Method for predicting edge shape of deformation area of rolled piece in variable-thickness rolling process

Abstract

The invention relates to a method for predicting the edge shape of a deformation area of a rolled piece in the variable-thickness rolling process, and belongs to the technical field of plastic forming. The outlet thickness gt before the thickness of the rolled piece is changed; if the outlet thickness is changed, thinning rolling is carried out; if the outlet thickness before the thickness of the rolled piece is changed is lt; if the outlet thickness is changed, thickening rolling is carried out; carrying out area division on a thinning rolling deformation area; geometric parameters of a thinning rolling deformation area are calculated; the width value of the center connecting line of the thinning rolling working rollers is calculated; calculating the width change rate at the center connecting line of the thinning rolling working rollers; calculating an edge curve function of the thinning rolling deformation area to realize edge shape prediction of the thinning rolling deformation area; geometric parameters of a thickening rolling deformation area are calculated; the width value of the center connecting line of the thickening rolling working rollers is calculated; and calculating an edge curve function of the thickening rolling deformation area to realize edge shape prediction of the thickening rolling deformation area. The method is safe, reliable and accurate in calculation.

Description

Technical Field

[0001] The present invention relates to the technical field of plate rolling forming, and in particular to a method for predicting the edge shape of a deformation zone of a rolled piece during a variable thickness rolling process. Background Art

[0002] The steel industry is a key pillar of national industrial development, and plate and strip production equipment and technology represent the industry's production capabilities. Lightweight design, which is crucial for demanding steel products like automobiles and heavy equipment, is a major trend. Reducing steel usage while maintaining strength is a key approach. Differential thickness plate is a key method for lightweighting components in the modern automotive industry, further supporting the nation's "dual carbon" strategy and contributing to lowering energy consumption and carbon emissions in the manufacturing industry.

[0003] Differential thickness plate is a plate and strip material with variable thickness produced by variable thickness rolling technology. Compared with laser-welded plates, it has the characteristics of high strength, good surface quality, and light structure. The use of differential thickness plate is an important means to achieve lightweighting, and it has a trend of being widely used in related fields such as automobiles and construction. Differential thickness plate requires the use of variable thickness rolling technology in the preparation process. The variable thickness rolling process is divided into thinning rolling and thickening rolling. Compared with the ordinary rolling process with a constant thickness setting, the variable thickness rolling technology has significant differences in the metal flow of the rolled piece and the edge shape of the deformation zone. The traditional rolling theory is not applicable, and the accurate calculation of the plate shape and thickness of the rolled piece needs to take into account the changes in the width direction during the rolling process, that is, the influence of the lateral flow of the metal, and the edge shape of the deformation zone. The Chinese invention patent with patent number CN201510917994.8 proposes a variable thickness rolling method for medium and thick plate rolling mills, and proposes to control the thickness of the rolled piece by controlling the thickness of the rolled piece. The invention relates to a method for realizing variable thickness rolling by adjusting the roll gap pressing speed in the vertical direction, but the patent does not involve a method for calculating the edge shape of the deformation zone of variable thickness rolling; the Chinese invention patent with patent number CN201310315225.1 proposes a length control method during variable thickness rolling. The method proposes to use the length measured by the length measuring roller and refer to the set strip profile to adjust the pressing position of the working roller in real time for length control, but the patent does not involve a method for calculating the edge shape of the deformation zone of variable thickness rolling. At present, there is a lack of a calculation method that can characterize the metal flow and edge shape of the rolled piece in the deformation zone. Summary of the Invention

[0004] The present invention proposes a method for predicting the edge shape of the deformation zone of a rolled piece during a variable thickness rolling process, comprising the following steps:

[0005] Step 1: Obtain the size parameters and rolling process parameters of the differential thickness plate;

[0006] Step 2: If the thickness of the rolled piece before thickness change is greater than the thickness after thickness change, it is thinning rolling, and steps 3 to 7 are performed in sequence; if the thickness of the rolled piece before thickness change is less than the thickness after thickness change, it is thickening rolling, and steps 8 to 10 are performed in sequence;

[0007] Step 3: Divide the thinning rolling deformation zone;

[0008] Step 4: Calculate the geometric parameters of the thinning rolling deformation zone;

[0009] Step 5: Calculate the width of the center line of the ironing rolling work rolls;

[0010] Step 6: Calculate the width change rate at the center line of the ironing rolling work rolls;

[0011] Step 7: Calculate the edge curve function of the thinning rolling deformation zone to achieve the edge shape prediction of the thinning rolling deformation zone;

[0012] Step 8: Calculate the geometric parameters of the thickening rolling deformation zone;

[0013] Step 9: Calculate the width of the thickened rolling work roll center line;

[0014] Step 10: Calculate the edge curve function of the thickening rolling deformation zone to predict the edge shape of the thickening rolling deformation zone.

