A control method for preventing the pinch roll of a width setting machine from not biting

Abstract

This invention relates to a control method for preventing the pinch rolls of a width-fixing machine from failing to engage, comprising: a. calculating a first roll gap of the inlet pinch roll based on the theoretical slab thickness, and implementing closed-loop control of the inlet pinch roll at the position corresponding to the first roll gap while waiting for the slab to enter; b. after the slab enters the inlet pinch roll, calculating a second roll gap based on the pressure of the inlet pinch roll, and, if it is determined that the pinch roll has engaged the steel, controlling the inlet pinch roll at the position corresponding to the second roll gap; c. maintaining the inlet pinch roll at the position corresponding to the second roll gap for a predetermined time. This invention effectively prevents the problem of non-engagement caused by the slab impacting the pinch roll and immediately applying pressure control to lower it, resulting in the pressure control reaching its lowest position at the moment of contact between the roll surface and the slab, when the actual slab thickness is significantly greater than the actual roll gap of the pinch roll. Furthermore, by appropriately reducing the pinch roll's swing position and appropriately increasing the theoretical slab thickness value during actual production, the judgment of the steel engagement signal can be facilitated.

Description

Technical Field

[0001] This invention belongs to the field of hot rolling process, and particularly relates to a control method for preventing the pinch rolls of a width-fixing machine from failing to engage. Background Technology

[0002] A sizing press (or simply sizing press) controls the hammer (...) Figure 1 Reference numeral 2) in the attached figure shows the slab ( Figure 1 The attached diagram (1) shows the reciprocating motion in the vertical direction of the movement, with the hammer striking the slab to achieve the purpose of width reduction. The width-fixing machine is an example of this. Figure 2 As shown, 1 is the slab, 2 is the hammer, 3 is the rolling direction, 4 is the inlet pinch roll of the width-fixing mill, 5 is the inlet guide roll, and 6 is the outlet guide roll.

[0003] The existing control method for the pinch rolls of the fixed width machine is as follows: after the steel is tapped from the heating furnace, the process computer sends the theoretical thickness of the slab to the basic automation controller, which calculates the roll gap of the inlet pinch rolls based on the theoretical slab thickness.

[0004] When the slab enters the inlet pinch roll, if the actual thickness of the slab is larger than the roll gap of the inlet pinch roll, the slab will generate a certain impact when it hits the pinch roll. The hydraulic equipment of the inlet pinch roll will detect the pressure fluctuation. When the actual pressure is greater than a certain value, the basic automation controller will immediately determine that the inlet pinch roll is biting the steel, and will immediately switch from the current position closed-loop control to the pressure closed-loop control.

[0005] In existing technologies, the thickness of a slab is a theoretically calculated value. However, in actual production, the slab may expand after heating, undergo salvage production, or be stripped during steelmaking. Consequently, the calculated thickness often exceeds or falls short of the actual slab thickness. If this deviation is significant, the following problems may arise:

[0006] When the actual thickness of the slab is greater than the theoretical thickness, the gap between the pinch rolls is too small. Due to the limited installation position, the pinch rolls at the entrance of the width-fixing mill are generally designed as free rolls. When the pinch roll surface contacts the slab, the pressure control is immediately applied. The slab may not have entered the pinch roll. The pinch roll pressure control is immediately pressed down, causing the slab to fail to bite into the pinch roll, resulting in the failure of the width-fixing mill to roll and requiring the machine to be stopped for treatment.

[0007] When the actual thickness of the slab is less than the theoretical thickness, the gap between the pinch rolls is too large. When the slab enters the pinch rolls, the large gap prevents the generation of biting pressure, resulting in the controller not sending a biting signal from the pinch rolls of the width-fixing mill. This leads to tracking abnormalities and directly causes the width-fixing mill to fail, requiring the machine to be shut down for repair.

