A method of rolling for producing a differential thickness plate by a hydraulic tension cold warm rolling mill

Abstract

A rolling method for preparing a differential thick plate by a hydraulic tension cold-temperature rolling mill belongs to the technical field of rolling and comprises the following steps: 1) setting the rolling speed, roll gap and tension of each zone; 2) if warm rolling, the roll is heated in advance, and the roll gap is reset to zero; if cold rolling, the roll does not need to be heated; 3) feeding: the roll gap is opened, the clamp clamps the rolled piece, drives the rolled piece to pass through the roll gap, and automatically stops at the limit position of the tension cylinder; 4) clamping and tensioning; 5) if warm rolling, the rolled piece is heated online to the set temperature; if cold rolling, the rolled piece does not need to be heated; 6) first-pass variable-thickness rolling; 7) the rolled piece returns to the original position; 8) second-pass variable-thickness rolling; and 9) unloading. The method can realize two-pass variable-thickness rolling of a single plate by a hydraulic tension cold-temperature rolling mill, accurately identify the inflection point of the transition zone, reduce the influence of the position deviation caused by the response time of the rolling mill on the rolling of the differential thick plate, ensure the size of the rolled piece, and improve the shape problem of the differential thick plate with large reduction in one pass.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rolling technology, and particularly relates to a rolling method for preparing a differential thick plate by using a hydraulic tension cold-temperature rolling mill. BACKGROUND

[0002] The differential thick plate is used in the fields of high-end equipment manufacturing and automobile manufacturing, and has the advantages of weight reduction and consumption reduction, energy saving and material reduction, process reduction, and flexible size design. At present, the differential thick plate rolling technology is to use the longitudinal variable thickness rolling technology to roll and form on a coiling type cold rolling mill. However, for some special thick specification (≥4mm) differential thick plate products, the raw materials cannot be provided in the form of a coil, and can only be rolled in the form of a plate, and thus cannot be prepared on the coiling type cold rolling mill. The hydraulic tension cold-temperature rolling mill is provided with a hydraulic tension device at the inlet and outlet of the rolling mill, and can realize the cold rolling and warm rolling with tension by using the hydraulic clamp to hold the metal plate. On this basis, the variable thickness rolling can be performed to realize the preparation of the differential thick plate with special requirements.

[0003] The hydraulic tension cold-temperature rolling mill with the function of preparing the differential thick plate can prepare the differential thick plate which needs to be heated, such as the magnesium alloy differential thick plate. The raw material needs to be heated to about 220-350℃ before the differential thick plate is rolled, and the roller needs to be heated to about 100-200℃. The ordinary cold rolling mill does not have this function.

[0004] Meanwhile, the hydraulic tension cold-temperature rolling mill with the function of preparing the differential thick plate can also provide the sample trial production service for the production rolling mill (the coiling type cold rolling mill). A few samples are cut from the raw material coil, and the differential thick plate trial production is performed on the hydraulic tension cold-temperature rolling mill to complete the single pass or multi-pass variable thickness rolling process exploration, which can greatly save the time for the trial production on the production rolling mill and avoid the waste of the raw material.

[0005] In the prior art, the disclosed differential thickness plate rolling technical solutions all adopt coiling type cold rolling mills, and are used for variable thickness cold rolling of coiled metal strips, and cannot realize variable thickness cold rolling of single piece metal plates, nor can they realize variable thickness warm rolling of single piece metal plates. The patent CN200910012399.4 (Method and system for controlling thickness in periodic variable thickness strip rolling process), the patent CN200910012398 (Periodic longitudinal variable thickness strip, longitudinal variable thickness plate and preparation method thereof), the patent CN201310315449.2 (Two-pass rolling method for variable thickness strip rolling), the patent CN201611100172.1 (Rolling method of single-sided periodic variable thickness plate strip), the patent CN201410828752.7 (Cold rolling variable thickness plate rolling method), the patent CN201710014476.4 (Rolling method of cold rolling variable thickness plate), CN201910093235.2 (Variable thickness automatic rolling control method of cold continuous rolling mill), and the patent CN20211101790.9 (Manufacturing method of stainless steel differential thickness plate related products) all belong to coiling type cold rolling differential thickness plate rolling process, the tension is controlled by a coiling motor, the tension fluctuates greatly during variable thickness rolling, and the response speed is slow; the position detection is calculated by lengthening roller speed accumulation, the accumulated error is large, during the second pass variable thickness rolling, the shape of the first pass variable thickness needs to be accurately identified by an identification instrument, the roll gap control point offset caused by starting, speed-up and speed-down cannot be effectively eliminated, the offset is amplified by accumulation, and the product is unqualified. This kind of method is not easy to realize two-pass variable thickness rolling.

