WO2022057757A1

WO2022057757A1 - Continuous surface treatment method for hot-rolled plates/strips

Info

Publication number: WO2022057757A1
Application number: PCT/CN2021/117943
Authority: WO
Inventors: 吴玮巍; 王宝森; 周庆军
Original assignee: 宝山钢铁股份有限公司
Priority date: 2020-09-17
Filing date: 2021-09-13
Publication date: 2022-03-24
Also published as: CN114192372A

Abstract

Disclosed are a continuous surface treatment method for hot-rolled plates/strips and a production line used therein. The method comprises the following steps: S1, uncoiling a coiled hot-rolled plate/strip and carrying out welding or welding a hot-rolled steel plate to form a continuous hot-rolled plate/strip, and then straightening the continuous hot-rolled plate/strip; S2, collecting oxide dust particles attached to the surface of the hot-rolled plate/strip by applying a force to the surface of the hot-rolled plate/strip; S3, coating the hot-rolled plate/strip by means of roller coating or spraying to form a coating on the surface of the hot-rolled plate/strip, and after the coating is solidified, cooling the hot-rolled plate/strip to room temperature; and S4, carrying out on-line inspection on the coating on the surface of the hot-rolled plate/strip, and if the coating is qualified, performing coiling or slitting and stacking according to requirements of a finished product. The present method not only can effectively recover the oxide dust particles on the surface of the hot-rolled plate/strip, but also can form a protective layer on the surface of the hot-rolled plate/strip, thereby preventing polluting the environment and rusting the surface of the hot-rolled plate/strip due to the strip steel generating oxide dust particles again during subsequent processing, storage, and transportation.

Description

Hot-rolled strip surface continuous treatment method and production line therefor

technical field

The invention belongs to the field of surface treatment of hot-rolled strips in the metallurgical industry, and particularly relates to a method for continuous surface treatment of hot-rolled strips and a production line therefor. The method and production line of the invention can not only recover the oxide dust particles on the surface of the hot-rolled steel sheet, and turn waste into treasure, but also can continuously treat the surface of the hot-rolled steel sheet.

Background technique

Hot rolling is one of the important production and processing procedures in steel production. Its purpose is to change the thickness of the heated billet, control its width or inner and outer diameter, and extend its length through a discontinuous or continuous rolling process, while combining the rolling process and cooling. The control gives the steel the desired mechanical properties. During the high temperature process, the surface of the steel is continuously oxidized to form an oxide scale. Usually, the surface of hot-rolled products is covered with a layer of black oxide scale with a thickness of several microns to tens of microns. This layer of black oxide scale provides protection for hot-rolled products during production, storage and transportation, and slows down product corrosion to a certain extent. Hot-rolled steel is mainly used in two aspects: one is to be used as raw material for cold rolling after pickling; the other is to directly supply users with pickling or without pickling. Affected by the increasingly fierce market competition and the increasingly strict environmental protection pressure, more and more hot-rolled materials are used directly without pickling, which also puts forward higher requirements for the protection of the oxide scale on the surface of hot-rolled materials. The protective properties of the oxide scale are mainly affected by the hot rolling, coiling and cooling processes of the product. However, with the development of high-strengthened products, the coiling temperature of hot-rolled steel sheets is generally low (often lower than the transition temperature of the eutectoid reaction of the oxide scale) and the cooling rate is generally high (often higher than the critical point for the decomposition of FeO in the oxide scale). Cooling speed), resulting in that the oxide scale of the product often contains more brittle phases, and a large number of cracks or holes will be generated in the oxide scale, which greatly reduces its protective properties, and it is easy to form black oxide scale particles or dust during the production, storage and transportation process. Corrosion produces red rust, which not only pollutes the environment, but also easily adversely affects subsequent production and product quality.

In the prior art, there are two most common ways to solve the above problems of hot-rolled sheets: one is to adjust the hot-rolling, cooling and coiling processes of the product to improve the structure of the oxide scale on the surface of the product, and to enhance the compactness and density of the oxide scale. Flexibility, reduce the shedding of oxide scale particles and delay the production of red rust. However, this type of method is extremely difficult, and it often inevitably affects on-site production rhythm, product organization and mechanical properties. Moreover, the improvement of oxide scale protection performance that can be brought about by improving the oxide scale structure is limited, which may not be able to meet the needs of users. demand. Another method is to help solve the corrosion resistance of products through other means, such as common anti-rust paper packaging, anti-rust oil, anti-rust wax, anti-rust liquid, anti-rust paint, etc. These measures can effectively slow down rust and prevent corrosion to a certain extent. To solve the problem of oxide dust particles polluting the user's environment. However, these methods will more or less affect the welding, forming and coating process of the material, resulting in an increase in the cost of the user's material use.