[0015] Further: the product size information of the differential thickness plate: the inlet thickness h0, the outlet thickness before thickness change h 11 , outlet thickness after thickness change h 12 , transition zone length L, width b0;

[0016] Rolling process parameters: working roll radius R, rolling speed v 轧 , working roll pressing speed v 压下 , friction factor f between the workpiece and the roller, and rolled length x1 of the transition zone.

[0017] Furthermore: the geometric parameters of the thinning rolling deformation zone include the thinning rolling deformation zone length l, the reduction amount, the transition zone inclination angle, the dividing boundary and the deformation zone edge curve boundary;

[0018] The calculation process of the thinning rolling deformation zone length l is as follows:

[0019]

[0020] Where: Δh1 is the reduction in the thinning rolling process at the rolled length x1, is the inclination angle of the transition zone,

[0021] In the thinning rolling, the deformation zone is divided into zone i and zone ii. The entry of the rolled piece is selected as the zero point x = 0, and the dividing line L1 between zone i and zone ii is:

[0022]

[0023] That is, 0≤x≤L1 is zone i, and L1<x≤l is zone ii.

[0024] Furthermore, the calculation process of the deformation zone width value b at the center line of the working rolls during the ironing rolling is as follows:

[0025]

[0026] Where: b0 is the outlet thickness of the rolled piece before variable thickness rolling, and f is the friction factor.

[0027] Furthermore, the calculation process of the width change rate b' of the deformation zone at the center line of the working rolls during the ironing rolling is as follows.

[0028]

[0029] Furthermore, the edge curve function during the thinning rolling is:

[0030] i area:

[0031]

[0032] Zone II:

[0033]

[0034] Where: x is the coordinate variable of the deformation zone from the entrance along the rolling direction, and k is the intermediate value for calculating the slope of the curve in zone ii.

[0035] Furthermore: the geometric parameters of the thickening rolling deformation zone include the edge curve boundary, the reduction amount and the length l of the thickening rolling deformation zone during thickening rolling;

[0036] The length l of the thickening rolling deformation zone is:

[0037]

[0038] That is, the range of thickening rolling deformation zone is 0≤x≤l,

[0039] Where: Δh2 is the reduction in the thickening rolling process when the rolled length is x1.

[0040] Furthermore, the calculation process of the width value b of the rolled piece at the center line of the working rolls during the thickening rolling is as follows.

[0041]

[0042] Furthermore: the edge curve during the thickening rolling is:

[0043]

[0044] Where: L2 is the distance between the thickening rolling entrance and the center line of the rolls.

[0045] The purpose of the present invention is to provide a method for predicting the edge shape of the deformation zone of a rolled piece in a variable thickness rolling process. The method obtains the size parameters of the differential thickness plate product and the rolling process parameters, and distinguishes whether it belongs to thinning rolling or thickening rolling according to the thickness before and after the thickness change. For thinning rolling, the rolling deformation zone is divided into two areas, the contact arc length of the deformation zone and the boundary of the deformation zone are calculated, and the width prediction value and the width change rate prediction value are calculated based on the rolled piece parameters. Based on the above, the edge shape curves on both sides of the rolling deformation zone in the thinning rolling process are calculated; for thickening rolling, the contact arc length of the deformation zone and the boundary of the deformation zone are calculated based on the rolled piece and the rolling process parameters, and the width prediction value is calculated based on the rolled piece and the rolling process parameters. Based on the above, the edge shape curves on both sides of the rolling deformation zone in the thickening rolling process are calculated.

[0046] Variable thickness rolling is divided into thinning rolling and thickening rolling according to the different parameters of the rolled product. By calculating the rolling mill parameters, rolled product parameters, and rolling pass process parameters, the edge shape curve of the rolled product deformation zone in the transition zone of the rolled product that changes with the rolled length during rolling is obtained, so that the shape parameters of the variable thickness rolling deformation zone and the metal flow law of the rolled product can be characterized.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] By calculating deformation zone parameters, the present invention obtains a deformation zone edge shape curve that is closer to the actual shape during variable thickness rolling. Taking into account different reduction speeds and rolling mill parameters, the deformation zone edge shape curve of the transition zone of the differential thickness plate during variable thickness rolling is accurately predicted, solving the problem of characterizing deformation zone shape parameters during variable thickness rolling. This invention is safe, reliable, and accurate, and can calculate the real-time edge shape curve of the deformation zone in the transition section of the differential thickness plate in real time online. It can be applied to fields such as real-time display of control systems and digital twins of variable thickness rolling. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The flow chart for calculating the edge shape curve of the deformation zone in the variable thickness rolling process;

