Calculation method of rolling mill roll change pressing position

Abstract

The invention relates to a method for calculating a rolling mill roll changing pressing position, and belongs to the technical field of rolling mill roll changing methods. According to the technical scheme, the method comprises the steps that CAD modeling is carried out, a constraint relation is established to simulate field reality, indication marking lines and a size relation are set, key parameter sizes are displayed in real time, related size links are established, data calculation and automatic correction are carried out through a set logic relation, and calculation and inspection of key parameters such as the rolling mill roll changing pressing position are completed. And meanwhile, a numerical value displayed on an operation interface is compared with a calculation result, and data is manually corrected. The method has the beneficial effects that key parameters such as an optimal screw-down position value can be displayed only by inputting diameter data by using the model when the supporting roll is replaced every time, so that the screw-down position corresponding to each set of supporting roll is suitable for working rolls in all diameter ranges, tedious calculation is avoided, and the method has the advantages of simplicity, rapidness, high calculation precision and the like, and is suitable for popularization and application. The method can effectively solve the problem of accurate calculation of the rolling mill roll change screw-down position.

Description

Technical Field

[0001] The invention relates to a method for calculating a rolling mill roll-changing depression position, and belongs to the technical field of rolling mill roll-changing methods. Background Art

[0002] The rolling mill press-down system usually consists of electric press-down and hydraulic AGC. The electric press-down is driven by the press-down motor and connected to the hydraulic AGC through the press-down reduction box, press-down screw, and press-down nut. The roll gap can be quickly set by electric press-down and the roll gap accuracy can be controlled by using hydraulic AGC.

[0003] The main process of replacing the working roll system of the rolling mill is that when the rolling mill changes rolls, the hydraulic AGC returns to zero, and the electric pressing roll changing position is the parking position of the pressing screw. The reading can be directly viewed on the operation interface. At the same time, this position is also the roll changing parking position of the upper support roll when changing rolls. The electric pressing stop setting position is crucial. If the value is not set accurately, the following situations will occur as the diameters of the working rolls and support rolls change: (1) The electric pressing position is too low and the lower roll system cannot be lifted into place: When the lower roll system is lifted, the lower working roll interferes with the upper working roll, so that the lower roll system cannot be lifted into place, resulting in the inability of the step pad frame to move the pad horizontally; (2) The electric pressing position is too high and the upper working roll cannot be lifted into place: When the upper plunger of the bending roll block extends to the maximum stroke, the upper working roll still cannot contact the upper support roll, resulting in abnormal subsequent roll gap calibration and abnormal production rolling data.

[0004] Therefore, it is necessary to make a detailed calculation of the stop position when changing the rollers according to the vertical dimension chain, determine the pressing value, and check and update the value in real time according to the changes in the diameters of the working rollers and the supporting rollers to avoid the above problems. However, due to the large number of parameters and variables involved in the vertical dimension chain (such as the large range of changes in the diameters of the supporting rollers and the working rollers, the upper limit gap and the lower limit gap need to be satisfied at the same time, etc.), the calculation workload is large and cumbersome. Due to the complex working conditions, the influence of factors such as the pressing gap leads to deviations between theory and practice, which ultimately makes it difficult to accurately calculate the value, resulting in the problem of the electric pressing position being too low or too low, affecting the normal production of the production line. Therefore, a new technical solution is urgently needed to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a method for calculating the rolling mill roll changing depression position, which simulates the actual situation on site through CAD modeling and establishing constraint relationships, sets a variety of indicator lines and dimensional relationships, performs data calculation and automatic correction through set logical relationships, completes the calculation and inspection of key parameters such as the rolling mill roll changing depression position, avoids tedious calculations, has the advantages of being simple, fast, and accurate in calculation, and effectively solves the above-mentioned problems existing in the background technology.