For example, application number CN 200810088982.9 discloses a method for continuous production of anti-rust primer-coated steel sheets. By continuously coating the surface of the hot-rolled sheet with primer coating, the user's primer coating process is reduced, and the hot-rolled sheet can be provided. Temporary protection during production, storage and transportation. However, this technical solution has complicated procedures and requires pickling of the hot-rolled sheet to remove oxide scale, which is easy to cause pollution to the environment. The applied primer requires high temperature baking and curing, which requires high energy consumption and high investment in fixed equipment. The formed primer layer will have adverse effects on subsequent welding, forming and other user use links. In addition, this method cannot solve the problem of falling oxide dust particles during the production of iron and steel products.

There are also some methods involving temporary protection of hot-rolled sheets, mainly focusing on the protection of high-temperature oxidative burning loss of steel sheets during hot-rolling production. For example, Application _No. CN _{200610076257.0} discloses a high _- temperature common low _- carbon steel anti _- oxidation coating and its application. The carbon reducing agent and inorganic binder are respectively ground to less ^than 100 mesh, mixed evenly, and then fully mixed with water and stirred evenly. The coating is sprayed on the hot-state (below 1000 ℃) billet before the hot rolling is heated in the furnace, and a continuous protective coating is formed on the surface of the billet under the action of high temperature, which effectively reduces the high-temperature oxidation during the transportation and soaking process of the slab before hot rolling. burn. Application No. CN 201510252212.3 discloses a protective coating for a steel billet in a hot rolling furnace, the coating can react with oxides generated by the billet itself at high temperature to obtain protective layers with different melting points, and the protective layer can effectively isolate The slab reacts with the atmosphere in the furnace. However, the above technical solutions can only play a role in preventing oxidative burning during the hot rolling process, and obviously cannot solve the problems of falling oxide dust particles and easy rusting after hot rolling and coiling of the hot rolled sheet.

The oxide dust particles produced on the surface of the hot-rolled sheet are mainly composed of ferric oxide and a small amount of ferrous oxide particles. Ferric oxide and ferrous oxide are important functional materials and are often used as magnetic materials. Specially made pure ferric tetroxide can be used as a raw material for audio tapes and telecommunications equipment, as well as in primers and topcoats, and even as an abrasive. Nano-sized ferric oxide is one of the important raw materials for making magnetic fluids. It has important applications in magnetic sealing, biomedical and other fields, and has extremely high added value. Ferrous oxide reacts with oxygen at high temperature to form ferric oxide. At the same time, ferrous oxide itself is also used as a pigment and polishing agent, and can also be used in the manufacture of audio tapes and telecommunication equipment.

However, all the treatment methods for the oxide dust particles of the hot-rolled sheet in the prior art can only simply treat the oxide dust particles as the waste of the polluted site and remove them, and do not realize the comprehensive utilization of the oxide dust particles. Far from realizing the purpose of turning waste into treasure.

In view of the above situation, it is urgent to develop a surface treatment method for hot-rolled strip, which can not only effectively recover the oxide dust particles on the surface of hot-rolled strip, and turn waste into treasure, but also can form a protective layer on the surface of hot-rolled strip to avoid During the subsequent processing, storage and transportation of hot-rolled strips, oxide dust particles are regenerated to pollute the environment, and the surface of hot-rolled strips is rusted.

SUMMARY OF THE INVENTION

In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a method for continuously treating the surface of a hot-rolled strip and a production line therefor. In the method and production line of the present invention, the oxide dust particles on the surface of the strip steel are collected by the oxide particle recovery equipment, which facilitates the recovery and treatment of the oxide dust particles, and truly realizes the transformation of the oxide dust particles into treasures. In addition, by using the method and production line of the present invention, a protective coating is formed on the surface of the strip by continuous coating on the surface of the strip, which improves the corrosion resistance of the hot-rolled strip to a certain extent, while avoiding the need for hot-rolled strips. In the subsequent storage, transportation and processing, oxide dust particles are generated again to pollute the environment.

