A method for controlling the shifting of hot rolling finishing work rolls

Abstract

The present invention discloses a control method for the shifting of working rolls of hot continuous rolling finishing, and belongs to the field of metallurgical rolling automation control. The control method for the shifting of working rolls divides the rolling process into the early stage of rolling and the late stage of rolling based on a rolling unit. The shifting of working rolls in the early stage of rolling adopts synchronous equal step length, and the shifting range is the entire range of the limit value interval of the shifting roll equipment; the shifting roll step length is adjusted in the late stage of rolling, and the late stage shifting roll step length is greater than the early stage shifting roll step length, so that the working rolls are shifted back and forth within the range of [L-2L1, L] or [-L,-L+2L1] near the limit value of the shifting roll equipment to avoid the harmful contact area (-L+2L1, L-2L1), and the shifting roll position of the current rolled strip is calculated accordingly. The present invention adopts different shifting roll control methods for different strips of the same rolling unit during the finishing rolling process, improves the local high point of the strip in the late stage of rolling, and extends the rolling mileage of the finishing rolls.

Description

Technical Field

[0001] The invention belongs to the field of metallurgical rolling automation control, and in particular relates to a method for controlling roll shifting of hot rolling finishing working rolls. Background Art

[0002] Hot rolling is a common way to produce plates and strips. The quality of the strip produced by hot rolling includes indicators such as convexity, straightness, wedge shape, and cross-sectional shape. With the use of automatic roll bending technology, the convexity and flatness of the strip are well controlled. Good strip profile shape has become a high-end product requirement in the plate and strip market. Among them, the protrusion of local high points on the strip section is an important manifestation of poor cross-sectional shape. If there are serious local high points on the profile of the finished rolled strip, it will affect the quality of the downstream reprocessed products, especially for steel types with high requirements for the cross-sectional shape of the strip produced by hot rolling, such as high value-added non-oriented silicon steel and cold-rolled steel.

[0003] The bulge of local high points of hot-rolled strip is generally caused by uneven wear or large local wear of the finishing work roll. The lateral temperature distribution of the strip is uneven during rolling, the temperature of the edge of the strip is lower than that of the middle, the deformation resistance and lateral flow of the metal at the edge are large, and the surface of the finishing work roll of the hot rolling mill fluctuates greatly, resulting in large wear on the edge; especially in a large number of same-width rolling processes, the contact part between the edge of the strip and the surface of the roll is the most severely worn, and further causes uneven wear of the finishing work roll. When the rolling kilometer is long and the rolling equipment capacity is limited, the serious uneven wear of the roll in the later stage of rolling is likely to cause bulges of local high points on the edge of the strip, thereby limiting the rolling kilometer of the finishing roll.

[0004] In the prior art, the uniform roll shifting with a fixed roll shifting step length or the uniform roll shifting with a variable stroke is generally used to adjust the strip edge shape. However, the uniform roll shifting does not take into account the problem that the wear is small in the early stage and the roll shifting near the zero position in the later stage of rolling is easy to cause local high points in the strip. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a control method for shifting the working rolls of hot rolling finishing mills, in which synchronous equal-step roll shifting is used to even out the wear of the rolls in the early stage of rolling, and the working rolls are shifted on one side of the frame in the later stage of rolling, and the step length of adjacent shifting rolls remains unchanged. The working rolls are shifted near the limit position of the roll shifting equipment to even out the wear on the edges of the strip, thereby improving the local high points of the strip in the later stage of rolling and extending the rolling mileage of the finishing rolls.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0007] A control method for hot rolling finishing work roll shifting, based on a rolling unit, divides the rolling process into an early rolling stage and a late rolling stage, wherein the working roll shifting in the early rolling stage adopts synchronous equal step length, and the shifting range is the entire range of the limit value interval of the roll shifting equipment; in the late rolling stage, the roll shifting step length is adjusted, and the late roll shifting step length is larger than the early roll shifting step length, so that the working roll shifts back and forth near the limit value of the roll shifting equipment and avoids the harmful area within the limit value interval.

[0008] As a preferred embodiment of the present invention, in the early stage of rolling, the upper working roll starts to shift from zero point to one side of the frame to the limit L of the roll shifting device, returns to zero point, and then continues to shift in the opposite direction along the other side of the frame to -L, and finally the working roll shifts back to the zero point position of the roll shifting device, which is a roll shifting cycle T1; the upper and lower working rolls are distributed in opposite symmetry, and the working rolls of the finishing mill group have opposite roll shifting positions in adjacent frames;

[0009] In each roll shifting cycle in the early stage of rolling, the current StripN strip being rolled is located at the phase StripD1 of a shifting cycle. The phase StripD1 is calculated by formula (1):

[0010] StripD1=(StripN / f1)%(4Step1) (1)

[0011] In formula (1), StripN is the current number of rolling blocks in a rolling unit, % represents the remainder, f1 is the shifting frequency, Step1 is the number of steps required for the working roll to shift from the zero position to the shifting amplitude L, and Step1 = L / ST1.

