Method for detecting chatter in a rolling mill foundation control system

Abstract

The application discloses a kind of detection methods of mill foundation control system jitter, first to the action setting period fixed pressure-down curve of mill foundation control system pressure-down process, pressure-down curve includes three kinds: single action period roll gap fluctuation curve, multiple action period roll gap fluctuation curve and continuous single action period roll gap fluctuation curve;Second pressure-down curve is in the length direction of rolled piece and is advanced preset roll gap logic, roll gap action section includes pressure-down pulse, lifting pulse and platform pulse, third, rolled piece rolling test, roll speed stabilizes after starting roll gap fluctuation curve action, the roll gap fluctuation curve is the pressure-down curve;Then the roughness of rolled piece rolling surface is measured;Then measurement data is grouped according to roll gap action section, and the data standard deviation in each group of data is calculated in turn, difference coefficient correction is carried out to data standard deviation, total difference number correction is carried out to each group of data, and total difference coefficient is obtained, i.e. the jitter value of mill foundation control system.

Description

Technical Field

[0001] This invention relates to a method for measuring the delay accuracy of a rolling mill control system, and more particularly to a method for detecting jitter in a rolling mill basic control system. Background Technology

[0002] Rolling mill production lines include hot rolling production lines and cold rolling production lines. The method for detecting jitter in the basic control system of a rolling mill described in this article is mainly used for the accuracy testing of the control system of hot-rolled plate rolling mills.

[0003] The information and automation system of a hot-rolled steel production line is the core computer system in steel production and manufacturing. Currently, it typically adopts a four-level architecture of L1 / L2 / L3 / L4, with L1 and L2 levels forming the industrial control system. L1 is the basic control system, which uses a programmable PLC system and relies on a certain network to control the actions of mechanical equipment through electrical components to achieve specific process control effects. Figure 1 This is a schematic diagram of the basic control framework of an industrial control system.

[0004] The rolling mill control system is complex, but its primary function is to ensure high precision in the rolling process. However, signal acquisition, processing, and transmission all require time. In complex systems, simultaneous processing of multiple signals can lead to conflicts or interference, and time delays exist in the feedback loop of any practical control system. Therefore, the time taken for each action cycle varies. Jitter is defined as the variation between the actual cycle intervals of a computational cycle task. Figure 2 This diagram illustrates the vibration, with the shaded area representing the vibration. It can be said that all control components exhibit system vibration. The vibration of the entire rolling mill system is influenced by more complex factors, and the mutual influence between these factors is also greater.

[0005] The vibration of the rolling mill control system directly affects the system's accuracy and performance, especially the basic control system. Significant vibration in the rolling mill's basic control system can severely impact the quality of the rolled product. Therefore, detecting and managing system vibration data is crucial for improvement and reduction.

[0006] Patent searches revealed that patents related to jitter detection and suppression technologies can be broadly categorized into three types. The first type involves methods for detecting system jitter using electronic components. However, the design cost of these components is high, requiring significant expertise, which hinders widespread adoption. For example, Chinese patent CN201210348185.6 discloses a phase detector based on CML logic, which designs a phase tester for the system and uses multiple acquisition branches to measure system execution errors. The second type involves algorithms for system jitter suppression. These methods are based on jitter theory, and their effectiveness cannot be directly determined. For instance, Chinese patent CN201610541650.6 discloses a method for suppressing through-wall radar coupling signals based on the minimum mean square error criterion. This method compares the maximum value of the interpolated current time-domain echo signal with the maximum value of the reference time-domain echo signal to obtain an amplitude compensation factor, thereby achieving amplitude compensation for time-varying coupling signals. The third category is devices for reducing system jitter. These devices are limited to special small systems and are not applicable to complex systems such as rolling mills. For example, Chinese patent CN103490775A discloses a clock recovery controller based on a dual-loop structure. By adding a data delay control circuit unit, a data delay control loop is added. Thus, the clock can be quickly restored through the coordinated work of the two control loops, which can be controlled by both clock loop and data loop.

[0007] The shortcomings of the existing related technologies are: (1) There is no clear method for measuring the vibration of the existing rolling mill control system; (2) The knowledge of system vibration involved in the patent search is mostly about optimizing and improving the vibration of a specific component, and does not mention the detection and improvement methods for improving the vibration of the large system. Summary of the Invention

[0008] The purpose of this invention is to provide a method for detecting jitter in the basic control system of a rolling mill. This method is designed for the rolling process of the rolling mill control system, sets a rolling curve, detects the surface of the rolled workpiece after rolling, calculates the action distance of the rolling pulse, and calculates the actual jitter of the rolling mill control system.

