Method for preventing edge quality defects of hot rolled strip steel

Abstract

The invention discloses a method for preventing edge quality defects of hot-rolled strip steel, which belongs to the technical field of hot-rolled strip steel quality control, and comprises the following steps: controlling the opening degree of a side guide plate, and respectively adopting a three-section independent control mode for a shear front side guide plate and a finishing mill side guide plate; the abrasion degree of the side guide plate is detected in real time or regularly, and when the abrasion degree of the side guide plate exceeds an abrasion threshold value, the side guide plate lining plate is replaced; otherwise, the side guide plate lining plate is not replaced; the oil cylinder pin shaft frame amount of the side guide plate is detected in real time or regularly, and when the oil cylinder pin shaft frame amount exceeds a frame amount threshold value, the oil cylinder pin shaft frame amount is processed; otherwise, not processing; the center line of the side guide plate is calibrated, and the center line of the side guide plate deviates from the transmission side or the operation side by Xmm with the center line of the archway as the benchmark according to the abrasion condition of the side guide plate; the method solves the problem of strip steel edge quality defects caused by abnormal rubbing of the strip steel edge and the side guide plate in the production process of hot-rolled strip steel, and particularly solves the quality problem caused by impact of head and tail side bends of the strip steel on the side guide plate.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-rolled strip quality control, and in particular relates to a method for preventing edge quality defects of hot-rolled strip. Background Art

[0002] Hot rolling is a continuous rolling process used to produce hot rolled steel strip. This process involves heating the slab to a specific temperature and then processing it into a strip of steel with the desired thickness and properties through a series of rolling steps such as rough rolling, finishing rolling, and finally cooling and coiling.

[0003] At present, the hot rolling production process mainly produces hot-rolled strip steel through the following steps: first, the slab is heated to the set temperature in the heating furnace; then the surface oxide scale is removed by high-pressure water descaling; then the slab is rolled into an intermediate billet by rough rolling; then the intermediate billet is rolled into the thickness of the finished strip by finishing rolling; finally, it is cooled to the set temperature by the laminar cooling system and coiled into a steel coil on the coiler. During the finishing rolling process, the side guide device is used to control the position of the strip and prevent deviation.

[0004] However, it was found during the production process that the edge of the strip was scratched due to abnormal scraping between the edge of the strip and the side guide; the side bending of the head and tail of the strip is a problem that is difficult to completely avoid. The side bending of the strip may be caused by many factors, such as uneven deformation during hot rolling, equipment accuracy problems, initial slab state, stress distribution during rolling, and uneven temperature distribution. Therefore, a method is urgently needed to effectively prevent the deflected hot-rolled strip from scratching abnormally with the side guide during production, resulting in edge quality defects, and improve product quality and production efficiency. Summary of the invention

[0005] The object of the present invention is to provide a method for preventing quality defects on the edge of hot-rolled strip, so as to solve the technical problem raised in the above-mentioned background technology that in the production process of hot-rolled strip, the edge of the strip is abnormally scratched against the finishing side guide plate due to the side bending of the strip head and tail, resulting in quality defects on the edge of the strip.

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

[0007] A method for preventing edge quality defects of hot-rolled strip steel, comprising:

[0008] Control the opening of the side guide plate, specifically including: using three-stage independent control methods for the shear front side guide plate and the finishing mill side guide plate respectively; to avoid the impact of the strip head and tail bending on the side guide plate, and reduce the probability of quality defects on the strip edge;

[0009] By detecting the wear degree of the side guide plate in real time or at regular intervals, when the wear degree of the side guide plate exceeds the wear threshold, the side guide plate lining is replaced; otherwise, the side guide plate lining is not replaced, so as to ensure the working accuracy of the side guide plate.

[0010] By real-time or periodic detection of the cylinder pin frame amount of the side guide plate, when the cylinder pin frame amount of the side guide plate exceeds the frame amount threshold, the cylinder pin frame amount is processed; otherwise, it is not processed, so as to improve the equipment accuracy and ensure the normal operation of the side guide plate.

