A method for precisely controlling the loop opening angle of a hot-rolled plate

Abstract

The application discloses a method for precisely controlling a hot-rolled plate loop unwinding angle, which adopts a control method of early intervention of speed adjustment amount, does not need to add equipment or detection components, and can be realized by using original equipment. First step: testing loop unwinding delay and unwinding time when the loop is in an empty state; second step: detecting and memorizing actual loop angle θ of the present strip steel at t4 moment after the strip steel is gripped by a downstream rack and maximum loop angle θ of the loop within 2 seconds of unwinding by a TDC controller max , calculating loop amount L corresponding to the actual loop angle θ of t4 moment and loop setting angle θ set of the loop at t4 moment set , and reaching loop amount value L of the loop when the maximum loop angle is reached max ; third step: comparing the actual loop angle θ of t4 moment with the setting angle θ set , accurately calculating speed adjustment amount required by the upstream rack, and putting the speed given to the upstream rack before the next strip steel enters a finishing rolling area, so that the loop stably and quickly reaches the setting height, improves head size precision, and realizes full-automatic control of the loop.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of automatic control of hot-rolled plate production line, in particular to a precise control method for the loop lifting angle of hot-rolled plate. BACKGROUND

[0002] After years of technical research and on-site polishing, the current loop control technology has basically matured, which can well buffer the inter-stand second flow changes caused by various disturbances in production, ensure stable operation of on-site production, and ensure product quality. However, at the initial moment of loop lifting, due to the matching degree of speed regulation data, dynamic speed drop at the moment of mill steel biting, etc., the phenomenon of high loop lifting or difficult loop lifting at the initial moment of loop lifting occurs, which causes large tension fluctuation of the strip head, cannot guarantee the size accuracy of the head of the rolled piece, and even there is a situation of large loop lifting of scrap steel, and frequent manual intervention is often required.

[0003] Currently, the loop lifting control time point of hot rolling is taken from the steel biting signal of the downstream stand adjacent to the current loop, and at the moment of loop lifting, the position closed-loop control with the set angle as the target is first carried out, and when the loop angle reaches a certain value close to the target angle, the double closed-loop control of tension control and angle control is entered. By calculating the difference between the set angle and the actual angle of the corresponding stored loop amount, the adjustment amount of the upstream stand speed is calculated and the speed of the upstream stand is adjusted, so that the loop runs stably at the set angle. This method adjusts the speed relatively slowly, which cannot well meet the needs of on-site high-precision production of product head and the actual need of no manual intervention. SUMMARY

[0004] In view of the above problems, the present application considers that the traditional way of loop lifting control is relatively lagging, there are many abnormal phenomena at the initial moment of loop lifting, manual intervention is frequent, and the size accuracy of the head of the rolled piece cannot well meet the actual situation of process requirements, and a precise control method for the loop lifting angle of hot-rolled plate is proposed. According to the difference between the actual loop lifting data and the ideal loop lifting data of the current strip head, the most suitable speed intervention amount of the upstream stand is calculated and applied to the next piece of steel, the deviation of the upstream stand speed of the current piece of steel in the loop lifting process is accurately calculated by using a TDC high-speed high-precision controller, and the deviation is compensated in the rolling of the next piece of steel, realizing precise cascade control, ensuring that the loop works stably in the set tension and height range, ensuring the size accuracy of the head of the rolled piece, and realizing the important purpose of no manual intervention in the whole rolling process.

[0005] The precise control method for the loop lifting angle of hot-rolled plate, the specific steps are as follows:

[0006] Step 1: Determine the loop lifting time of the rolled steel.

[0007] Step 2: Calculate the looper clearance L and the looper set angle θ when the current strip is lifted to the set angle. set Corresponding looper quantity L set And the looper length L when the looper angle reaches its maximum value. max .

[0008] Step 3: The actual loop angle θ at the ideal moment when the loop is raised to the set angle is compared with the set angle θ. set Compare and make the following judgments:

[0009] 1) θ≥θ set At that time, calculate the maximum hoisting angle θ within 2 seconds after the hoisting command is issued. max Looping quantity L max and the starting set angle θ set Looping quantity L set The difference ΔL between them is used to calculate the speed deviation ΔV of the upstream rack. set -L max ) / T, where ΔV is a negative value and T is the time required from the moment the lifting command is issued to the ideal moment when the loop is raised to the set angle.

[0010] 2) θ<θ set At that time, the actual loop angle θ at the ideal moment when the loop is raised to the set angle is calculated, along with the loop amount L and the ideal lifting angle θ. set The looper quantity L0 at the time of the test, and the difference between the two looper quantities ΔL = L0 - L, are used to calculate the speed deviation ΔV = (L0 - L) of the upstream frame. set -L) / T, where ΔV is a positive value.

[0011] Step 4: Add the adjustment value ΔV calculated for each strip of steel that has been rolled to the cascade speed setting of the next strip of steel on the upstream stand of the looper.