[0009] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: A method for detecting vibration in a rolling mill foundation control system, characterized in that: the detection method is based on the rolling mill foundation control system, and its steps are as follows: S1, a fixed-cycle rolling curve is set for the rolling process of the rolling mill base control system. The rolling curve includes three types: single-cycle roll gap fluctuation curve, multi-cycle roll gap fluctuation curve and continuous single-cycle roll gap fluctuation curve. S2, the roll gap logic is preset in advance in the length direction of the rolled piece. The roll gap is divided into a constant roll gap section and a moving roll gap section. The moving roll gap section includes roll gap pulse, lifting pulse and platform pulse. The roll gap in the constant roll gap section is a fixed value. S3, Rolling test of the workpiece: The roll speed is set to high speed and uniform speed. The initial roll gap is set according to the thickness of the workpiece. The workpiece bites in. After the roll speed stabilizes, the roll gap fluctuation curve action is started. The roll gap fluctuation curve is the pressing curve, that is: single action cycle roll gap fluctuation curve, multi action cycle roll gap fluctuation curve and continuous single action cycle roll gap fluctuation curve. The rolling ends. S4. The surface roughness of the rolled workpiece is measured. A high-precision needle tip measuring instrument is used to measure the surface curvature of the workpiece, and the roll gap fluctuation curve measurement data of three operation cycles are obtained. S5, the measured data of the roll gap fluctuation curve are grouped according to the roll gap action segment, that is, grouped according to the pressing pulse, lifting pulse and platform pulse; S6, calculate the standard deviation of the data within each data set; S7, adjust the difference coefficient for the standard deviation of the data within each group; S8. Finally, the total difference number of each group of data is corrected to obtain the total difference coefficient, which is the jitter value of the mill foundation control system.

[0010] The single-action cycle roll gap fluctuation curve is set as follows: the constant roll gap segment includes a high segment and a low segment; the roll gap action segment includes roll gap pressing and roll gap lifting; the roll gap action segment consists of one pulse, which is either one pressing pulse or one lifting pulse; when measuring a single action cycle, the starting position of the roll gap action segment is marked as X11, and the ending position of the roll gap action segment is marked as X12. X12-X11 is the length of one pressing pulse or one lifting pulse. The measurement cycle consisting of roll gap pressing, roll gap low segment, roll gap lifting, and roll gap high segment is measured, and a total of n measurement cycles are measured; the dataset of the measured length of the pressing pulse is summarized as X1-d{}, and the dataset of the measured length of the lifting pulse is summarized as X1-u{}.

[0011] The multi-action cycle roll gap fluctuation curve is set as follows: the constant roll gap segment includes a high segment and a low segment; the roll gap action segment includes roll gap pressing, roll gap holding, and roll gap pressing again; and roll gap lifting, roll gap holding, and roll gap lifting again. Each roll gap action segment consists of three pulses: one transition pulse and two pressing pulses, or one transition pulse and two lifting pulses. When measuring in a multi-action cycle, the starting point of the first measurement pulse is marked as X21, and the ending point is marked as X22; the starting point of the transition pulse is X22, and the ending point is X23, where X23-X22 is the length of the transition pulse; X23 is the starting point of the third pulse, and the ending point is X24. 4-X23 represents the length of the third pulse. The measurement cycle consists of the multi-action roll gap pressing, the lower section of the roll gap, the multi-action roll gap lifting, and the upper section of the roll gap, with a total of n measurement cycles. The dataset of the first pulse measurement length during pressing is X2-d1{}, the dataset of the pulse measurement length during the pressing process platform is X2-p1{}, and the dataset of the third pulse measurement length during pressing is X2-d3{}. The dataset of the first pulse measurement length during lifting is X2-u1{}, the dataset of the pulse measurement length during the lifting process platform is X2-p2{}, and the dataset of the third pulse measurement length during lifting is X2-u3{}.