[0006] The technical solution of the present invention is: a method for calculating the roll change down position of a rolling mill, comprising the following steps: S1, upper support roll, lower support roll, upper working roll, lower working roll, upper working roll bearing seat, bending roll block, lower support roll bearing seat and step pad frame are virtually assembled into the mill arch according to the actual position and assembly relationship, and form a CAD model in a 1:1 ratio; S2. Set the rolling line elevation line, the lower working roll position indication line, the upper working roll position indication line, the upper working roll limit position marking line, the upper support roll horizontal center line and the press-down position zero position marking line to indicate key positions or as calculation standard lines; S3. Input, modify and display key parameters in the key parameter display area and link them with the CAD model. Under the premise of maintaining the original constraint relationship, update the data according to the set data relationship and calculate according to the set logic to meet the conditions that the minimum spacing between the lower working roll and the upper working roll after lifting is greater than zero, the spacing between the upper working roll position and the limit position is greater than zero, and the difference between the two is within a reasonable range, and obtain the roller change pressing position that meets the conditions; S4. Use the CAD model to input diameter data each time the backup roll is replaced, and the optimal key parameters of the pressing position are displayed, so that the pressing position corresponding to each set of backup rolls is suitable for working rolls within all diameter ranges; S5. Compare the numerical value displayed on the operation interface with the calculation result and correct the model based on the data.

[0007] In the step S1, the upper support roll is tangent to the upper working roll, the upper working roll bearing seat is concentrically arranged with the upper working roll, the two side surfaces of the upper working roll bearing seat coincide with the two slide surfaces of the bending roll block, the upper part of the upper working roll bearing seat coincides with the upper surface of the upper plunger of the bending roll block, and the upper plunger of the bending roll block moves up and down and retracts; The lower support roller is tangent to the lower working roller, the lower support roller is concentrically arranged with the lower support roller bearing seat, and the relative position and distance between the stepped pad frame and the lower support roller bearing seat remain unchanged.

[0008] In the step S2, the rolling line elevation line simulates the actual rolling line elevation line position; The lower working roll position indicator line is the horizontal tangent line of the top of the upper roll surface of the lower working roll after the lower roll system is lifted by a distance of F; The upper working roll position indicator line is a horizontal line between the upper working roll and the upper plunger of the bending roll block and keeps a constant relative position with the upper working roll, and is used to indicate the actual position of the upper working roll; The upper working roll limit position marking line is set on the rolling mill arch and corresponds to the upper working roll limit position fixed marking line when the upper plunger of the bending roll block has the maximum stroke theoretically calculated; The zero mark of the depression position is a fixed mark arranged on the rolling mill arch and coincides with the horizontal center line of the upper support roller position corresponding to when the theoretically calculated depression position is zero.

[0009] In the lower working roll position indicator line, the lower roll system is composed of a lower working roll, a lower support roll, a lower support roll bearing seat and a stepped pad frame; in the down-pressing position zero position mark line, the theoretically calculated down-pressing position is zero, which means that the electric down-pressing is zero and the hydraulic AGC is zero.

[0010] In step S3, in the CAD model, the data relationships are as follows: The minimum distance between the lower working roll and the upper working roll after lifting A1 = the minimum distance between the upper working roll and the rolling line elevation line B1 - the minimum distance between the lower working roll after lifting and the rolling line elevation line C1, that is, A1 = B1-C1; The distance between the upper working roll position and the limit position A2 = the distance between the upper working roll limit position and the rolling line elevation line B2 - the distance between the upper working roll position and the rolling line elevation line C2, that is, A2 = B2-C2; The roller-changing pressing position A3 is the horizontal centerline spacing of the support rollers on the pressing position zero mark. This value is theoretically consistent with the electric pressing value displayed on the operation interface.