[0012] As a preferred embodiment of the present invention, in each roll shifting cycle in the early rolling stage, the roll shifting position Shift_result of the current StripN strip in the early rolling stage is calculated as follows:

[0013] If the phase StripD1 of the strip in a shifting cycle is less than the number of shifting steps Step1, the shifting roller position Shift_result is:

[0014]

[0015] If StripD1 is greater than or equal to Step1 and less than or equal to 3Step1, the shifting roller position Shift_result is:

[0016]

[0017] If StripD1 is greater than 3Step1, the roller position is:

[0018]

[0019] In formulas (2)-(4), Stand is the corresponding rack number.

[0020] As a preferred embodiment of the present invention, in the later stage of rolling, the working rolls move back and forth within the amplitude range of the roll shifting device [L-2L1, L] or [-L, -L+2L1], and the shifting step length ST2 of each time remains unchanged; wherein L-2L1 represents the minimum value of the later roll shifting position in the positive direction, and the later roll shifting avoids the position (-L+2L1, L-2L1); the upper and lower working rolls are distributed in an anti-symmetrical manner, and the working rolls of the finishing mill group have opposite shifting positions in adjacent frames;

[0021] The step length ST2 of roller shifting in the later rolling process satisfies:

[0022]

[0023] Among them, ST1 is the roll shifting step length in the early stage of rolling.

[0024] As a preferred embodiment of the present invention, it is assumed that the roll shifting in the late rolling stage starts from the Mth strip steel in a rolling unit; a roll shifting cycle T2 in the late rolling stage requires 4 Step2 steps to complete, Step2 = L / ST2; the shifting frequency is f2, and the shifting step length ST2 of each time remains unchanged; the phase StripD2 of the rolled StripNth strip steel in a late rolling shifting cycle is:

[0025]

[0026] As a preferred embodiment of the present invention, in a rolling cycle T2 of a late rolling period, the roll shifting position Shift_result of the current StripN strip in the late rolling period is calculated as follows:

[0027] If StripN is greater than or equal to M, and StripD2 is less than Step2, the shifting roller position Shift_result is:

[0028]

[0029] If StripN is greater than or equal to M, and StripD2 is not less than Step2, and less than or equal to 3Step2, then the shifting roller position Shift_result is:

[0030]

[0031] If StripN is greater than or equal to M, and StripD2 is greater than 3Step2, the shifting roller position Shift_result is:

[0032]

[0033] The control method for the shifting of the working rolls of hot rolling finishing provided by the embodiment of the present invention divides the rolling process into the early rolling stage and the late rolling stage based on a rolling unit, wherein in the early rolling stage, the working rolls start to shift from the zero point to one side of the frame to the limit L of the shifting roll equipment, and the working rolls continue to shift in the opposite direction along the other side of the frame to the shifting roll amplitude -L, and finally the working rolls shift to the zero point of the shifting roll, which is a shifting roll cycle; the upper and lower working rolls work in opposite directions and symmetrically; in the late rolling stage, the shifting step length of the shifting rolls is adjusted, and the working rolls begin to shift back and forth within the range of [L-2L1, L] or [-L, -L+2L1] of the shifting roll equipment limit, and the shifting step length remains unchanged each time. The present invention adopts different shifting roll control methods for different strips in the same rolling unit during the finishing rolling process, improves the local high points of the strips in the late rolling stage, and extends the rolling mileage of the finishing rolls. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A flow chart of a method for controlling the shifting of hot rolling finishing work rolls provided in an embodiment of the present invention;

[0036] Figure 2 for Figure 1 Schematic diagram of the principle of the control method shown;

[0037] Figure 3 It is a schematic diagram of the cross section of the strip steel produced by the roll shifting control method in the prior art;