[0012] The setting of the continuous single-action cycle roll gap fluctuation curve includes a constant roll gap segment comprising a high segment and a low segment, and a roll gap action segment comprising continuous roll gap pressing and continuous roll gap lifting. The roll gap action segment consists of 3 pulses, divided into 3 continuous pressing pulses and 3 continuous lifting pulses. When measuring a continuous single-action cycle, the starting position of the first measured pressing or lifting pulse is marked as X31, and the ending position of the third measured pulse is directly measured, with the ending position being X34. The length of the three consecutive action pulses is X34-X31. The measurement cycle consisting of continuous single-action roll gap pressing, low roll gap segment, continuous single-action roll gap lifting, and high roll gap segment is measured, for a total of n measurement cycles. The dataset of summing the lengths of the 3 pressing pulses / 3 is X3-d{}, and the dataset of summing the lengths of the 3 lifting pulses / 3 is X3-u{}.

[0013] The constant roll gap time is 5 to 10 times the pulse of the mill control system; the single-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 20 micrometers; the multi-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 10 micrometers; the continuous single-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 10 micrometers.

[0014] The value of n is 10, and the standard length of the pulse is V*p, where V is the roll speed of the rolling mill and p is the pulse of the rolling mill control system.

[0015] The standard deviation of the data in each group of data is corrected by the coefficient of variation. The coefficient of variation is as follows: single-cycle compression or lifting measurements account for 50%, multi-cycle and cyclic compression or lifting measurements account for 25%, and platform pulse lifting and compression measurements both account for 50%.

[0016] Finally, each set of data is corrected for the total difference, and the total difference coefficient is: 40% for pressure measurement difference coefficient, 40% for lifting measurement difference coefficient, and 20% for platform measurement difference coefficient.

[0017] When measuring the surface roughness of the rolled workpiece, a high-precision needle tip measuring instrument calculates the average value Y of the height variation of the constant roll gap section during the sliding process. p and extreme value difference Y m The travel distance is marked as X. The curvature variation of the rolled surface after rolling in the constant roll gap section is within 0.2 micrometers. Any abnormal points exceeding this range need to be removed.

[0018] When measuring the surface roughness of rolled workpieces, the high-precision needle tip measuring instrument approaches the roll gap movement section, and the change in curvature at that location exceeds Y. m +0.5*Y p Define the starting point of the test segment and record that position.

[0019] The present invention provides a method for detecting jitter in the basic control system of a rolling mill. This method sets a special reduction curve for the rolling process of the rolling mill control system, uses high-precision measuring equipment to detect the surface of the rolled workpiece after rolling, calculates the action distance of the reduction pulse, and then calculates the actual jitter of the rolling mill control system to characterize and evaluate the system accuracy.

[0020] This invention employs a fixed operating cycle for the rolling mill control system during the pressing process, ensuring consistent operating patterns and thus making it evaluable. A pre-set pressing curve is used in the rolling mill control system, and this curve possesses measurable characteristics. By combining physical measurements with simulation calculations of the jitter amount, the jitter of the basic rolling mill control system is obtained by directly comparing the set curve with the actual post-rolling thickness curve and then performing a reverse calculation. This data serves as a basis for subsequent evaluation and improvement of the basic rolling mill control system's condition.

[0021] The detection method for the vibration of the rolling mill foundation control system of this invention has an easy-to-understand detection principle, is convenient to use, and is suitable for small and medium-sized rolling mills for scientific research and production line rolling mills with high equipment precision. Attached Figure Description

[0022] Figure 1 A schematic diagram of the basic control framework of an industrial control system; Figure 2 This is a diagram illustrating the shaking. Figure 3This is a flowchart of the method for detecting jitter in the rolling foundation control system of the present invention; Figure 4 This is a schematic diagram of the single-action cycle roll gap fluctuation of the present invention; Figure 5 This is a schematic diagram of the multi-cycle roll gap fluctuation of the present invention; Figure 6 This is a schematic diagram of the continuous single-action cycle roll gap fluctuation of the present invention; Figure 7 This is a schematic diagram confirming the connection between the constant section and the moving section (roll gap pressing) of the measuring roll gap in the present invention. Figure 8 This is a schematic diagram of the vibration detection device of the rolling foundation control system of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] A method for detecting jitter in a rolling mill foundation control system is provided. The basic idea of ​​this method is as follows: First, a rolling process with a fixed cycle and measurable characteristics is set for the rolling process. Second, the surface roughness of the rolled workpiece is measured. Third, the measurement results are compared with the characteristics of the set curve to obtain the system jitter.

[0025] A method for detecting vibration in a rolling mill foundation control system, the steps of which are as follows: See Figure 3 .

[0026] S1, a fixed-cycle reduction curve is set for the rolling mill base control system during the rolling process. This reduction curve includes three types: a single-cycle roll gap fluctuation curve, a multi-cycle roll gap fluctuation curve, and a continuous single-cycle roll gap fluctuation curve. The cycle comprises a curve period consisting of roll gap reduction, roll gap lower section, roll gap lifting, and roll gap upper section.