[0011] In step S3, when performing calculation, the upper support roller diameter D1 and the lower support roller diameter D2 are input in the key parameter display area, the initial value A3 of the roller change pressing position is input, and the relevant dimensions of the CAD model maintain the relevant matching relationship and are updated, and the calculation is performed according to the following logic: (1) Take the maximum values ​​of the upper working roll diameter d1 and the lower working roll diameter d2, collect the minimum distance B1 between the upper working roll and the rolling line elevation line in the model, and the minimum distance C1 between the lower working roll after lifting and the rolling line elevation line, and calculate the minimum distance A1 between the lower working roll and the upper working roll after lifting; (2) Take the minimum value of the upper working roll diameter d1 and the lower working roll diameter d2, collect the distance B2 between the upper working roll limit position and the rolling line elevation line and the distance C2 between the upper working roll position and the rolling line elevation line in the model, and calculate the distance A2 between the upper working roll position and the limit position; (3) If ①A1>0, ②A2>0 and ③A1-A2<10 or A2-A1<10 are satisfied at the same time, that is, the roller change pressing position is moderate, then the result is directly displayed, and the A3 value at this time is the roller change pressing position; (4) If the above conditions cannot be met, the A3 value will be automatically corrected and the calculation will continue until the above conditions are met.

[0012] A3 revised calculation logic is as follows: If A1-A2>10, increase the value of A3 and perform the above calculation until the above requirements are met; If A2-A1>10, reduce the value of A3 and perform the above calculation until the above requirements are met.

[0013] In step S5, the specific operation steps are as follows: (1) Check the actual electric pressure value, AGC hydraulic cylinder extension and roll gap value on the operation interface during the production process, and set the same roll diameter and roll gap parameters as the actual ones in the model. The A3 value is the theoretical roll change pressure position value. At this time, A3 does not perform the above calculation; (2) Compare the sum of the actual electric pressing value and the AGC hydraulic cylinder extension on the operation interface with the difference A3 and correct the zero mark position of the pressing position in the model to realize the verification and manual correction of the pressing position.

[0014] The beneficial effects of the present invention are as follows: CAD modeling is used to simulate the actual situation on site and to establish constraint relationships, a variety of indicator lines and dimensional relationships are set, data calculation and automatic correction are performed through set logical relationships, and calculation and inspection of key parameters such as the rolling mill roll change down position are completed, thus avoiding tedious calculations and having the advantages of being simple, fast, and accurate in calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the CAD model structure of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 3 It is a schematic diagram of the key parameters and their interrelationships of the present invention; Figure 4 is a schematic diagram of an embodiment of the present invention; Figure 5 It is a schematic diagram of the rolling mill structure in the background technology; Figure 6 It is a schematic diagram of the structure of a rolling mill press-down system in the background technology; Figure 7 It is a flow chart of replacement of working roll system of a rolling mill in the background technology; Figure 8 It is a schematic diagram of the structure in which the upper and lower working rolls interfere with each other due to the electric pressing position being too low in the background technology; Fig. 9 It is a structural schematic diagram of the background technology in which the electric pressing position is too high, resulting in the upper working roll and the upper supporting roll not being in contact; In the figure: upper support roll 1, lower support roll 2, upper working roll 3, lower working roll 4, upper working roll bearing seat 5, bending roll block 6, upper plunger 601 of bending roll block, lower support roll bearing seat 7, step pad frame 8, rolling mill arch 9, rolling line elevation line 10, lower working roll position indication line 11, upper working roll position indication line 12, upper working roll limit position marking line 13, horizontal center line 14, pressing position zero position marking line 15, key parameter display area 16; The minimum distance between the lower working roll and the upper working roll after lifting is A1, the minimum distance between the upper working roll and the rolling line elevation line B1, the minimum distance between the lower working roll position after lifting and the rolling line elevation line C1, the distance between the upper working roll position and the limit position A2, the distance between the upper working roll limit position and the rolling line elevation line B2, the distance between the upper working roll position and the rolling line elevation line C2, the roll change down position A3, the upper support roll diameter D1, the lower support roll diameter D2, the upper working roll diameter d1, the lower working roll diameter d2, and the lower roll system lifting distance F; Electric pressing down 01, pressing down reducer 011, pressing down screw 012, pressing down nut 013, hydraulic AGC 02, rolling mill working roll system 03, original lower working roll 031, original upper working roll 032, original bending roll block 04, original bending roll block lower plunger 041, original bending roll block upper plunger 042, original step pad frame 05, original rolling mill support roll system 06, original lower support roll 061, original upper support roll 062, original roll changing guide rail 07, original rolling mill arch 08. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] A method for calculating a rolling mill roll change depression position comprises the following steps: S1, upper support roll, lower support roll, upper working roll, lower working roll, upper working roll bearing seat, bending roll block, lower support roll bearing seat and step pad frame are virtually assembled into the mill arch according to the actual position and assembly relationship, and form a CAD model in a 1:1 ratio; S2. Set the rolling line elevation line, the lower working roll position indication line, the upper working roll position indication line, the upper working roll limit position marking line, the upper support roll horizontal center line and the press-down position zero position marking line to indicate key positions or as calculation standard lines; S3. Input, modify and display key parameters in the key parameter display area and link them with the CAD model. Under the premise of maintaining the original constraint relationship, update the data according to the set data relationship and calculate according to the set logic to meet the conditions that the minimum spacing between the lower working roll and the upper working roll after lifting is greater than zero, the spacing between the upper working roll position and the limit position is greater than zero, and the difference between the two is within a reasonable range, and obtain the roller change pressing position that meets the conditions; S4. Use the CAD model to input diameter data each time the backup roll is replaced, and the optimal key parameters of the pressing position are displayed, so that the pressing position corresponding to each set of backup rolls is suitable for working rolls within all diameter ranges; S5. Compare the numerical value displayed on the operation interface with the calculation result and correct the model based on the data.