[0038] Figure 4 It is a schematic diagram of the cross section of the strip steel produced by the control method of the shifting rollers in the embodiment of the present invention. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0040] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Aiming at the problems in the prior art that the equipment capacity of the finishing mill stand unit is limited and the rolling mileage is long, the rolling rolls are unevenly worn seriously in the later stage of rolling, and the edge of the strip at the finishing outlet has serious local bulges, etc., the present invention proposes a control method for the working roll shifting of a hot rolling finishing mill, and divides the roll shifting control into two periods, corresponding to the early stage of rolling and the late stage of rolling respectively, which can improve the local high points of the strip in the later stage of rolling, even the roll wear, and extend the rolling mileage. Among them, the thermal expansion and thermal wear of the rolls in the early stage of rolling are relatively small. Aiming at the relatively small thermal convexity and thermal wear in the early stage of rolling, a uniform roll shifting strategy with synchronous equal step length is adopted. The roll shifting positions of each stand are the same in the first rolling block, and the step length of each shifting of the working roll remains unchanged. The finishing working roll first shifts to one side of the stand to reach the limit value of the roll shifting equipment, and then the working roll shifts in the opposite direction to the limit value of the roll shifting equipment. The working roll shifts back and forth on both sides of the stand to even out the wear of the rolls. As the rolling progresses, the temperature fluctuation of the roll surface becomes larger, the lower temperature of the edge of the strip and the larger lateral flow of metal aggravate the wear of the edge of the working roll, resulting in greater wear of the edge of the roll, and then local bulges are prone to appear on the edge of the strip. Therefore, due to the increase in thermal expansion and wear in the later stage of rolling, the step length of the roll shifting is increased to avoid the shifting position of the roll in the early stage of rolling to even out the wear of the rolls. The working roll shifts on one side of the stand. The step length of the roll shifting makes the working roll shift near the limit position of the roll shifting equipment to even out the wear of the edge of the strip. The step length of the adjacent shifting rolls remains unchanged to control the shifting rolls to avoid the harmful area.

[0042] like Figure 1 As shown, the control method for the shifting of the working rolls of hot rolling finishing provided in an embodiment of the present invention divides the rolling process into the early stage and the late stage of rolling based on one rolling unit. In the early stage of rolling, the working rolls shift with synchronous equal step lengths, and the shifting range is the entire range of the limit value interval of the roll shifting equipment; in the late stage of rolling, the roll shifting step length is adjusted, and the roll shifting step length in the late stage is larger than the roll shifting step length in the early stage, so that the working rolls shift back and forth near the limit value of the roll shifting equipment and avoid the harmful area within the limit value interval.

[0043] Specifically, the steps include:

[0044] Step S1, in the early stage of rolling, the upper working roll starts to move from the zero point to one side of the frame to the limit L of the roll shifting device, returns to the zero point, and then continues to move in the opposite direction along the other side of the frame to -L, and finally the working roll moves back to the zero point position of the roll shifting device, which is a roll shifting cycle T1; the upper and lower working rolls are distributed in opposite and symmetrical manner.

[0045] In this step, the lower working roll first moves from zero to the limit of the roll shifting device -L, returns to zero, then moves in the opposite direction to L, and then moves back to the zero position of the roll shifting device from L. During this period, the step length ST1 of the roll shifting remains unchanged, and the working rolls shift periodically. During the rolling process, the working rolls of the finishing mill have opposite positions in adjacent stands.

[0046] In this step, in each roll shifting cycle in the early stage of rolling, the phase of the current StripN strip steel being rolled in a shifting cycle is StripD1, and the phase StripD1 is calculated by formula (1):

[0047] StripD1=(StripN / f1)%(4Step1) (1)

[0048] In formula (1), StripN is the current number of rolling blocks in a rolling unit, % represents the remainder, f1 is the shifting frequency, Step1 is the number of steps required for the working roll to shift from the zero position to the shifting amplitude L, and Step1 = L / ST1.

[0049] The calculation of the shifting roll position Shift_result of the current StripN strip in the early stage of rolling is as follows:

[0050] If the phase StripD1 of the strip in a shifting cycle is less than the number of shifting steps Step1, the shifting roller position Shift_result is:

[0051]

[0052] If StripD1 is greater than or equal to Step1 and less than or equal to 3Step1, the Shift_result at the roller shifting position is:

[0053]

[0054] If StripD1 is greater than 3Step1, the roller shifting position is:

[0055]

[0056] In formulas (2)-(4), Stand is the corresponding rack number.

[0057] Step S2, as thermal wear and thermal expansion increase in the later stage of rolling, the step length ST2 of roll shifting is increased. The working rolls move back and forth within the amplitude range [L-2L1, L] or [-L, -L+2L1] of the roll shifting equipment, and the step length ST2 of each shifting remains unchanged; wherein, L-2L1 represents the minimum value of the later roll shifting position in the positive direction, that is, the later roll shifting avoids the position (-L+2L1, L-2L1). Similarly, the upper and lower working rolls are distributed in opposite symmetry, and the positions of the adjacent frames of the working rolls of the finishing mill are opposite. Among them, L1 is the value of the harmful area or wear area corresponding to the actual production wear state, and its value is obtained according to actual production or experience.

