outlet 9. By analogy, the bellows outlet of the sub-bellows unit closest to the upper end sprays out a mixed fluid containing alloy powder, which enters the bellows from the alloy powder return air port of the uppermost sub-bellows unit, and flows out of the bellows from its alloy powder air outlet 9; the flow field forms a vortex structure, and the multi-layer vortex structure can achieve the stability of the strip steel.

[0074] like Figure 3-4 As shown, the alloy powder-containing mixed fluid enters the alloy powder delivery inlet pipe 13 through the connecting device 1, and then passes through the alloy powder delivery branch pipe 12 to divide the alloy powder-containing mixed fluid into several streams, and is connected to the multi-layer uniform pipe 1 in each sub-wind box unit through the alloy powder delivery branch pipe 11. The alloy powder-containing mixed fluid passes through the first layer of uniform distribution pipe 1-1, the second layer of uniform distribution pipe 1-2 and the third layer of uniform distribution pipe 1-3 in sequence, that is, through the first distribution port 1-1-1, the second layer of distribution port 1-2-1 and the third layer of distribution port 1-3-1 for uniform flow redistribution. It is used to improve the uniformity of the distribution of the alloy powder along the bandwidth direction, and then enters the channel divided by the re-air balancing porous plate 6 and the bellows outlet 2 to mix with the re-air balancing air entering from the re-air balancing inlet 8 and passing through the re-air balancing porous plate 6, further improving the uniformity of the distribution of the alloy powder, and then flows out from the bellows outlet, and enters the corresponding sub-bellows unit from the alloy powder return air port of the adjacent upper sub-bellows unit, so that the overall flow field presents multiple vortex structures, avoiding the influence between the outlets and return ports of multiple alloy powders, making it easier to stabilize the strip and achieve uniform and stable airflow.

[0075] The uniform powder spraying bellows in the uniform device distributes alloy powder particles by means of a main pipe and branch pipes to initially achieve uniform distribution of the alloy powder-containing fluid; then, the bellows is divided internally into sub-bellows units, which transforms the problem from solving the large-space airflow distribution problem to solving the small-space airflow distribution problem of a single outlet. The small area can ensure more uniform mixing and is easy to achieve standardized amplification; the uniformity of the alloy powder-containing fluid along the width of the strip is improved by multi-layer uniform tubes, thereby improving the uniformity of the bellows for spraying alloy powder; and the alloy powder redistribution problem is achieved by re-evening and re-mixing the air, further improving the uniformity of the alloy powder distribution. A structure in which multiple pairs of bellows outlets (alloy powder spraying ports) and alloy powder return air ports are arranged in pairs is adopted to achieve a multi-layer vortex structure flow field. At the same time, the bellows on both sides are slightly staggered in the vertical direction to avoid the influence between multiple inlets and outlets, making it easier to stabilize the strip and achieve uniform and stable airflow.

[0076] Example 1

[0077] A zinc-aluminum-magnesium coating process based on an alloy powder spraying system is used to produce 19 aluminum 6 magnesium zinc-aluminum-magnesium coating products, specifically comprising the following steps:

[0078] Preparation: Select 19 aluminum 6 magnesium zinc aluminum magnesium alloy powder with a particle size of 15 μm, and dry it by air drying or vacuum drying to control the moisture content of the alloy powder below 0.1%, and then place the dried alloy powder in an alloy powder storage tank for standby use; when preparing the alloy powder, melt the 19 aluminum 6 magnesium zinc aluminum magnesium alloy in a zinc aluminum magnesium pot, control the temperature in the pot to 490 ± 2 ° C, and stir it thoroughly to form a relatively uniform hot dip molten solution in the zinc aluminum magnesium pot, and use it when waiting for hot dip galvanizing;

[0079] Coating coating: The strip steel to be plated with 19 aluminum 6 magnesium zinc aluminum magnesium is pickled, annealed, and the soaking temperature after annealing is controlled. The production strip steel specification is CQ, and the annealing soaking temperature is controlled to be 720℃. The annealed strip steel passes through the rapid cooling section, the equalization section and the furnace nose in turn, and the temperature of the equalization section and the outlet temperature of the rapid cooling section are controlled to be 495℃, and finally enters the zinc aluminum magnesium pot, and is hot-dip plated in the zinc aluminum magnesium pot. Then the strip steel comes out of the zinc aluminum magnesium pot and is treated by an air knife. The coating weight obtained by the air knife is 275g / m 2 After that, it enters the alloy powder spraying coating system, and adopts a variety of control methods (such as air cooling or natural cooling, etc.) to control the temperature of the strip entering the alloy powder spraying system to 480℃.

