阅读说明：本技术 一种基于三维曲面理论的宽厚板压平矫直方法 (Wide and thick plate flattening and straightening method based on three-dimensional curved surface theory ) 是由 马晓宝 陈鹏 王涛 张齐 曹益忠 李江江 马宝 于 2021-07-13 设计创作，主要内容包括：本发明涉及宽厚板矫直领域,具体涉及一种基于三维曲面理论的宽厚板压平矫直方法。该方法通过结构光相机或者双目视觉相机识别压平机的宽厚板局部区域翘曲离散点坐标,拟合得到翘曲曲面方程,优化计算垫铁位置,采用微分几何理论精确计算宽厚板翘曲曲率,进而计算压平相关的工艺参数。本发明的方法可以较为精确地计算宽厚板翘曲曲率,根据翘曲曲率对垫铁位置进行布局,并计算确定下压量,预测压下力,提高宽厚板压平矫直的效果及压平精整的作业效率。(The invention relates to the field of straightening of wide and thick plates, in particular to a method for flattening and straightening a wide and thick plate based on a three-dimensional curved surface theory. According to the method, a structural light camera or a binocular vision camera is used for identifying the warping discrete point coordinates of the local area of the wide and thick plate of the flattening machine, a warping surface equation is obtained through fitting, the position of a sizing block is optimized and calculated, the warping curvature of the wide and thick plate is accurately calculated by adopting a differential geometry theory, and then the related technological parameters of flattening are calculated. The method can accurately calculate the buckling curvature of the wide and thick plate, arrange the sizing block positions according to the buckling curvature, calculate and determine the pressing amount, pre-measure the pressing force, and improve the flattening and straightening effects of the wide and thick plate and the flattening and finishing operation efficiency.)

1. A flattening and straightening method for a wide and thick plate based on a three-dimensional curved surface theory is characterized by comprising the following steps:

and S1, acquiring wide and thick plate data: thickness delta, width b, regardless of the modulus of elasticity E at the time of material deformation strengthening₀Taking into account the reinforcing modulus E at the time of material reinforcement₁；

S2, identifying the warping appearance of the local area of the wide and thick plate sent into the flattening machine through a structured light or binocular vision camera, defining the advancing direction of the plate as an x axis, the width direction of the plate as a y axis, locating the origin of coordinates at the center O point of the rectangular plate, and obtaining the discrete points of the wide and thick plate;

s3, performing three-dimensional surface fitting on the discrete points obtained in the step S2 by using a least square method to obtain a local surface contour surface equation z (f (x, y)) of the wide and thick plate, and further calculating partial derivatives of the surface equationObtaining a first partial derivative and a second partial derivative of the curved surface;

s4, judging the concavity and convexity of the curved surface through the first partial derivative and the second partial derivative of the curved surface, when the part of the outline curved surface of the wide and thick plate is a downward convex three-dimensional curved surface, turning the wide and thick plate by using a plate turning machine to ensure that the curved surface in the field range is in an upward convex form, and then symmetrically processing the outline curve;

s5, obtaining the first basic quantity E as 1+ p according to the normal curvature calculation theory of the curved surface equation in the differential geometric theory²，F＝pq，G＝1+q²To obtain a second basic quantity According to the thickness delta of the incoming material and the yield strength sigma of the material_sAnd modulus of elasticity E₀Calculating limit value of elastic bending curvature of wide and thick plateWhere rho_wThe radius of the limit value of the elastic recovery curvature of the wide and thick plate is;