[0027] S2, the roll gap logic is pre-set in the length direction of the rolled piece for the reduction curve. The roll gap is divided into a constant roll gap section and a moving roll gap section. The moving roll gap section includes reduction pulses, lifting pulses, and plateau pulses. The roll gap in the constant roll gap section is a fixed value. Specifically: S2.1, Setting the single-action cycle roll gap fluctuation curve: The roll gap logic is pre-set along the length of the rolled piece. The constant roll gap segment includes a high segment and a low segment, while the moving roll gap segment includes roll gap pressing and roll gap lifting. See [link to relevant documentation]. Figure 4The roll gap in the constant roll gap section is a fixed value and does not change. The duration of the constant roll gap section is 5 to 10 times the pulse of the rolling mill control system. The roll gap movement section consists of one pulse, which is either one downward pulse or one upward pulse. The pulse action of the downward and upward pulses is greater than 20 micrometers. For example, if the rolling mill control system pulse is 0.016s, then the duration of each constant roll gap section is 10 rolling mill control system pulses, and its length is 0.16s; the duration of the roll gap movement section is one rolling mill control system pulse, and its length is 0.016s.

[0028] S2.2, Setting the multi-cycle roll gap fluctuation curve: Roll gap logic is pre-set along the length of the rolled piece. The constant roll gap segment includes a high segment and a low segment. The roll gap action segment includes roll gap downward, roll gap maintenance, and roll gap downward, as well as roll gap lifting, roll gap maintenance, and roll gap lifting. See [link to documentation]. Figure 5 The roll gap in the constant gap section is a fixed value and does not change. The duration of the constant gap section is 5 to 10 times the pulse of the mill control system. The roll gap action section consists of 3 pulses, divided into 1 transition pulse and 2 pressing pulses, or 1 transition pulse and 2 lifting pulses. The pulse action of the pressing pulse and the lifting pulse is greater than 10 micrometers.

[0029] S2.3, Setting the continuous single-action cycle roll gap fluctuation curve: The roll gap logic is pre-set along the length of the rolled piece. The constant roll gap segment includes a high segment and a low segment. The roll gap action segment includes continuous roll gap downward pressure and continuous roll gap upward pressure. See [link / reference] Figure 6 The roll gap in the constant gap section is a fixed value and does not change. The duration of the constant gap section is 5 to 10 times the pulse of the mill control system. The roll gap action section consists of 3 pulses: 3 continuous pressing pulses and 3 continuous lifting pulses. The pulse action of the pressing and lifting pulses is greater than 10 micrometers.

[0030] S3, Rolling Test: The roll speed is set to high speed and constant speed. The initial roll gap is set according to the workpiece thickness. The workpiece bites in, and after the roll speed stabilizes, the roll gap fluctuation curve operation is initiated. This roll gap fluctuation curve is the reduction curve, namely: single-cycle roll gap fluctuation curve, multi-cycle roll gap fluctuation curve, and continuous single-cycle roll gap fluctuation curve. Each fluctuation cycle consists of more than 10 cycles, and rolling ends. Specifically: S3.1 The timing of the test: The system vibration test during the pressing process is arranged in the early to middle stage after the mill has been running for a period of time, when its mechanical structure has passed the break-in stage and the gap is stable.

[0031] S3.2 The selected test piece has good strength and thickness uniformity, and the rolling deformation is almost entirely caused by the roll gap action.

[0032] S3.3 Rolling test of the workpiece: set the roll speed to high speed and uniform speed - workpiece bites in - after the roll speed stabilizes, start the roll gap fluctuation curve - rolling ends, set the roll speed to V.

[0033] S4. The surface roughness of the rolled workpiece is measured. A high-precision needle tip measuring instrument is used to measure the surface curvature of the workpiece, and the roll gap fluctuation curve measurement data of the three operation cycles are obtained.