[0080] Alloy powder spraying: the alloy powder is sprayed onto the strip steel entering the homogenizing device, wherein the volume fraction of the alloy powder is controlled at 0.05-0.5%, which is used to achieve high-intensity cooling control during the solidification process of the 19-aluminum-6-magnesium-zinc aluminum-magnesium coating;

[0081] Specifically, the prepared alloy powder is stored in the alloy powder storage tank and transported to the inlet of the recycling device through the alloy powder conveying device to realize alloy powder replenishment; wherein the recycling device is connected to the uniform device for realizing the uniform distribution of wind and metal alloy powder through the connecting device 1, and the alloy powder-containing mixed fluid is sprayed to the strip through the air outlet of the uniform device through the uniform device, so that the alloy powder acts as a coolant and nucleation function, that is, the solidification process control of the high magnesium-zinc-aluminum-magnesium coating is realized; wherein the alloy powder-containing mixed fluid is recycled through the return air port of the uniform device, and it is recycled through the recycling negative pressure device 1 and the recycling negative pressure device 2 respectively; wherein the recycling negative pressure device 1 is connected to the uniform device through the connecting device 2, so as to realize the recycling of the alloy powder-containing mixed fluid, and then the alloy powder-containing mixed fluid passes through the drying and cooling device, and the drying and cooling device is used to contain the alloy powder The moisture and temperature of the mixed fluid are controlled, and then the mixed fluid containing alloy powder enters the inlet of the recycling device for next use. The proportion of this part is 75%, and this proportion is adjusted by adjusting the power ratio of the recycling negative pressure device 1 and the recycling negative pressure device 2; at the same time, the recycling negative pressure device 2 is connected to the uniform device through the connecting device 3, and then passes through the filtering device, the filtering device is used to filter large-particle metal powder, that is, to filter particles exceeding 25μm, and then is recovered through the metal powder recovery device in turn. The recovered alloy metal powder is processed by the alloy powder processing device and then placed in the alloy powder storage tank. The alloy powder-containing mixed fluid with large-particle alloy powder removed enters the drying and cooling device, and enters the inlet of the recycling device for next use. The proportion of this part is 25%, and this proportion is adjusted by adjusting the power ratio of the recycling negative pressure device 1 and the recycling negative pressure device 2.

[0082] Subsequent treatment: After the strip is sprayed with alloy powder, it enters the stages of final cooling, skin pass and straightening, and finally becomes a finished coil.

[0083] Preferably, in this embodiment, a uniform distribution of the mixed fluid (mixed fluid containing alloy powder) is achieved through a uniform device, and at the same time, the possibility of the fluid containing alloy powder directly contacting the surface of the hot-dip coated steel strip is increased through the uniform device; when spraying, by increasing the proportion of the mixed fluid in direct contact with the surface of the hot-dip coated steel strip, about 10%wt of the coating weight of the alloy powder enters the high-Mg-Zn-Al-Mg coating, and the alloy powder entering the high-Mg-Zn-Al-Mg coating quickly reduces the coating temperature through melting heat absorption and sensible heat absorption; secondly, the volume fraction of the alloy powder in the mixed fluid (i.e., the volume ratio of the alloy powder to the volume of the mixed fluid) is controlled to be about 0.2%; at this time, the mixed fluid carrying the alloy powder has The mass of the fluid is about 10 times the mass of the gas without alloy powder, which greatly improves the ability of the mixed fluid to carry heat. At the same time, the thermal conductivity of the mixed fluid carrying alloy powder is greatly improved. The thermal conductivity of the mixed fluid carrying alloy powder is more than 500 times that of the gas without alloy powder. At the same time, the presence of alloy powder in the mixed fluid enhances the turbulence intensity of the mixed fluid flow field, reduces the height of the viscous bottom layer of the impact jet, and further enhances the heat exchange capacity of the mixed fluid. At the same time, the presence of alloy powder increases the radiation heat exchange intensity between the mixed fluid and the surface of the strip after hot dip plating. In summary, the cooling rate of the strip in the uniform device reaches 200℃ / s through the alloy powder spraying system. In other embodiments, the cooling intensity can be flexibly adjusted by adjusting the alloy powder spraying parameters (i.e., the volume fraction of alloy powder in the mixed fluid) to achieve an adjustable and controllable cooling rate of 50-200℃ / s.

[0084] In this embodiment, the 19 aluminum 6 magnesium zinc aluminum magnesium product has excellent surface quality, good appearance uniformity, uniform color, greatly reduced surface defects such as black spots, segregation, local oxidation, etc., the coating structure is dense and uniform, the grains are fine, and the average grain size is significantly smaller than the particle size of the coating structure produced by traditional processes.

