Method for assisting threading of a coiler pinch roll in a hot strip production line

Abstract

The application discloses a method for assisting strip threading of a coiler pinch roll of a hot-rolled strip steel production line, and belongs to the field of steel production. The control mode of the pinch roll comprises a pressure control mode, a speed control mode and a position control mode. In the position control mode, the lower pinch roll is horizontally moved to a position perpendicular to the center of the upper pinch roll when the strip head is threading, and the upper pinch roll is pressed down to a set roll gap position G1. The application adjusts the position, speed and pressure control of the coiler pinch roll, so that the pinch roll provides the function of assisting the strip head in threading, thereby reducing the strip head from being wrapped, improving the production stability of thin specifications, and increasing the economic benefits of the hot-rolled strip steel production line.

Description

Technical Field

[0001] This invention relates to a steel production method, and more particularly to a method for assisting strip threading with the pinch rolls of a coiler in a hot-rolled strip steel production line. Background Technology

[0002] The hot-rolled coiler is the final process in a hot continuous rolling production line. During the process of transporting strip from the finishing mill to the coiler, it passes through pinch rolls. The main function of the pinch rolls is to apply a certain clamping force to the strip during the head-biting stage, while simultaneously inducing its initial bending deformation. Due to limited space below the pinch rolls, guide plates are used to connect the pinch rolls to the roller conveyors before and after them, and the guide plate at the exit of the pinch rolls is relatively long. When thin strips pass through this pinch roll and are threaded downstream into the coiler, the strip is prone to buckling at this point due to high resistance after contacting the guide plate below the pinch roll. In severe cases, this can lead to stacking and scrap-like accidents, seriously hindering the production stability of thin strips.

[0003] In existing technologies, abnormal strip threading caused by the strip head impacting the guide plate during uncoiling can only be detected and handled promptly. For example, the "Method and Device for Preventing Scrap Steel from Coilers" (CN201811005100.8) achieves automatic detection and automatic scrap recovery of strip head flipping and impact with the guide plate during uncoiling, thereby reducing scrap steel accidents in coilers. The "Method for Controlling Hot-Rolled Coiling Tension" (CN201210133378.X) addresses the uncoiling problem of the tail of thin-gauge high-temperature hot-rolled strip on the roller table. It improves the stability of the strip tail running on the roller table through a new tension conversion method at the tail of the coiler, reducing the resulting poor coiling shape and edge defects.

[0004] In summary, the problem of abnormal strip threading caused by the impact of the strip head on the guide plate during unsleeving cannot be improved. Summary of the Invention

[0005] The technical objective of this invention is to address the shortcomings of the prior art by providing a method for assisting strip threading with the pinch rolls of a coiler in a hot-rolled strip steel production line. By adjusting the position, speed, and pressure control of the pinch rolls, the pinch rolls can provide the function of assisting strip threading at the head of the strip, thereby reducing the head-gearing failure of thin-gauge strips, improving the production stability of thin-gauge strips, and increasing the economic benefits of the hot-rolled strip steel production line.

[0006] The technical solution of this invention to solve its technical problem is: a method for assisting strip threading with pinch rolls in a coiler of a hot-rolled strip steel production line, characterized in that: the pinch roll control mode includes pressure control mode, speed control mode and position control mode;

[0007] In the position control mode, when the strip head is threaded, the lower pinch roller moves laterally to a position perpendicular to the center of the upper pinch roller; the upper pinch roller is pressed down to the set roll gap position G1; the pinch roller operates using a new speed control mode; if the coiler is not coiling steel, the upper pinch roller is pressed down to the set roll gap G1 according to the strip thickness H; if the coiler is coiling steel and the upper pinch roller is already in the pressed position, the upper pinch roller is kept under pressure control until the downstream coiler sets tension, then the roll gap of the upper pinch roller is opened to G2; the lower pinch roller moves laterally to the position to be coiled.

[0008] In the speed control mode, if the coiler is not coiling steel, after the upper pinch roll is pressed down to the set roll gap G1, the upper and lower pinch rolls run at the advance speed V1; if the coiler is coiling steel, after the high-speed flying shear cuts, it runs at the advance speed V1, and after the downstream coiler sets up the strip, it runs at the strip speed V0.