s6, locally adopting an optimization algorithm to search the highest point (x) of the inner curved surface of the action domain for the contour curved surface of the convex wide and thick plate_max,y_max,h_max) And nadir (x)_min,y_min,h_min) Calculating an included angle theta between a connecting line of the highest point and the lowest point and the plate conveying advancing direction of the flattening machine, recording a vertical plane where the included angle theta is located as a pi plane, and searching a local minimum point (x) from the highest point along a direction of the theta angle back to the connecting line of the lowest point and the highest point_lm,y_lm,h_lm) Calculating the distance between the highest point and the lowest pointDistance from the highest point and the local minimum pointComparing the maximum limit distance 2l of the arrangement of the sizing blocks of the flattening machine_sAnd l_m-mAnd l_m-lmDetermining the first sizing block position, the second sizing block position, the spacing l of the sizing blocks, the maximum height difference delta h between the highest point and the sizing block position and the pressing head pressing position;

s7, calculating the curve where the pi plane intersects with the curved surface profile z ═ f (x, y) at the highest point (x_max,y_max,h_max) Of (2) curvatureThe curvature is the buckling curvature of the wide and thick plate, and the buckling curvature of the wide and thick plate is further calculatedAnd limit of elastic curvatureRatio ofMaking the reverse bending rateAnd limit of elastic curvatureRatio ofAccording to the relation between elastic restoring moment and plastic bending moment, 2% is obtained³+(4λ-3)χ²+(2λ²-6λ)χ-3λ²And (4) obtaining chi through a chi-lambda curve distribution rule and the value of lambda, and further calculating to obtain the inverse bending ratio

S8, obtaining the pressing amount according to the reverse bending rateCalculating the elastic deflectionAccording to the mechanics of materials, the shaping bending moment of the bending of the thick plate can be obtainedFurther obtaining the average pressing force of the pressing cylinderAnd the displacement of a pressing cylinder of the flatting machine is s ═ delta h + f, wherein delta h is the maximum height difference between the highest point and the sizing block;

and the flattening and finishing precision of the flattening machine is ensured through the calculation.

2. The flattening and straightening method for the wide and thick plate based on the three-dimensional curved surface theory as claimed in claim 1, wherein the flattening and straightening method is characterized in that the flattening and straightening method is carried out when l is_m-m+l_m-lm＜2l_sWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) And position two is (x)_min,y_min,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks isThe head depression position is (x)_max,y_max,h_max) (ii) a When 2l_s＜l_m-lm+l_m-mAnd l_m-lm＜l_s＜l_m-mWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) Position two is symmetrical to position one about the highest point and at a point (x) in the direction of angle theta_ls,y_ls,h_lm) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_lmThe distance between the sizing blocks is l-2 l_m-lmThe head depression position is (x)_max,y_max,h_max)；

When 2l_s＜l_m-lm+l_m-mAnd l_m-m＜l_s＜l_m-lmWhen the position 1 of the sizing block is determined to be (x)_min,y_min,h_min) Position two is a point (x) symmetrical to position one about the highest point and in the direction along angle theta_s,y_s,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks is l-2 l_m-m。

3. The flattening and straightening method for the wide and thick plate based on the three-dimensional curved surface theory as claimed in claim 1, wherein the reverse bending rate in S7 is the reverse bending rate when the material strengthening is consideredWhereinCalculating KThe values of the reverse curvature obtained without taking the strengthening conditions into consideration.

Technical Field

The invention relates to the field of straightening of wide and thick plates, in particular to a method for flattening and straightening a wide and thick plate based on a three-dimensional curved surface theory.

Background

The wide and thick plate is widely applied to the fields of bridges, high-rise buildings, pressure vessels, petrochemical industry and the like. The wider and thicker the wide and thick plates, the higher the requirement for flatness. Due to uneven stretching deformation, uneven distribution of the structure in the cooling process and the like, the wide and thick plates are easy to form internal stress, and the wider thick plates are easy to bend or buckle. For thin plates with bending and buckling degree smaller than a certain range, a roller straightening machine is generally adopted for straightening, but for large-thickness and cold-state wide thick plates, the flattening treatment is required due to the limitation of the straightening machine capability, and particularly, a flattening machine must be arranged in a medium plate factory of high-end steel plates.