[0085] In summary, the present invention uses the alloy powder spraying method for high-Mg-Zn-Al-Mg coating production to solve the problem of high-strength and flexibly adjustable cooling strength required in the production of high-Mg-Zn-Al-Mg coating products such as 19-Al-6-Mg, that is, the alloy powder is used as a coolant to greatly enhance the cooling strength, achieving a much higher than the existing air cooling strength, thereby effectively inhibiting defects such as oxidation and local segregation, and improving the uniformity and quality of the coating;

[0086] Secondly, it is used to solve problems such as black spots, segregation and oxidation in the production of 19 aluminum 6 magnesium high magnesium zinc aluminum-magnesium coating products. That is, the alloy powder acts as the solidification nucleus of the coating, increasing the nucleation density, thereby greatly improving the surface density and smoothness, and effectively solving surface quality problems such as black spots and segregation.

[0087] In order to realize the above alloy powder spraying zinc-aluminum-magnesium coating production, the present invention designs a set of alloy powder spraying system, realizes temperature and moisture control through drying and cooling device, greatly reduces temperature accumulation and alloy powder agglomeration, realizes alloy powder recycling and recovery function through reasonable proportion control of two recirculating negative pressure absorption devices, conveys alloy powder through alloy powder conveying device, realizes alloy powder replenishment, and at the same time, the air outlet and return air outlet of the uniform device of the alloy powder spraying system are arranged in pairs and periods along the direction of strip movement, and multiple pairs are arranged. At the same time, the uniform device is arranged in zones along the direction of strip movement, and the functions of stabilizing strip steel and cooling intensity segmented control are realized through the paired periodic arrangement and zone arrangement of the uniform device. The present invention mainly adjusts the quality of alloy powder and supplements it with gas intensity to realize adjustable cooling intensity, improves the cooling adaptability of high-magnesium zinc-aluminum-magnesium coating products of different thicknesses such as 19 aluminum 6 magnesium, and meets diversified production needs.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An alloy powder spraying system, characterized in that: A uniform device for spraying alloy powder on a steel strip is included, wherein the uniform device includes an air cavity for passing the steel strip and two uniform powder spraying wind boxes arranged on both sides of the steel strip and connected to the air cavity; The uniform powder spraying bellows comprises a bellows body, wherein the bellows body has a partition plate 2 which divides the bellows body into a plurality of sub-bellows units in a vertical direction; The sub-bellows units at the lowest end and the middle part are provided with multi-layer uniform tubes arranged parallel to the steel strip to transport alloy powder to the corresponding sub-bellows units, and partitions one and three are arranged oppositely and connected to the inner wall of the sub-bellows unit on the outer side to divide the corresponding sub-bellows unit into upper and lower parts in the vertical direction, and the sub-bellows units at the lowest end and the middle part are provided with a bellows outlet connected to the wind cavity on the side close to the steel strip, and a re-uniform air inlet is provided on the side away from the steel strip, and the sub-bellows units in the middle part are also provided with an alloy powder return air inlet connected to the wind cavity on the side close to the steel strip, and an alloy powder outlet is also provided on the side away from the steel strip, and the bellows outlet, the re-uniform air inlet and the outlet of the multi-layer uniform tube are all arranged in the upper part, and the alloy powder return air inlet and the alloy powder outlet are both arranged in the lower part; An alloy powder return air port connected to the air cavity is provided on the side of the sub-wind box unit located at the uppermost end close to the steel strip, and an alloy powder outlet is provided on the side away from the steel strip.

2. The alloy powder spraying system according to claim 1, characterized in that: The upper part is also provided with a re-air-distributing porous plate whose two ends are respectively connected to the inner wall of the sub-wind box unit and the multi-layer uniform tube, and the re-air-distributing porous plate is arranged above the outlet of the multi-layer uniform tube.

3. The alloy powder spraying system according to claim 1, characterized in that: The multi-layer uniform pipe comprises a first-layer uniform pipe, a second-layer uniform pipe and a third-layer uniform pipe arranged in sequence from the inside to the outside, both ends of the second-layer uniform pipe and the third-layer uniform pipe are closed, one end of the first-layer uniform pipe is closed, and the other end is connected to the alloy powder conveying branch pipe; A first distribution port is provided on the outer side of the first layer of equal distribution pipe, a second distribution port is provided on the outer side of the second layer of equal distribution pipe, and a third distribution port is provided on the outer side of the third layer of equal distribution pipe, and the first distribution port and the second distribution port are staggered by 40-60° on the circumference, the second distribution port and the third distribution port are staggered by 40-60° on the circumference, and the third distribution port is arranged at the upper part of the sub-bellows unit to connect to the wind cavity through the bellows outlet.