[0008] Through technical exchanges, it was learned that the problem of slabs not biting or having no biting signal at the pinch rolls of the width-fixing mill has occurred on various hot rolling lines. Since the actual thickness of most slabs is too large to avoid, and in order to reduce the occurrence of no biting signal at the pinch rolls, most production lines have increased the position of the pinch rolls, which further leads to the difference between the pinch roll gap and the actual thickness of the slab, which may exacerbate the situation of the pinch rolls not biting, and at the same time increase the impact on the pinch rolls, affecting the quality of the roll surface and the service life of the mechanical equipment.

[0009] In summary, how to change the control method of the inlet pinch roll of the width-fixing machine in actual production process so as to solve the problem of the pinch roll not biting in, avoid the pinch roll not biting steel signal, and at the same time take into account the quality of the roll surface and the service life of the mechanical equipment is an urgent problem to be solved in actual production.

[0010] Therefore, existing technologies still need improvement. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the purpose of this invention is to provide a control method for preventing the pinch rolls from failing to engage. This method solves the problem of slabs failing to engage with the pinch rolls of the width-fixing machine by changing the control mode of the pinch rolls, while also reducing equipment impact.

[0012] Specifically, the present invention provides a control method for preventing the pinch roll of a width-fixing machine from failing to engage, comprising the following steps: a. calculating a first roll gap of the inlet pinch roll based on the theoretical slab thickness, and the inlet pinch roll is controlled in a closed loop at the position corresponding to the first roll gap to wait for the slab to enter; b. after the slab enters the inlet pinch roll, calculating a second roll gap based on the pressure of the inlet pinch roll, and if it is determined that the pinch roll has engaged the steel, the inlet pinch roll is controlled at the position corresponding to the second roll gap; c. the inlet pinch roll is controlled at the position corresponding to the second roll gap for a predetermined time.

[0013] In an embodiment of the present invention, in step a, the first roll gap is calculated using the following formula 1:

[0014] PR GAP = H - A1 (Formula 1)

[0015] Wherein, PR GAP is the first roll gap, H is the theoretical slab thickness, and A1 is the first adjustment parameter.

[0016] In an embodiment of the present invention, A1 is 10-15 mm.

[0017] In an embodiment of the present invention, in step b, when the pressure of the inlet pinch roll is greater than a predetermined value, the second roll gap is calculated.

[0018] In an embodiment of the present invention, in step b, the second roll gap is calculated using the following formula 2:

[0019] PR GAP1 = PR GAP + A2 (Formula 2)

[0020] Wherein, PR GAP1 is the second roll gap and A2 is the second adjustment parameter.

[0021] In an embodiment of the invention, A2 is greater than or equal to A1, and step b includes controlling the inlet pinch roller to lift.

[0022] In an embodiment of the present invention, in step b, the predetermined value is 40-60 kN.

[0023] In an embodiment of the present invention, in step c, the predetermined time is 100-200ms.

[0024] In an embodiment of the present invention, in step c, after the predetermined time has elapsed, pressure control is applied to press down the inlet pinch roller.

[0025] In an embodiment of the present invention, step a includes a first controller receiving the theoretical slab thickness from a second controller and calculating the first roll gap based on the theoretical slab thickness; step b includes the first controller calculating the second roll gap based on the inlet pinch roll pressure, and, if it is determined that the pinch roll has bitten steel, raising the inlet pinch roll based on the second roll gap.

[0026] Compared with the prior art, the advantages of the present invention are at least as follows:

[0027] (1) By adopting the technical solution of the present invention, the problem of non-biting can be effectively eliminated when the actual slab thickness is much greater than the actual roll gap of the pinch roll, and the pressure control is immediately applied to press down when the slab impacts the pinch roll, and the pressure control is pressed to the lowest position at the moment the roll surface contacts the slab.

[0028] (2) After adopting the technical solution of the present invention, the position of the pinch roll can be appropriately reduced and the theoretical slab thickness can be appropriately increased in the actual production process, which is conducive to the judgment of the bite signal.