The flattening machine operates on the basis of a three-point bending principle, the warped plate needs to be subjected to reverse bending deformation according to the initial warping degree of the thick plate, and therefore a sizing block needs to be placed below the warped plate before flattening operation. The sizing block is a key part for finishing flattening and reverse bending straightening, and the span and the position of the spacing of the supporting points of the sizing block are important parameters for influencing the deformation of the flattening and reverse bending. The sizing block position setting and the recurve deflection control of the existing wide and thick plate flattening machine all need an on-site operator to observe the initial warping degree of the wide and thick plate, the setting and the control are carried out based on experience, and the setting and the control can be finished only by closely matching more than two operators during working. Thus, the process requires a good visual field and a great experience of the operator, the quality of the flattening is very much dependent on the skill and expertise of the workers, there are great adjustment errors and efficiency fluctuations, severely limiting the productivity and efficiency of the finishing operation. Therefore, the arrangement of the sizing blocks of the base of the flattening machine is guided reasonably and scientifically, and the warping curvature of the wide and thick plate is calculated accurately, so that the method is an important premise and basis for improving the efficiency of finishing and flattening operation.

In order to further improve the finishing efficiency of the wide and thick plate, reduce the number of operators, reduce the cost and realize the automatic and intelligent control of the flattening of the wide and thick plate, a patent document named as a metal plate flattening process model (CN 110681723A) proposes the buckling curvature and the recurved deflection of the wide and thick plate based on two-dimensional buckling consideration, and considers that the rectangular wide and thick plate is buckled along the plate length direction and the deflection deformation in the width direction is ignored, so the maximum value of the buckling curvature calculated based on a two-dimensional plane theory and the optimal position of a sizing block are not very accurate. The wide and thick plate generates buckling deformation due to uneven stress distribution, the deformation curved surface is a three-dimensional warping surface, the maximum curvature and the reverse bending deflection are calculated according to the curvature of the three-dimensional warping surface, the method is an important premise for accurately setting and controlling the position of the sizing block, the flattening force and the pressing stroke, and the curvature of the warping surface of the wide and thick plate is calculated based on the space three-dimensional curved surface theory, so that the flattening quality of the wide and thick plate is further improved.

Therefore, the sizing block positions are arranged, the operation efficiency is improved, and a sizing block layout calculation model needs to be established to guide the setting of the stroke of the pressing cylinder.

Disclosure of Invention

The invention discloses a method for flattening and straightening a wide and thick plate based on a three-dimensional curved surface theory based on machine vision technology reconstruction of the warped shape of the wide and thick plate, and the method is a method for controlling the position of a sizing block, the pressure of a pressure head and the displacement of a pressing cylinder on a flattening machine in a metallurgical rolling and finishing process. The method can accurately calculate the warping curvature of the wide and thick plate, arrange the sizing block positions according to the warping curvature, calculate and determine the pressing amount, pre-measure the pressing force, and improve the flattening and straightening effects of the wide and thick plate and the working efficiency of flattening and finishing.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

a flattening and straightening method for a wide and thick plate based on a three-dimensional curved surface theory comprises the following steps:

and S1, acquiring wide and thick plate data: thickness delta, width b, regardless of the modulus of elasticity E at the time of material deformation strengthening₀Taking into account the reinforcing modulus E at the time of material reinforcement₁；

S2, identifying the warping appearance of the local area of the wide and thick plate sent into the flattening machine through a structured light or binocular vision camera, defining the advancing direction of the plate as an x axis, the width direction of the plate as a y axis, locating the origin of coordinates at the center O point of the rectangular plate, and obtaining the discrete points of the wide and thick plate;

s3, performing three-dimensional surface fitting on the discrete points obtained in the step S2 by using a least square method to obtain a local surface contour surface equation z ═ f of the wide and thick plate(x, y) and calculating the partial derivatives of the surface equationObtaining a first partial derivative and a second partial derivative of the curved surface;