In order to achieve the above object, the present invention adopts the following technical scheme:

A first aspect of the present invention provides a method for continuously treating the surface of a hot-rolled strip, comprising the following steps:

S1: uncoiling and welding the coiled hot-rolled strip or welding the hot-rolled steel plate to form a continuous hot-rolled strip, and then straightening the continuous hot-rolled strip;

S2: Collect oxide dust particles by exerting force on the oxide scale attached to the surface of the hot-rolled strip;

S3: The hot-rolled strip is coated by roller coating or spraying to form a coating on the surface of the hot-rolled strip; after the coating is cured, the hot-rolled strip is cooled to room temperature;

S4: On-line inspection of the coating on the surface of the hot-rolled strip, if the coating is qualified, coiling or slitting and stacking are carried out according to the requirements of the finished product.

In a preferred embodiment, in step S2, the force is applied by an oxide particle recovery device.

In one embodiment, the oxide particle recovery device is selected from one or more of a gravity recovery device, a negative pressure recovery device, an electrostatic recovery device, and a magnetic recovery device.

In one embodiment, the oxide dust particles are desorbed from the upper and lower surfaces of the strip by means of mechanical friction or mechanical vibration by means of a scraping device in the gravity recovery apparatus, and the desorbed oxide dust particles are collected by gravity into the first collection container.

In one embodiment, a negative pressure is formed on the surface of the strip steel by the air extraction mechanism in the negative pressure recovery device, so that the oxide dust particles are desorbed from the surface of the strip steel, enter the air extraction port, and are sent into the second collection container through the air extraction pipeline .

In one embodiment, the oxide dust particles are charged with an electrostatic charge of a different polarity from that of the third collection container by an electrostatic generator in the electrostatic recovery device, and the oxide dust particles are collected into the third collection container by electrostatic adsorption. .

In one embodiment, a magnetic field is formed on the surface of the strip by the strong magnetic device in the magnetic recovery device, and the oxide dust particles are collected into the fourth collection container by the magnetic force.

In a preferred embodiment, in step S3, before the hot-rolled strip is coated, impurities on the surface of the hot-rolled strip are removed by pretreatment; the pretreatment includes degreasing, air drying, pickling and phosphating. one or more of.

In a preferred embodiment, in step S3, the thickness of the coating layer before curing is 1-500 μm.

In a preferred embodiment, in step S3, the coating is cured by air drying at room temperature, hot air drying, ultraviolet irradiation, heating furnace heating or electromagnetic induction heating, the curing temperature is 25-200°C, and the curing time is 0.1-25min, Preferably 0.3～25min.

In a preferred embodiment, in step S3, the coating is cooled by air cooling or natural cooling.

In a preferred embodiment, in step S4, when performing on-line testing, the coating thickness and coverage on the surface of the strip steel are tested by on-line testing equipment.

A second aspect of the present invention provides a production line that can be used in the method for continuous surface treatment of a hot-rolled strip according to the first aspect of the present invention, comprising an uncoiler (in the case of a hot-rolled strip), a welding machine, a straightening Straight machine, oxide particle recovery equipment, degreasing section, pickling section, phosphating section, coating equipment, heating equipment, cooling equipment, online testing equipment and coiling section or slitting and stacking section;

The oxide particle recovery device collects the oxide dust particles attached to the surface of the strip by exerting a force on the surface of the strip.

In a preferred embodiment, the scraping device is a roller, a movable scraper or a brush; and/or the strong magnetic device is an electromagnet.

In a preferred embodiment, the production line further includes an information control system; the online processing speed of the production line is 3-100 m/min.

