Method for controlling height of crocodile mouth of hot-rolled aluminum plate

Abstract

The invention belongs to the field of aluminum plate preparation, and discloses a method for controlling the height of a crocodile mouth of a hot-rolled aluminum plate, which comprises the following steps: S1, constructing a hot rough rolling emulsion system; s2, the head and tail cutting thickness of the strip is increased; s3, optimizing the biting speed of the strip; and S4, a hot rough rolling emulsion system is used for spraying emulsion, the head temperature of the hot-rolled aluminum plate is reduced, and the metal fluidity of the head surface layer of the hot-rolled aluminum plate is reduced. According to the method, by installing and optimizing the starting and stopping opportunities of rough rolling strip cooling, the temperature of the rough rolling head is reduced, the deformation resistance is increased, longitudinal flowing of metal on the surface layer of the head of the aluminum alloy cast ingot is reduced, under the same biting condition, the height of a crocodile mouth is reduced, meanwhile, the thickness and the biting speed of a rough rolling head and tail cutting pass plate are optimized in an assisted mode, and therefore the yield of the aluminum alloy cast ingot is improved. And the crocodile mouth height of the head is improved together.

Description

Technical Field

[0001] The invention belongs to the field of aluminum plate preparation, and in particular relates to a method for controlling the height of the crocodile mouth of a hot-rolled aluminum plate. Background Art

[0002] Aluminum and aluminum alloy strips have the advantages of light weight, high specific strength, good corrosion resistance, easy processing, and beautiful surface. They are widely used in important national economic fields such as aerospace, automobile, machinery manufacturing, shipbuilding and chemical industry. During the hot rolling process, aluminum alloy eliminates the defects of casting structure due to large reduction rolling, and transforms the casting structure into deformation structure. Its continued products have great advantages in deep drawing performance, surface quality and precision control. However, the initial thickness of the initial slab of aluminum alloy hot rolling is large, and the rolling reduction cannot penetrate into the core, resulting in the surface metal fluidity greater than the core metal fluidity, and the accumulated deformation forms an obvious "crocodile mouth" at the head and tail. "Crocodile mouth" refers to the open mouth at the head and tail caused by multiple reciprocating pressure during the rolling process of hot-rolled plate ingots. During the rolling process of aluminum plates, the height of the "crocodile mouth" is relatively high, and the following problems usually exist: 1). It is easy to damage the equipment and scratch the guard plate of the rolling mill; 2). The aluminum chips generated by scratching are easy to press into the plate to form peeling defects.

[0003] According to relevant research literature, variables such as rolling temperature, reduction rate, rolling speed and roll diameter are important process parameters for controlling the "crocodile mouth" phenomenon during metal hot rolling. However, there is no relevant research at home and abroad on the impact of strip cooling and emulsion system control on the height of the strip's "crocodile mouth". Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for controlling the height of the crocodile mouth of hot-rolled aluminum plates. The present invention aims to solve the problems of the "crocodile mouth" being too high during the hot rolling process of aluminum plates, which is easy to damage equipment and cause peeling.

[0005] To achieve the above object, the present invention provides a method for controlling the height of the crocodile mouth of a hot-rolled aluminum plate, comprising the following steps:

[0006] S1. Constructing a hot rough rolling emulsion system;

[0007] The hot rough rolling emulsion system is used to cool the working rolls and the hot rolled aluminum plate, and is used to reduce the friction between the working rolls and the hot rolled aluminum plate;

[0008] S2. Increase the thickness of the strip cutting head and tail;

[0009] The thickness of the strip at the cut end is proportional to the height of the alligator mouth after hot rolling;

[0010] S3. Optimize the strip biting speed;

[0011] The strip biting speed is inversely proportional to the height of the alligator mouth after hot rolling;

[0012] S4. Use the hot rough rolling emulsion system to spray the emulsion to reduce the head temperature of the hot rolled aluminum sheet and reduce the metal fluidity of the head surface of the hot rolled aluminum sheet;

[0013] Before the plate bites in, start the bite spray in advance to cool the working roll and reduce the head temperature of the hot-rolled aluminum plate;

[0014] At the entrance of the deformation zone, the emulsion is sprayed to fill the gap between the working roll and the surface of the hot-rolled aluminum plate with the emulsion, thereby establishing an oil film with a certain load-bearing capacity, further reducing the friction between the hot-rolled aluminum plate and the working roll, and finally producing a hot-rolled aluminum plate with a low crocodile mouth height.

[0015] Furthermore, the hot rough rolling emulsion system includes spray beams arranged on both sides of the upper and lower working rolls. The number of the spray beams is four. The four spray beams are provided with a number of evenly spaced spray valves on the side facing the hot-rolled aluminum plate. One spray valve is equipped with one nozzle, and the spray valve is controlled by a solenoid valve for signal control.