[0006] The patent CN20151024606.6 (Rolling device of continuous differential thickness plate) drives the rolling roller to move along the guide groove of the guide plate by the sliding block, so that the profile shape of the differential thickness plate finally rolled is consistent with the profile of the sliding surface of the guide groove of the guide plate, and different specifications of the differential thickness plate need to replace the guide plate. The patent CN20171062725.2 (Device for producing transverse variable thickness special-shaped plate and transverse variable thickness plate strip and rolling method thereof) adopts preforming rollers, thinning rollers and flattening rollers, and realizes transverse differential thickness plate rolling by designing different roller shapes. The patent CN20191013269.2 (Single-stand continuous preparation multi-stage differential thickness plate rolling roller, double-roller rolling mill and process) designs different radii along the circumference of the rolling roller, and different differential thickness plates need to replace different rolling rollers. The rolling rollers adopted in the above patents are all special-shaped rollers, and one kind of differential thickness plate product corresponds to one kind of rolling roller.

[0007] Patent CN20171124792.8 (a kind of clad composite metal differential thick plate pulse current rolling process) utilizes pulse current to realize the improvement of composite strip interface welding quality and the comprehensive improvement of mechanical properties of composite strip. Patent CN20181016011.5 (a rolling preparation method of high-performance asymmetric two-stage differential thick plate), an oil is coated on one surface of two aluminum alloy plate strips with the same size, then the aluminum alloy plate strips are stacked and the edges are spot welded, and the welded aluminum alloy composite plate strip is subjected to variable thickness rolling. The above-mentioned patents focus on the raw material preparation technology before variable thickness rolling, and do not describe the specific method of variable thickness rolling.

[0008] In the existing technology, only plate materials can be used as raw materials, how to perform variable thickness rolling to prepare differential thick plates with a differential thickness ratio (the ratio of the minimum thickness to the maximum thickness of the differential thick plate) less than 1:2.0, there is no practical and feasible solution. Therefore, it is necessary to propose a method for preparing differential thick plates by a hydraulic cold temperature rolling mill, which can prepare differential thick plates that cannot be rolled into coils, and can also explore single-pass or multi-pass variable thickness rolling process for existing production rolling mills. SUMMARY

[0009] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present application is to provide a rolling method for preparing differential thick plates by a hydraulic tension cold temperature rolling mill, which can be used to prepare differential thick plates with a differential thickness ratio less than 1:2.0. Taking right rolling as an example, as shown in FIG. 1, the method comprises the following steps: Figure 1

[0010] (1) Rolling parameter setting: according to the target size of the differential thick plate and the set reduction amount of each pass, the profile size of the rolled piece after the first pass and the required raw material plate length are calculated, the rolling speed, roll gap and tension of each zone are set, and the roll gap action strategy during each pass rolling is set;

[0011] (2) Roll heating: if warm rolling, the roll is heated to the required temperature in advance, and the roll gap is reset to zero to eliminate the thermal expansion of the roll; if cold rolling, the roll does not need to be heated;

[0012] (3) Right side feeding: open the roll gap, the right clamp clamps the right end of the rolled piece, the right tension cylinder moves to the left, drives the rolled piece to pass through the roll gap, and automatically stops when the right tension cylinder moves to the left limit position, at this time the rolled piece is on the left side of the rolling mill;

[0013] (4) Left clamping and tension building: the left clamp clamps the left end of the rolled piece, the roll gap is closed to the set value, and the left tension and the right tension are built according to the tension setting value;