s4, judging the concavity and convexity of the curved surface through the first partial derivative and the second partial derivative of the curved surface, when the part of the outline curved surface of the wide and thick plate is a downward convex three-dimensional curved surface, turning the wide and thick plate by using a plate turning machine to ensure that the curved surface in the field range is in an upward convex form, and then symmetrically processing the outline curve;

s5, obtaining the first basic quantity E as 1+ p according to the normal curvature calculation theory of the curved surface equation in the differential geometric theory²，F＝pq，G＝1+q²To obtain a second basic quantity According to the thickness delta of the incoming material and the yield strength sigma of the material_sAnd modulus of elasticity E₀Calculating limit value of elastic bending curvature of wide and thick plateWhere rho_wThe radius of the limit value of the elastic recovery curvature of the wide and thick plate is;

s6, locally adopting an optimization algorithm to search the highest point (x) of the inner curved surface of the action domain for the contour curved surface of the convex wide and thick plate_max,y_max,h_max) And nadir (x)_min,y_min,h_min) Calculating an included angle theta between a connecting line of the highest point and the lowest point and the plate conveying advancing direction of the flattening machine, recording a vertical plane where the included angle theta is located as a pi plane, and searching a local minimum point (x) from the highest point along a direction of the theta angle back to the connecting line of the lowest point and the highest point_lm,y_lm,h_lm) Calculating the distance between the highest point and the lowest pointDistance from the highest point and the local minimum pointComparing the maximum limit distance 2l of the arrangement of the sizing blocks of the flattening machine_sAnd l_m-mAnd l_m-lmDetermining the first sizing block position, the second sizing block position, the spacing l of the sizing blocks, the maximum height difference delta h between the highest point and the sizing block position and the pressing head pressing position;

s7, calculating the curve where the pi plane intersects with the curved surface profile z ═ f (x, y) at the highest point (x_max,y_max,h_max) Of (2) curvatureThe curvature is the buckling curvature of the wide and thick plate, and the buckling curvature of the wide and thick plate is further calculatedAnd limit of elastic curvatureRatio ofMaking the reverse bending rateAnd limit of elastic curvatureRatio ofAccording to the relation between elastic restoring moment and plastic bending moment, 2% is obtained³+(4λ-3)χ²+(2λ²-6λ)χ-3λ²And (4) obtaining chi through a chi-lambda curve distribution rule and the value of lambda, and further calculating to obtain the inverse bending ratio

S8, obtaining the amount of the depression, rootAccording to the inverse bending ratioCalculating the elastic deflectionAccording to the mechanics of materials, the shaping bending moment of the bending of the thick plate can be obtainedFurther obtaining the average pressing force of the pressing cylinderAnd the displacement of a pressing cylinder of the flatting machine is s ═ delta h + f, wherein delta h is the maximum height difference between the highest point and the sizing block;

and the flattening and finishing precision of the flattening machine is ensured through the calculation.

Further, when l_m-m+l_m-lm＜2l_sWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) And position two is (x)_min,y_min,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks isThe head depression position is (x)_max,y_max,h_max) (ii) a When 2l_s＜l_m-lm+l_m-mAnd l_m-lm＜l_s＜l_m-mWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) Position two is symmetrical to position one about the highest point and at a point (x) in the direction of angle theta_ls,y_ls,h_lm) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_lmThe distance between the sizing blocks is l-2 l_m-lmThe head depression position is (x)_max,y_max,h_max)；

When 2l_s＜l_m-lm+l_m-mAnd l_m-m＜l_s＜l_m-lmWhen the position 1 of the sizing block is determined to be (x)_min,y_min,h_min) Position two is a point (x) symmetrical to position one about the highest point and in the direction along angle theta_s,y_s,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks is l-2 l_m-m。

Further, when the material reinforcement is considered for the reverse bending ratio in S7, the reverse bending ratioWhereinCalculating KThe values of the reverse curvature obtained without taking the strengthening conditions into consideration.