[0029] (3) After adopting the technical solution of the present invention, the clamping roller of the width-fixing machine can lift up at the moment of biting the steel, thereby reducing the impact of mechanical equipment. Attached Figure Description

[0030] Figure 1 A schematic diagram of the width-fixing machine is shown.

[0031] Figure 2 A schematic diagram is shown before the slab enters the inlet pinch rolls;

[0032] Figure 3 A schematic flowchart of a control method for preventing the pinch rollers of a width-fixing machine from failing to engage, provided by an embodiment of the present invention, is shown.

[0033] Figure 4 The diagram shows usage data of a width-fixing machine based on the control method for preventing the pinch rollers of a width-fixing machine from failing to engage, provided by an embodiment of the present invention. Detailed Implementation

[0034] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0035] According to the present invention, a control method for preventing the pinch rollers of a width-fixing machine from failing to engage is provided, such as... Figure 3 As shown, it includes the following steps:

[0036] a. Calculate the first roll gap of the inlet pinch roll based on the theoretical slab thickness, and the inlet pinch roll is controlled in a closed loop at the position corresponding to the first roll gap to wait for the slab to enter;

[0037] b. After the slab enters the inlet pinch roll, the second roll gap is calculated based on the pressure of the inlet pinch roll, and if it is determined that the pinch roll has bitten the steel, the inlet pinch roll is controlled at the position corresponding to the second roll gap;

[0038] c. The inlet pinch roller is controlled to remain in position corresponding to the second roller gap for a predetermined time.

[0039] In an embodiment of the present invention, in step a, after the steel is tapped from the heating furnace, the second controller sends the theoretical slab thickness H to the first controller. The first controller calculates the roll gap PR GAP of the inlet pinch rolls based on the theoretical slab thickness H and the following calculation formula 1:

[0040] PR GAP = H - A1 (Formula 1)

[0041] Wherein, PR GAP is the first roll gap, H is the theoretical slab thickness, and A1 is the first adjustment parameter. Before the slab enters the pinch rolls, the pinch rolls are controlled in a closed loop at the PR GAP position, waiting for the slab to enter at this roll gap.

[0042] In embodiments of the present invention, the first controller may be a basic automation controller, and the second controller may be a process computer.

[0043] In the embodiments of the present invention, A1 is 10-15mm. In other embodiments, the value of A1 can be modified according to the actual situation.

[0044] In an embodiment of the present invention, in step b, when the slab enters the pinch roll and impacts the pinch roll, if the pressure of the inlet pinch roll is determined to be greater than a predetermined value, the first controller determines that the pinch roll has bitten the steel. At this time, the pinch roll is still controlled by position, and the pinch roll is raised based on the second roll gap PR GAP1 calculated by the following formula 2:

[0045] PR GAP1 = PR GAP + A2 (Formula 2)

[0046] Wherein, PR GAP1 is the second roll gap and A2 is the second adjustment parameter.

[0047] In an embodiment of the present invention, A2 is greater than or equal to A1.

[0048] In an embodiment of the present invention, in step b, the predetermined value is 40-60 kN.

[0049] In an embodiment of the present invention, in step c, after the pinch roller is raised for a predetermined time T1, the pressure control is applied again after a delay of T1. At this time, the slab has completely entered the pinch roller of the width-fixing machine within the time T1, thus solving the problem that the width-fixing machine does not bite into the pinch roller.

[0050] In an embodiment of the present invention, the predetermined time T1 is 100-200ms, which can be set according to the actual situation on site and the response of the servo valve.

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0052] Example 1

[0053] This invention has been put into use on a 2050mm hot rolling mill width-fixing machine, and the data is as follows: Figure 4 As shown, the specific applications are as follows:

[0054] (1) After the steel is tapped from the heating furnace, the process computer L2 sends the theoretical slab thickness H 230mm to the basic automation controller L1. The controller L1 calculates the roll gap PR GAP of the inlet pinch roll according to the theoretical slab thickness H and calculation formula 1.