[0012] The advantages of this invention are:

[0013] 1. The present invention provides a precise control method for the looper starting angle of hot-rolled steel sheets. Based on the actual production data of the current strip steel, it accurately calculates the theoretical value of the speed adjustment and applies it before the next strip steel bites in. This not only enables the entire rolling process to participate in the closed-loop adjustment of the looper height, ensuring the dimensional accuracy of the head, but also eliminates the need for manual intervention by operators, achieving fully automatic looper setting and control. This simplifies the adjustment process, reduces the labor intensity of operators, and enables unmanned operation of this position, achieving cost reduction and efficiency improvement, and enhancing the economic benefits of the factory. 2. The present invention provides a precise control method for the looper starting angle of hot-rolled steel sheets, employing a pre-intervention speed adjustment control method. It eliminates the need for new equipment or detection components, and can utilize the existing programmable controller, looper angle detection encoder, and hydraulic servo valve. Attached Figure Description

[0014] Figure 1 This is a schematic diagram showing the positional relationship between the rolling mill and the looper rolls.

[0015] Figure 2 This is a graph showing the relationship between the amount of looper used and time.

[0016] Figure 3 This is a flowchart of the method for precisely controlling the starting angle of the looper on hot-rolled sheet metal according to the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings.

[0018] The positional relationship between the rolling mill and the looper rolls is as follows: Figure 1 As shown. Where S i Represents upstream racks, S i+1 LP represents the downstream rack, L3 represents the looper, and L3 represents the upstream rack. i With downstream rack S i+1 Center distance, L1 represents upstream rack S i The distance to the looper fulcrum is L2, which represents the height of the looper fulcrum from the rolling line; θ represents the actual angle of the looper; R represents the looper arm length; and r represents the looper roll radius.

[0019] The relationship between the amount of looper used and time, such as Figure 2 As shown in the figure. Where L0(t) represents the looper's looping quantity curve when unloaded, L1(t) represents the looper's looping quantity curve when the looper starts looping late, and L2(t) represents the looper's looping quantity curve when the looper starts looping large. (t2-t1) is the dead zone time of the looper's operation; (t3-t1) is the time it takes for the looper roller to reach the set angle under unloaded conditions; (t4-t1) is the ideal time for the looper roller to reach the set angle under load; (t5-t1) is the memory time after the downstream stand bites the steel, this value can be modified. L set L is the looping amount at a set angle when the looper is unloaded; L is the actual looping amount of the looper roller within a set time. max This represents the maximum amount of looping of the looper roller within t5.

[0020] Generally, the dead load test, the loop-up roll action dead time (t2-t1) and the time (t3-t1) for the loop-up roll to reach the set angle under the dead load condition are relatively fixed, the time for the actual loop-up process of the strip to reach the set angle is slightly different for different width and thickness of the strip, in the actual tracking process in the field, a time offset is added to the time for the strip to reach the set angle under the dead load condition or a different coefficient is multiplied according to different strip specifications as the ideal time (t4-t1) for the strip to reach the set angle, the loop-up amount difference calculated in the time is obtained, that is, the upstream stand speed to be adjusted is obtained. The adjustment speed is transmitted to the upstream stand before the next strip arrives, so that the next strip can quickly enter the loop-up stable adjustment operation state, the phenomenon of steel piling or steel drawing is avoided, the head size accuracy is ensured, the whole control process does not need the intervention of the operator, the adjustment process is simplified and the labor intensity of the operator is reduced.

[0021] In summary, the precise control method for the loop-up angle of the hot-rolled plate loop-up, focuses on the loop-up angle control and does not consider the tension control problem, and considers that the tension control is normal. As shown in the formula (1), the specific steps are as follows: Figure 3

[0022] Step 1: Determine the loop-up time of the loop-up during rolling.

[0023] The actual time required from the loop-up instruction issuing time t1 to the loop-up reaching the set angle time t3 under the dead load condition is T0, T0=t3-t1. The loop-up time T0 of each hot-rolled loop-up is fixed, due to the differences in mechanical properties and hydraulic properties, T0 is usually between 300-800 ms.

[0024] The loop-up instruction during rolling is issued according to the downstream rolling mill biting steel signal, that is, the loop-up instruction is issued to start the loop-up when the downstream stand bites the steel at t1, and the loop-up is lifted to the set angle at t4, and the time required is T, T=t4-t1, wherein t4 is the ideal time for the loop-up to be lifted to the set angle. Due to the action of the strip gravity, T is usually longer than T0, T0<T<1.1*T0, and T is usually taken as 1.05*T0. Thus, according to the loop-up time T0 under the dead load condition obtained in step 1, the loop-up time T during rolling can be calculated by the above formula.

[0025] Step 2: Calculate the loop-up amount L of the current strip at the time when the loop-up is lifted to the set angle and the loop-up set angle θ set The corresponding loop-up amount L set And the loop-up amount value L when the loop-up angle reaches the maximum value max .

[0026] ​The actual loop angle θ of the current strip at the time t4 after the strip is bitten by the downstream stand is detected and recorded by the TDC controller, and the maximum loop angle θ within 2 seconds after the loop command is sent at the time t1, i.e. from t1 to t5 (t5=t1+2) max The time range of 2 seconds can ensure that the maximum loop angle can be sampled, and other peak values in the subsequent adjustment process can be avoided.