[0050] Figure 2 It is a schematic diagram of the transition zone of the variable thickness rolled piece;

[0051] Figure 3 This is a schematic diagram of the deformation zone of the rolled piece during the thinning rolling process;

[0052] Figure 4Schematic diagram of the deformation zone of the rolled piece during the thickening rolling process. DETAILED DESCRIPTION

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 The flow chart for calculating the edge shape curve of the deformation zone in the variable thickness rolling process;

[0055] A method for predicting the edge shape of a deformation zone of a rolled piece during a variable thickness rolling process comprises the following steps:

[0056] Step 1: Obtain the size parameters and rolling process parameters of the differential thickness plate;

[0057] Step 2: If the thickness of the rolled piece before thickness change is greater than the thickness after thickness change, it is thinning rolling, and steps 3 to 7 are performed; if the thickness of the rolled piece before thickness change is less than the thickness after thickness change, it is thickening rolling, and steps 8 to 10 are performed;

[0058] Step 3: Divide the thinning rolling deformation zone;

[0059] Step 4: Calculate the geometric parameters of the thinning rolling deformation zone;

[0060] Step 5: Calculate the width of the center line of the ironing rolling work rolls;

[0061] Step 6: Calculate the width change rate at the center line of the ironing rolling work rolls;

[0062] Step 7: Calculate the edge curve function of the thinning rolling deformation zone to achieve the edge shape prediction of the thinning rolling deformation zone;

[0063] Step 8: Calculate the geometric parameters of the thickening rolling deformation zone;

[0064] Step 9: Calculate the width of the thickened rolling work roll center line;

[0065] Step 10: Calculate the edge curve function of the thickening rolling deformation zone to predict the edge shape of the thickening rolling deformation zone.

[0066] Step 1 and step 2 are executed sequentially, step 3, step 4, step 5, step 6, step 7 are executed sequentially, step 8, step 9, and step 10 are executed sequentially, and step 3 or step 8 is executed after step 2 is executed; step 3 and step 8 are executed in parallel;

[0067] Further: the product size information of the differential thickness plate: the inlet thickness h0, the outlet thickness before thickness change h 11 , outlet thickness after thickness change h 12 , transition zone length L, width b0;

[0068] Rolling process parameters: working roll radius R, rolling speed v 轧 , working roll pressing speed v 压下 , friction factor f between the workpiece and the roller, and rolled length x1 of the transition zone.

[0069] Furthermore: the geometric parameters of the thinning rolling deformation zone include the thinning rolling deformation zone length l, the reduction amount, the transition zone inclination angle, the dividing boundary and the deformation zone edge curve boundary;

[0070] The calculation process of the thinning rolling deformation zone length l is as follows:

[0071]

[0072] Where: Δh1 is the reduction amount during the thinning rolling process when the rolled length is x1, is the inclination angle of the transition zone,

[0073] In the thinning rolling, the deformation zone is divided into zone i and zone ii. The entry of the rolled piece is selected as the zero point x = 0, and the dividing line L1 between zone i and zone ii is:

[0074]

[0075] That is, 0≤x≤L1 is zone i, and L1<x≤l is zone ii.

[0076] Furthermore, the calculation process of the deformation zone width value b at the center line of the working rolls during the ironing rolling is as follows:

[0077]

[0078] Where: b0 is the outlet thickness of the rolled piece before variable thickness rolling, and f is the friction factor.

[0079] Furthermore, the calculation process of the width change rate b' of the deformation zone at the center line of the working rolls during the ironing rolling is as follows.

[0080]

[0081] Furthermore: the edge curve function during the thinning rolling is:

[0082] i area:

[0083]

[0084] Zone II:

[0085]

[0086] Where: x is the coordinate variable of the deformation zone from the entrance along the rolling direction, and k is the intermediate value for calculating the slope of the curve in zone ii.

[0087] Furthermore, the geometric parameters of the thickening rolling deformation zone include the edge curve boundary, the reduction amount and the length l of the thickening rolling deformation zone during thickening rolling.

[0088] The length l of the thickening rolling deformation zone is:

[0089]

[0090] That is, the range of thickening rolling deformation zone is 0≤x≤l,

[0091] Where: Δh2 is the reduction in the thickening rolling process when the rolled length is x1.