The invention has the beneficial effects that: the shape of the wide and thick plate can be accurately reconstructed through machine vision, the warping curvature, the reverse bending rate and the like of the wide and thick plate are accurately calculated based on a three-dimensional warping curvature theory, the positions of the sizing blocks are scientifically distributed according to the warping curvature, the flattening and straightening effects of the wide and thick plate are improved, and the flattening and finishing operation efficiency is improved.

Machine vision, an optimization algorithm, a bending theory and the like are applied to the sizing block layout setting analysis of the wide and thick plate pressing machine, a mathematical model is provided for automatic control, and the basis of intelligent control is laid.

Drawings

The invention is further illustrated but not limited by the following figures and examples.

FIG. 1 is a schematic diagram of the curvature of a three-dimensional curved surface of a wide and thick plate warping according to the present invention.

FIG. 2 is a schematic illustration of the wide and thick sheet buckle flattening of the present invention.

Fig. 3 is a schematic view of a deforming model of the leveler of the present invention.

FIG. 4 is a schematic view of the wide plank and leveler application field of the present invention.

Fig. 5 is a curved surface fitted with machine vision recognition points of the present invention.

Fig. 6 is a schematic view of the distribution of the warped surface and the pi-plane of the over-peak and the lowest point of the present invention.

In the figure: 1-wide and thick plate; 2-sizing block; and 3-pressing head of the flattening machine.

Detailed Description

Example 1

Referring to fig. 1-6, a method for flattening and straightening a wide and thick plate based on a three-dimensional curved surface theory comprises the following steps:

and S1, acquiring wide and thick plate data: thickness delta, width b, regardless of the modulus of elasticity E at the time of material deformation strengthening₀Taking into account the reinforcing modulus E at the time of material reinforcement₁；

S2, identifying the warping appearance of the local area of the wide and thick plate sent into the flattening machine through a structured light or binocular vision camera, defining the advancing direction of the plate as an x axis, the width direction of the plate as a y axis, locating the origin of coordinates at the center O point of the rectangular plate, and obtaining the discrete points of the wide and thick plate;

s3, performing three-dimensional surface fitting on the discrete points obtained in the step S2 by using a least square method to obtain a local surface contour surface equation z (f (x, y)) of the wide and thick plate, and further calculating partial derivatives of the surface equationObtaining a first partial derivative and a second partial derivative of the curved surface;

s4, judging the concavity and convexity of the curved surface through the first partial derivative and the second partial derivative of the curved surface, when the part of the outline curved surface of the wide and thick plate is a downward convex three-dimensional curved surface, turning the wide and thick plate by using a plate turning machine to ensure that the curved surface in the field range is in an upward convex form, and then symmetrically processing the outline curve;

s5, obtaining the first basic quantity E as 1+ p according to the normal curvature calculation theory of the curved surface equation in the differential geometric theory²，F＝pq，G＝1+q²To obtain a second basic quantity According to the thickness delta of the incoming material and the yield strength sigma of the material_sAnd modulus of elasticity E₀Calculating limit value of elastic bending curvature of wide and thick plateWhere rho_wThe radius of the limit value of the elastic recovery curvature of the wide and thick plate is;

s6, locally adopting an optimization algorithm to search the highest point (x) of the inner curved surface of the action domain for the contour curved surface of the convex wide and thick plate_max,y_max,h_max) And nadir (x)_min,y_min,h_min) Calculating an included angle theta between a connecting line of the highest point and the lowest point and the plate conveying advancing direction of the flattening machine, recording a vertical plane where the included angle theta is located as a pi plane, and searching a local minimum point (x) from the highest point along a direction of the theta angle back to the connecting line of the lowest point and the highest point_lm,y_lm,h_lm) Calculating the distance between the highest point and the lowest pointDistance from the highest point and the local minimum pointComparing the maximum limit distance 2l of the arrangement of the sizing blocks of the flattening machine_sAnd l_m-mAnd l_m-lmDetermining the first sizing block position, the second sizing block position, the spacing l of the sizing blocks, the maximum height difference delta h between the highest point and the sizing block position and the pressing head pressing position;