[0011] Calibrate the center line of the side guide plate. According to the wear of the side guide plate, the center line of the side guide plate is based on the center line of the arch and offset by Xmm on the transmission side or the operating side; it is used to compensate for the deviation caused by wear and ensure working accuracy.

[0012] Preferably, the three-stage independent control method of the front-shear side guide plate is: along the direction of strip transmission, the opening of the No. 1 head side guide plate, the opening of the No. 1 middle side guide plate, and the opening of the No. 1 tail side guide plate are independently set according to demand.

[0013] Preferably, the three-stage independent control method of the opening of the shear front side guide plate specifically includes:

[0014] Head setting: before the strip enters the flying shear, the opening = basic opening - X1;

[0015] Middle setting: After finishing rolling F1 bites steel, the opening = basic opening - X2;

[0016] Tail setting: When the tail of the strip is 2 meters away from the flying shear, the opening = basic opening - X3;

[0017] Where: X1 <X2,X3<X2。

[0018] Preferably, both sides of the shear front side guide plate adopt a gear rack transmission structure, the gear rack transmission structures on both sides are controlled by the same oil cylinder, and the three-stage position control setting range is ±150mm.

[0019] Preferably, the No. 1 oil cylinder is used to control the operating side of the finishing mill side guide plate, and the No. 2 oil cylinder controls the transmission side of the finishing mill side guide plate; the three-stage control is set for both sides separately, and the setting range is ±50mm.

[0020] Preferably, the hot-rolled strip finishing equipment includes F1 to F n There are n finishing mills in total, where n is a natural number greater than 1. Each finishing mill adopts a three-stage independent control method, and along the strip transmission direction, the side guide plate opening of the lower finishing mill is reduced by the side guide plate opening of the upper finishing mill.

[0021] Preferably, for the finishing mill F i , i is a natural number from 1 to n; the side guide plate opening is specifically:

[0022] Finishing Mill F i Head setting: Strip enters finishing mill F i Before, opening = basic opening - Y i1 ;

[0023] Finishing Mill F i Middle setting: Finishing mill F i After biting steel, opening = basic opening - Y i2 ;

[0024] Finishing Mill F i Tail setting: Finishing mill F i After casting, opening = basic opening - Y i3 ;

[0025] Where: Y i1 <Y i2 , Y i3 <Y i2 .

[0026] Preferably, n=7.

[0027] Preferably, the basic opening of the side guide plate = strip steel width + 80 mm.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a method for preventing edge quality defects of hot-rolled strip steel, which solves the problem of edge quality defects caused by abnormal scratching between the edge of the strip steel and the side guide plate during the production process of the hot-rolled strip steel, especially the quality problems caused by the impact of the side bending of the head and tail of the strip steel on the side guide plate. The present invention divides the side guide plate control into three sections, namely, head, middle and tail, by setting a three-section position control system, and adopts differentiated opening settings. The head and tail openings are larger, which effectively avoids the impact of the head and tail of the strip on the side guide plate, and prevents the edge of the strip from being scratched by precise opening control; through precise side guide plate control, the front side guide plate of the shear adopts a gear rack structure with a control range of ±150mm; the side guide plate of the finishing mill adopts independent control of double cylinders with a control range of ±50mm, and a decreasing opening design is adopted from F1 to F7 frames to achieve precise control; the present invention also sets strict equipment maintenance standards, controls the side guide plate wear within 5mm, controls the cylinder pin shaft frame amount within 3mm, flexibly adjusts the calibration center line (0-20mm offset) according to the wear conditions, and regularly inspects and maintains to ensure equipment accuracy. Through the comprehensive application of the above-mentioned technical means, the present invention can not only effectively solve the problem of quality defects of strip edges and improve product yield, but also reduce customer quality complaints, reduce corporate economic losses, improve production efficiency and product quality, and bring significant economic and social benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A top view of a finishing mill in a preferred embodiment of the present invention;

[0031] Figure 2 It is a structural schematic diagram of the side guide plate of the finishing mill in a preferred embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of three-stage control of the side guide plate of a preferred embodiment of the present invention.