The beneficial effects of the present invention are as follows:

1. The method for continuously treating the surface of hot-rolled strips of the present invention and the production line therefor use oxide particle recovery equipment to collect oxide dust particles on the surface of the strip, which is convenient for the recovery and treatment of oxide dust particles and truly realizes hot rolling. The oxide dust particles turn waste into treasure. By continuously coating the surface of the strip, a protective coating is formed on the surface of the strip, which improves the corrosion resistance of the hot-rolled strip to a certain extent, while avoiding the need for hot-rolled strips. The oxide scale on the surface will pollute the environment by generating oxide dust particles during subsequent storage, transportation and processing;

2. The hot-rolled strip surface continuous treatment method and the used production line of the present invention not only effectively solve the problems of oxide dust particles and easy corrosion on the surface of the hot-rolled strip, but also realize the comprehensive utilization of oxide dust particles. Significantly improves the corrosion resistance of hot-rolled strips and reduces user coating;

3. The hot-rolled strip surface continuous treatment method of the present invention and the production line used therefor can realize the continuous on-line treatment of 3-100 m/min of products, and satisfy the continuous processing and production of the hot-rolled strip under the conventional production rhythm of 60 m/min. The demand for rapid and continuous slitting of hot rolled steel sheets.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

Fig. 1 is the structural representation of the used production line of the hot-rolled strip surface continuous treatment method of the present invention;

Figure 2 is a schematic structural diagram of the oxide particle recovery device of the present invention, (a) is a gravity recovery device; (b) is a negative pressure recovery device, (c) is an electrostatic recovery device, and (d) is a magnetic recovery device.

detailed description

The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form.

1 and 2, the method for continuously treating the surface of a hot-rolled strip provided by the present invention includes the following steps:

The specific steps of S1 are: the coiled hot-rolled strip is uncoiled under the action of the uncoiler 1, and the coil tail of the previous hot-rolled coil is welded to the coil head of the latter hot-rolled coil by the welding machine 2. Repeating in this way, a continuous hot-rolled strip is formed, and the continuous hot-rolled strip enters the straightening machine 3 for straightening treatment;

S2: After the process (such as uncoiling, straightening) that easily causes the peeling of oxide scale on the surface of the strip steel, and before the coating process, the oxide dust particles 14 attached to the surface of the strip steel are collected by exerting a force on the surface of the strip steel, wherein the force The application is performed by the oxide particle recovery device 4. According to the difference of the applied force, the oxide particle recovery device 4 is selected from a gravity recovery device, a negative pressure recovery device, an electrostatic recovery device, and a magnetic recovery device as shown in FIG. 2 . or more.

(1) Use gravity recovery equipment to collect oxide dust particles by gravity: as shown in (a) in Figure 2, one or more scraping devices 41 in the gravity recovery equipment are respectively arranged on the lower surface and the upper surface of the strip; more than one The first collection container 42 is respectively arranged below the contact parts between the scraping device 41 and the lower surface and the upper surface of the strip; the relative movement between the strip and the scraping device 41 is used to oxidize the strip through mechanical friction or mechanical vibration. The oxide dust particles 14 are desorbed from the surface of the strip; the desorbed oxide dust particles 14 are collected into the first collection container 42 under the action of gravity; the scraping device 41 can be a roller, a movable scraper or a brush, etc., which can be used for Scraping device.

(2) Use negative pressure recovery equipment to collect oxide dust particles with negative pressure: As shown in (b) in Figure 2, a negative pressure is formed on the surface of the strip through the exhaust mechanism 45 in the negative pressure recovery device, so that the surface of the strip adheres to the The oxide dust particles 14 are desorbed from the surface of the strip steel under the action of negative pressure and enter the exhaust port 43 ; the final oxide dust particles 14 are sent into the second collection container 46 through the exhaust pipe 44 .

(3) Use electrostatic recovery equipment to collect oxide dust particles by electrostatic adsorption: As shown in (c) in Figure 2, the oxide dust particles 14 attached to the surface of the strip are brought to the surface of the strip through the electrostatic generator 48 in the electrostatic recovery equipment. The electrostatic charges of different polarities in the third collection container 47 utilize electrostatic adsorption to make the oxide dust particles 14 detach from the surface of the strip steel and enter the third collection container 47 under the suction force of the different charges.

(4) Use magnetic recovery equipment to collect oxide dust particles by magnetic adsorption: As shown in (d) in Figure 2, a strong magnetic field is formed near the surface of the strip through the strong magnetic device (such as an electromagnet) in the magnetic recovery equipment, so that The magnetic force between the fourth collection container 49 and the oxide dust particles 14 is greater than the combination of the adsorption force between the strip steel and the oxide dust particles 14 and the particle gravity, so that the oxide dust particles 14 are collected to the fourth collection container under the action of the magnetic force 49.