s7, calculating the curve where the pi plane intersects with the curved surface profile z ═ f (x, y) at the highest point (x_max,y_max,h_max) Of (2) curvatureThe curvature is the buckling curvature of the wide and thick plate, and the buckling curvature of the wide and thick plate is further calculatedAnd limit of elastic curvatureRatio ofMaking the reverse bending rateAnd limit of elastic curvatureRatio ofAccording to the relation between elastic restoring moment and plastic bending moment, 2% is obtained³+(4λ-3)χ²+(2λ²-6λ)χ-3λ²And (4) obtaining chi through a chi-lambda curve distribution rule and the value of lambda, and further calculating to obtain the inverse bending ratio

S8, obtaining the pressing amount according to the reverse bending rateCalculating the elastic deflectionAccording to the mechanics of materials, the shaping bending moment of the bending of the thick plate can be obtainedFurther obtaining the average pressing force of the pressing cylinderAnd the displacement of a pressing cylinder of the flatting machine is s ═ delta h + f, wherein delta h is the maximum height difference between the highest point and the sizing block;

and the flattening and finishing precision of the flattening machine is ensured through the calculation.

Example 2

In actual use:

s1, obtaining data of the wide and thick plate to be straightened: thickness delta, width b, regardless of the modulus of elasticity E at the time of material deformation strengthening₀Taking into account the reinforcing modulus E at the time of material reinforcement₁；

S2, identifying the warping appearance of the local area of the wide and thick plate sent into the flattening machine through a structured light or binocular vision camera, defining the advancing direction of the plate as an x axis, the width direction of the plate as a y axis, locating the origin of coordinates at the center O point of the rectangular plate, and obtaining the discrete points of the wide and thick plate;

s3, performing three-dimensional surface fitting on the discrete points obtained in the step S2 by using a least square method to obtain a local surface contour surface equation z (f (x, y)) of the wide and thick plate, and further calculating partial derivatives of the surface equationObtaining a first partial derivative and a second partial derivative of the curved surface;

s4, judging the concavity and convexity of the curved surface through the first partial derivative and the second partial derivative of the curved surface, when the part of the outline curved surface of the wide and thick plate is a downward convex three-dimensional curved surface, turning the wide and thick plate by using a plate turning machine to ensure that the curved surface in the field range is in an upward convex form, and then symmetrically processing the outline curve;

s5, obtaining the first basic quantity E as 1+ p according to the normal curvature calculation theory of the curved surface equation in the differential geometric theory²，F＝pq，G＝1+q²To obtain a second basic quantity According to the thickness delta of the incoming material and the yield strength sigma of the material_sAnd modulus of elasticity E₀Calculating limit value of elastic bending curvature of wide and thick plateWhere rho_wThe radius of the limit value of the elastic recovery curvature of the wide and thick plate is;

locally, searching the highest point (x) of the inner curved surface of the action domain by adopting an optimization algorithm for the contour curved surface of the convex wide and thick plate_max,y_max,h_max) And nadir (x)_min,y_min,h_min) Calculating an included angle theta between a connecting line of the highest point and the lowest point and the plate conveying advancing direction of the flattening machine, recording a vertical plane where the included angle theta is located as a pi plane, and searching a local minimum point (x) from the highest point along a direction of the theta angle back to the connecting line of the lowest point and the highest point_lm,y_lm,h_lm) Calculating the distance between the highest point and the lowest pointDistance from the highest point and the local minimum pointComparing the maximum limit distance 2l of the arrangement of the sizing blocks of the flattening machine_sAnd l_m-mAnd l_m-lmDetermining the first sizing block position, the second sizing block position, the spacing l of the sizing blocks, the maximum height difference delta h between the highest point and the sizing block position and the pressing head pressing position;

when l is_m-m+l_m-lm＜2l_sWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) And position two is (x)_min,y_min,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks isThe head depression position is (x)_max,y_max,h_max) (ii) a When 2l_s＜l_m-lm+l_m-mAnd l_m-lm＜l_s＜l_m-mWhen the position of the sizing block is determined to be (x)_lm,y_lm,h_lm) Position two is symmetrical to position one about the highest point and at a point (x) in the direction of angle theta_ls,y_ls,h_lm) At the highest point and the sizing block positionThe maximum height difference is set as delta h ═ h_max-h_lmThe distance between the sizing blocks is l-2 l_m-lmThe head depression position is (x)_max,y_max,h_max)；