[0027] Further, the actual loop angle θ at the time t4 is detected by the aforementioned TDC controller, and the loop amount L corresponding to the actual loop angle θ, the set loop angle θ set The corresponding loop amount L set The loop amount L when the loop angle reaches the maximum value max is calculated, and the specific formula is as follows:

[0028]

[0029] θ, θ max , and θ set are substituted into the above formula, respectively, so that the values of L, L max , and L set of the strip can be calculated. In the above formula, the constants L1, L2, L3, R, and r are fixed after the main rolling mill and the loop equipment are manufactured and installed, and the data can be obtained according to the equipment parameters or actual measurement.

[0030] Step 3: The actual loop angle θ at the time t4 is compared with the set loop angle θ set , and the following judgment is made:

[0031] 1) When θ≥θ set , the difference ΔL between the loop amount L max when the maximum loop angle θ max is sent at the time t1-t5 and the loop amount L set when the set loop angle θ set is sent is calculated, i.e. ΔL=L set -L max , ΔL can be regarded as the overshoot value of the loop amount of the strip within the time T, so that the speed deviation ΔV of the upstream stand can be calculated, i.e. ΔV=(L set -L max ) / T, and ΔV is a negative value.

[0032] 2) When θ<θ set , the difference ΔL between the loop amount L set at the time t4 and the loop amount L set when the ideal loop angle θ set is sent is calculated, i.e. ΔL=L setΔV is positive.

[0033] Step 4: According to the above 1) and 2), the adjustment value ΔV generated by each piece of strip steel of the same specification after rolling is calculated and added to the cascade speed setting of the next piece of steel under the looper upstream stand, that is:

[0034]

[0035] Wherein, V act_set represents the adjusted upstream stand speed setting value; V set represents the original upstream stand setting speed; i represents the first piece of rolling of the same specification, and n represents the current strip steel.

[0036] Thus, the speed matching between stands will be quickly improved, the rolling mill will quickly start to roll and stably run.

Claims

1. A method for precisely controlling the starting angle of the looper on hot-rolled sheet metal, characterized in that: The specific steps are as follows: Step 1: Determine the looper start-up time during steel rolling; Let T0 be the time required from the moment the looper command is issued (t1) to the moment the looper reaches the set angle (t3) under no-load conditions, where T0 = t3 - t1; the looper start-up time T during steel rolling satisfies T0 < T < 1.1 * T0; Step 2: Calculate the looper clearance L and the looper set angle θ when the current strip is lifted to the set angle. set Corresponding looper quantity L set And the looper length L when the looper angle reaches its maximum value. max ; Step 3: The actual loop angle θ at the ideal moment when the loop is raised to the set angle is compared with the set angle θ. set Compare and make the following judgments: 1) θ≥θ set At that time, calculate the maximum hoisting angle θ within 2 seconds after the hoisting command is issued. max Looping quantity L max and the starting set angle θ set Looping quantity L set The difference ΔL between them is used to calculate the speed deviation ΔV of the upstream rack. set -L max ) / T, where ΔV is a negative value and T is the time required from the moment the lifting command is issued to the ideal moment when the loop is raised to the set angle; 2) θ < θ set At that time, the actual loop angle θ at the ideal moment when the loop is raised to the set angle is calculated, along with the loop amount L and the ideal lifting angle θ. set The looper quantity L0 at the time of the test, and the difference between the looper quantities ΔL = L0 - L, are used to calculate the speed deviation ΔV = (L0 - L) of the upstream frame. set -L) / T, where ΔV is a positive value; Step 4: Add the adjustment value ΔV calculated for each strip of steel that has been rolled to the cascade speed setting of the next strip of steel on the upstream stand of the looper.

2. The method for precisely controlling the looper starting angle of hot-rolled sheet metal as described in claim 1, characterized in that: The calculation method for the looper start-up time during steel rolling is as follows: T=1.05*T0 In the formula, T is the start-up time of the looper when it is unloaded; T0 is the time required from the moment the start-up command is issued to the moment the looper reaches the set angle when it is unloaded.

3. The method for precisely controlling the starting angle of the looper for hot-rolled sheet metal as described in claim 1, characterized in that: In step 2, L, L set and L max The method for obtaining it is as follows: The actual looper angle θ at time t4 after the current strip is bitten on the downstream stand, and the maximum looper angle θ within 2 seconds after the looper release command is issued are detected. max ; Based on the above test data, calculate the looper allowance L corresponding to the looper angle θ and the looper setting angle θ. set Corresponding looper quantity L set The amount of looper L when the looper angle reaches its maximum value max The specific formula is as follows: Let θ, θ max θ set Substituting these values ​​into the above formula, we can calculate L and L' of the strip. max and L set The value of ; In the above formula, the constants L1, L2, and L3 are the distance from the upstream stand to the looper support point, the height from the looper support point to the rolling line, and the center distance between the upstream and downstream stands, respectively; R and r are the looper arm length and the looper roll radius, respectively.

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