A method for controlling the first knife of a rotary flying shear

Abstract

The present application relates to a kind of rotary flying shear first knife shearing control method, comprising: real-time positioning the position of the first shearing point of strip steel and the angular position of flying shear blade;Calculate the distance l' of the first shearing point to flying shear at current time, according to distance l' the angular position setting value of flying shear blade at current time is calculated;Judge the difference between angular position setting value and the actual value of the angular position of flying shear blade at current time whether in set range, if in set range, maintain the output torque of flying shear motor unchanged, if not in set range, then adjust the output torque of flying shear motor, so that the difference between the angular position setting value and the actual value of the angular position of flying shear blade at next time is in set range.The present application realizes the closed-loop control of the angular position of flying shear blade by the output torque control of flying shear motor, can greatly improve the accuracy of flying shear blade position, avoid the situation such as the lag of flying shear position and the overshoot of flying shear position, to improve the shearing precision of rotary flying shear first knife.

Description

Technical Field

[0001] This invention belongs to the field of strip steel production technology, specifically relating to a method for controlling the first cut of a rotary flying shear. Background Technology

[0002] Rotary flying shears are key pieces of equipment in metallurgical production lines, used to precisely slit strip steel during operation. In the production process, data such as the strip slitting method, the position of the first shearing point, and the sampling / scrap shearing length are pre-set, thus determining the position of each shearing point on the strip steel. Figure 1 As shown. Accurately hitting each shearing point on the strip during operation is the core objective of flying shear control, and accurately hitting the first shearing point is an extremely important step in flying shear control, which is the foundation for achieving subsequent precise length shearing.

[0003] Regardless of the structural form of the rotary flying shear, its basic working principle is that the motor drives the shear blade to make circular motion through the gearbox. The running trajectory of the shear blade during the cutting process is an approximate circle. When the flying shear rotates once, the upper shear blade is at the lowest point and the lower shear blade is at the highest point. The upper and lower shear blades intersect each other to completely cut the strip steel.

[0004] The point where the upper and lower blades of the flying shear completely intersect, i.e., the lowest point of the upper blade, is generally called the shearing point. Each time the flying shear passes this shearing point, the blade angle is manually set to 0°. Therefore, with each shear cut, the blade angle changes from 0° to 360°. To ensure the safety of the blades and prevent damage to the strip when the flying shear is shearing, the relative velocity between the shear and the strip must be zero during contact. The blades only contact the strip within a certain angular range to the left and right of the shearing point; this angle is called the shearing angle.

[0005] The shearing angle is related to the overlap between the upper and lower blades of the flying shear, the thickness of the strip, and the rotation radius of the flying shear blades. The calculation formula is as follows:

[0006]

[0007] In the formula: α is the shearing angle; R is the rotation radius of the shear blade; MD is the strip thickness; MU is the overlap between the upper and lower shear blades.

[0008] Currently, a measuring roller is typically installed at the front of the flying shear. When the cutting point reaches the set position, the encoder count value of the measuring roller is reset to zero. The distance from the next cutting point to the flying shear is calculated using the accumulated value of the encoder pulses on the measuring roller. The calculation formula is as follows:

[0009]

[0010] In the formula, l is the distance from the next shearing point to the flying shear; L0 is the shearing length setting or the distance from the first shearing point to the flying shear when the flying shear is started; I1 is the cumulative value of the measuring roller encoder pulses; D1 is the diameter of the measuring roller; i1 is the gear ratio of the measuring roller gearbox; and n1 is the number of pulses per revolution of the measuring roller encoder.

[0011] During normal production, the shear blade stops at a fixed position, such as... Figure 2 Position D. The strip runs at a fixed speed V. When the first shearing point on the strip reaches the set position, the flying shear enters the shearing start process. The flying shear blade starts from the start position and accelerates to the same speed as the strip in the horizontal direction, then intersects the first shearing point on the strip at the front shearing angle A, and passes through the shearing point B at the same speed as the strip in the horizontal direction, completing the first cut. After that, it enters the fixed length shearing process.