[0034] See Figure 8 The surface curvature of rolled piece 1 was measured using a high-precision needle tip measuring instrument via a stylus method. The high-precision needle tip measuring instrument includes a stylus tip 2, a sensor beam 3, and a calculation and display element 4. A diamond stylus tip 2 with a curvature radius of 2 micrometers is slowly slid along the surface of the rolled piece 1 being measured. The horizontal measurement accuracy is within 10 micrometers, and the vertical measurement accuracy is within 0.1 micrometers. During the sliding process within the constant roll gap section, the high-precision needle tip measuring instrument calculates the average height variation Y of the constant roll gap section. p and extreme value difference Y m The travel distance is marked as X. The curvature variation range of the rolled workpiece surface after rolling in the constant roll gap section is generally within 0.2 micrometers. Points exceeding this range must be removed as outliers. This 0.2-micrometer value refers to empirically measured values, representing variations in measured values ​​within a 10-micrometer length. When the stylus tip 2 of the high-precision needle tip measuring instrument approaches the roll gap movement section, the change in height curvature exceeds Y. m +0.5*Y p Define this as the starting point of the test segment and record this position. See also Figure 7 The figure shows the confirmation of the connection between the constant roll gap section and the moving roll gap section (pressing section).

[0035] S4.1 When measuring a single-cycle motion, mark the starting position of the roll gap motion segment as X11 and the ending position as X12. X12-X11 represents the length of one pressing pulse or one lifting pulse. See [reference needed]. Figure 4 The measurement cycle consists of the roll gap downward pressure, the lower section of the roll gap, the roll gap upward pressure, and the upper section of the roll gap. A total of n measurement cycles are measured, where n is 10. The dataset of the measured lengths of the downward pressure pulses is X1-d{}, and the dataset of the measured lengths of the upward pressure pulses is X1-u{}. The standard pulse length is V*p, where V is the roll speed of the mill, and p is the pulse of the mill control system.

[0036] S4.2 When performing measurements with multiple action cycles, mark the start point of the first measurement pulse as X21 and the end point as X22; mark the start point of the transition pulse as X22 and the end point as X23, where X23-X22 is the length of the transition pulse; mark X23 as the start point of the third pulse and the end point as X24, where X24-X23 is the length of the third pulse. See [reference needed]. Figure 5The measurement cycle consists of the multi-action roll gap downward pressing, the roll gap low section, the multi-action roll gap lifting, and the roll gap high section. A total of n measurement cycles are measured, with n being 10. The dataset of the first pulse measurement length during pressing is X2-d1{}, the dataset of the pulse measurement length during the pressing process platform is X2-p1{}, and the dataset of the third pulse measurement length during pressing is X2-d3{}. The dataset of the first pulse measurement length during lifting is X2-u1{}, the dataset of the pulse measurement length during the lifting process platform is X2-p2{}, and the dataset of the third pulse measurement length during lifting is X2-u3{}.

[0037] S4.3 When performing continuous single-action cycle measurements, mark the starting position of the first measurement pressure or lift pulse as X31. Because of the continuous action, the slope of the measurement pulse is not easily identified; therefore, directly measure the ending position of the third measurement pulse, and mark the ending position as X34. The length of the three consecutive action pulses is X34-X31. See [reference needed]. Figure 6 The measurement cycle consists of continuous single-action roll gap downward pressing, roll gap low section, continuous single-action roll gap lifting, and roll gap high section. A total of n measurement cycles are measured, where n is 10. The dataset consisting of 3 pulse lengths / 3 of the pressing is X3-d{}, and the dataset consisting of 3 pulse lengths / 3 of the lifting is X3-u{}.

[0038] S5. The measured data of the roll gap fluctuation curve are grouped according to the roll gap action segment, that is, according to the pressing pulse, lifting pulse and plateau pulse. See Table 1.

[0039] The lengths of multiple pressing or lifting pulses are measured. Because the roll speed of the rolling mill is constant, and the pulses are from the rolling mill control system, the differences in measurement distances are highly consistent with the differences in cycle time. Therefore, the differences in length differences are used to determine the differences in the jitter of the pressing process in the rolling mill control system.

[0040] S6, calculate the standard deviation of the data within each group to identify the differences in their distribution.

[0041] The standard deviation of the data within the pressure pulse group, lifting pulse group, and platform pulse group is calculated to identify their distribution differences and represent the fluctuation characteristics of each data group.

[0042] Standard deviation is calculated using the classic formula. σ=sqrt(((x1-x)^2 +(x2-x)^2 +...(xn-x)^2) / n ) .

[0043] S7, the difference coefficient is corrected for the standard deviation of the data in each group. Because there are measurement differences in the three processes of pressure pulse, lifting pulse and plateau pulse, the measurement results are corrected to a certain extent. The correction ratio logic is as follows: difference coefficient: single-cycle pressure or lifting measurement accounts for 50%, multi-cycle and cyclic pressure or lifting measurement accounts for 25%, and plateau pulse lifting and pressure measurement both account for 50%.