[0092] Furthermore, the calculation process of the width value b of the rolled piece at the center line of the working rolls during the thickening rolling is as follows.

[0093]

[0094] Furthermore: the edge curve during the thickening rolling is:

[0095]

[0096] Where: L2 is the distance between the thickening rolling entrance and the center line of the rolls.

[0097] Example 1

[0098] In this embodiment, Figure 2 As shown in the figure, the thickness of the entry is 10mm, the thickness of the exit is 8mm before thickness variation, the thickness of the exit is reduced to 6mm after thickness variation, and the length of the transition zone is 40mm. The method for predicting the edge shape of the deformation zone of the rolled piece in the variable thickness rolling process with a rolled length of the transition zone of 20mm is described. The dimensional data of the rolled plate and strip are shown in Table 1, and the rolling process parameters are shown in Table 2.

[0099] Table 1 Dimensions of plate and strip products in Example 1

[0100]

[0101] Table 2 Variable thickness rolling process parameters

[0102]

[0103] As shown in Tables 1 and 2, the 10 mm thick strip undergoes one variable thickness rolling to obtain a thinning rolling transition section with a thickness reduced from 8 mm to 6 mm and a transition zone length of 40 mm.

[0104] like Figure 4 As shown, the method for predicting and calculating the edge shape of the deformation zone of a rolled piece during a variable thickness rolling process proposed in this embodiment specifically includes the following steps:

[0105] Step 1: Collect the rolled piece dimensions and rolling process parameters of the variable thickness rolling process;

[0106] Step 2: Determine whether the variable thickness rolling is thinning or thickening rolling, and perform different steps:

[0107] In this embodiment, the outlet thickness before thickness changing is 8 mm, and the outlet thickness after thickness changing is reduced to 6 mm. The outlet thickness before thickness changing is greater than the outlet thickness after thickness changing, which is thinning rolling, and steps 3, 4, 5, and 6 are performed;

[0108] Step 3: Calculate the relevant parameters such as the length l of the thinning rolling deformation zone and the boundary of the deformation zone:

[0109]

[0110] like Figure 3 In the thinning rolling process, the deformation zone is divided into zone i and zone ii. The entry point of the rolled piece is selected as zero point x = 0, and the boundary between zone i and zone ii is:

[0111]

[0112] That is, 0≤x≤L1 is zone i, and L1<x≤l is zone ii.

[0113] Step 4: The calculation process of the predicted value b of the width at the center line of the thinning rolling work roll is as follows:

[0114]

[0115] Step 5: The calculation process of the width change rate b' of the deformation zone at the center line of the work rolls during ironing rolling is as follows:

[0116]

[0117] Step 6: Calculate the edge curve function during thinning rolling:

[0118] i area:

[0119]

[0120] Zone II:

[0121]

[0122] The program ends and the edge curve of the deformation zone of the thinning rolled piece in this embodiment is calculated as

[0123]

[0124] Example 2

[0125] This embodiment takes the thickening rolling process with an inlet thickness of 10 mm, an outlet thickness of 6 mm before thickness variation, a thickness of 8 mm after thickness variation, and a transition zone length of 40 mm as an example to illustrate the method for predicting the edge shape of the deformation zone of the rolled piece in the variable thickness rolling process with a transition zone rolled length of 20 mm. The rolled plate and strip dimension data are shown in Table 3, and the rolling process parameters are shown in Table 4.

[0126] Table 3 Dimensions of plate and strip products in Example 2

[0127]

[0128] Table 2 Variable thickness rolling process parameters

[0129]

[0130] As shown in Tables 3 and 4, the 10 mm thick strip undergoes one variable thickness rolling to obtain a thinning rolling transition section with a thickness reduced from 6 mm to 8 mm and a transition zone length of 40 mm.

[0131] like Figure 4 As shown, the method for predicting the edge shape of the deformation zone of a rolled piece during a variable thickness rolling process proposed in this embodiment specifically includes the following steps:

[0132] Step 1: Collect the rolled piece dimensions and rolling process parameters of the variable thickness rolling process;

[0133] Step 2: Determine whether the variable thickness rolling is thinning or thickening rolling, and perform different steps:

[0134] In this embodiment, the outlet thickness before thickness changing is 6 mm, and the outlet thickness after thickness changing is increased to 8 mm. The outlet thickness before thickness changing is less than the outlet thickness after thickness changing, which is thickening rolling, and steps 7, 8, and 9 are performed;

[0135] Further, such as Figure 4 As shown, calculate the relevant parameters such as the length l of the thickening rolling deformation zone and the boundary of the deformation zone:

[0136]

[0137] That is, the range of the thickening rolling deformation zone is 0≤x≤l.