[0009] In the pressure control mode, if the coiler is not coiling steel, when the strip head reaches the coiler's pinch roll, the pinch roll executes the low pressure control mode, and the pressure setting value is executed according to F1; if the coiler is coiling steel, after the high-speed flying shear cuts, the pressure setting value changes from pressure F0 to the low pressure mode setting pressure F1. After the downstream coiler sets tension, the pressure mode is canceled, the roll gap is opened, and the position control mode is switched.

[0010] Furthermore, the lateral movement of the lower pinch roller is achieved through a lateral movement mechanism.

[0011] Furthermore, the aforementioned lateral movement of the lower pinch roller to a position perpendicular to the center of the upper pinch roller specifically refers to the deflection angle α = 0 of the upper pinch roller relative to the lower pinch roller.

[0012] Furthermore, the calculation formula for the roll gap G1 is as follows: G1 = H - a1; where H is the strip thickness and a1 is a fixed value.

[0013] Furthermore, the formula for calculating the aforementioned lead speed V1 is: V1=V0×(1+a2); where: V0 is the strip speed at the finishing mill exit, and a2 is a different set value given according to different strip thicknesses.

[0014] Furthermore, the aforementioned F1 is a fixed pressure value given by looking up a table based on the strip thickness T.

[0015] Compared with the prior art, the present invention has the following outstanding advantages:

[0016] 1. By applying the method of the present invention, the pinch roller can play the function of assisting in strip feeding, which can significantly reduce the phenomenon of strip head slippage during strip feeding and suppress the slippage that occurs upstream of the pinch roller.

[0017] 2. Reduce the risk of steel stacking and assembling for thin-gauge steel and improve the production stability of thin-gauge steel;

[0018] 3. It can be used in conjunction with multiple coiler clamping rollers to improve the production efficiency of hot-rolled thin specifications and increase the output of thin specifications. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pinch roller position control mode of the present invention.

[0020] Figure 2 This is a schematic diagram of the position of the pinch rollers in the prior art.

[0021] Figure 3 This is a schematic diagram of the transverse movement mechanism of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] For the purposes of the following detailed description, it should be understood that the invention may take various alternative variations and sequences of steps unless explicitly stated otherwise. Furthermore, except in any operational instance or where otherwise indicated, all figures representing quantities of ingredients as used, for example, in the specification and claims, should in all cases be understood to be modified by the term “about.” At least, and without attempting to limit the application of the principle of equivalents to the scope of the claims, each numerical parameter should be understood at least according to the number of significant figures reported and by applying common rounding techniques.

[0024] Although the numerical ranges and parameters illustrating the broad scope of the invention are approximate, the values ​​described in the specific examples are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation found in its corresponding test measurement.

[0025] It should also be understood that any range of values ​​stated herein is intended to include all subranges included therein. For example, the range “1 to 10” is intended to include all subranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, that is, a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0026] In this application, unless otherwise specified, the use of the singular includes the plural and the plural encompasses the singular. Additionally, in this application, unless otherwise expressly stated, the use of "or" means "and / or," even if "and / or" may be explicitly used in certain circumstances. Furthermore, in this application, unless otherwise specified, the use of "a" or "an" means "at least one / a." For example, "an" first material, "an" coating composition, etc., refer to one or more of any of these items.

[0027] This invention relates to a method for assisting strip threading with pinch rolls in a hot-rolled strip steel production line. By controlling the position, pressure, and speed of the pinch rolls, while ensuring normal coiling at the tail end of the steel coil, an additional function is added for the pinch rolls to assist threading the head of the lower strip. Specifically, when the head of the strip passes through the pinch rolls and enters the downstream coiler pinch rolls, the pinch rolls are in a pressed-down position, and the strip is fed into the downstream coiler by the clamping of the upper and lower pinch rolls.

[0028] The pinch roller control modes include pressure control mode, speed control mode, and position control mode. The specific control contents are as follows:

[0029] (1) Position control mode

[0030] like Figure 1 As shown, in the pinch roll position mode of the present invention, when the strip head is threaded, the lower pinch roll 2 moves laterally to a position perpendicular to the center of the upper pinch roll 1, and the upper pinch roll 1 is pressed down to the set roll gap position G1; the pinch roll operates in a new speed control mode, at which time both the upper and lower pinch rolls provide forward power to the strip head.