[0058] In this step, the later rolling roll shifting step length ST2 satisfies:

[0059]

[0060] Among them, ST1 is the roll shifting step length in the early stage of rolling.

[0061] Assume that the roll shifting in the late rolling period starts from the Mth strip in a rolling unit. A roll shifting cycle T2 requires 4Step2 steps to complete, Step2 = L / ST2. The shifting frequency is f2, and the step length ST2 of each shifting remains unchanged. The phase StripD2 of the rolled strip in a late rolling shifting cycle is determined by StripN, M, L1, and f2:

[0062]

[0063] The shifting position Shift_result of the current StripN strip in the late rolling period is calculated as follows:

[0064] If StripN is greater than or equal to M, and StripD2 is less than Step2, the shifting roller position Shift_result is:

[0065]

[0066] If StripN is greater than or equal to M, and StripD2 is not less than Step2, and less than or equal to 3Step2, then the shifting roller position Shift_result is:

[0067]

[0068] If StripN is greater than or equal to M, and StripD2 is greater than 3Step2, the shifting roller position Shift_result is:

[0069]

[0070] Through the above-mentioned roll shifting control, the position change of the working roll is realized, and the shifting process of the working roll in the later stage of rolling is optimized, so that the edge wear of the strip is uniform, and a longer rolling mileage can be achieved.

[0071] The following is a further detailed description of the embodiment of the present invention through a specific implementation.

[0072] Taking a hot rolling production line of a certain factory as an example, due to the limited capacity of the finishing rolling unit equipment, when rolling high value-added non-oriented silicon steel, local high points are prone to appear on the edge of the finishing export strip in the later stage of rolling. Due to the long rolling kilometer of a rolling unit, the fast rolling rhythm, and the limited capacity of mechanical equipment, the problem of local high points on the edge of the strip in the later stage of rolling is more serious. There are 7 sets of stands for finishing rolling, and the maximum value of the roll shifting equipment is L=60mm. A rolling unit is 60 pieces of silicon steel strips, of which the first 38 pieces are in the early stage of rolling and the last 22 pieces are in the later stage of rolling.

[0073] Using the hot rolling finishing rolling work roll shifting control method described in the embodiment of the present invention, the work roll position curve when the roll is shifted is as follows: Figure 2 In the early stage of rolling, synchronous equal-step roll shifting is adopted. According to the actual situation on site, the roll shifting frequency is 1. It takes 8 steps for the working roll to shift from zero to 60mm, and the step length is According to the actual situation and formulas (1)-(4), the phase of the swaying cycle StripD1 is:

[0074] StripD 1 = (StripN)% (32)

[0075] If the phase StripD1 of the shifting is in [0,8), the position of the shifting roller is:

[0076]

[0077] If the phase StripD1 of the shifting is at [8,24], the position of the shifting roller is:

[0078]

[0079] If the phase of the shifting StripD1 is greater than 24, the shifting roller position is:

[0080]

[0081] Stand is the rack number.

[0082] In the later stage of rolling, the step length of roll shifting is adjusted so that the working roll shifts near the limit of the roll shifting equipment on one side of the stand. According to the actual situation on site, starting from the 39th strip in the later stage of rolling, the frequency of roll shifting is 1, L1 is taken as 20mm according to the actual production status or experience on site, and the working roll shifts from 20mm to 60mm or -20mm to -60mm. One roll shifting cycle requires 8 steps with a step length of 10mm. According to the actual situation and formulas (5)-(8), the phase StripD2 of the strip in the shifting cycle is:

[0083] StripD2=(StripN-39)%8

[0084] If the phase StripD2 of the shifting is in [0,2), the position of the shifting roller is:

[0085] shift_result = [10(-1) Stand+1 {(StripN-38)%8}]+40

[0086] If the phase StripD2 of the shifting is at [2,6], the position of the shifting roller is:

[0087] shift_result = [10(-1) Stand+1 {(StripN-38)%8-4}]+40

[0088] If the phase StripD2 of the shifting is greater than 6, the position of the shifting roller is:

[0089] shift_result = [10(-1) Stand+1 {(StripN-38)%8-8}]+40.

[0090] like Figure 3 and Figure 4 As shown, taking the F6 and F7 stands as examples, i.e., Stand=6, Stand=7, the silicon steel strips rolled by the roll shifting control method of the embodiment of the present invention are compared with the silicon steel strips rolled by the roll shifting control method in the prior art. The silicon steel strips produced in this embodiment have smoother strip edges, more uniform wear on the strip edges, and no obvious local high points. The rolling units can be expanded, such as from the original 60 blocks to 70 blocks.