[0044] S8. Finally, the total difference number of each group of data is corrected to obtain the total difference coefficient, which is the jitter value of the mill foundation control system.

[0045] Finally, each set of data is corrected for the total difference, and the total difference coefficient is: 40% for pressure measurement difference coefficient, 40% for lifting measurement difference coefficient, and 20% for platform measurement difference coefficient.

[0046] The correction values ​​in S7 and S8, such as 0.5, 0.25, 0.25 in S7, 0.5, 0.5 in S7, and 0.4, 0.4, 0.2 in S8, are all empirical coefficients that can be adjusted. The empirical coefficients in each difference coefficient calculation formula are added together to get 1.

[0047] Table 1 shows the correction details for the measurement data.

[0048] The physical meanings of each letter in Table 1 are as follows: The surface condition of the rolled piece was obtained according to different rolling gap curves. The surface of the rolled piece was directly detected by a stylus. The position of the roll gap during pressing down, lifting up, and constant platform was determined by measuring the height. The lengths were measured and a data set was formed. Among them, X1-d{}, X2-d1{}, X2-d3{}, and X3-d{} are the rolled piece lengths corresponding to the pressing down pulses measured under each curve condition; X1-u{}, X2-u1{}, X2-u3{}, and X3-u{} are the rolled piece lengths corresponding to the lifting pulses measured under each curve condition; X2-p1{} and X2-p2{} are the rolled piece lengths corresponding to the platform pulses measured under curve 2 (i.e., the multi-action cycle roll gap fluctuation curve).

[0049] To ensure measurement accuracy, the surface inspection instrument (high-precision needle tip measuring instrument) uses the high section of the constant roll gap as its base for inspection, with the probe making downward contact. Because the surface inspection instrument requires high precision, the measurement direction can only be from beginning to end along the length. Therefore, measurements of X2-d3{} corresponding to the pressed roll gap and X2-u1{} corresponding to the raised roll gap, where the probe makes contact, will have poor accuracy and can be discarded. If the surface inspection instrument can measure accurately, it can be used.

[0050] σ 1-d σ2-d σ 3-d The standard deviations σ corresponding to X1-d{}, X2-d1{} and X2-d3{}, X3-d{} are respectively. 1-u σ 2-u σ 3-u The standard deviations of X1-u{}, X2-u1{} and X2-u3{}, X3-u{} are respectively, σ 2-p1 σ 2-p2 The standard deviations of X2-p1 and X2-p2 are respectively.

[0051] σ d The difference coefficient σ corresponds to the standard deviation of the length of the roll gap in one cycle. u The difference coefficient σ corresponds to the standard deviation of the length for one cycle of roll gap lifting. p The difference coefficient is the standard deviation of the length corresponding to one cycle of roll gap lifting. σ is the difference coefficient characterizing one cycle of the roll gap pressing system.

[0052] The method for detecting jitter in the basic control system of a rolling mill, as described in this invention, can clearly indicate the difference in pulses in the rolling process and the rolling reduction system, thereby characterizing the system jitter. The higher the accuracy of the measuring equipment used, the more accurate the characterization of system jitter.

[0053] This invention discloses a method for detecting jitter in a rolling mill foundation control system. This method is based on the rolling mill foundation control system utilizing a set roll gap movement process with specific height and undulations to generate thickness fluctuations on the rolled workpiece, and then measuring these thickness fluctuations to detect jitter in the control system. The steps are as follows: First, determine the minimum control cycle of the rolling mill foundation control system's pressing mechanism. The refresh time for each functional element of the pressing mechanism to receive or send signals is the element cycle, generally measured in milliseconds (ms). The functional element cycles are the same or multiples of each other, and the minimum control cycle is the maximum value of the element cycles; one control cycle is one control pulse. Then, establish special roll gap movement curves based on the minimum control cycle of the pressing mechanism. These curves mainly correspond to three types of roll gap movements: pressing, holding, and lifting. The pressing and lifting movements are more prone to significant jitter in the foundation control system. To address this characteristic, this invention designs three specific roll gap curves: Curve 1 mainly tests the system jitter of a single pressing and lifting movement; Curve 2 mainly detects the system jitter of intermittent pressing and lifting movements; and Curve 3 mainly detects the system jitter of continuous pressing and lifting movements. The single action and multiple actions here refer to the single control cycle set by the system and its multiples; all three curves have four processes of periodic compression, low segment, lifting and high segment, which together form a measurement cycle. This measurement cycle is the curve cycle. Each curve contains multiple measurement cycles to ensure that more samples can be detected to detect jitter. Example

[0054] Rolling mill: Roll diameter 100mm, roll length 300mm; Rolling mill control system pulse: 20ms Rolled part: lead, single piece size: 50*100*2000mm; Rolling speed: 1 m / s.