[0055] PR GAP = H - A1 (Formula 1)

[0056] Where A1 = 10 mm.

[0057] Before the slab enters the pinch rolls, the pinch rolls are controlled in a closed loop with the PR GAP position, waiting for the slab to enter at a roll gap of 220mm.

[0058] (2) When the slab enters the pinch roll and impacts the pinch roll, if the pressure of the inlet pinch roll is greater than 50KN, the controller L1 determines that the pinch roll has bitten the steel. At this time, the pinch roll is still controlled by position, and the pinch roll is raised by the new pinch roll gap PR GAP1 reference of Formula 2.

[0059] PR GAP1 = PR GAP + A2 (Formula 2)

[0060] A2 = 10mm

[0061] (3) After the pinch roll is raised for T1 = 106ms, the pressure control is activated again after a delay of T1. At this time, the slab has completely entered the pinch roll of the width-fixing machine within the time T1, which solves the problem that the width-fixing machine does not bite into the pinch roll.

[0062] exist Figure 4 In the middle, at the top, is the slab thickness calculated by the model. Figure 4 The center gap is approximately 231mm. The gap between the pinch rolls before steel feeding is 221mm, and this is used as a reference for position control. Figure 4 The middle section shows the reference position (mm, indicated by a thin blue line) and the actual position (mm, indicated by a thin red line). Figure 4 The thick red line at the bottom represents position control (Entry PR Position control on), and the thick blue line represents pinch roll loading (Entry PR Loaded). When the pinch roll is loading, position control is maintained for a period of time, and the position control reference is increased by more than 10mm to raise the pinch roll. After the delay time, pressure control (Entry PR Force control on, indicated by the thick green line) is switched on and pressed down again.

[0063] Normally, pressure control is applied immediately upon biting the slab. However, there's a possibility that the slab might be pressed down too far upon biting, failing to be properly engaged. The feed roller at the width-fixing mill's inlet is a free roller, and this occurrence increases with decreasing mechanical precision. This application addresses this by first raising the roller to allow the slab to pass before pressing it down, which facilitates proper slab engagement.

[0064] The technical solution of this invention has been put into use on a 2050mm hot rolling line in a certain factory. After long-term actual operation, it has fully achieved the expected technical effect and basically eliminated the situation where the pinch rolls do not bite in.

[0065] Example 2

[0066] This invention has been put into use on a 2050mm hot rolling mill for width determination. The specific application is as follows:

[0067] (1) After the steel is tapped from the heating furnace, the process computer L2 sends the theoretical slab thickness H 220mm to the basic automation controller L1. The controller L1 calculates the roll gap PR GAP of the inlet pinch roll according to the theoretical slab thickness H and calculation formula 1.

[0068] PR GAP = H - A1 (Formula 1)

[0069] Where A1 = 15mm.

[0070] Before the slab enters the pinch rolls, the pinch rolls are controlled in a closed loop with PR GAP position, waiting for the slab to enter at a roll gap of 205mm.

[0071] (2) When the slab enters the pinch roll and impacts the pinch roll, if the pressure of the inlet pinch roll is greater than 55KN, the controller L1 determines that the pinch roll has bitten the steel. At this time, the pinch roll is still controlled by position, and the pinch roll is raised by the new pinch roll gap PR GAP1 reference of Formula 2.

[0072] PR GAP1 = PR GAP + A2 (Formula 2)

[0073] A2 = 12mm

[0074] (3) After the pinch roll is raised for T1 = 150ms, the pressure control is activated again after a delay of T1. At this time, the slab has completely entered the pinch roll of the width-fixing machine within the time T1, which solves the problem that the width-fixing machine does not bite into the pinch roll.