[0014] (5) Rolled piece heating: if the material needs to be warm rolled, the rolled piece is heated to the set temperature by using an online heating device; if cold rolling, the rolled piece does not need to be heated;

[0015] ​(6) First pass of variable thickness rolling to the right: Roll to the right according to the first pass of variable thickness rolling procedure, with the exit length of the rolled piece (measured by the displacement sensor built into the right tension cylinder) as the reference, and automatically control the roll gap, speed and tension;

[0016] (7) Return the rolled piece to its original position: If the rolled piece needs to undergo a second pass of variable thickness rolling, the roll gap is opened, and the tension cylinders on both sides drive the rolled piece to move synchronously to the left. The right tension cylinder automatically stops when it reaches its left limit position. At this time, the rolled piece is on the left side of the mill, and the right tension cylinder coincides with the position after the material is loaded in step (3). If the rolled piece does not need to undergo a second pass of variable thickness rolling, skip directly to step (9).

[0017] (8) Second pass variable thickness rolling to the right: The roll gap is closed, tension is established, and rolling is performed to the right according to the second pass variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the entry length of the workpiece (measured by the displacement sensor inside the left tension cylinder).

[0018] (9) Unloading: Release the tension, open the roll gap, loosen the jaws on both sides, retract the tension cylinders on both sides, and take out the differential thickness plate rolled piece.

[0019] Taking leftward rolling as an example, step (3) selects left-side loading, step (4) clamps and tensions the right side, step (6) is the first pass of leftward variable thickness rolling, the exit length is the length measured by the displacement sensor built into the left tension cylinder, step (7) the tension devices on both sides drive the rolled piece to move synchronously to the right, the position of the left tension cylinder coincides with the position after loading in step (3), and step (8) is the second pass of leftward variable thickness rolling, the inlet length is the length measured by the displacement sensor built into the right tension cylinder.

[0020] In steps (6) and (8), the starting positions of the right tension cylinder coincide during the two rolling processes, so that the positional offset caused by the mill response time is consistent during the two rolling processes, effectively reducing the error caused by positional offset during the rolling process.

[0021] In step (1), the target size of the differential thickness plate includes the nominal length and nominal thickness of n equal thickness zones, and the nominal length and curve type of m transition zones. The origin of the mathematical model of the transition curve is the point connecting the thin zone and the transition zone. The outline size of the rolled piece after the first pass and the required length of the raw material plate are calculated as follows:

[0022] The nominal length of the i-th equal-thickness zone in the first pass:

[0023]

[0024] The nominal length of the j-th transition zone in the first pass:

[0025]

[0026] The length of the raw material plate required for the i-th equal thickness zone:

[0027]

[0028] The length of the raw material plate required for the j-th transition zone:

[0029]

[0030] The total length L of the raw material plate required for the differential thickness plate is:

[0031]

[0032] Where i = 1, 2, ..., n;

[0033] j = 1, 2, ..., m;

[0034] h (2,i) Let be the nominal thickness of the i-th equal thickness zone of the differential thickness plate, in mm;

[0035] l (2,i) Let be the nominal length of the i-th equal-thickness zone of the differential-thickness plate, in mm;

[0036] Let J be the minimum thickness of the j-th transition zone of the differential thickness plate, in mm;

[0037] T (2,j) Let J be the nominal length of the j-th transition zone of the differential thickness plate, in mm;

[0038] h (1,i) The nominal thickness of the i-th uniform thickness zone in the first pass, in mm;

[0039] l (1,i) Let be the nominal length of the i-th equal-thickness zone in the first pass, in mm;

[0040] The minimum thickness of the j-th transition zone in the first pass, in mm;

[0041] T (1,j) The nominal length of the j-th transition zone in the first pass, in mm;

[0042] H represents the thickness of the raw material plate, in mm;

[0043] l (0,i) Let be the length of the raw material plate required for the i-th equal thickness zone of the differential thickness plate, in mm;

[0044] T (0,j) Let be the length of the raw material plate required for the j-th transition zone of the differential thickness plate, in mm;

[0045] f (2,j) (x) is the mathematical model expression for the j-th transition zone of the differential thickness plate;

[0046] f (1,j) (x) is the mathematical model expression for the j-th transition zone in the first pass;

[0047] l1 and l2 represent the reserved lengths of the sheet metal to be clamped by the left and right clamps, in mm.