[0138] Furthermore, in step 8, the calculation process of the workpiece width value b at the center line of the work rolls during thickening rolling is as follows:

[0139]

[0140] Where b0 is the exit thickness of the rolled piece before variable thickness rolling, and f is the friction coefficient.

[0141] Furthermore, in step 9, the edge curve during thickening rolling is:

[0142]

[0143] The program ends and the edge curve of the deformation zone of the thinning rolled piece in this embodiment is calculated as

[0144] f(x)=0.00016x 3 -0.0045x 2 +150 0≤x≤16.15

[0145] The variable thickness rolling described in the present invention is a rolling process for producing plates of different thicknesses by utilizing the online adjustment function of the roll lifting and pressing down controlled by the roll system pressing down device during the rolling process.

[0146] Matters not fully described in the present invention are known in the art.

[0147] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for predicting the edge shape of the deformation zone of a rolled piece during a variable thickness rolling process, characterized in that: The following steps are involved: Step 1: Obtain the size parameters and rolling process parameters of the differential thickness plate; Step 2: If the thickness of the rolled piece before thickness change is greater than the thickness after thickness change, it is thinning rolling, and steps 3 to 7 are performed in sequence; if the thickness of the rolled piece before thickness change is less than the thickness after thickness change, it is thickening rolling, and steps 8 to 10 are performed in sequence; Step 3: Divide the thinning rolling deformation zone; Step 4: Calculate the geometric parameters of the thinning rolling deformation zone; Step 5: Calculate the width of the center line of the ironing rolling work rolls; Step 6: Calculate the width change rate at the center line of the ironing rolling work rolls; Step 7: Calculate the edge curve function of the thinning rolling deformation zone to achieve the edge shape prediction of the thinning rolling deformation zone; Step 8: Calculate the geometric parameters of the thickening rolling deformation zone; Step 9: Calculate the width of the thickened rolling work roll center line; Step 10: Calculate the edge curve function of the thickening rolling deformation zone to predict the edge shape of the thickening rolling deformation zone.

2. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The product size information of the differential thickness plate: entrance thickness h0, exit thickness before thickness change h 11 , outlet thickness after thickness change h 12 , transition zone length L, width b0; Rolling process parameters: working roll radius R, rolling speed v 轧 , working roll pressing speed v 压下 , friction factor f between the workpiece and the roller, and rolled length x1 of the transition zone.

3. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The geometric parameters of the thinning rolling deformation zone include the thinning rolling deformation zone length l, the reduction amount, the transition zone inclination angle, the dividing boundary and the deformation zone edge curve boundary; The calculation process of the thinning rolling deformation zone length l is as follows: Where: Δh1 is the reduction in the thinning rolling process at the rolled length x1, is the inclination angle of the transition zone, In the ironing rolling process, the deformation zone is divided into zone i and zone ii. The entry point of the rolled piece is selected as zero point x = 0, and the dividing line L1 between zone i and zone ii is: That is, 0≤x≤L1 is zone i, and L1<x≤l is zone ii.

4. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The calculation process of the deformation zone width value b at the center line of the work rolls during the ironing rolling is as follows: Where: b0 is the outlet thickness of the rolled piece before variable thickness rolling, and f is the friction factor.

5. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The calculation process of the width change rate b' of the deformation zone at the center line of the working rolls during the ironing rolling is as follows.

6. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The edge curve function during the thinning rolling is: i area: Zone II: Where: x is the coordinate variable of the deformation zone from the entrance along the rolling direction, and k is the intermediate value for calculating the slope of the curve in zone ii.

7. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The geometric parameters of the thickening rolling deformation zone include the edge curve boundary, the reduction amount and the length l of the thickening rolling deformation zone during thickening rolling; The length l of the thickening rolling deformation zone is: That is, the range of thickening rolling deformation zone is 0≤x≤l, Where: Δh2 is the reduction in the thickening rolling process when the rolled length is x1.

8. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The calculation process of the width value b of the rolled piece at the center line of the working rolls during the thickening rolling is as follows.

9. The method for predicting edge shape of deformation zone of rolled piece during variable thickness rolling process according to claim 1, characterized in that: The edge curve during thickening rolling is: Where: L2 is the distance between the thickening rolling entrance and the center line of the rolls.

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