[0016] Furthermore, the number of injection valves on each injection beam is 20, the distance between two adjacent injection valves is 90 mm, the 8 injection valves in the middle of the injection beam are controlled by a solenoid valve, and the remaining 12 injection valves on both sides of the injection beam are controlled by 6 solenoid valves in a left-right symmetrical manner.

[0017] Furthermore, the flow rate of the nozzle is 35 L / min.

[0018] Furthermore, the width of the strip radiated by the spray beam nozzle is ≥1920 mm.

[0019] Furthermore, the working pressure of the hot rough rolling emulsion system nozzle spraying emulsion is 4 to 10 Bar, the filtration accuracy is 250 microns, and the metal particle content is ≤100ppm.

[0020] Beneficial effects:

[0021] The present invention provides a method for controlling the height of the crocodile mouth of a hot-rolled aluminum plate. By installing and optimizing the opening and closing timing of the cooling of the rough-rolled strip, the temperature of the rough-rolled head is reduced, the deformation resistance thereof is increased, and the longitudinal flow of the surface metal of the head of the aluminum alloy ingot is reduced. Under the same biting conditions, the height of the "crocodile mouth" is reduced. At the same time, the thickness of the plate in the rough-rolled head and tail pass and the biting speed are optimized to jointly improve the height of the "crocodile mouth" of the head.

[0022] The method of the present invention is suitable for solving the problem of the crocodile mouth height of the strip rolled by the rough rolling mill in the aluminum processing industry, reducing the amount of sawing and thus reducing metal loss, while directly improving the defect of aluminum chips being pressed into the guide plate caused by the head scratching the guide plate, and can protect the transport roller and reduce the risk of collision with the guide ruler, while being beneficial to ensuring the stability of the equipment and improving the quality of the plate.

[0023] 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

[0024] Figure 1 It is a schematic diagram of the structure of the hot rough rolling emulsion system;

[0025] Figure 2 It is the structural schematic diagram of the spray beam;

[0026] Figure 3 A drawing of a rolling mill is provided;

[0027] Reference numerals: working roll 1, hot-rolled aluminum plate 2, spray beam 3. DETAILED DESCRIPTION

[0028] In order to make the technical solutions, advantages and purposes of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of this application.

[0029] like Figure 1 to Figure 3 As shown, the present invention provides a method for controlling the height of the crocodile mouth of a hot-rolled aluminum plate, comprising the following steps:

[0030] S1. construct a hot rough rolling emulsion system, which is used to cool the working roll 1 and the hot rolled aluminum plate 2, and to reduce the friction between the working roll 1 and the hot rolled aluminum plate 2;

[0031] The emulsion sprayed in the hot rough rolling emulsion system has two main functions: lubrication and cooling. The cooling effect mainly depends on the evaporation of water in the emulsion, while the lubrication effect is mainly manifested in reducing the friction coefficient.

[0032] The hot rough rolling emulsion system includes a single-cavity stainless steel structure spray beam 3 arranged on both sides of the upper and lower working rolls 1, and there are four spray beams 3 at the inlet and outlet. The four spray beams 3 are each provided with 20 spray valves at even intervals on one side facing the hot-rolled aluminum plate 2. One spray valve is equipped with one nozzle, and the spray valve is controlled by a signal through a solenoid valve.

[0033] The distance between two adjacent injection valves is 90 mm. The eight injection valves in the middle of the injection beam 3 are controlled by one solenoid valve. The remaining 12 injection valves on both sides of the injection beam 3 are controlled by six solenoid valves in a left-right symmetrical manner. The two injection valves symmetrical about the rolling line on the upper and lower injection beams 3 on the outlet side and the inlet side are controlled by the same signal.

[0034] There are 20 nozzles on one spray beam 3, one spray valve controls one nozzle, the flow rate of each nozzle is 35L / min, and the flow rate of a single spray beam 3 is 700L / min (the maximum flow rate of the spray beam 3 and pipeline without nozzles is designed to be 1000L / min / piece);

[0035] The eight injection valves in the middle of the injection beam 3 are controlled simultaneously to cover the minimum strip width of 900 mm;

[0036] There are 6 injection valves on each side, which are symmetrically controlled in pairs to adapt to the change of material width. The width of the strip radiated by the 3 nozzles of the injection beam is ≥1920mm;

[0037] The working pressure of the hot rough rolling emulsion system nozzle spraying emulsion is 4 to 10Bar, the filtration accuracy is 250 microns or better, and the metal particle content is ≤100ppm.

