Processing method of ultra-low carbon steel cold-rolled steel coil

Abstract

The invention discloses a machining method of an ultra-low carbon steel cold-rolled steel coil. The machining method mainly comprises the steps of shearing process control, circle shear overlapping amount and side gap control, circle shear cutter matching, matching control and circle shear sleeve design. In the shearing process, a circle shear serves as a power shear and does not depend on a moving steel belt. The overlapping amount of the circle shear is controlled to be 1-1.5 mm, and the side clearance is 0.3-0.35 mm; an upper cutter sleeve of the circle shear is composed of a small cutter sleeve and a large cutter sleeve, and the large cutter sleeve is arranged on the side, away from an upper cutter head, of the small cutter sleeve. The number of the lower cutter sleeve of the circle shear is one. The defects of saw-tooth edges and bright marks after ultra-low carbon steel cold hard rolling and rolling are overcome through control of all the processes.

Description

Technical Field

[0001] The invention relates to the technical field of cold-rolled steel coils, and in particular to a processing method for ultra-low carbon steel cold-rolled steel coils. Background Art

[0002] The steel industry has always been an important basic industry of my country's national economy and an important symbol of the country's economic level and comprehensive national strength. The importance of steel in the national economy is self-evident. It is not only the pillar of infrastructure construction, but also a key factor in promoting national industrialization and modernization.

[0003] There is a special type of carbon steel, which is ultra-low carbon steel. Ultra-low carbon steel has excellent corrosion resistance, toughness and good mechanical properties, and is often used in applications that require high corrosion resistance and high strength. However, during the cold rolling process, ultra-low carbon steel is prone to surface bright marks, jagged edges and other defects, which seriously affect the use of downstream galvanizing lines and aluminum-zinc coating lines. At present, the existing technology mainly has the following two deficiencies: 1. After cold rolling, the edge of the steel coil has a serrated edge, that is, after rolling, a small serrated notch appears on the edge of the steel strip, with a depth of about 2mm. Figure 1 shown.

[0004] 2. After cold rolling, there is a bright print defect on the surface of the steel strip, which is mainly concentrated on the lower plate surface of the cold hard coil, such as Figure 2 shown. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method for processing an ultra-low carbon steel cold-rolled coil.

[0006] The present invention is achieved through the following technical solutions: A processing method for ultra-low carbon steel cold-rolled steel coil: Pickling: Use push-pull shallow tank turbulent pickling line; Shearing process control: The disc shear always acts as a power shear to rotate and shear the steel belt, without the need for the moving steel belt to pull the shearing; Disc shear overlap and side clearance control: Disc shear overlap is controlled at 1-1.5mm, and side clearance is controlled at 0.3-0.35mm; Through shearing process control and disc shear overlap and side clearance control, the shearing surface is less than or equal to one third of the hot rolled coil thickness; Knife sheath of disc shears: The upper knife sheath of disc shears consists of 1 small knife sheath and 1 large knife sheath, and the large knife sheath is arranged on the side of the small knife sheath away from the upper knife disc; the lower knife sheath of disc shears is 1 lower knife sheath; Disc shears with knives and matching controls: the diameter of the upper knife disc is 4-5mm larger than the diameter of the small knife sleeve, the diameter of the upper knife disc is 2-3mm larger than the diameter of the large knife sleeve, and the diameter of the lower knife disc is 2-3mm smaller than the diameter of the lower knife sleeve.

[0007] Preferably, the mass percentages of the components of the ultra-low carbon steel cold-rolled coil are: C≤0.005%, Si≤0.03%, Mn≤0.25%, S≤0.03%, P≤0.03%, N≤0.005%, Als≤0.065%, and Ti≤0.06%.

[0008] Preferably, the ultra-low carbon steel cold-rolled coil is cold rolled using a six-roll reversing rolling mill.

[0009] Preferably, the shearing speed of the ultra-low carbon steel cold-rolled coil is ≥100 m / min.

[0010] The beneficial effects of the present invention are as follows: the present invention can make the shearing surface less than or equal to one third of the thickness of the hot-rolled coil by shearing process control and the control of the overlap amount and side clearance of the disc shear; the bright print defect is eliminated by the disc shear sleeve design and the disc shear knife matching and matching control. The present invention solves the defects of the ultra-low carbon steel cold hard coil, the jagged edge and bright print after rolling, and provides a high-quality substrate for the downstream galvanizing line and galvanized aluminum line. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0012] Figure 1 This is a picture of small jagged notches on the edge of the steel strip after cold rolling.

[0013] Figure 2 This is a picture of a bright mark on the surface of the steel strip after cold rolling.

[0014] Figure 3 This is a fully cropped image.

[0015] Figure 4 The composition of the shear section.

[0016] Figure 5 The following are product photos of each experiment in Table 1.

[0017] Figure 6 Structural view of the upper and lower cutters for the disc shears.

[0018] In the attached figure: 1. Upper knife disc; 2. Small knife cover; 3. Large knife cover; 4. Lower knife disc; 5. Lower knife cover; a, collapsed shoulder area; b, shear surface; c, tearing layer; d, burr area. DETAILED DESCRIPTION

[0019] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited to the specific embodiments disclosed below.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0021] The present invention is described in detail below: The present invention provides a processing method for ultra-low carbon steel cold-rolled coil, which solves the defects of surface bright printing and edge jagged edges that are easy to appear during the cold rolling process in the prior art. The mass percentage of each component of the ultra-low carbon steel cold-rolled coil is: C≤0.005%, Si≤0.03%, Mn≤0.25%, S≤0.03%, P≤0.03%, N≤0.005%, Als≤0.065%, Ti≤0.06%.