S3: The hot-rolled strip is coated by roller coating or spraying, and a coating is formed on the surface of the hot-rolled strip; after the coating is cured, the hot-rolled strip is cooled to room temperature;

The specific steps of S3 are: before painting, check the cleanliness of the surface of the strip steel. If the coating requirements are met, or the coating quality requirements are not high, the coating can be carried out directly. If the quality requirements are high, the surface impurities should be removed by pretreatment before the strip coating. The pretreatment includes degreasing, air drying, pickling and phosphating. After removing the impurities on the strip surface, confirm that the strip surface meets the coating requirements. , Continuously coat the surface of the strip by roller coating or spraying, and control the amount of paint by adjusting the gap between the coating roller and the surface of the strip or the nozzle pressure to form a coating with a thickness of 1 to 500 μm, and then send the strip into the The heating device 9 accelerates the curing of the coating to form a film, and then the cooling device 10 is used for air cooling or natural cooling to room temperature, wherein the strip steel is solidified by air drying at room temperature, hot air drying, ultraviolet irradiation, heating furnace heating or electromagnetic induction heating, The curing temperature is 25~200℃, and the curing time is 0.2~25min; the coating thickness can be calculated and accurate according to the consumption of the coating and the online processing speed of the production line, the width of the strip, the consumption of the coating and the set thickness of the coating Control, the specific calculation method of coating thickness and coating consumption refers to the "gravimetric analysis method" in GB/T 13452.2, so as to achieve stable and precise control of coating thickness and ensure that the coating thickness meets product requirements.

S4: On-line inspection of the coating on the surface of the hot-rolled strip, if the coating on the surface of the strip is qualified, coiling or slitting and stacking are carried out according to the requirements of the finished product.

The specific steps of S4 are: after the coating on the surface of the strip is solidified and stabilized, online detection of key indicators such as the coverage of the coating is carried out to ensure that the surface of the strip is effectively covered. The hole condition is judged, and the coating coverage is detected by an online detection device 11 (such as an online pinhole detector). When the number of pores per square meter or the diameter of pores in the detection area is greater than the required upper limit (see Table 1 for details), the coating is unqualified. Record the position of the unqualified area, and transmit the signal to the information control system, and then repaint or cut the unqualified area. The detection standard of the coating coverage is determined according to the type of coating and the thickness of the coating. The detection criteria in Table 1 were tested. When the coating coverage is qualified, according to the requirements of the finished product, coiling or slitting and stacking are carried out. If the finished product is required to be a steel coil, the strip steel with qualified coating shall be trimmed, slitted into strips and re-coiled, and then packaged and put into storage by spraying code. If the finished product is required to be a steel plate, trim the edge of the strip with qualified coating, and then chamfer, cut to length, cross-cut and stack, and then spray code and pack it into storage.

As shown in Figure 1, the method for continuous surface treatment of hot-rolled strip steel is carried out using the following production line, which includes an uncoiler 1, a welder 2, a straightener 3, an oxide particle recovery device 4, a degreasing section 5, an acid Washing section 6, phosphating section 7, coating equipment 8, heating equipment 9, cooling equipment 10, online testing equipment 11 and coiling section 12 or slitting and stacking section 13; wherein coating equipment 8 can be a roll coater , the online detection device 11 may be an online pinhole detector. The above-mentioned production line can also include an information control system, so as to realize automatic online control of coating, curing, cooling, online detection, shearing, coiling or slitting, and stacking process, and its online processing speed is 3 ~ 100m/min .

The oxide particle recovery device 4 collects the oxide dust particles 14 adhering to the surface of the strip by exerting a force on the surface of the strip. Depending on the applied force, the oxide particle recovery device 4 is selected from one or more of a gravity recovery device, a negative pressure recovery device, an electrostatic recovery device, and a magnetic recovery device as shown in FIG. 2 .

(1) Gravity recovery equipment for collecting oxide dust particles by gravity: as shown in (a) in FIG. 42. The scraping device 41 is a roller, a movable scraper or a brush. When the gravity recovery equipment is in use, one or more scraping devices 41 are respectively arranged on the upper and lower surfaces of the strip, and the scraping devices 41 are in contact with the upper and lower surfaces of the strip, and are respectively arranged below the contact parts. The first collection container 42 . Using the relative motion between the strip and the scraping device 41, the oxide dust particles 14 are desorbed from the surface of the strip by means of mechanical friction or mechanical vibration, and the desorbed oxide dust particles 14 are collected under the action of gravity into the first collection container 42 .