[0038] S2. Increase the thickness of the strip cutting head and tail;

[0039] The thickness of the strip cutting head and tail has an impact on the "crocodile mouth" of the strip. Generally speaking, the thicker the cutting head and tail thickness, the lower the height of the "crocodile mouth", that is, the thickness of the strip cutting head and tail is proportional to the height of the crocodile mouth after hot rolling;

[0040] S3. Optimize the strip biting speed;

[0041] The strip biting speed has an improving effect on the head "crocodile mouth". The faster the strip biting speed, the more sudden changes in rolling force will occur at the junction of the tail of the "crocodile mouth" and the plate after the head is successfully threaded, thus causing the "crocodile mouth" to tear and increasing the height of the "crocodile mouth". That is, the strip biting speed is inversely proportional to the height of the crocodile mouth after hot rolling.

[0042] S4. Use the hot rough rolling emulsion system to spray the emulsion to reduce the head temperature of the hot-rolled aluminum sheet 2 and reduce the metal fluidity of the head surface of the hot-rolled aluminum sheet 2;

[0043] Before the plate bites in, start the bite spray in advance (use emulsion to spray the roll gap area of ​​the working roll 1) to cool the working roll 1 and reduce the head temperature of the hot-rolled aluminum plate 2;

[0044] At the entrance of the deformation zone, the emulsion is sprayed to fill the gap between the working roll 1 and the surface of the hot-rolled aluminum plate 2 with the emulsion, thereby establishing an oil film with a certain load-bearing capacity. Fluid dynamics research shows that when the solid surface moves, the liquid layer connected to it is driven to move at the same speed, that is, there is almost no relative sliding between the solid and liquid contact layers, further reducing the friction between the plate and the working roll 1, thereby reducing the height of the plate's crocodile mouth.

[0045] 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 protection scope of the present invention.

Claims

1. A method for controlling the height of the crocodile mouth of a hot-rolled aluminum sheet, characterized in that: The following steps are involved: S1. Constructing a hot rough rolling emulsion system; The hot rough rolling emulsion system is used to cool the working rolls and the hot rolled aluminum plate, and is used to reduce the friction between the working rolls and the hot rolled aluminum plate; S2. Increase the thickness of the strip cutting head and tail; The thickness of the strip at the cut end is proportional to the height of the alligator mouth after hot rolling; S3. Optimize the strip biting speed; The strip biting speed is inversely proportional to the height of the alligator mouth after hot rolling; S4. Use the hot rough rolling emulsion system to spray the emulsion to reduce the head temperature of the hot rolled aluminum sheet and reduce the metal fluidity of the head surface of the hot rolled aluminum sheet; Before the plate bites in, start the bite spray in advance to cool the working roll and reduce the head temperature of the hot-rolled aluminum plate; At the entrance of the deformation zone, the emulsion is sprayed to fill the gap between the working roll and the surface of the hot-rolled aluminum plate with the emulsion, thereby establishing an oil film with a certain load-bearing capacity, further reducing the friction between the hot-rolled aluminum plate and the working roll, and finally producing a hot-rolled aluminum plate with a low crocodile mouth height.

2. The method for controlling the height of the crocodile mouth of a hot-rolled aluminum sheet according to claim 1, characterized in that: The hot rough rolling emulsion system includes spray beams arranged on both sides of the upper and lower working rolls. There are four spray beams. The four spray beams are provided with a plurality of spray valves with even intervals on one side facing the hot-rolled aluminum plate. One spray valve is equipped with one nozzle. The spray valve is controlled by a signal through an electromagnetic valve.

3. The method for controlling the height of the crocodile mouth of a hot-rolled aluminum sheet according to claim 2, characterized in that: There are 20 injection valves on each injection beam, and the distance between two adjacent injection valves is 90 mm. The 8 injection valves in the middle of the injection beam are controlled by a solenoid valve, and the remaining 12 injection valves on both sides of the injection beam are controlled by 6 solenoid valves in a left-right symmetrical manner.

4. The method for controlling the height of the crocodile mouth of a hot-rolled aluminum sheet according to claim 3, characterized in that: The flow rate of the nozzle is 35 L / min.

5. The method for controlling the height of the crocodile mouth of a hot-rolled aluminum sheet according to claim 4, characterized in that: The strip width radiated by the spray beam nozzle is ≥1920 mm.

6. A method for controlling the height of the crocodile mouth of a hot-rolled aluminum plate according to claim 5, characterized in that: The working pressure of the hot rough rolling emulsion system nozzle spraying emulsion is 4 to 10 Bar, the filtration accuracy is 250 microns, and the metal particle content is ≤100ppm.

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