When 2l_s＜l_m-lm+l_m-mAnd l_m-m＜l_s＜l_m-lmWhen the position 1 of the sizing block is determined to be (x)_min,y_min,h_min) Position two is a point (x) symmetrical to position one about the highest point and in the direction along angle theta_s,y_s,h_min) At this time, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_minThe distance between the sizing blocks is l-2 l_m-m；

S7, calculating the curve where the pi plane intersects with the curved surface profile z ═ f (x, y) at the highest point (x_max,y_max,h_max) Of (2) curvatureThe curvature is the buckling curvature of the wide and thick plate, and the buckling curvature of the wide and thick plate is further calculatedAnd limit of elastic curvatureRatio ofMaking the reverse bending rateAnd limit of elastic curvatureRatio ofAccording to the relation between elastic restoring moment and plastic bending moment, 2% is obtained³+(4λ-3)χ²+(2λ²-6λ)χ-3λ²+1 ═ 0, generalObtaining chi through the chi-lambda curve distribution rule and the value of lambda, and further calculating to obtain the reverse bending ratio

Reverse bending ratio when material reinforcement is considered, reverse bending ratio(whereinCalculating KThe value of the reverse curvature obtained without considering the strengthening condition);

s8, obtaining the pressing amount according to the reverse bending rateCalculating the elastic deflectionAccording to the mechanics of materials, the shaping bending moment of the bending of the thick plate can be obtainedFurther obtaining the average pressing force of the pressing cylinderAnd the displacement of a pressing cylinder of the flatting machine is s ═ delta h + f, wherein delta h is the maximum height difference between the highest point and the sizing block;

the position of the sizing block is adjusted through the obtained data of the first position of the sizing block and the second position of the sizing block, the displacement of the pressing cylinder is set, the average pressing force of the pressing cylinder is predicted, the effect of local flattening and straightening of the wide and thick plate is achieved more accurately, and the flattening and finishing operation efficiency is improved.

The first basic quantities E, F, G and the second basic quantities L, M, N are coefficients defined in differential geometry, which are calculated by partial derivatives, and the first and second, that is, coefficients obtained from different methods, which are important variables for calculating the curvature.

The optimization algorithm has a constrained nonlinear optimization method, and the specific algorithm can select a Rosen gradient projection method, an interior point method and a step-by-step quadratic programming method.

In FIG. 1-the normal vector of the curved surface at the highest point,-tangent vector, pi-normal vector, in the plane of the highest point and having an angle theta with the x-directionAndand determining a plane, wherein the angle between the theta and the pi plane and the x direction is equal to f (x, y) -the buckling curved surface of the wide and thick plate, the x-the feeding direction of the wide and thick plate, the y-the width direction of the wide and thick plate, and the z-the buckling height direction of the wide and thick plate.

Example 3

Taking the warped wide and thick plate of fig. 5 as an example, the thickness δ of the plate is 10mm, the width b is 2000mm, and the density ρ is 7850kg/m₃Modulus of elasticity E₀＝2.06×10¹¹Pa, reinforcing modulus E₁＝5×10⁷Pa, yield limit material yield strength sigma_s235 MPa. The length and width of the action area of the flattening machine are 3500mm wide with the central point of the flattening machine as the original point and 2000mm long, and the maximum distance of the sizing block in the action area of the flattening machine is 2l_sThe action area of the flattening machine and the distribution area of the wide and thick plates are schematically shown in figure 4, which is 4000 mm.