(2) Negative pressure recovery equipment for collecting oxide dust particles through negative pressure: As shown in (b) in FIG. The air extraction mechanism 45 sends the oxide dust particles 14 entering the air extraction port 43 into the second collection container 46 through the air extraction duct 44 . When the negative pressure recovery equipment is in use, the air outlet 43 is aimed at the upper and lower surfaces of the strip, and the air extraction mechanism 45 is used to form a negative pressure on the surface of the strip, so that the oxide dust particles 14 attached to the surface of the strip are removed from the strip under the action of the negative pressure. The strip steel surface is desorbed and enters the air extraction port 43 ; the final oxide dust particles 14 are sent into the second collection container 46 through the air extraction duct 44 .

(3) Electrostatic recovery equipment for collecting oxide dust particles by electrostatic adsorption: As shown in (c) of FIG. 2 , the negative pressure recovery equipment includes an electrostatic generator 48 and a third collection container 47 . The electrostatic generator 48 charges the oxide dust particles 14 with electrostatic charges of different polarities from the third collection container 47 , and collects the oxide dust particles 14 into the third collection container 47 through electrostatic adsorption. When the negative pressure recovery equipment is in use, the third collection container 47 is respectively arranged on the upper and lower surfaces of the strip. When the electrostatic generator 48 is in the working state, the oxide dust particles 14 are negatively charged, and the third collection container 47 is positively charged. , the oxide dust particles 14 are collected into the third collection container 47 by electrostatic adsorption.

(4) Magnetic recovery equipment for collecting oxide dust particles by magnetic adsorption: As shown in (d) in Figure 2, the magnetic recovery equipment includes a fourth collection container 49 provided with a strong magnetic device; a strong magnetic device (such as an electromagnet) A magnetic field is formed on the surface of the continuous steel plate, and the oxide dust particles 14 are collected into the fourth collection container 49 by the magnetic force; when the magnetic recovery equipment is in use, one or more fourth collection containers 49 with strong magnetic devices are respectively installed on the belt On the upper and lower surfaces of the steel, a strong magnetic field is formed near the surface of the strip through the strong magnetic device, so that the magnetic force between the fourth collection container 49 and the oxide dust particles 14 is greater than the adsorption force between the strip steel and the oxide dust particles 14 and the particle gravity , so that the oxide dust particles 14 are collected into the fourth collection container 49 under the action of the magnetic force.

When the production line is in working state, the coiled hot-rolled strip is placed on the uncoiler 1 for uncoiling. The coil tail of the previous hot-rolled steel strip or hot-rolled steel plate and the coil head of the latter hot-rolled steel strip or hot-rolled steel plate are welded by the welding machine 2, so as to repeatedly form a continuous form of hot-rolled steel strip. Then, after the continuous hot-rolled strip enters the straightening machine 3 for straightening, the oxide scale on the surface of the strip will fall off to form oxide dust particles 14 attached to the surface of the strip. Then, the strip steel enters the oxide particle recovery device 4, and the oxide dust particles 14 are collected by the force exerted by the oxide particle recovery device 4, so as to prevent the oxide dust particles 14 from contaminating the surface of the strip steel and affecting the coating effect, and at the same time realize oxidation recycling of dust particles 14. After that, the strip steel enters the pretreatment process, and degreasing, air drying, pickling and phosphating are carried out in the degreasing section 5, the pickling section 6 and the phosphating section 7, so that the surface cleanliness of the strip steel meets the coating requirements. Then, the steel strip enters the coating equipment 8, and the coating material is applied on the surface of the steel strip by roller coating or spraying to form a coating with a wet film thickness of 1-500 μm. Then, the strip steel enters the heating device 9, and is heated to the curing temperature by hot air, heating furnace or electromagnetic induction (for example, the curing temperature is 25-200°C) or by continuous ultraviolet light irradiation to promote the curing of the coating, and maintain for a period of time (for example, the curing time 0.1-25min or 0.2-25min). After the coating is cured and stabilized, stop heating and let the strip cool naturally or air-cool to room temperature. After that, the thickness and coverage of the coating are detected by the online detection device to judge whether it is qualified or not. If the coating is not qualified, the position of the unqualified area will be transmitted to the information control system, and the unqualified area will be removed before coiling, slitting and stacking. It is cut off and treated as waste; if the coating is qualified, it will enter the coiling section 12 or the slitting and stacking section 13 according to the requirements of the finished product to form the finished product for storage.

