阅读说明：本技术 一种超厚锌层镀锌板减轻边厚的控制方法 (Control method for reducing edge thickness of super-thick zinc layer galvanized plate ) 是由 马占军 陈国涛 贾海超 唐嘉悦 吴一浩 刘需 李彩云 王广英 于 2021-08-16 设计创作，主要内容包括：本发明涉及一种超厚锌层镀锌板减轻边厚的控制方法,属于冶金行业超厚锌层产品生产技术领域。技术方案是：按照以下步骤进行控制：(1)以热轧板为基板,锌层厚度≥500g/㎡；(2)热轧板凸度采用正凸度：其正凸度数值为40-70μm；(3)热轧板切边后确保端部平滑无毛刺；(4)热轧板退火温度：670-690℃,入锌锅温度460-465℃；(5)气刀间隙以中间1.2-1.4mm为基础,向两端分别以0.02-0.3mm增加量逐渐增大,直至增加到1.5-1.7mm为止。本发明的有益效果是：能够减轻边厚,减小镀锌板厚度差,避免产生浪形等缺陷。(The invention relates to a control method for reducing edge thickness of a super-thick zinc layer galvanized plate, belonging to the technical field of production of super-thick zinc layer products in the metallurgical industry. The technical scheme is as follows: the control is carried out according to the following steps: (1) hot rolled plates are taken as substrates, and the thickness of a zinc layer is more than or equal to 500g per square meter; (2) the convexity of the hot rolled plate adopts positive convexity: the positive convexity value is 40-70 μm; (3) after the edge of the hot rolled plate is cut, the end part is ensured to be smooth and have no burrs; (4) annealing temperature of hot rolled plate: 670 ℃ plus 690 ℃, and 460 ℃ plus 465 ℃ in a zinc pot; (5) the air knife gap is gradually increased by 0.02-0.3mm on the basis of 1.2-1.4mm in the middle to two ends until the distance is increased to 1.5-1.7 mm. The invention has the beneficial effects that: the thickness of the edge can be reduced, the thickness difference of the galvanized sheet can be reduced, and the defects of wave shape and the like can be avoided.)

1. A control method for reducing the edge thickness of a super-thick zinc layer galvanized plate comprises acid pickling, edge cutting, continuous annealing, galvanizing and finishing, and is characterized in that: the control is carried out according to the following steps:

(1) hot rolled plates are taken as substrates, and the thickness of a zinc layer is more than or equal to 500g per square meter;

(2) the convexity of the hot rolled plate adopts positive convexity: the positive convexity value is 40-70 μm;

(3) after the edge of the hot rolled plate is cut, the end part is ensured to be smooth and have no burrs;

(4) annealing temperature of hot rolled plate: 670 ℃ plus 690 ℃, and 460 ℃ plus 465 ℃ in a zinc pot;

(5) the air knife gap is gradually increased by 0.02-0.3mm on the basis of 1.2-1.4mm in the middle to two ends until the distance is increased to 1.5-1.7 mm.

2. The method for controlling the edge thickness reduction of the galvanized sheet with the ultra-thick zinc layer according to claim 1, characterized in that: the aluminum content in the zinc liquid is 0.2-0.23 wt%, and the iron content is less than or equal to 0.018 wt%.

3. The method for controlling the edge thickness reduction of the galvanized sheet with the ultra-thick zinc layer according to claim 1, characterized in that: the process speed of the hot rolled plate is controlled at 30-70 m/min.

4. The method for controlling the edge thickness reduction of the galvanized sheet with the ultra-thick zinc layer according to claim 1, characterized in that: and (3) finishing the hot rolled plate after galvanizing, wherein the convexity of a working roll of the finishing machine is 0-20 mu m, and the rolling force is 2700KN-4000 KN.

5. The method for controlling the edge thickness reduction of the galvanized sheet with the ultra-thick zinc layer according to claim 1, characterized in that: the thickness specification of the galvanized plate is 1.8-5.0 mm.

Technical Field

The invention relates to a control method for reducing edge thickness of a super-thick zinc layer galvanized plate, belonging to the technical field of production of super-thick zinc layer products in the metallurgical industry.

Background

The galvanized sheet is used as a deep-processing high-added-value product in the metallurgical industry, has the characteristics of strong corrosion resistance, excellent surface quality, good processing performance, strong economic applicability and the like, and is widely applied. With the rapid improvement of national economy and the optimization and adjustment of industrial structures, the rapid development of new energy sources, sponge cities and other emerging fields puts higher requirements on the corrosion resistance of galvanized products, and for example, photovoltaic power stations built on gobi deserts, deeply buried utility tunnels and the like all need to ensure sufficient service life in severe service environments. Too thin or uneven zinc layers can affect corrosion resistance, which requires an ultra-thick zinc layer for protection.