4. The alloy powder spraying system according to claim 3, characterized in that: The first distribution opening, the second distribution opening and the third distribution opening are provided in plurality and arranged along the width direction of the steel strip, and the wind box outlet and the alloy powder return air opening are both long strip air openings arranged along the width direction of the steel strip.

5. The alloy powder spraying system according to claim 3, characterized in that: Each alloy powder conveying branch pipe connected to the multi-layer uniform pipe is connected to an alloy powder conveying branch pipe arranged along the vertical direction of the wind box body, and the alloy powder conveying branch pipe is connected to the alloy powder conveying inlet pipe.

6. The alloy powder spraying system according to claim 5, characterized in that: The alloy powder spraying system also includes an alloy powder storage tank, an alloy powder conveying device, a recycling device and a connecting device. The alloy powder storage tank, the alloy powder conveying device, the recycling device, the connecting device and the alloy powder conveying inlet pipe are connected in sequence to form an alloy powder-containing mixed fluid from the alloy powder storage tank and convey it to the multi-layer uniform pipe to spray the alloy powder on both sides of the strip through the bellows outlet.

7. The alloy powder spraying system according to claim 6, characterized in that: The alloy powder spraying system also includes a recirculating negative pressure device 1, a connecting device 2, a drying and cooling device, a recirculating negative pressure device 2, a connecting device 3, a filtering device, an alloy powder recovery device and an alloy powder processing device; The alloy powder outlet in the alloy powder spraying system is connected to the connection device 2 and the connection device 3 respectively, and the connection device 2, the recycling negative pressure device 1, the drying and cooling device and the recycling device are connected in sequence to directly recycle the alloy powder-containing mixed fluid in the wind chamber through drying and cooling, and the connection device 3, the recycling negative pressure device 2, the filtering device and the drying and cooling device are connected in sequence, and the filtering device is also connected with the alloy powder recovery device, the alloy powder processing device and the alloy powder storage tank in sequence, so that the alloy powder-containing mixed fluid is filtered and dried and cooled through the filtering device for recycling, and the large-particle alloy powder obtained after filtration is processed by the alloy powder recovery device and the alloy powder processing device and then sent to the alloy powder storage tank for storage.

8. The alloy powder spraying system according to claim 7, characterized in that: The alloy powder-containing mixed fluid in the alloy powder spraying system is recycled by the first recirculating negative pressure device for a proportion of 70-100%, and recycled by the second recirculating negative pressure device for a proportion of 0-30%.

9. The alloy powder spraying system according to claim 1, characterized in that: The two uniform powder spraying bellows arranged on both sides of the steel strip are staggered with each other in the vertical direction.

10. A zinc-aluminum-magnesium coating process based on an alloy powder spraying system, characterized in that: The following steps are involved: Step 1. Dry the alloy powder for later use. While preparing the alloy powder, melt the high-magnesium zinc-aluminum-magnesium alloy in a zinc-aluminum-magnesium pot to form a hot-dip plating melt to be used when hot-dip plating is in progress; Step 2. feeding the steel strip into a zinc-aluminum-magnesium pot for hot-dip plating to form a high-magnesium zinc-aluminum-magnesium coating on the surface of the steel strip, and performing an air knife treatment on the high-magnesium zinc-aluminum-magnesium coating; Step 3. Use the alloy powder reserved in step 1 as a coolant, and simultaneously spray the alloy powder on both sides of the strip after hot dip coating through the alloy powder spraying system described in any one of claims 1 to 9, so as to cool the high-magnesium-containing zinc-aluminum-magnesium coating and serve as a nucleus for the solidification of the zinc-aluminum-magnesium coating alloy.

11. The zinc-aluminum-magnesium coating process based on the alloy powder spraying system according to claim 10, characterized in that: The composition of the alloy powder is the same as that of the high-magnesium-containing zinc-aluminum-magnesium alloy powder in the zinc-aluminum-magnesium pot.

12. The zinc-aluminum-magnesium coating process based on an alloy powder spraying system according to any one of claim 10, characterized in that: The method also includes step 4: sequentially air cooling, water cooling, skin pass and straightening the strip steel coated with alloy powder, and rolling it into a high magnesium-zinc-aluminum-magnesium content product.

13. The zinc-aluminum-magnesium coating process based on the alloy powder spraying system according to claim 10, characterized in that: The high magnesium-zinc-aluminum-magnesium alloy is 19 aluminum 6 magnesium zinc aluminum magnesium.

14. The zinc-aluminum-magnesium coating process based on the alloy powder spraying system according to claim 10, characterized in that: The particle size of the alloy powder is 5-20 μm, and the moisture content is controlled below 0.1 wt % after drying.

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