The method for continuously treating the surface of a hot-rolled strip of the present invention and the production line used therefor will be further introduced below with reference to specific embodiments.

Examples 1 to 7

In Examples 1 to 7, the hot-rolled strips were BS960E with a thickness of 2 mm and a width of 1080 mm, and were surface-treated by the above-mentioned treatment methods, and the surface oxide dust particles were collected and painted using the process parameters shown in Table 1.

Corrosion resistance tests were carried out on the surface-treated BS960E products of the above-mentioned Examples 1 to 7 and the BS960E hot-rolled strips without surface treatment of the comparative example. Take the samples of the products in Examples 1 to 7 and the BS960E hot-rolled strip samples in the comparative example respectively, and conduct a neutral salt spray test after the shearing part is treated with 3M tape. The test standard refers to ASTM B117, and the surface of the sample is recorded respectively. The time when slight rusting occurs (the rusted area is less than 5% of the total area).

Combining with Table 1, it can be seen that after the neutral salt spray test of the BS960E samples treated in Examples 1 to 7 and the BS960E samples in the comparative example, the corrosion resistance of the BS960E samples treated in Examples 1 to 7 is much higher than that in the comparative example. The corrosion resistance of the surface-treated BS960E samples; the coating thickness of the products obtained in Examples 1, 3, and 4 is large, and the products have high corrosion resistance, and can be used directly without coating; the coating thickness of the product in Example 5 is moderate, It is suitable for reapplying the intermediate paint and topcoat after processing at the user (no primer is required); the coating of the products in Examples 2, 6 and 7 is relatively thin, which can provide sufficient temporary protection during the subsequent storage, transportation and processing of the products. It provides protection against the generation of oxide dust particles and rust, and because the coating is thin, it basically has no effect on the user's use process such as butt welding, simple bending and shot blasting to remove oxide skin of subsequent products, which is convenient to use.

With reference to Examples 1 to 7, it can be seen that the continuous surface treatment method for hot-rolled strips of the present invention and the production line used therefor use oxide particle recovery equipment to collect oxide dust particles on the surface of the strip, which is convenient for oxide dust particles. Through the continuous coating on the surface of the strip, a protective coating is formed on the surface of the strip, which improves the corrosion resistance of the hot-rolled strip to a certain extent. At the same time, it avoids the generation of oxide dust particles in the subsequent storage, transportation and processing of the oxide scale on the surface of the hot-rolled sheet and strip to pollute the environment; The problems of oxide dust particles and easy rust on the belt surface realize the comprehensive utilization of oxide dust particles, and significantly improve the corrosion resistance of the hot-rolled strip and reduce the user's coating; the surface of the hot-rolled strip of the present invention is The continuous processing method and the production line used can realize continuous online processing of 3-100 m/min of products, and meet the needs of continuous processing of hot-rolled strips and rapid and continuous slitting of hot-rolled steel sheets under the conventional production rhythm of 60 m/min.

To sum up, the above-mentioned embodiments and examples are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should The technical solutions can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the claims of the present invention.

Claims

A method for continuously treating the surface of a hot-rolled strip, comprising the following steps:

S1: uncoiling and welding the coiled hot-rolled strip or welding the hot-rolled steel plate to form a continuous hot-rolled strip, and then straightening the continuous hot-rolled strip;

S2: collecting oxide dust particles attached to the surface of the hot-rolled strip by applying a force to the surface of the hot-rolled strip;

S3: The hot-rolled strip is coated by roller coating or spraying to form a coating on the surface of the hot-rolled strip; after the coating is cured, the hot-rolled strip is cooled to room temperature;