[0031] In existing technologies, the position of the pinch roller is as follows: Figure 2 As shown, when the strip head is threaded through the pinch rolls, the lower pinch roll moves laterally to the exit side position, the upper pinch roll opens, and the pinch rolls run at a leading speed. In this mode, only the lower pinch roll provides the propulsion for the strip head to advance during threading. In a hot-rolled strip production line, when the strip head passes through the pinch rolls into the downstream coiler, the upper pinch roll gap of the coiler is in the open position, and the lower pinch roll moves laterally to the exit side position.

[0032] The lower clamping roller of the winding machine is designed to be transversely movable. The transverse movement of the lower clamping roller is achieved by a transverse movement mechanism; and the space formed by the transverse movement is filled by a guide plate that moves with the transverse movement mechanism.

[0033] Before the strip head needs to pass through this pinch roll to be threaded into the downstream coiler, the lower pinch roll is moved laterally to a position perpendicular to the center of the upper pinch roll, that is, the deflection angle (also called the offset angle) α of the upper pinch roll relative to the lower pinch roll is 0.

[0034] If the coiler does not coil steel, the upper pinch roll will be pressed down to the set roll gap G1 according to the strip thickness H.

[0035] G1=H-a1

[0036] Where: H is the strip thickness, and a1 is a fixed value.

[0037] If the coiler is currently coiling steel and the upper pinch roll is already in the pressed position, maintain pressure control on the upper pinch roll. After the downstream coiler sets the tension, open the upper pinch roll gap to G2 (fixed value) and move the lower pinch roll laterally to the position S where the steel is to be coiled. The lower pinch roll is in position S when waiting to coil the steel; it needs to be moved laterally to a position perpendicular to the center of the upper and lower pinch rolls before the downstream coiler can coil the steel.

[0038] (2) Pinch roller speed control mode

[0039] If the coiler is not coiling steel, after the upper pinch roll is pressed down to the set roll gap G1, the upper and lower pinch rolls run at a certain lead speed V1 according to the strip speed V0 at the finishing mill exit.

[0040] V1 = V0 × (1 + a2)

[0041] Where: V0 is the strip speed at the finish rolling exit, and a2 is a different set value given according to different strip thicknesses.

[0042] If the coiler is coiling steel, after the high-speed flying shear cuts, adjust the coiling tension torque T on the drum. R The speed setting value is set so that the upper and lower clamping rollers of the coiler run at a certain advance speed V1, so that the coiler can both coil the strip at a certain advance speed V1 and provide sufficient tail tension, and quality problems such as loose coiling and flat coiling will not occur. After the downstream coiler is tensioned, it runs at the strip speed V0.

[0043] Tension torque T R The calculation formula is:

[0044]

[0045] Where: T2 is the strip tension force, D is the coil diameter, c is the transmission ratio, and β is a coefficient given according to different strip thicknesses.

[0046] (3) Pressure control mode

[0047] If the coiler is not coiling steel, when the head of the strip reaches the pinch roll of the coiler, the pinch roll executes a low-pressure control mode, and the pressure setting value is executed according to F1. F1 is a fixed pressure value given by the lookup table method based on the strip thickness T (the lookup table method is existing technology and will not be elaborated here).

[0048] If the coiler is coiling steel, after the high-speed flying shear cuts, the pressure setting changes from the pressure F0 calculated based on the strip thickness and tension to the low-pressure setting F1. After the downstream coiler builds tension, the pressure mode is canceled, the roll gap is opened, and the position control mode is switched.

[0049] The formula for calculating pressure F0 is:

[0050]

[0051] Where: W is the strip width; H is the strip thickness; T is the tension.

[0052] (4) Used in conjunction with the clamping rollers of a multi-winding machine

[0053] The number of coilers varies on different production lines. On a production line with three coilers, coilers #1 and #2 can use the auxiliary threading function simultaneously, or coilers #1 and #2 can take turns using the auxiliary threading function to send the strip head to coiler #3.

[0054] After applying the method of the present invention, the occurrence rate of strip head slippage is reduced, and the slippage of strip on the roller table in front of the pinch roll is suppressed, reducing the risk of slippage and steel accumulation; and the production efficiency of hot-rolled thin specifications is improved, and the output of thin specifications is increased.