[0048] In step (1), the reduction amount in each cold rolling pass satisfies the following: The reduction in each pass of warm rolling must meet the following requirements: The reduction amount in each pass of warm rolling is related to the heating temperature; the higher the heating temperature, the greater the allowable reduction amount.

[0049] In step (2), the rolling temperature varies with the workpiece heating temperature, and the rolling temperature can be room temperature to 300℃.

[0050] In step (5), during the heating process of the rolled piece, the required heating temperature varies depending on the material of the rolled piece. The heating temperature of the rolled piece can be room temperature to 800℃.

[0051] In the above method, taking leftward rolling as an example, step (3) selects left-side feeding, step (4) clamps and tensions the right side, step (6) is the first pass of leftward variable thickness rolling, the exit length is the length measured by the displacement sensor built into the left tension cylinder, step (7) the tension devices on both sides drive the rolled piece to move synchronously to the right, the position of the left tension cylinder coincides with the position after feeding in step (3), and step (8) is the second pass of leftward variable thickness rolling, the inlet length is the length measured by the displacement sensor built into the right tension cylinder.

[0052] The beneficial effects achieved by this invention are:

[0053] (1) This invention can be used on hydraulic tension cold and warm rolling mills without modifying existing hydraulic cold and warm rolling mills, only requiring modification of existing programs;

[0054] (2) When only sheet metal can be used as raw material, single-pass or multi-pass tension variable thickness cold rolling and warm rolling can be achieved;

[0055] (3) The first pass of variable thickness rolling is based on the exit length, and the roll gap, speed and tension are automatically controlled. The second pass of variable thickness rolling is based on the inlet length, and the roll gap, speed and tension are automatically controlled. There is no need to change the length setting value in the second pass rolling procedure, which is the same as the first pass. It can accurately identify the inflection point of the transition zone and has high accuracy in identifying the outline dimensions of the rolled piece after the first pass. It reduces the influence of the position offset caused by the mill response time on the differential thickness plate rolling, and can produce differential thickness plates with a differential thickness ratio <1:2.0, and ensure good plate shape.

[0056] (4) The tension of this invention is controlled by a hydraulic cylinder, with small tension fluctuation and fast response speed; the position detection is directly measured by the displacement sensor built into the tension hydraulic cylinder, with high accuracy and no cumulative error. There is no need to add a first-pass variable thickness shape recognition instrument. In addition, considering the elimination method of roll gap control point offset caused by starting, speeding up and speeding down, it is easy to realize two-pass variable thickness rolling.

[0057] (5) This invention uses ordinary rolls with equal circumference and flexibly controls the roll gap change according to the size requirements of the differential thickness plate to perform variable thickness rolling without changing the rolls, which is different from the principle of variable thickness rolling with special-shaped rolls. Attached Figure Description

[0058] Figure 1 This is a flowchart of the differential thickness plate rolling method of the present invention;

[0059] Figure 2 This is a schematic diagram of the structure of a hydraulic tension cold and warm rolling mill used in the differential thickness plate rolling method of the present invention;

[0060] Among them, 1-left tension cylinder, 2-left tension gauge, 3-left clamp, 4-support roll, 5-work roll, 6-rolling mill stand, 7-right clamp, 8-right tension gauge, 9-right tension cylinder, 10-left tension cylinder built-in displacement sensor, 11-left temperature measuring instrument, 12-right temperature measuring instrument, 13-rolled workpiece, 14-right tension cylinder built-in displacement sensor, 15-left power adjustment device, 16-left transformer, 17-cable, 18-right power adjustment device, 19-right transformer;

[0061] Figure 3 This is a schematic diagram showing the dimensions of the second pass of rightward differential thickness plate rolling in Example 1;