[0018] In the step S1, the upper support roll 1 is tangent to the upper working roll 3, the upper working roll bearing seat 5 is concentrically arranged with the upper working roll 3, the two side surfaces of the upper working roll bearing seat 5 coincide with the two slide surfaces of the bending roll block 6, the upper part of the upper working roll bearing seat 5 coincides with the upper surface of the upper plunger 601 of the bending roll block, and the upper plunger 601 of the bending roll block moves up and down and retracts; The lower support roller 2 is tangent to the lower working roller 4, the lower support roller 2 is concentrically arranged with the lower support roller bearing seat 7, and the stepped cushion frame 8 and the lower support roller bearing seat 7 maintain a constant relative position and distance.

[0019] In the step S2, the rolling line elevation line 10 simulates the actual rolling line elevation line position; The lower working roll position indicator line 11 is the horizontal tangent line of the top of the upper roll surface of the lower working roll 4 after the lower roll system is lifted by a distance F; The upper working roll position indicator line 12 is a horizontal line between the upper working roll 3 and the upper plunger 601 of the bending roll block and keeps a constant relative position with the upper working roll 3, and is used to indicate the actual position of the upper working roll 3; The upper working roll limit position mark 13 is set on the rolling mill arch 9 and is a fixed mark of the upper working roll 3 limit position corresponding to the maximum stroke of the upper plunger 601 of the bending roll block in theoretical calculation; The zero mark line 15 of the pressing position is a fixed mark line arranged on the rolling mill arch 9 and coincides with the horizontal center line 14 of the position of the upper support roll 1 corresponding to the theoretically calculated pressing position being zero.

[0020] In the lower working roll position indicator line, the lower roll system is composed of the lower working roll 4, the lower support roll 2, the lower support roll bearing seat 7 and the stepped pad frame 8; in the depression position zero mark line 15, the theoretically calculated depression position is zero, which means that the electric depression is zero and the hydraulic AGC is zero.