The production difficulty of the super-thick zinc layer product is high, and one of the main problems is that the edge is thick, and the edge thickness can cause the defects of large thickness difference range, wave shape and the like of the galvanized sheet, so that the galvanized sheet cannot be used by customers. The reasons and influencing factors for generating the edge thickness are complex, and mainly comprise: poor quality of the edge of the substrate, fast cooling of the edge of the strip steel, dispersion of air knife pressure at the position, high zinc liquid tension at the edge, high viscosity and the like, and finally, poor zinc liquid fluidity is caused to generate edge thickness defects. Many patents or documents propose solutions, but most methods only control the air knife gap adjustment and the reduction of the distance between the baffle plates, however, most air knives can only perform gap adjustment on line, and cannot meet the production of multi-specification strip steel, and in addition, the reduction of the distance between the baffle plates and the strip steel increases the risk that the baffle plates are adhered with slag, and after a certain amount of slag is accumulated, the slag is very easily hung on the strip steel, so that other defects are caused. Aiming at the problems, the method and the device have the advantages that various influencing factors are combined, the edge thickness is reduced by reasonably matching process parameters without modifying the existing equipment, and the production requirements of the galvanized plates with various specifications can be met.

Disclosure of Invention

The invention aims to provide a control method for reducing the edge thickness of a super-thick zinc layer galvanized plate, which can reduce the edge thickness, reduce the thickness difference of the galvanized plate, avoid the defects of wave shape and the like and solve the problems in the background technology.

The technical scheme of the invention is as follows:

a control method for reducing the edge thickness of an ultra-thick zinc layer galvanized plate comprises the steps of pickling, edge cutting, continuous annealing, galvanizing and finishing, and is controlled according to the following steps:

(1) hot rolled plates are taken as substrates, and the thickness of a zinc layer is more than or equal to 500g per square meter;

(2) the convexity of the hot rolled plate adopts positive convexity: the positive convexity value is 40-70 μm;

(3) after the edge of the hot rolled plate is cut, the end part is ensured to be smooth and have no burrs;

(4) annealing temperature of hot rolled plate: 670 ℃ plus 690 ℃, and 460 ℃ plus 465 ℃ in a zinc pot;

(5) the air knife gap is gradually increased by 0.02-0.3mm on the basis of 1.2-1.4mm in the middle to two ends until the distance is increased to 1.5-1.7 mm.

The aluminum content in the zinc liquid is 0.2-0.23% by mass, and the iron content is less than or equal to 0.018%.

The process speed of the hot rolled plate is controlled to be 30-70 m/min.

And the hot rolled plate is finished after being galvanized, the convexity of a working roll of the finishing machine is 0-20 mu m, and the rolling force is 2700KN-4000 KN.

The thickness specification of the galvanized plate is 1.8-5.0 mm.

The raw materials adopt positive convexity, which is beneficial to obtaining good plate shape and better matching air knife clearance; the width precision of the base plate after edge cutting is higher, so that the phenomenon that the distance between the air knife baffle and the strip steel is suddenly close and suddenly far in the galvanizing process is avoided, and the baffle function is weakened; the smooth and burr-free end part after edge cutting can effectively prevent the zinc from being carried too much or the zinc liquid from flowing unsmoothly, and provides quality guarantee for galvanization.

The annealing temperature of the hot rolled plate is 670-690 ℃, which is the optimal temperature range for obtaining good reducing sponge iron on the surface of the strip steel, the temperature is too high, the subsequent cooling is difficult, and the process speed is limited; the temperature is too low, the coating adhesion is poor, and the temperature drop of the edge part is more obvious. The temperature of the zinc pot is controlled between 460 and 465 ℃, the aluminum content of the zinc liquid is controlled between 0.2 percent and 0.23 percent, and the iron content is less than or equal to 0.018 percent, so that the fluidity of the zinc liquid can be effectively improved. The gradual increase of the air knife clearance is an approximate dumbbell-shaped clearance obtained by fully combining complex influence factors such as strip steel convexity, edge temperature drop, zinc liquid fluidity and the like, the uniformity of zinc scraping amount is ensured, and the uneven zinc layer is avoided.

The air knife baffle is 2-4mm away from the edge of the strip steel, so that the phenomenon that the baffle is stuck with slag due to the fact that the air knife baffle is too close to the edge of the strip steel (less than 2 mm) can be effectively avoided, the slag is very easy to hang on the strip steel after being accumulated to a certain amount, other defects are caused, and meanwhile, the phenomenon that the distance is too far is avoided, and the function of the baffle is reduced.

After galvanization, a flat roller or a small-convexity roller is used for smoothing, and meanwhile, the whole plate surface is smoothed by the rolling force between 2700 and 4000KN, so that the thickness of a zinc layer at the edge part can be further reduced. The problems that the rolling force is too small, the elongation is low, the effect is not obvious, and the rolling force is too large, so that wave shape or belt breakage is easily caused are avoided.

The invention has the beneficial effects that: under the condition of not reforming the existing equipment, the edge thickness is reduced, the thickness difference of the galvanized sheet is reduced, the defects of wave shape and the like are avoided and the production requirements of the galvanized sheets with various specifications are met by optimizing the raw material convexity, the trimming quality, the process speed, the annealing temperature, the air knife parameters, the zinc liquid components, the rolling force of a finishing machine, the roll shape convexity and the like.

Drawings

FIG. 1 is a schematic view of an air knife lip gap;

in the figure: 1. and adjusting the bolt.