[0075] The technical solution of this invention has been put into use on a 2050mm hot rolling line in a certain factory. After long-term actual operation, it has fully achieved the expected technical effect and basically eliminated the situation where the pinch rolls do not bite in.

[0076] Example 3

[0077] This invention has been put into use on a 2050mm hot rolling mill for width determination. The specific application is as follows:

[0078] (1) After the steel is tapped from the heating furnace, the process computer L2 sends the theoretical slab thickness H 235mm to the basic automation controller L1. The controller L1 calculates the roll gap PR GAP of the inlet pinch roll according to the theoretical slab thickness H and calculation formula 1.

[0079] PR GAP = H - A1 (Formula 1)

[0080] Where A1 = 11 mm.

[0081] Before the slab enters the pinch rolls, the pinch rolls are controlled in a closed loop with PR GAP position, waiting for the slab to enter at a roll gap of 224mm.

[0082] (2) When the slab enters the pinch roll and impacts the pinch roll, if the pressure of the inlet pinch roll is greater than 55KN, the controller L1 determines that the pinch roll has bitten the steel. At this time, the pinch roll is still controlled by position, and the pinch roll is raised by the new pinch roll gap PR GAP1 reference of Formula 2.

[0083] PR GAP1 = PR GAP + A2 (Formula 2)

[0084] A2 = 13mm

[0085] (3) After the pinch roll is raised for T1 = 200ms, the pressure control is activated again after a delay of T1. At this time, the slab has completely entered the pinch roll of the width-fixing machine within the time T1, which solves the problem that the width-fixing machine does not bite into the pinch roll.

[0086] The technical solution of this invention has been put into use on a 2050mm hot rolling line in a certain factory. After long-term actual operation, it has fully achieved the expected technical effect and basically eliminated the situation where the pinch rolls do not bite in.

[0087] This invention can be widely used in the field of production process control for hot rolling mills.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A control method for preventing the pinch rollers of a width-fixing machine from failing to engage, characterized in that, Includes the following steps: a. Calculate the first roll gap of the inlet pinch roll based on the theoretical slab thickness, and the inlet pinch roll is controlled in a closed loop at the position corresponding to the first roll gap to wait for the slab to enter; b. After the slab enters the inlet pinch roll, the second roll gap is calculated based on the pressure of the inlet pinch roll, and if it is determined that the pinch roll has bitten the steel, the inlet pinch roll is raised based on the second roll gap and the inlet pinch roll is controlled at the position corresponding to the second roll gap; c. The inlet pinch roller is controlled to remain at the position corresponding to the second roll gap for a predetermined time, wherein step c includes pressing down the inlet pinch roller with cutting pressure control after the predetermined time has expired.

2. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 1, characterized in that, In step a, the first roll gap is calculated using the following formula 1: PR GAP = H - A1 Formula 1 Wherein, PR GAP is the first roll gap, H is the theoretical slab thickness, and A1 is the first adjustment parameter.

3. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 2, characterized in that, A1 is 10-15mm.

4. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 2, characterized in that, In step b, when the pressure of the inlet pinch roll is greater than a predetermined value, the second roll gap is calculated.

5. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 4, characterized in that, In step b, the second roll gap is calculated using the following formula 2: PR GAP1 = PR GAP + A2 (Formula 2) Wherein, PR GAP1 is the second roll gap and A2 is the second adjustment parameter.

6. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 5, characterized in that, A2 is greater than or equal to A1.

7. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 4, characterized in that, In step b, the predetermined value is 40-60 kN.

8. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 1, characterized in that, In step c, the predetermined time is 100-200ms.

9. The control method for preventing the pinch rollers of a width-fixing machine from failing to engage according to claim 1, characterized in that, Step a includes the first controller receiving the theoretical slab thickness from the second controller and calculating the first roll gap based on the theoretical slab thickness; step b includes the first controller calculating the second roll gap based on the inlet pinch roll pressure.

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