[0055] Roll gap reduction and lifting curve settings: Single-pulse roll gap action amount 20μm (i.e., the roll gap action amount in a single cycle of reduction and lifting is 20μm). The roll gap constant period is 5 times the pulse time, which is 100ms. Set the roll gap according to the three roll gap curves respectively, and ensure that the curve period is more than 20 cycles for each curve.

[0056] Stylus measuring instrument accuracy: vertical accuracy 0.02μm; horizontal accuracy 10μm. X2-d3{} corresponding to the pressing roll gap and X2-u1{} corresponding to the lifting roll gap, which cannot be effectively measured or have poor measurement accuracy, can be discarded.

[0057] The measurement data for the embodiments are shown in Table 2, and the correction details for the measurement data are shown in Table 3.

[0058] Table 2 Measurement data from the example

[0059] Table 3. Correction of Measurement Data in Examples

[0060] The formulas for calculating the parameters in Table 3 are as follows: The standard deviation is calculated using the classic formula: σ = sqrt(((x1-x)^2 +(x2-x)^2 +......(xn-x)^2) / n).

[0061] The coefficient of variation is an empirical ratio, and the formula for calculating the coefficient of variation is: σ d =0.5*σ 1-d +0.25*σ 2-d +0.25*σ 3-d =0.5*0.442+0.25*0.547+0.25*0.458 = 0.472; σ u =0.5*σ 1-u +0.25*σ 2-u +0.25*σ 3-u =0.5*0.551+0.25*0.740+0.25*0.596 = 0.609; σ p =0.5*σ2-p1 +0.5*σ 2-p1 = 0.5*0.614+0.5*0.461=0.537.

[0062] Overall coefficient of variation: σ = 0.4 * σ d +0.4*σ u +0.2*σ p =0.4*0.472+0.4*0.609+0.2*0.537 =0.54.

[0063] The values ​​0.5, 0.25, 0.4, and 0.2 are all empirical coefficients that can be adjusted. The sum of the empirical coefficients in each formula is 1.

[0064] Therefore, the total difference coefficient of this rolling mill reduction system can be calculated to be 0.54, that is, the jitter value of the rolling mill reduction system is 0.54.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting vibration in a rolling mill foundation control system, characterized in that: This detection method is based on the rolling mill's basic control system, and its steps are as follows: S1, a fixed-cycle rolling curve is set for the rolling process of the rolling mill base control system. The rolling curve includes three types: single-cycle roll gap fluctuation curve, multi-cycle roll gap fluctuation curve and continuous single-cycle roll gap fluctuation curve. S2, the roll gap logic is preset in advance in the length direction of the rolled piece. The roll gap is divided into a constant roll gap section and a moving roll gap section. The moving roll gap section includes roll gap pulse, lifting pulse and platform pulse. The roll gap in the constant roll gap section is a fixed value. S3, Rolling test of the workpiece: The roll speed is set to high speed and uniform speed. The initial roll gap is set according to the thickness of the workpiece. The workpiece bites in. After the roll speed stabilizes, the roll gap fluctuation curve action is started. The roll gap fluctuation curve is the pressing curve, that is: single action cycle roll gap fluctuation curve, multi action cycle roll gap fluctuation curve and continuous single action cycle roll gap fluctuation curve. The rolling ends. S4. The surface roughness of the rolled workpiece is measured. A high-precision needle tip measuring instrument is used to measure the surface curvature of the workpiece, and the roll gap fluctuation curve measurement data of three operation cycles are obtained. S5, the measured data of the roll gap fluctuation curve are grouped according to the roll gap action segment, that is, grouped according to the pressing pulse, lifting pulse and platform pulse; S6, calculate the standard deviation of the data within each data set; S7, adjust the difference coefficient for the standard deviation of the data within each group; S8. Finally, the total difference number of each group of data is corrected to obtain the total difference coefficient, which is the jitter value of the mill foundation control system.