Detailed Description

The invention is further illustrated by way of example in the following with reference to the accompanying drawings.

A control method for reducing the edge thickness of an ultra-thick zinc layer galvanized plate comprises the steps of pickling, edge cutting, continuous annealing, galvanizing and finishing, and is controlled according to the following steps:

(1) hot rolled plates are taken as substrates, and the thickness of a zinc layer is more than or equal to 500g per square meter;

(2) the convexity of the hot rolled plate adopts positive convexity: the positive convexity value is 40-70 μm;

(3) after the edge of the hot rolled plate is cut, the end part is ensured to be smooth and have no burrs;

(4) annealing temperature of hot rolled plate: 670 ℃ plus 690 ℃, and 460 ℃ plus 465 ℃ in a zinc pot;

(5) the air knife gap is gradually increased by 0.02-0.3mm on the basis of 1.2-1.4mm in the middle to two ends until the distance is increased to 1.5-1.7 mm.

The aluminum content in the zinc liquid is 0.2-0.23 wt%, and the iron content is less than or equal to 0.018 wt%.

The process speed of the hot rolled plate is controlled at 30-70 m/min.

And (3) finishing the hot rolled plate after galvanizing, wherein the convexity of a working roll of the finishing machine is 0-20 mu m, and the rolling force is 2700KN-4000 KN.

The thickness specification of the galvanized plate is 1.8-5.0 mm.

Example 1:

the thickness specification of the galvanized sheet is as follows: 1.8mm, 1500mm width, zinc layer thickness of 700 g/square meter, hot rolled plate as base plate, convexity as follows: 70 μm, and cutting edge, with smooth end and no burr, annealing temperature of 670 deg.C (plate temperature), and zinc pot temperature of 465 deg.C. The air knife gap is gradually increased by 0.02-0.3mm increments towards both ends based on the middle 1.4mm, until the air knife gap is increased to 1.7 mm. The specific increment is as follows: 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.2, 0.24, 0.3mm, the gap values are shown in Table 1.

The air knife is a Posjet air knife, the length of a knife lip is 2000mm, and the air knife is treated by adopting a titanium nitride coating and has the characteristics of high temperature resistance, difficult adhesion of zinc liquid and easy cleaning. The knife lip gap can be adjusted by manually adjusting bolts, the distance between every two adjacent adjusting bolts is about 40mm, and the schematic diagram of the knife lip gap is shown in the attached figure 1.

The aluminum content in the zinc liquid is controlled to be 0.23 percent, the iron content is less than or equal to 0.018 percent, the process speed is 70m/min, the air knife baffle plate is 4mm away from the edge of the strip steel, the working roll convexity is 0 mu m after the galvanizing and the rolling force is 2700 KN. The zinc layer thickness measurements before and after the method were performed are shown in table 2.

Table 1 example 1 mid-to-end gap values

Table 2 table for measuring thickness of zinc layer before and after the method of example 1 is performed

Example 2:

the thickness specification of the galvanized sheet is as follows: 4.0mm, 1500mm width, zinc layer thickness 500 g/square meter, use hot rolled plate as the base plate, the convexity is: 40 mu m, and the smooth end without burr annealing temperature is 690 ℃ (plate temperature) after edge cutting, and the temperature of the zinc pot is 460 ℃. The air knife gap is gradually increased by 0.02-0.3mm increments towards both ends based on the middle 1.2mm, until the air knife gap is increased to 1.5 mm. The specific increment is as follows: 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.2, 0.24, 0.3mm, the gap values are shown in Table 3. The air knife was the same as in example 1.

The aluminum content in the zinc liquid is controlled to be 0.20 percent, the iron content is less than or equal to 0.018 percent, the process speed is 30m/min, the distance between an air knife baffle plate and the edge of the strip steel is 2mm, the working roll convexity is 20 mu m after the galvanizing and the rolling force is 4000 KN. The zinc layer thickness measurements before and after the method were performed are shown in Table 4.

Table 3 example 2 mid to end gap values

Table 4 table for measuring thickness of zinc layer before and after the method of example 2

Example 3:

the thickness specification of the galvanized sheet is as follows: 3.0mm, 1500mm width, zinc layer thickness 600 g/square meter, hot rolled plate as base plate, convexity is: 50 μm, trimming, and annealing at 680 deg.C (plate temperature) and 462 deg.C in a zinc pot. The air knife gap is gradually increased by 0.02-0.3mm increments towards both ends based on the middle 1.3mm, until the air knife gap is increased to 1.6 mm. The specific increment is as follows: 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.2, 0.24, 0.3mm, the gap values are shown in Table 5. The air knife was the same as in example 1.

The aluminum content in the zinc liquid is controlled to be 0.22 percent, the iron content is less than or equal to 0.018 percent, the process speed is 50m/min, the air knife baffle plate is 2mm away from the edge of the strip steel, the working roll convexity is 10 mu m after the galvanizing and the rolling force is 3200 KN. The zinc layer thickness measurements before and after the method were performed are shown in Table 6.

Table 5 example 3 mid to end gap values

Table 6 table for measuring thickness of zinc layer before and after the method of example 3

。