[0021] In step S3, in the CAD model, the data relationships are as follows: The minimum distance between the lower working roll and the upper working roll after lifting A1 = the minimum distance between the upper working roll and the rolling line elevation line B1 - the minimum distance between the lower working roll after lifting and the rolling line elevation line C1, that is, A1 = B1-C1; The distance between the upper working roll position and the limit position A2 = the distance between the upper working roll limit position and the rolling line elevation line B2 - the distance between the upper working roll position and the rolling line elevation line C2, that is, A2 = B2-C2; The roller-changing pressing position A3 is the distance between the pressing position zero mark 15 and the horizontal center line 14 of the upper supporting roller. This value is theoretically consistent with the electric pressing value displayed on the operation interface.

[0022] In step S3, when performing calculation, the upper support roller diameter D1 and the lower support roller diameter D2 are input in the key parameter display area 16, and the initial value A3 of the roller change pressing position is input, and the relevant dimensions of the CAD model maintain the relevant matching relationship and are updated, and the calculation is performed according to the following logic: (1) Take the maximum values ​​of the upper working roll diameter d1 and the lower working roll diameter d2, collect the minimum distance B1 between the upper working roll and the rolling line elevation line in the model, and the minimum distance C1 between the lower working roll after lifting and the rolling line elevation line, and calculate the minimum distance A1 between the lower working roll and the upper working roll after lifting; (2) Take the minimum values ​​of the diameter d1 of the upper working roll 3 and the diameter d2 of the lower working roll, collect the distance B2 between the upper working roll limit position and the rolling line elevation line and the distance C2 between the upper working roll position and the rolling line elevation line in the model, and calculate the distance A2 between the upper working roll position and the limit position; (3) If ①A1>0, ②A2>0 and ③A1-A2<10 or A2-A1<10 are satisfied at the same time, that is, the roller change pressing position is moderate, then the result is directly displayed, and the A3 value at this time is the roller change pressing position; (4) If the above conditions cannot be met, the A3 value will be automatically corrected and the calculation will continue until the above conditions are met.

[0023] A3 revised calculation logic is as follows: If A1-A2>10, increase the value of A3 and perform the above calculation until the above requirements are met; If A2-A1>10, reduce the value of A3 and perform the above calculation until the above requirements are met.

[0024] In step S5, the specific operation steps are as follows: (1) Check the actual electric pressure value, AGC hydraulic cylinder extension and roll gap value on the operation interface during the production process, and set the same roll diameter and roll gap parameters as the actual ones in the model. The A3 value is the theoretical roll change pressure position value. At this time, A3 does not perform the above calculation; (2) Compare the sum of the actual electric pressing value and the AGC hydraulic cylinder extension on the operation interface with the difference A3 and correct the position of the zero mark 15 of the pressing position in the model to realize the verification and manual correction of the pressing position.

[0025] In practical applications, the present invention mainly includes an upper supporting roll 1, a lower supporting roll 2, an upper working roll 3, a lower working roll 4, an upper working roll bearing seat 5, a bending roll block 6, a lower supporting roll bearing seat 7, a step pad frame 8, a rolling mill arch 9, a rolling line elevation line 10, a lower working roll position indicator line 11, an upper working roll position indicator line 12, an upper working roll limit position marking line 13, an upper supporting roll horizontal center line 14, a down-pressing position zero position marking line 15 and a key parameter display area 16, etc.

[0026] The upper supporting roll 1, the lower supporting roll 2, the upper working roll 3, the lower working roll 4, the upper working roll bearing seat 5, the bending roll block 6, the lower supporting roll bearing seat 7 and the stepped pad frame 8 are virtually assembled into the rolling mill arch 9 according to the actual position and assembly relationship, and form a CAD model at a ratio of 1:1.

[0027] The upper supporting roll 1 always maintains a tangential relationship with the upper working roll 3, the upper working roll bearing seat 5 maintains a concentric relationship with the upper working roll 3, the two side surfaces of the upper working roll bearing seat 5 maintain an overlapping relationship with the two slide surfaces of the bending roll block 6, the upper part of the upper working roll bearing seat 5 maintains an overlapping relationship with the upper surface of the upper plunger 601 of the bending roll block, and the upper plunger 601 of the bending roll block extends and retracts as the upper working roll 3 and the upper working roll bearing seat 5 move up and down.