[0055] The lateral movement mechanism in the pinch roll position control mode is designed to move the lower pinch roll of the coiler to a position perpendicular to the center of the upper pinch roll. The forward and backward movement is set based on the strip's direction. Figure 3 To the right is front, and to the opposite is back.

[0056] like Figure 3 As shown, the transverse movement mechanism includes a frame 8, a lower clamping roller bracket 3, a connecting shaft 4, and a transverse movement hydraulic cylinder 5.

[0057] The frame 8 is connected to the winding frame and is located directly below the upper pinch roller 1. The lower pinch roller bracket 3 is slidably connected to the upper surface of the frame 8. To increase safety, baffles 6 are provided in front of and behind the frame 8 to limit the lateral movement area of ​​the lower pinch roller bracket 3.

[0058] The lower clamping roller 2 is located inside the lower clamping roller bracket 3, and both ends of the lower clamping roller 2 are rotatably connected to the side plates of the lower clamping roller bracket 3 through bearings.

[0059] The front end of the lower pinch roll support 3 is connected to the transverse hydraulic cylinder 5 via a connecting shaft 4. The transverse hydraulic cylinder 5 provides power to realize the forward and backward movement of the lower pinch roll support 3. The front end of the transverse hydraulic cylinder 5 is connected to the winding frame.

[0060] To increase the stability of sliding, the upper surface of the frame 8 has a track 7, and the corresponding position of the lower clamping roller bracket 3 has a groove. The track 7 is embedded in the groove, and the two are slidably connected.

[0061] In the optimized solution, there is a limit switch on the track 7. When the rear end of the lower clamping roller bracket 3 contacts the limit switch, the transverse hydraulic cylinder 5 is closed.

[0062] It should be noted that the specific embodiments of the present invention have been described in detail. For those skilled in the art, various obvious changes made to it without departing from the spirit and scope of the present invention are within the protection scope of the present invention.

Claims

1. A method for assisting strip threading with pinch rolls in a coiler of a hot-rolled strip steel production line, characterized in that: The pinch roller control modes include pressure control mode, speed control mode, and position control mode; In the position control mode, when the strip head is threaded, the lower pinch roller moves laterally to a position perpendicular to the center of the upper pinch roller; specifically, the lower pinch roller moves laterally to a position perpendicular to the center of the upper pinch roller, meaning the deflection angle α of the upper pinch roller relative to the lower pinch roller is 0; the upper pinch roller is pressed down to the set roll gap position G1; the calculation formula for G1 is: G1 = H - a1; where: H is the strip thickness, and a1 is a fixed value; the pinch roller operates in speed control mode; if the coiler is not coiling steel, the upper pinch roller is pressed down to the set roll gap G1 according to the strip thickness H; if the coiler is coiling steel, and the upper pinch roller is already in the pressed position, the upper pinch roller is kept under pressure control until the downstream coiler sets tension, at which point the roll gap of the upper pinch roller opens to G2; the lower pinch roller moves laterally to the position to be coiled. In the speed control mode, if the coiler is not coiling steel, after the upper pinch roll is pressed down to the set roll gap G1, the upper and lower pinch rolls run at a leading speed V1; the formula for calculating the leading speed V1 is: V1=V0×(1+a2); where: V0 is the strip speed at the finishing mill exit, and a2 is a different set value given according to different strip thicknesses; if the coiler is coiling steel, after the high-speed flying shear cuts, it runs at a leading speed V1, and after the downstream coiler sets up tension, it runs at the strip speed V0; In the pressure control mode, if the coiler is not coiling steel, when the strip head reaches the coiler's pinch roll, the pinch roll executes the low pressure control mode, and the pressure setting value is executed according to F1; if the coiler is coiling steel, after the high-speed flying shear cuts, the pressure setting value changes from pressure F0 to the low pressure mode setting pressure F1. After the downstream coiler sets tension, the pressure mode is canceled, the roll gap is opened, and the position control mode is switched.

2. The method for assisting strip threading with pinch rolls in a hot-rolled strip steel production line according to claim 1, characterized in that: In the position control mode, the lateral movement of the lower clamping roller is achieved through a lateral movement mechanism.

3. The method for assisting strip threading with pinch rolls in a hot-rolled strip steel production line according to claim 1, characterized in that: In the pressure control mode, F1 is a fixed pressure value given by looking up a table based on the strip thickness T.

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