S4: On-line inspection of the coating on the surface of the hot-rolled strip, if the coating is qualified, coiling or slitting and stacking are carried out according to the requirements of the finished product.
The method for continuously treating the surface of a hot-rolled strip according to claim 1, characterized in that, in the step S2, the force is applied by an oxide particle recovery device.
The method for continuous surface treatment of hot-rolled strips according to claim 2, wherein the oxide particle recovery equipment is selected from one of gravity recovery equipment, negative pressure recovery equipment, electrostatic recovery equipment and magnetic recovery equipment or variety;

Wherein, the scraping device in the gravity recovery equipment uses mechanical friction or mechanical vibration to desorb oxide dust particles from the upper and lower surfaces of the strip, and the desorbed oxide dust particles are removed by gravity. collected into the first collection container;

Negative pressure is formed on the surface of the strip steel by the air extraction mechanism in the negative pressure recovery equipment, so that the oxide dust particles are desorbed from the surface of the strip steel, enter the air extraction port, and are sent into the second collection container through the air extraction duct ;

The oxide dust particles are charged with electrostatic charges of different polarities from the third collection container through the electrostatic generator in the electrostatic recovery device, and the oxide dust particles are collected into the third collection container by electrostatic adsorption. ;and / or

A magnetic field is formed on the surface of the strip steel by the strong magnetic device in the magnetic recovery device, and the oxide dust particles are collected into a fourth collection container by using the magnetic force.
The method for continuously treating the surface of a hot-rolled strip as claimed in claim 1, characterized in that, in the step S3, before coating the hot-rolled strip, the surface of the hot-rolled strip is removed by pretreatment. Impurities; the pretreatment includes one or more of degreasing, air drying, pickling and phosphating.
The method for continuously treating the surface of a hot-rolled strip according to claim 1, characterized in that, in the step S3, the thickness of the coating layer before curing is 1-500 μm.
The method for continuously treating the surface of a hot-rolled strip as claimed in claim 1, characterized in that, in the step S3, the coating is cured by using hot air drying, ultraviolet irradiation, heating furnace heating or electromagnetic induction heating, and curing is performed. The temperature is 25～200℃, and the curing time is 0.1～25min, preferably 0.3～25min.
The method for continuously treating the surface of a hot-rolled strip according to claim 1, characterized in that, in the step S3, the coating is cooled by air cooling or natural cooling.
The method for continuously treating the surface of a hot-rolled strip as claimed in claim 1, characterized in that, in the step S4, during the on-line detection, the coating thickness and coverage on the surface of the strip are detected by on-line detection equipment.
The production line used for the continuous surface treatment method for hot-rolled strips according to any one of claims 1 to 8, characterized in that the production line includes optional uncoilers, welding machines, straightening machines, oxidation machines that are arranged in sequence. Material particle recovery equipment, degreasing section, pickling section, phosphating section, coating equipment, heating equipment, cooling equipment, online testing equipment and coiling section or slitting and stacking section;

The oxide particle recovery device collects the oxide dust particles attached to the surface of the strip by exerting a force on the surface of the strip.
The production line according to claim 9, wherein the oxide particle recovery equipment is selected from one or more of gravity recovery equipment, negative pressure recovery equipment, electrostatic recovery equipment and magnetic recovery equipment;

Wherein, the scraping device in the gravity recovery equipment is used to desorb oxide dust particles from the upper and lower surfaces of the strip through mechanical friction or mechanical vibration, and the desorbed oxide dust particles are desorbed by gravity. collected into the first collection container;

Negative pressure is formed on the surface of the strip steel by the air extraction mechanism in the negative pressure recovery equipment, so that the oxide dust particles are desorbed from the surface of the strip steel, enter the air extraction port, and are sent into the second collection container through the air extraction duct ;

The oxide dust particles are charged with electrostatic charges of different polarities from the third collection container through the electrostatic generator in the electrostatic recovery device, and the oxide dust particles are collected into the third collection container by electrostatic adsorption. ;and / or

A magnetic field is formed on the surface of the strip steel by the strong magnetic device in the magnetic recovery device, and the oxide dust particles are collected into a fourth collection container by using the magnetic force.
The production line according to claim 10, wherein the scraping device is a roller, a movable scraper or a brush; and/or

The strong magnetic device is an electromagnet.
The production line according to any one of claims 9 to 11, characterized in that, the production line further comprises an information control system; and the online processing speed of the production line is 3-100 m/min.