[0028] The lower support roller 2 and the lower working roller 4 always maintain a tangential relationship, the lower support roller 2 and the lower support roller bearing seat 7 always maintain a concentric relationship, and the stepped pad frame 8 and the lower support roller bearing seat 7 maintain a constant relative position and distance.

[0029] The rolling line elevation line 10 simulates the actual rolling line elevation line position, and the lower working roll position indicator line 11 is the horizontal tangent line of the upper roll surface vertex of the lower working roll 4 after the lower roll system (lower working roll 4, lower support roll 2, lower support roll bearing seat 7, step pad frame 8) is lifted by a distance F.

[0030] The upper working roll position indicator line 12 is a horizontal marking line between the upper working roll 3 and the upper plunger 601 of the bending roll block and maintains a constant relative position with the upper working roll 3, and is used to indicate the actual position of the upper working roll 3; the upper working roll limit position marking line 13 is a fixed marking line of the upper working roll 3 set on the rolling mill arch 9 and corresponding to the maximum stroke of the upper plunger 601 of the bending roll block when theoretically calculated.

[0031] The depression position zero mark 15 is a fixed mark arranged on the rolling mill arch 9 and coincides with the horizontal center line 14 of the upper support roll 1 position corresponding to when the theoretically calculated depression position is zero (electric depression is zero, hydraulic AGC is zero).

[0032] The key parameter display area 16 is used to input, modify and display key parameters such as the diameters of the upper and lower working rolls and support rolls, the roll change pressing position, the minimum spacing between the lower working roll and the upper working roll after lifting, and the spacing between the upper working roll position and the limit position. At the same time, these parameters can be linked to the CAD model, and the relevant parameters can be modified and displayed in real time to check whether they can meet production needs.

[0033] like Figure 3 In the CAD model of virtual assembly, the relationship between each data is as follows: the minimum distance between the lower working roll and the upper working roll after lifting A1 = the minimum distance between the upper working roll and the rolling line elevation line B1 - the minimum distance between the lower working roll position after lifting and the rolling line elevation line C1, that is, A1=B1-C1; the distance between the upper working roll position and the limit position A2 = the distance between the upper working roll limit position and the rolling line elevation line B2 - the distance between the upper working roll position and the rolling line elevation line C2, that is, A2=B2-C2; the roll change down position A3 is the distance between the down position zero mark 15 and the horizontal center line 14 of the upper support roll. This value is theoretically consistent with the electric down value displayed on the operation interface.

[0034] When performing relevant calculations, the upper support roller diameter D1 and the lower support roller diameter D2 are input in the key parameter display area 16, and the initial value A3 of the roller change pressing position is input. The relevant dimensions of the CAD model maintain the relevant matching relationship and are updated. The calculation is performed according to the following logic: (1) Take the maximum values ​​of the upper working roll diameter d1 and the lower working roll diameter d2, collect B1 and C1 in the model, and calculate A1; (2) Take the minimum value of the upper working roll diameter d1 and the lower working roll diameter d2, collect B2 and C2 in the model, and calculate A2; (3) If ①A1>0, ②A2>0, ③A1-A2<10 or A2-A1<10 are satisfied at the same time (ensuring that the roller change pressing position is appropriate), the result is displayed directly, and the A3 value at this time is the roller change pressing position.

[0035] (4) If it cannot be satisfied, the A3 value will be automatically corrected and the calculation will continue until the above conditions are met. The A3 correction calculation logic is as follows: If A1-A2>10, increase the value of A3 and perform the above calculation until the above requirements are met; If A2-A1>10, reduce the value of A3 and perform the above calculation until the above requirements are met.