[0033] In the figure: 1. Side guide plate. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. All other embodiments obtained by ordinary technicians in the field without making creative work based on the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0035] like Figure 1-2 As shown:

[0036] A method for preventing edge quality defects of hot rolled strip steel,

[0037] In the main process of hot rolling production, the slab is heated by the heating furnace, descaled by high-pressure water, rough rolled, finished rolled, laminar cooled, and coiled; the specific process flow is as follows:

[0038] After the slab is heated to the set slab discharge temperature in the heating furnace, the slab is lifted out by the steel discharging machine and placed on the discharge roller of the heating furnace. The discharged slab is transported to the high-pressure water descaling box via the roller. After the oxidized iron scale on the surface of the slab is removed by high-pressure water, the rough rolling mill performs five to seven reversible rollings to roll the slab into an intermediate slab with a thickness of 30mm to 50mm. The intermediate slab rolled by the rough rolling mill is sent to the finishing mill area via the roller. Before the intermediate slab enters the finishing mill, it first passes through the head-cutting flying shear to remove the head and tail of the intermediate slab. The flying shear is equipped with a front side guide plate to play a role in centering the intermediate slab before entering the finishing mill. After the head is cut, the intermediate slab passes through the finishing high-pressure water descaling box to remove the secondary oxidized iron scale, and then enters the 7 stands of the finishing mill for continuous rolling. There is a side guide plate 1 in front of each stand of the finishing mill. The control mode is position control. Different opening setting values ​​are set according to different widths of strip steel. Its function is to correct the deviation of the rolled piece during the rolling process. Finish rolling rolls the intermediate billet into the finished strip thickness. The laminar cooling system uses an appropriate cooling system to cool the hot rolled strip from the final rolling temperature to the set coiling temperature. The strip is sent to the coiler by the hot output roller, and is coiled into a steel coil by passing through the coiling side guide 1, the pinch roller, the auxiliary coiling roller and the reel in sequence.

[0039] The causes of hot-rolled strip head and tail bending include:

[0040] 1. Uneven deformation during hot rolling: During the hot rolling production process, the strip steel undergoes multiple rolling passes, which may cause uneven deformation due to factors such as uneven temperature distribution and uneven rolling force, resulting in head and tail lateral bending.

[0041] 2. Equipment accuracy problem: The control accuracy deviation of the side guide plate 1 is large and the equipment accuracy is reduced, which may cause uneven deformation during the rolling process, and then cause the head and tail of the strip to bend sideways.

[0042] 3. The slab coming out of the heating furnace may have some unevenness or curvature, and this initial state may be magnified or retained in the subsequent rolling process.

[0043] 4. During the continuous rolling process, complex internal stress distribution may occur in the strip, especially in the head and tail parts. These stresses may cause the strip to bend sideways after leaving the rolling mill.

[0044] 5. From coming out of the heating furnace to going through each rolling pass, the temperature distribution of the strip may be uneven, especially there may be a temperature difference between the head and tail parts and the middle part, which may lead to uneven shrinkage during the cooling process and cause lateral bending.

[0045] As can be seen from the above, the lateral bending of the head and tail of the strip is a problem that is difficult to completely avoid; therefore, in order to control and reduce the negative impact caused by the lateral bending, this embodiment adopts various measures on the side guide plate 1 to prevent the edge of the hot-rolled strip from being abnormally scratched against the side guide plate 1, resulting in quality defects of the edge of the hot-rolled strip.

[0046] First, the abnormal scratches between the edge of the hot-rolled strip and the side guide plate 1 mostly occur on the shear front side guide plate and the finishing mill front side guide plate;

[0047] Since the opening of the side guide 1 remains fixed, when the strip head and tail bend sideways, the side guide 1 cannot effectively adapt to the actual position and shape of the strip. At this time, the side guide 1 cannot guide normally, and the strip may deviate, increasing the risk of abnormal contact with the side guide 1; even the side-bent strip head and tail may directly impact the side guide 1, not only causing damage to the strip edge, but also reducing the equipment accuracy of the side guide 1.

[0048] Therefore, the three-stage independent control method of the front-side guide plate is: along the direction of strip transmission, the opening of the No. 1 head side guide plate, the opening of the No. 1 middle side guide plate, and the opening of the No. 1 tail side guide plate are independently set according to demand.