[0012] The existing control method for rotary flying shears calculates the real-time speed setpoint of the flying shear based on the distance from the first cutting point to the flying shear, and then uses the flying shear speed to control the position of the flying shear blades. However, due to the presence of interference factors such as rotational inertia and friction, the speed control of the flying shear may suffer from lag and overshoot, making it difficult to guarantee the accuracy of the blade position control. Summary of the Invention

[0013] This invention relates to a method for controlling the first cutter of a rotary flying shear, which can at least solve some of the defects of the prior art.

[0014] This invention relates to a method for controlling the first cutter of a rotary flying shear, the method comprising:

[0015] Real-time positioning of the first shearing point of the strip steel and the angle position of the flying shear blade;

[0016] Calculate the distance l' from the first cutting point to the flying shear at the current moment, and calculate the angular position setting value of the flying shear blade at the current moment based on the distance l';

[0017] Determine whether the difference between the set angular position value and the actual angular position value of the flying shear blade at the current moment is within the set range. If it is within the set range, maintain the output torque of the flying shear motor unchanged. If it is not within the set range, adjust the output torque of the flying shear motor so that the difference between the set angular position value and the actual angular position value of the flying shear blade at the next moment is within the set range.

[0018] As one implementation method, adjusting the output torque of the flying shear motor specifically includes:

[0019] A torque pre-control value is obtained, which is calculated based on the flying shear start-up acceleration and the flying shear's moment of inertia;

[0020] A torque adjustment amount is obtained, which is calculated based on the current flying shear speed set value and the actual flying shear speed value;

[0021] The torque output value of the flying shear motor is obtained based on the torque pre-control value and the torque adjustment amount, and the output torque of the flying shear motor is adjusted based on the torque output value.

[0022] As one implementation method, the torque pre-control value is calculated using the following formula:

[0023]

[0024] In the formula: Tq A This is the torque pre-control value; J F a1 is the fixed moment of inertia of the flying shear; R is the starting acceleration of the flying shear; R is the rotation radius of the shear blade. i represents the gear ratio of the flying shear motor's gearbox.

[0025] As one implementation method, the starting acceleration of the flying shear is calculated using the following formula:

[0026]

[0027] In the formula: a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip steel; α is the shearing angle; β is the angle of the starting position of the shear blade; R is the rotation radius of the shear blade.

[0028] As one implementation method, the flying shear speed setpoint is obtained by adding an additional speed adjustment amount to the theoretical flying shear speed setpoint at the current moment. The additional speed adjustment amount is calculated using the following formula:

[0029]

[0030] In the formula: ΔV1 is the additional speed adjustment; Kp is the proportional gain of the angle closed-loop control; θ is the set value of the angular position of the flying shear blade at the current moment; γ is the actual value of the angular position of the flying shear blade at the current moment.

[0031] As one implementation method, the theoretical set value of the flying shear speed is calculated using the following formula:

[0032]

[0033] In the formula: V1 is the theoretical set value of the flying shear speed; l' is the distance from the first shearing point to the flying shear at the current moment; a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip steel; α is the shearing angle.

[0034] As one implementation method, the current angular position setting value θ of the flying shear blade is calculated using the following formula:

[0035]

[0036] In the formula: θ satisfies β<θ<360-α; a1 is the starting acceleration of the flying shear; l' is the distance from the first shearing point to the flying shear at the current moment; R is the rotation radius of the shear blade; α is the shearing angle; β is the angle of the starting position of the shear blade; V is the actual linear velocity of the strip.

[0037] As one implementation method, when adjusting the output torque of the flying shear motor, the current of the flying shear motor is adjusted in advance based on the torque pre-control value, and then the output torque of the flying shear motor is further adjusted in combination with the torque adjustment amount.

[0038] As one implementation method, the position of the first shearing point of the strip is referenced to the weld position. The position of the first shearing point of the strip is located in real time by locating the weld position in real time.