[0036] At the same time, the numerical values ​​displayed on the operation interface can be compared with the calculation results and the data can be corrected to eliminate the influence of actual working conditions such as wear and clearance. The specific operations are as follows: (1) Check the actual electric pressing value, AGC hydraulic cylinder extension and roll gap value on the operation interface during the production process, and set the same roll diameter and roll gap parameters as the actual ones in the model, and obtain the A3 value as the theoretical pressing position value (A3 does not perform the above calculation at this time).

[0037] (2) Compare the sum of the actual electric pressing value and the AGC hydraulic cylinder extension on the operation interface with the difference A3 and correct the position of the zero mark 15 of the pressing position in the model to realize the verification and manual correction of the pressing position.

[0038] When using the specific operation of the present invention, it is implemented according to the following detailed steps: (1) Open the model and enter the actual values ​​of D1 and D2 in the key parameter display area 16.

[0039] (2) Check the A3 value in the key parameter display area 16, use this value as the optimal pressing position value of the rolling mill, and modify this value in the on-site electrical automation program.

[0040] An embodiment of the present invention is as follows: The diameter of the upper supporting roller is D1=2090.38mm, the diameter of the lower supporting roller is D2=2080.28mm, the upper working roller diameter d1 is in the range of 950mm-1050mm, the lower working roller diameter d2 is in the range of 950mm-1050mm, the minimum distance between the lower working roller and the upper working roller after lifting is A1=20.62mm, the distance between the upper working roller position and the limit position is A2=19.14mm, and the roller changing down position is A3=90mm.

Claims

1. A method for calculating the rolling mill roll change down position, characterized in that The following steps are involved: S1, upper support roll, lower support roll, upper working roll, lower working roll, upper working roll bearing seat, bending roll block, lower support roll bearing seat and step pad frame are virtually assembled into the mill arch according to the actual position and assembly relationship, and form a CAD model in a 1:1 ratio; S2. Set the rolling line elevation line, the lower working roll position indication line, the upper working roll position indication line, the upper working roll limit position marking line, the upper support roll horizontal center line and the press-down position zero position marking line to indicate key positions or as calculation standard lines; S3. Input, modify and display key parameters in the key parameter display area and link them with the CAD model. Under the premise of maintaining the original constraint relationship, update the data according to the set data relationship and calculate according to the set logic to meet the conditions that the minimum spacing between the lower working roll and the upper working roll after lifting is greater than zero, the spacing between the upper working roll position and the limit position is greater than zero, and the difference between the two is within a reasonable range, and obtain the roller change pressing position that meets the conditions; S4. Use the CAD model to input diameter data each time the backup roll is replaced, and the optimal key parameters of the pressing position are displayed, so that the pressing position corresponding to each set of backup rolls is suitable for working rolls within all diameter ranges; S5. Compare the numerical value displayed on the operation interface with the calculation result and correct the model based on the data.

2. The method for calculating the roll change position of a rolling mill according to claim 1, characterized in that: In the step S1, the upper support roll is tangent to the upper working roll, the upper working roll bearing seat is concentrically arranged with the upper working roll, the two side surfaces of the upper working roll bearing seat coincide with the two slide surfaces of the bending roll block, the upper part of the upper working roll bearing seat coincides with the upper surface of the upper plunger of the bending roll block, and the upper plunger of the bending roll block moves up and down and retracts; The lower support roller is tangent to the lower working roller, the lower support roller is concentrically arranged with the lower support roller bearing seat, and the relative position and distance between the stepped pad frame and the lower support roller bearing seat remain unchanged.