[0022] The edge of the cold hardened coil has serrated edges after rolling. The main reason is that the pickling line disc shear is not shearing well. The pickling line is a push-pull shallow groove turbulent pickling line. When shearing ultra-low carbon steel hot-rolled coils, the shear surface is large after shearing, close to full shearing, such as Figure 3 shown.

[0023] In order to solve the problem of poor shearing of the disc shear in the pickling line, we tackled the problem from the following two aspects: (1) Changes in shearing process Original shearing process: When the disc shear is threaded at low speed, under the action of the overrunning clutch, it acts as a power shear to shear the steel strip. Under normal working speed, the speed is ≥100m / min, the overrunning clutch is disengaged, and the disc shear acts as a pulling shear to shear the steel strip. All push-pull shallow groove turbulent pickling lines are based on this shearing principle.

[0024] New shearing process: Whether it is low-speed threading or normal working speed, the disc shear acts as a power shear to shear the steel belt. That is to say, the disc shear does not need to be pulled by the running steel belt to shear. By providing power to the disc shear, the disc shear can rotate and shear the steel belt. This effectively reduces the shearing force of the disc shear, thereby reducing the shearing amount.

[0025] (2) Optimization of the overlap and side clearance of the disc shear Ultra-low carbon steel coils, due to the low C (carbon) content and very soft raw materials, are very difficult to shear for push-pull pickling lines. The overlap and side clearance process parameters are very important. After several process tests, we finally determined the optimal process parameter values. The overlap is 1-1.5mm and the side clearance is 0.3-0.35mm, which can effectively control the shear surface within one-third. The experimental data are shown in Tables 1 and 2. For example, if the thickness of the hot-rolled coil is 3.0mm, the shear surface should be less than or equal to 1mm. The composition of the shear section is as follows: Figure 4 shown.

[0026] Table 1 Table 2 After cold rolling, bright printing defects on the surface of the steel coil: After the cold-hardened coil is rolled, there are bright print defects on the surface of the steel coil. Through our on-site inspection during the cold rolling production, we determined that it was not caused by the cold rolling production line. Therefore, we traced it back and finally found that it was caused by the pickling line. In order to solve this defect, we tackled the problem from the following two aspects: (1) The knife cover of the circular shears: the upper knife is changed from 1 knife cover to 1 small knife cover and 1 large knife cover The disc shear consists of an upper blade and a lower blade. The upper blade is mainly used for shearing, while the lower blade mainly plays a supporting role and cooperates with the upper blade to complete the entire shearing process. Each blade has only one knife sleeve to fix it. The disadvantage of this method is that during the shearing process, the upper blade rotates at high speed and is fixed with only one knife sleeve. The upper blade is easy to shake up and down, making the upper blade and the lower blade fit too tightly. The blade of the lower blade has a certain friction with the lower plate surface of the steel plate, that is, the blade of the lower blade is printed on the plate surface. Therefore, the cold rolling cannot be eliminated during rolling, resulting in a light print without hand feeling. In order to solve this drawback, we made a change. The upper blade was changed from 1 knife sleeve to 1 small knife sleeve and 1 large knife sleeve, which can make the shearing more stable and effectively reduce the occurrence of light print defects.

[0027] (2) Optimization of disc shears and matching methods The diameter of the upper knife disc is 4-5mm larger than the diameter of the small knife sleeve, the diameter of the upper knife disc is 2-3mm larger than the diameter of the large knife sleeve, and the diameter of the lower knife disc is 2-3mm smaller than the diameter of the lower knife sleeve.

[0028] After the above two changes, the bright printing defect after cold hard coil rolling was completely eliminated.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for processing ultra-low carbon steel cold-rolled coils, characterized in that: Pickling: Use push-pull shallow tank turbulent pickling line; Shearing process control: The disc shear always acts as a power shear to rotate and shear the steel belt, without the need for the moving steel belt to pull the shearing; Disc shear overlap and side clearance control: Disc shear overlap is controlled at 1-1.5mm, and side clearance is controlled at 0.3-0.35mm; Through shearing process control and disc shear overlap and side clearance control, the shearing surface is less than or equal to one third of the hot rolled coil thickness; The knife sheath of the circular shears: the upper knife sheath of the circular shears is composed of a small knife sheath (2) and a large knife sheath (3), and the large knife sheath (3) is arranged on the side of the small knife sheath (2) away from the upper knife disc (1); the lower knife sheath of the circular shears is a lower knife sheath (5); The disc shears are equipped with knives and matching controls: the diameter of the upper knife disc (1) is 4-5 mm larger than the diameter of the small knife sleeve (2), the diameter of the upper knife disc (1) is 2-3 mm larger than the diameter of the large knife sleeve (3), and the diameter of the lower knife disc (4) is 2-3 mm smaller than the diameter of the lower knife sleeve (5).

2. The method for processing an ultra-low carbon steel cold-rolled coil according to claim 1, characterized in that: The mass percentages of the components of the ultra-low carbon steel cold-rolled coil are: C≤0.005%, Si≤0.03%, Mn≤0.25%, S≤0.03%, P≤0.03%, N≤0.005%, Als≤0.065%, and Ti≤0.06%.

3. The method for processing an ultra-low carbon steel cold-rolled coil according to claim 1, characterized in that: Ultra-low carbon steel cold-rolled coils are cold rolled using a six-roll reversing rolling mill.

4. The method for processing an ultra-low carbon steel cold-rolled coil according to claim 1, characterized in that: The shearing speed of ultra-low carbon steel cold-rolled coil is ≥100m / min.

Images