[0039] As one implementation method, the real-time positioning of the weld seam includes:

[0040] The strip steel production line is divided into multiple zones, and the encoder of the drive motor in each zone is used to calculate the actual position of the weld.

[0041] And / or, the real-time positioning of the weld seam includes:

[0042] A weld inspection instrument is placed before the flying shear to detect the position of the weld and achieve real-time positioning of the weld.

[0043] The present invention has at least the following beneficial effects:

[0044] In this invention, by controlling the output torque of the flying shear motor, closed-loop control of the flying shear blade position is achieved, which can greatly improve the accuracy of the flying shear blade position and avoid situations such as flying shear position lag and flying shear position overshoot, thereby improving the cutting accuracy of the first cut of the rotary flying shear. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A schematic diagram showing the layout of equipment related to the control of a rotary flying shear.

[0047] Figure 2 This is a schematic diagram showing the position of the blades of a rotary flying shear.

[0048] Figure 3 This is a schematic diagram showing the change in the blade angle during the first cut.

[0049] Figure 4 This diagram illustrates the relationship between the distance from the first cutting point to the flying shear, the blade angle, and the blade speed during the first cutting process.

[0050] Figure 5 A schematic diagram of the control flow for the first cut of the flying shears. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] like Figure 4 and Figure 5 This invention provides a method for controlling the first cutter of a rotary flying shear, the method comprising:

[0053] Real-time positioning of the first shearing point of the strip steel and the angle position of the flying shear blade;

[0054] Calculate the distance l' from the first cutting point to the flying shear at the current moment, and calculate the angular position setting value of the flying shear blade at the current moment based on the distance l';

[0055] Determine whether the difference between the set angular position value and the actual angular position value of the flying shear blade at the current moment is within the set range. If it is within the set range, maintain the output torque of the flying shear motor unchanged. If it is not within the set range, adjust the output torque of the flying shear motor so that the difference between the set angular position value and the actual angular position value of the flying shear blade at the next moment is within the set range.

[0056] The location of the first shearing point of the strip is generally referenced to the weld position, which can improve the shearing accuracy. In this embodiment, the location of the first shearing point of the strip is located in real time by locating the weld position.

[0057] In one embodiment, the real-time positioning of the weld seam includes:

[0058] The strip steel production line is divided into multiple zones, and the encoders of the drive motors in each zone are used to calculate the actual position of the weld.

[0059] Taking a cold rolling production line as an example, the cold rolling production line can be divided into multiple zones, such as the entrance zone, entrance looper zone, tension leveler zone, pickling zone, exit looper zone, and rolling mill zone.

[0060] Each drive motor encoder is electrically connected to the central processing unit (CPU). The CPU contains a software counter (including but not limited to a 32-bit software counter). When the weld enters a certain tracking zone, the corresponding software counter is activated to accumulate the pulse increment of the zone's drive motor encoder. The value of the software counter is multiplied by the length of the unit pulse of the zone's drive motor encoder to obtain the actual length of the strip from the starting point of the tracking zone to the weld.

[0061] Length = I × Li × CORR × MF

[0062] Where: I is the number of pulses accumulated by the software counter from the moment the weld enters the tracking zone; Li is the length of a unit pulse [mm / pulse]; MF is the model factor, which should take into account the elongation of the strip when calculating this factor in the tension leveler / smoothing mill / rolling mill zone; CORR is the algorithm correction factor based on the theoretical length and the measured length when the weld passes the synchronization point (generally in the range of 0.98~1.02).

[0063] The formula for calculating CORR is:

[0064]

[0065] In the formula: A is the amplification factor of the algorithm correction factor; K is the theoretical length / measured length; The K value calculated for this period; This is the K value calculated for the previous period.

[0066] In one embodiment, the real-time positioning of the weld seam includes:

[0067] A weld inspection instrument is placed before the flying shear to detect the position of the weld and achieve real-time positioning of the weld.