[0049] The two sides of the shear front side guide plate adopt a gear rack transmission structure, the gear rack transmission structures on both sides are controlled by the same oil cylinder, and the three-stage position control setting range is ±150mm.

[0050] The three-stage independent control method of the opening of the shear front side guide plate specifically includes:

[0051] Head setting: before the strip enters the flying shear, the opening = basic opening - X1;

[0052] Middle setting: After finishing rolling F1 bites steel, the opening = basic opening - X2;

[0053] Tail setting: When the tail of the strip is 2 meters away from the flying shear, the opening = basic opening - X3;

[0054] Where: X1 <X2,X3<X2。

[0055] Hot rolled strip finishing equipment includes F1~F n There are n finishing mills in total, where n is a natural number greater than 1. Each finishing mill adopts a three-stage independent control method, and along the strip transmission direction, the opening of the side guide plate 1 of the lower finishing mill is reduced by the opening of the side guide plate 1 of the upper finishing mill.

[0056] For finishing mill F i , i is a natural number from 1 to n; the opening of the side guide plate 1 is specifically:

[0057] Finishing Mill F i Head setting: Strip enters finishing mill F i Before, opening = basic opening - Y i1 ;

[0058] Finishing Mill F i Middle setting: Finishing mill F i After biting steel, opening = basic opening - Y i2 ;

[0059] Finishing Mill F i Tail setting: Finishing mill F i After casting, opening = basic opening - Y i3 ;

[0060] Where: Y i1 <Y i2 , Y i3 <Y i2 .

[0061] The No. 1 oil cylinder controls the operating side of the finishing mill side guide plate, and the No. 2 oil cylinder controls the transmission side of the finishing mill side guide plate; the three-stage control is set for both sides separately, and the setting range is ±50mm.

[0062] In this embodiment: n=7,

[0063] The opening of the front guide plate head = basic opening - 10mm, the opening of the middle = basic opening - 40mm, and the opening of the tail = basic opening - 10mm;

[0064] The head side guide plate of the F1 frame sets the head opening = basic opening - 20mm, the middle opening = basic opening - 40mm, and the tail opening = basic opening - 35mm;

[0065] The head side guide plate of the F2 frame sets the head opening = basic opening - 20mm, the middle opening = basic opening - 35mm, and the tail opening = basic opening - 30mm;

[0066] The head side guide plate of the F3 frame is set to the head opening = basic opening - 20mm, the middle opening = basic opening - 35mm, and the tail opening = basic opening - 30mm;

[0067] The head side guide plate of the F4 frame is set to the head opening = basic opening - 20mm, the middle opening = basic opening - 35mm, and the tail opening = basic opening - 30mm;

[0068] The head side guide plate of the F5 frame sets the head opening = basic opening - 20mm, the middle opening = basic opening - 35mm, and the tail opening = basic opening - 25mm;

[0069] The head side guide plate of the F6 frame sets the head opening = basic opening - 20mm, the middle opening = basic opening - 30mm, and the tail opening = basic opening - 25mm;

[0070] The head side guide plate of the F7 frame sets the head opening = basic opening - 20mm, the middle opening = basic opening - 25mm, and the tail opening = basic opening - 15mm;

[0071] In this embodiment, the width of the strip is 1500mm, and the basic opening of the shear front side guide plate and the finishing mill side guide plate = strip width + 80mm = 1580mm.

[0072] In order to ensure the effect of the three-stage control of the side guide plate 1, this embodiment also strengthens equipment maintenance and precision control from the following three aspects:

[0073] By real-time or periodic detection of the wear degree of the side guide plate 1 , when the wear degree of the side guide plate 1 exceeds the wear threshold, the lining of the side guide plate 1 is replaced; otherwise, the lining of the side guide plate 1 is not replaced; this is used to ensure the working accuracy of the side guide plate 1 .

[0074] By real-time or periodic detection of the cylinder pin frame amount of the side guide plate 1, when the cylinder pin frame amount of the side guide plate 1 exceeds the frame amount threshold, the cylinder pin frame amount is processed; otherwise, it is not processed, so as to improve the equipment accuracy and ensure the normal operation of the side guide plate 1.