[0091] It can be seen from the above technical scheme that the control method for shifting of the hot rolling finishing working rolls provided in the embodiment of the present invention adjusts the step size of the shifting rolls in the later stage of finishing rolling. The step size of the shifting rolls makes the working rolls move back and forth near the limit value of the shifting roll equipment, thereby making the edge of the strip wear evenly, improving the local high points of the edge of the strip, and extending the rolling mileage of the finishing rolls.

[0092] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0093] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for controlling the shifting of hot rolling finishing work rolls, characterized in that: The rolling process is divided into the early rolling stage and the late rolling stage based on a rolling unit. In the early rolling stage, the working rolls are shifted synchronously with equal steps, and the shifting range is the entire range of the limit value interval of the roll shifting equipment; in the late rolling stage, the roll shifting step length is adjusted, and the late roll shifting step length is larger than the early roll shifting step length, so that the working rolls are shifted back and forth near the limit value of the roll shifting equipment, avoiding the harmful area within the limit value interval; In the early stage of rolling, the upper working roll starts to move from zero point to one side of the frame to the limit L of the roll shifting device, returns to zero point, and then continues to move in the opposite direction along the other side of the frame to -L, and finally the working roll moves back to the zero point position of the roll shifting device, which is a roll shifting cycle T1; the upper and lower working rolls are symmetrically distributed in opposite directions, and the working rolls of the finishing mill group have opposite roll shifting positions in adjacent frames; In each roll shifting cycle in the early stage of rolling, the current StripN strip being rolled is located at the phase StripD1 of a shifting cycle. The phase StripD1 is calculated by formula (1): StripD1=(StripN / f1)%(4Step1) (1) In formula (1), StripN is the current number of rolling blocks in a rolling unit, % represents the remainder, f1 is the shifting frequency, Step1 is the number of steps required for the working roll to shift from the zero position to the shifting amplitude L, Step1 = L / ST1; And calculate the roller shifting position of the current StripN strip being rolled; The calculation of the roll shifting position of the current StripN piece of strip steel during rolling, in each roll shifting cycle in the early rolling period, the roll shifting position Shift_result of the current StripN piece of strip steel in the early rolling period is calculated as follows: If the phase StripD1 of the strip in a shifting cycle is less than the number of shifting steps Step1, the shifting roller position Shift_result is: If StripD1 is greater than or equal to Step1 and less than or equal to 3Step1, the shifting roller position Shift_result is: If StripD1 is greater than 3Step1, the roller position is: In formulas (2)-(4), Stand is the corresponding rack number; In the later stage of rolling, the working rolls move back and forth within the amplitude range of the roll shifting device [L-2L1, L] or [-L, -L+2L1], and the shifting step length ST2 of each time remains unchanged; wherein L-2L1 represents the minimum value of the later roll shifting position in the positive direction, and the later roll shifting avoids the position (-L+2L1, L-2L1); the upper and lower working rolls are distributed in an anti-symmetrical manner, and the working rolls of the finishing mill group have opposite shifting positions in adjacent stands; The step length ST2 of roller shifting in the later rolling process satisfies: Among them, ST1 is the roll shifting step length in the early stage of rolling.

2. The method for controlling the shifting of hot rolling finishing work rolls according to claim 1, characterized in that: Assume that the roll shifting in the late rolling stage starts from the Mth strip steel in a rolling unit; a roll shifting cycle T2 in the late rolling stage requires 4Step2 steps to complete, Step2 = L / ST2; the shifting frequency is f2, and the step length ST2 of each shifting remains unchanged; the phase StripD2 of the rolled StripNth strip steel in a late rolling shifting cycle is: And calculate the roller shifting position of the current StripN strip being rolled.

3. The method for controlling the shifting of hot rolling finishing work rolls according to claim 2, characterized in that: The calculation of the roll shifting position of the current StripN piece of strip steel during rolling is performed. In a rolling cycle T2 of a late rolling period, the roll shifting position Shift_result of the current StripN piece of strip steel in the late rolling period is calculated as follows: If StripN is greater than or equal to M, and StripD2 is less than Step2, the shifting roller position Shift_result is: If StripN is greater than or equal to M, and StripD2 is not less than Step2, and less than or equal to 3Step2, then the shifting roller position Shift_result is: If StripN is greater than or equal to M, and StripD2 is greater than 3Step2, the shifting roller position Shift_result is:

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