[0068] Optionally, holes are drilled at the weld location during strip welding. When the hole is detected by the weld inspection instrument, it indicates that the actual location of the weld is at the weld inspection instrument.

[0069] In the first positioning method described above, the tracking range of each encoder is reduced by using zone detection, which can improve the tracking accuracy of the weld seam. However, due to factors such as slippage of the drive roller, loss of pulse signals, and changes in strip length caused by the heating furnace, the tracking error of the weld seam may be relatively large. Preferably, the combination of the two positioning methods described above can significantly improve the positioning accuracy of the weld seam.

[0070] The flying shear is located in a zone with a fixed length. During initial testing, the fixed length L from the defined zone head to the weld inspection instrument can be measured. In the strip length calculation formula Length=I×Li×CORR×MF, Li, CORR, and MF are constants for the flying shear zone. Therefore, the encoder pulse value I1 that the software counter should record when the weld travels from the zone head to the weld inspection instrument can be calculated in reverse.

[0071] I1 = L / (Li×CORR×MF)

[0072] In the formula: I1 is the encoder pulse value that the software counter should record when the weld moves from the head of the partition to the weld inspection instrument after reverse calculation; L is the fixed length value from the head of the exit partition to the weld inspection instrument.

[0073] When the weld inspection instrument detects a weld, it forcibly writes I1 to the software counter that tracks the weld. In this way, the weld is accurately located. Since the weld inspection instrument is installed very close to the flying shear and the strip length of the section is fixed, the distance from the first shearing point to the flying shear is accurately corrected.

[0074] Optionally, the actual angular position of the flying shear blade can be calculated using a flying shear drive encoder.

[0075] Further optimize the above control methods, such as Figure 5 The adjustment of the output torque of the flying shear motor specifically includes:

[0076] A torque pre-control value is obtained, which is calculated based on the flying shear start-up acceleration and the flying shear's moment of inertia;

[0077] A torque adjustment amount is obtained, which is calculated based on the current flying shear speed set value and the actual flying shear speed value;

[0078] The torque output value of the flying shear motor is obtained based on the torque pre-control value and the torque adjustment amount, and the output torque of the flying shear motor is adjusted based on the torque output value.

[0079] The flying shear accelerates continuously from the starting position D to the forward shearing angle A. Due to the large moment of inertia of the rotary flying shear, it is difficult to overcome the flying shear position lag during acceleration and the flying shear position overshoot at the end of acceleration by controlling the flying shear speed. In this embodiment, closed-loop control of the flying shear blade angle position is achieved by controlling the output torque of the flying shear motor. This can greatly improve the accuracy of the flying shear blade position and avoid situations such as flying shear position lag and flying shear position overshoot, thereby improving the cutting accuracy of the first cut of the rotary flying shear.

[0080] In the above-mentioned output torque adjustment scheme, the torque output value of the flying shear motor is obtained based on the torque pre-control value and the torque adjustment amount. This can effectively reduce the influence of factors such as the rotational inertia of the rotary flying shear, avoid the occurrence of flying shear position lag and overshoot, and enable the flying shear blade to reach the target angle position quickly and accurately.

[0081] In particular, when adjusting the output torque of the flying shear motor, the current of the flying shear motor is adjusted in advance based on the torque pre-control value, and then the output torque of the flying shear motor is further adjusted in combination with the torque adjustment amount. This can greatly accelerate the control process of the output torque of the flying shear motor.

[0082] Preferably, the torque pre-control value is calculated using the following formula:

[0083]

[0084] In the formula: Tq A This is the torque pre-control value; J F a1 is the fixed moment of inertia of the flying shear; R is the starting acceleration of the flying shear; R is the rotation radius of the shear blade. i represents the gear ratio of the flying shear motor's gearbox.