The coordinate points of the wide and thick plates by the visual recognition mechanism are shown in table 1. Calculating limit value of elastic bending curvature of wide and thick plateFitting by least squaresThe resultant surface equation is as follows: f (x, y) ═ a_f(x-80)(x+80)+b_f(y-50) (x +40) wherein a_f＝-1×10^-5，b_f＝-1×10^-4. Calculating partial derivative of the surface equation to obtain

TABLE 1 machine vision recognition of location points of a curved surface

In the interval x e-100,100]γ＝-2×10^-5In the interval y e-100,100]t＝-2×10^-4，

According to the concave-convex principle of the curve equation, f (x, y) can be judged to be an upward convex curved surface in the region x e-1000, 1000 y e-1000, 1000. The fitted surface is shown in fig. 5.

Optimizing to obtain a maximum value point (x) of the curved surface based on a sequence quadratic programming algorithm adopted by the matlab internal function fmincon_max,y_max,h_max) Is (0, 5, 0.2665), minimum value point (x)_min,y_min,h_min) Is (1000, 1000, -108.736), the equation of the connection line between the highest point and the lowest point satisfies the condition

Find k as 0.995 b_j5. Fig. 6 shows a resulting t plane with a warped surface of 44.856 ° and a highest point and a lowest point.

The local minimum is obtained by searching in the action area of the flattening machine and the area of the wide and thick plate by adopting a Newton method along the connecting line of the highest point and the lowest pointPoint (x)_lm,y_lm,h_lm) Is (-1000, -995, -108.736). Calculating the distance between the highest point and the lowest pointDistance between local lowest point and highest pointSatisfy l_m-m+l_m-lm＜2l_sFurther, it was determined that the position of the back iron 1 was (1000, 1000, -108.736), the position of the back iron 2 was (-1000, -990, -108.736), the pressing position of the indenter was (0, 5, 0.2665), and the back iron pitch was (m) in the following mannerAt the moment, the maximum height difference between the highest point and the sizing block is delta h ═ h_max-h_min＝109.0025mm。

Calculating a first basic quantity E of the highest point of the warped wide and thick plate to be 1+ p according to the partial derivative equation of the curve equation obtained in the previous step²≈1，F＝pq≈0，G＝1+q²1, second basic quantity The actual curvature is

Further calculating to obtain the warping curvature of the wide and thick plateAnd limit of elastic curvatureRatio ofAccording to the distribution rule of chi-lambda curve and the selection of lambdaValue of obtaining

Further obtaining the reverse bending rateWhen material strengthening is considered, obtainWithout taking into account and taking into account the reinforcement, from the reverse bending ratioCalculating the elastic deflectionOrThe average pressing force without considering material reinforcement is calculated according to the bending moment of the thick plateAnd average depression force taking into account material reinforcementThe displacement of the pressing cylinder not considering the material reinforcement is 335.8654mm, and the displacement of the pressing cylinder considering the material reinforcement is 714.2852 mm.

The final flattening process parameters are as follows: the position of the sizing block 1 is (1000, 1000, -108.736), the position of the sizing block 2 is (-1000, -990, -108.736), the pressing position of the pressing head is (0, 5, 0.2665), and the average pressing force of the material reinforcement is not consideredAnd average depression force taking into account material reinforcementThe displacement of the pressing cylinder not considering the material reinforcement is 335.8654mm, and the displacement of the pressing cylinder considering the material reinforcement is 714.2852 mm.

The method is based on image vision, a curvature calculation theory and a straightening theory of a three-dimensional curved surface method, is optimized by combining with actual working conditions, calculates to obtain the sizing block position, the pressing position and the pressing stroke of the flatting machine, and simultaneously pre-measures the pressing force, and provides a basic model and a method for the intelligent control of the flatting machine.

While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art, and the scope of the present invention is defined by the claims. The components and structures of the present embodiments that are not described in detail are well known in the art and do not constitute essential structural elements or elements.