2. The method for detecting vibration in the rolling mill foundation control system according to claim 1, characterized in that: The single-action cycle roll gap fluctuation curve is set as follows: the constant roll gap segment includes a high segment and a low segment; the roll gap action segment includes roll gap pressing and roll gap lifting; the roll gap action segment consists of one pulse, which is either one pressing pulse or one lifting pulse; when measuring a single action cycle, the starting position of the roll gap action segment is marked as X11, and the ending position of the roll gap action segment is marked as X12. X12-X11 is the length of one pressing pulse or one lifting pulse. The measurement cycle consisting of roll gap pressing, roll gap low segment, roll gap lifting, and roll gap high segment is measured, and a total of n measurement cycles are measured; the dataset of the measured length of the pressing pulse is summarized as X1-d, and the dataset of the measured length of the lifting pulse is summarized as X1-u.

3. The method for detecting vibration in the rolling mill foundation control system according to claim 1, characterized in that: The multi-action cycle roll gap fluctuation curve is set as follows: the constant roll gap segment includes a high segment and a low segment; the roll gap action segment includes roll gap pressing, roll gap holding, and roll gap pressing again; and roll gap lifting, roll gap holding, and roll gap lifting again. Each roll gap action segment consists of three pulses: either one transition pulse and two pressing pulses, or one transition pulse and two lifting pulses. When measuring in a multi-action cycle, the starting point of the first measurement pulse is marked as X21, and the ending point is marked as X22; the starting point of the transition pulse is X22, and the ending point is X23, where X23 - X22 is the length of the transition pulse; X23 is the starting point of the third pulse, and the ending point is... X24 and X24-X23 represent the lengths of the third pulse. The measurement cycle consists of the multi-action roll gap pressing, the lower section of the roll gap, the multi-action roll gap lifting, and the upper section of the roll gap, with a total of n measurement cycles. The dataset summing the measurement lengths of the first pulse during pressing is X2-d1, the dataset summing the measurement lengths of the platform pulses during pressing is X2-p1, and the dataset summing the measurement lengths of the third pulse during pressing is X2-d3. The dataset summing the measurement lengths of the first pulse during lifting is X2-u1, the dataset summing the measurement lengths of the platform pulses during lifting is X2-p2, and the dataset summing the measurement lengths of the third pulse during lifting is X2-u3.

4. The method for detecting vibration in the rolling mill foundation control system according to claim 1, characterized in that: The setting of the continuous single-action cycle roll gap fluctuation curve includes a constant roll gap segment comprising a high segment and a low segment, and a roll gap action segment comprising continuous roll gap pressing and continuous roll gap lifting. The roll gap action segment consists of 3 pulses, divided into 3 continuous pressing pulses and 3 continuous lifting pulses. When measuring a continuous single-action cycle, the starting position of the first measured pressing or lifting pulse is marked as X31, and the ending position of the third measured pulse is directly measured, which is X34. The length of the three consecutive action pulses is X34-X31. The measurement cycle consisting of continuous single-action roll gap pressing, low roll gap segment, continuous single-action roll gap lifting, and high roll gap segment is measured, for a total of n measurement cycles. The dataset of summing the lengths of the 3 pressing pulses / 3 is X3-d, and the dataset of summing the lengths of the 3 lifting pulses / 3 is X3-u.

5. The method for detecting vibration in the rolling mill foundation control system according to any one of claims 2-4, characterized in that: The constant roll gap time is 5 to 10 times the pulse of the mill control system; the single-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 20 micrometers; the multi-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 10 micrometers; the continuous single-action cycle roll gap fluctuation curve is set such that the pulse action amount of the pressing pulse and the lifting pulse is greater than 10 micrometers.

6. The method for detecting vibration in the rolling mill foundation control system according to any one of claims 2-4, characterized in that: The value of n is 10, and the standard length of the pulse is V*p, where V is the roll speed of the rolling mill and p is the pulse of the rolling mill control system.

7. The method for detecting vibration in the rolling mill foundation control system according to claim 1, characterized in that: The standard deviation of the data in each group of data is corrected by the coefficient of variation. The coefficient of variation is as follows: single-cycle compression or lifting measurements account for 50%, multi-cycle and cyclic compression or lifting measurements account for 25%, and platform pulse lifting and compression measurements both account for 50%.

8. The method for detecting vibration in the rolling mill foundation control system according to claim 1 or 7, characterized in that: Finally, each set of data is corrected for the total difference, and the total difference coefficient is: 40% for pressure measurement difference coefficient, 40% for lifting measurement difference coefficient, and 20% for platform measurement difference coefficient.

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