[0085] like Figure 2 The flying shear start-up acceleration is the acceleration of the flying shear at the moment of start-up. To ensure that the horizontal velocity component of the shear blade is consistent with the strip velocity during shearing, the velocity of the flying shear blade when it reaches the front shear angle A should be V / (cosα). When the shear blade moves from the waiting position D to the front shear angle A, the velocity increases from 0 to V / (cosα). Therefore, the flying shear start-up acceleration is calculated using the following formula:

[0086]

[0087] In the formula: a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip steel; α is the shearing angle; β is the angle of the starting position of the shear blade; R is the rotation radius of the shear blade.

[0088] In one embodiment, such as Figure 5 The flying shear speed setpoint is obtained by adding an additional speed adjustment amount to the theoretical flying shear speed setpoint at the current moment. The additional speed adjustment amount is calculated using the following formula:

[0089]

[0090] In the formula: ΔV1 is the additional speed adjustment; Kp is the proportional gain of the angle closed-loop control; θ is the set value of the angular position of the flying shear blade at the current moment; γ is the actual value of the angular position of the flying shear blade at the current moment.

[0091] Based on the above design, the speed oscillation that may be caused by the position control of the flying shear blade can be reduced, thereby improving the cutting accuracy of the first cut of the rotary flying shear.

[0092] This includes, but is not limited to, using a proportional controller to execute the aforementioned additional speed adjustment output.

[0093] Among them, such as Figure 3 The current angular position setting value θ of the flying shear blade is calculated using the following formula:

[0094]

[0095] In the formula: θ satisfies β<θ<360-α; a1 is the starting acceleration of the flying shear; l' is the distance l' from the first shearing point at the current moment to the flying shear; R is the rotation radius of the shear blade; α is the shearing angle; β is the angle of the starting position of the shear blade; V is the actual linear velocity of the strip steel.

[0096] Preferably, the theoretical set value of the flying shear speed is calculated using the following formula:

[0097]

[0098] In the formula: V1 is the theoretical set value of the flying shear speed; l' is the distance from the first shearing point to the flying shear at the current moment; a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip steel; α is the shearing angle.

[0099] For the aforementioned Kp, preferably, Kp is initially determined based on the maximum allowable additional speed ΔV_Lim of the flying shear (generally 3%~5% of the actual linear speed V of the strip) and the maximum possible angular deviation ΔS_max, ensuring that the additional speed adjustment does not exceed ΔV_Lim at the maximum angular deviation, i.e.: Kp ≤ ΔV_Lim / ΔS_max. During debugging and optimization, a smaller initial Kp can be set to ensure no significant impact or overshoot during flying shear startup; then, Kp is gradually increased while monitoring the flying shear's movement. If overshoot occurs during flying shear movement (i.e., the actual angular position exceeds the set angular position), it indicates that Kp is too large and needs to be appropriately reduced; if the actual angular position significantly lags behind the set angular position during startup, it indicates that Kp is too small and needs to be appropriately increased. Based on this, a suitable Kp can be obtained through debugging and optimization.

[0100] The torque adjustment can be obtained through conventional speed PI control. Based on the current flying shear speed setpoint and the actual flying shear speed, the torque adjustment is generated through PI regulation.

[0101] Understandably, such as Figure 5 When adjusting the output torque of the flying shear motor, the actual value of the flying shear motor's output torque is obtained in real time to determine whether the adjustment of the flying shear motor's output torque is complete, so as to ensure the accuracy of the adjustment.

[0102] In addition, the above control method also includes: based on the calculated distance l' from the first shearing point to the flying shear at the current moment, comparing it with the theoretical distance l1' to determine whether to start the flying shear; if l' is less than or equal to l1', the flying shear is started immediately, otherwise the flying shear is not started.

[0103] Specifically, the theoretical distance l1' is calculated using the following formula:

[0104]

[0105] In the formula: α is the theoretical distance from the first shearing point on the strip to the flying shear when it is started; β is the shearing angle; R is the angle of the starting position of the shear blade; R is the rotation radius of the shear blade.