[0075] The center line of the side guide plate 1 is calibrated. According to the wear condition of the side guide plate 1, the center line of the side guide plate 1 is offset by X mm to the transmission side or the operating side with respect to the center line of the arch. During specific production, according to the corresponding relationship between the wear condition and the offset of the side guide plate 1, the rolling center line is offset by 0 to 20 mm to the side with severe wear with respect to the center line of the arch.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preventing edge quality defects of hot-rolled strip, characterized in that: include: Controlling the opening of the side guide plate (1) specifically comprises: using a three-stage independent control method for the shear front side guide plate and the finishing mill side guide plate; By detecting the degree of wear of the side guide plate (1) in real time or at a fixed time, when the degree of wear of the side guide plate (1) exceeds a wear threshold, the side guide plate lining is replaced; otherwise, the side guide plate lining is not replaced; By real-time or periodic detection of the cylinder pin frame amount of the side guide plate (1), when the cylinder pin frame amount of the side guide plate (1) exceeds a frame amount threshold, the cylinder pin frame amount is processed; otherwise, no processing is performed; The center line of the side guide plate (1) is calibrated. According to the wear condition of the side guide plate (1), the center line of the side guide plate (1) is offset from the transmission side or the operating side by X mm based on the center line of the arch.

2. The method for preventing edge quality defects of hot-rolled strip according to claim 1, characterized in that: The three-stage independent control method of the front-side guide plate is: along the direction of strip transmission, the opening of the No. 1 head side guide plate, the opening of the No. 1 middle side guide plate, and the opening of the No. 1 tail side guide plate are independently set according to demand.

3. The method for preventing edge quality defects of hot-rolled strip according to claim 2, characterized in that: The three-stage independent control method of the opening of the shear front side guide plate specifically includes: Head setting: before the strip enters the flying shear, the opening = basic opening - X1; Middle setting: After finishing rolling F1 bites steel, the opening = basic opening - X2; Tail setting: When the tail of the strip is 2 meters away from the flying shear, the opening = basic opening - X3; Where: X1 <X2,X3<X2。 4. The method for preventing edge quality defects of hot-rolled strip according to any one of claims 1 to 3, characterized in that: The two sides of the shear front side guide plate adopt a gear rack transmission structure, the gear rack transmission structures on both sides are controlled by the same oil cylinder, and the three-stage position control setting range is ±150mm.

5. The method for preventing edge quality defects of hot-rolled strip according to any one of claims 1 to 3, characterized in that: The No. 1 oil cylinder controls the operating side of the finishing mill side guide plate, and the No. 2 oil cylinder controls the transmission side of the finishing mill side guide plate; the three-stage control is set for both sides separately, and the setting range is ±50mm.

6. The method for preventing edge quality defects of hot-rolled strip according to claim 1, characterized in that: Hot rolled strip finishing equipment includes F1~F n There are n finishing mills in total, where n is a natural number greater than 1. Each finishing mill adopts a three-stage independent control method, and along the strip transmission direction, the opening degree of the side guide plate (1) of the lower finishing mill is reduced by the opening degree of the side guide plate (1) of the upper finishing mill.

7. The method for preventing edge quality defects of hot-rolled strip according to claim 6, characterized in that: For finishing mill F i , i is a natural number from 1 to n; the opening of the side guide plate (1) is specifically: Finishing Mill F i Head setting: Strip enters finishing mill F i Before, opening = basic opening - Y i1 ; Finishing Mill F i Middle setting: Finishing mill F i After biting steel, opening = basic opening - Y i2 ; Finishing Mill F i Tail setting: Finishing mill F i After casting, opening = basic opening - Y i3 ; Where: Y i1 <Y i2 , Y i3 <Y i2 .

8. The method for preventing edge quality defects of hot-rolled strip according to claim 6, characterized in that: n＝7。 9. The method for preventing edge quality defects of hot-rolled strip according to claim 1, characterized in that: The basic opening of the side guide plate (1) = the strip width + 80 mm.

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