3. The method for calculating the roll change position of a rolling mill according to claim 1, characterized in that: In the step S2, the rolling line elevation line simulates the actual rolling line elevation line position; The lower working roll position indicator line is the horizontal tangent line of the top of the upper roll surface of the lower working roll after the lower roll system is lifted by a distance of F; The upper working roll position indicator line is a horizontal line between the upper working roll and the upper plunger of the bending roll block and keeps a constant relative position with the upper working roll, and is used to indicate the actual position of the upper working roll; The upper working roll limit position marking line is set on the rolling mill arch and corresponds to the upper working roll limit position fixed marking line when the upper plunger of the bending roll block has the maximum stroke theoretically calculated; The zero mark of the depression position is a fixed mark arranged on the rolling mill arch and coincides with the horizontal center line of the upper support roller position corresponding to when the theoretically calculated depression position is zero.

4. The method for calculating the roll change down position of a rolling mill according to claim 3, characterized in that: In the lower working roll position indicator line, the lower roll system is composed of a lower working roll, a lower support roll, a lower support roll bearing seat and a stepped pad frame; in the down-pressing position zero position mark line, the theoretically calculated down-pressing position is zero, which means that the electric down-pressing is zero and the hydraulic AGC is zero.

5. The method for calculating the roll change position of a rolling mill according to claim 1, characterized in that: In step S3, in the CAD model, the data relationships are as follows: The minimum distance between the lower working roll and the upper working roll after lifting A1 = the minimum distance between the upper working roll and the rolling line elevation line B1 - the minimum distance between the lower working roll after lifting and the rolling line elevation line C1, that is, A1 = B1-C1; The distance between the upper working roll position and the limit position A2 = the distance between the upper working roll limit position and the rolling line elevation line B2 - the distance between the upper working roll position and the rolling line elevation line C2, that is, A2 = B2-C2; The roller-changing pressing position A3 is the distance between the pressing position zero mark and the horizontal center line of the upper supporting roller. This value is theoretically consistent with the electric pressing value displayed on the operation interface.

6. A method for calculating the roll change depression position of a rolling mill according to claim 5, characterized in that: In step S3, when performing calculation, the upper support roller diameter D1 and the lower support roller diameter D2 are input in the key parameter display area, the initial value A3 of the roller change pressing position is input, and the relevant dimensions of the CAD model maintain the relevant matching relationship and are updated, and the calculation is performed according to the following logic: (1) Take the maximum values ​​of the upper working roll diameter d1 and the lower working roll diameter d2, collect the minimum distance B1 between the upper working roll and the rolling line elevation line in the model, and the minimum distance C1 between the lower working roll after lifting and the rolling line elevation line, and calculate the minimum distance A1 between the lower working roll and the upper working roll after lifting; (2) Take the minimum value of the upper working roll diameter d1 and the lower working roll diameter d2, collect the distance B2 between the upper working roll limit position and the rolling line elevation line and the distance C2 between the upper working roll position and the rolling line elevation line in the model, and calculate the distance A2 between the upper working roll position and the limit position; (3) If ①A1>0, ②A2>0 and ③A1-A2<10 or A2-A1<10 are satisfied at the same time, that is, the roller change pressing position is moderate, then the result is directly displayed, and the A3 value at this time is the roller change pressing position; (4) If the above conditions cannot be met, the A3 value will be automatically corrected and the calculation will continue until the above conditions are met.

7. A method for calculating the roll change depression position of a rolling mill according to claim 6, characterized in that: A3 revised calculation logic is as follows: If A1-A2>10, increase the value of A3 and perform the above calculation until the above requirements are met; If A2-A1>10, reduce the value of A3 and perform the above calculation until the above requirements are met.

8. The method for calculating the roll change down position of a rolling mill according to claim 1, characterized in that: In step S5, the specific operation steps are as follows: (1) Check the actual electric pressure value, AGC hydraulic cylinder extension and roll gap value on the operation interface during the production process, and set the same roll diameter and roll gap parameters as the actual ones in the model. The A3 value is the theoretical roll change pressure position value. At this time, A3 does not perform the above calculation; (2) Compare the sum of the actual electric pressing value and the AGC hydraulic cylinder extension on the operation interface with the difference A3 and correct the zero mark position of the pressing position in the model to realize the verification and manual correction of the pressing position.

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