[0106] l represents the distance the strip travels during the process from the start of the flying shear blade to its intersection with the first shearing point, calculated using the following formula:

[0107]

[0108] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the first cut of a rotary flying shear, characterized in that, The method includes: Real-time positioning of the first shearing point of the strip steel and the angle position of the flying shear blade; Calculate the distance l' from the first cutting point to the flying shear at the current moment, and calculate the angular position setting value of the flying shear blade at the current moment based on the distance l'; Determine whether the difference between the set angular position value and the actual angular position value of the flying shear blade at the current moment is within the set range. If it is within the set range, maintain the output torque of the flying shear motor unchanged. If it is not within the set range, adjust the output torque of the flying shear motor so that the difference between the set angular position value and the actual angular position value of the flying shear blade at the next moment is within the set range. The adjustment of the output torque of the flying shear motor specifically includes: A torque pre-control value is obtained, which is calculated based on the flying shear start-up acceleration and the flying shear's moment of inertia; A torque adjustment amount is obtained, which is calculated based on the current flying shear speed set value and the actual flying shear speed value; The torque output value of the flying shear motor is obtained based on the torque pre-control value and the torque adjustment amount, and the output torque of the flying shear motor is adjusted based on the torque output value; When adjusting the output torque of the flying shear motor, the current of the flying shear motor is adjusted in advance based on the torque pre-control value, and then the output torque of the flying shear motor is further adjusted in combination with the torque adjustment amount.

2. The first-blade cutting control method of the rotary flying shear as described in claim 1, characterized in that, The torque pre-control value is calculated using the following formula: ； In the formula: Tq A This is the torque pre-control value; J F a1 is the fixed moment of inertia of the flying shear; R is the starting acceleration of the flying shear; R is the rotation radius of the shear blade. i represents the gear ratio of the flying shear motor's gearbox.

3. The method for controlling the first cutter of a rotary flying shear as described in claim 1 or 2, characterized in that, The starting acceleration of the flying shear is calculated using the following formula: ； In the formula: a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip steel; α is the shearing angle; β is the angle of the starting position of the shear blade; R is the rotation radius of the shear blade.

4. The first-blade cutting control method of the rotary flying shear as described in claim 1, characterized in that, The flying shear speed setpoint is obtained by adding an additional speed adjustment amount to the theoretical flying shear speed setpoint at the current moment. The additional speed adjustment amount is calculated using the following formula: ； In the formula: ΔV1 is the additional speed adjustment; Kp is the proportional gain of the angle closed-loop control; θ is the set value of the angular position of the flying shear blade at the current moment; γ is the actual value of the angular position of the flying shear blade at the current moment.

5. The first-blade cutting control method of the rotary flying shear as described in claim 4, characterized in that, The theoretical setpoint for the flying shear speed is calculated using the following formula: ； In the formula: V1 is the theoretical set value of the flying shear speed; l' is the distance from the first shearing point to the flying shear at the current moment; a1 is the starting acceleration of the flying shear; V is the actual linear velocity of the strip; α is the shearing angle.

6. The first-blade cutting control method of the rotary flying shear as described in claim 4, characterized in that, The current angular position setting θ of the flying shear blade is calculated using the following formula: ； In the formula: θ satisfies β<θ<360-α; a1 is the starting acceleration of the flying shear; l' is the distance from the first shearing point to the flying shear at the current moment; R is the rotation radius of the shear blade; α is the shearing angle; β is the angle of the starting position of the shear blade; V is the actual linear velocity of the strip.

7. The first-blade cutting control method of the rotary flying shear as described in claim 1, characterized in that, The position of the first shearing point of the strip is referenced by the weld position. The position of the first shearing point of the strip is located in real time by locating the weld position.

8. The method for controlling the first cutter of a rotary flying shear as described in claim 7, characterized in that, The real-time positioning of the weld seam includes: The strip steel production line is divided into multiple zones, and the encoder of the drive motor in each zone is used to calculate the actual position of the weld. And / or, the real-time positioning of the weld seam includes: A weld inspection instrument is placed before the flying shear to detect the position of the weld and achieve real-time positioning of the weld.

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