[0062] Figure 4 This is a schematic diagram showing the dimensions of the first pass of rightward differential thickness plate rolling in Example 1;

[0063] Figure 5 This is a schematic diagram showing the dimensions of the raw material plate required for the differential thickness plate in Example 1;

[0064] Figure 6 This is a schematic diagram of the mathematical model expression for the transition curve of the thick plate in Example 1;

[0065] Figure 7 This is a schematic diagram showing the dimensions of the second pass of left-side differential thick plate rolling in Example 2;

[0066] Figure 8 This is a graph showing the nominal thickness versus actual thickness of the differential thickness plate in Example 2.

[0067] Figure 9 This is a front view of the differential thickness plate rolled product in Example 2;

[0068] Figure 10This is a side view of the differential thickness plate rolled product in Example 2;

[0069] Figure 11 This is a schematic diagram showing the dimensions of a single-pass temperature differential rolling thick plate in Example 3;

[0070] Figure 12 This is a diagram showing the edge defects of the AZ31B magnesium alloy differential thickness plate in Example 3.

[0071] Figure 13 This is a side view of the AZ31B magnesium alloy differential thickness plate in Example 3. Detailed Implementation

[0072] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0073] A schematic diagram of the rolling device used in the hydraulic tension cold-warm rolling mill for differential thickness plate rolling is shown below. Figure 2 As shown, the rolling device is divided into a rolling section and a heating section. The rolling section is provided from left to right with the following components: left tension cylinder with built-in displacement sensor 10, left tension cylinder 1, left tension gauge 2, left clamp 3, left temperature measuring instrument 11, support roll 4, rolling mill stand 6, work roll 5, right temperature measuring instrument 12, rolled piece 13, right clamp 7, right tension gauge 8, right tension cylinder 9, and right tension cylinder with built-in displacement sensor 14. The heating section is provided from left to right with the following components: left power adjustment device 15, left transformer 16, cable 17, right power adjustment device 18, and right transformer 19.

[0074] Example 1

[0075] A method for preparing differential thickness plates using a hydraulic tension cold and warm rolling mill, wherein a certain sample requires the following dimensions after rolling: Figure 3 As shown, the differential thickness plate includes 3 equal thickness zones and 4 transition zones. The transition curve is a linear dominant type. The origin of the mathematical model of the transition curve is the point connecting the thin zone and the transition zone. The thickness of the thick zone is 4.2 mm and the length is 80 mm. The thickness of the thin zone is 2 mm and the length is 80 mm. The length of the transition zone is 220 mm. The thickness of the raw material plate is 5 mm and the width is 80 mm. The diameter of the work roll is 150 mm. The rolling speed is 0.03 m / s. The tension is 8 kN. The single-sided zero-adjustment rolling force of the rolling mill is 200 kN. The material of the raw material plate is a certain aluminum alloy. The rolling method is two-pass variable thickness cold rolling.

[0076] (1) Rolling parameter setting: Based on the target size of the differential thickness plate and the nominal thickness h of each equal thickness zone in the first pass. (1,i) Calculate the outline dimensions of the rolled piece after the first rolling pass and the required length of the raw material plate, such as... Figure 4 and Figure 5 As shown, the rolling speed, roll gap, and tension of each zone are set, as well as the roll gap action strategy during each rolling pass;

[0077] Set the nominal thickness of each equal-thickness zone in the first pass:

[0078] h (1,1) =3mm

[0079] h (1,2) =4.6mm

[0080] h (1,3) =3mm

[0081] Nominal length of each equal-thickness zone in the first pass:

[0082]

[0083]

[0084]

[0085] Since the four transition zones have the same size, the mathematical model expression for calculating the transition curve of the differential thickness plate is as follows:

[0086]

[0087] The transition curve is a linear curve, with the origin at the point connecting the thin region and the transition region; that is, it is a linear function, y = kx, as shown below. Figure 6 As shown, the thick section is 4.2mm, the thin section is 2mm, the transition section length is 220mm, and the coordinates of the transition section endpoint are (220, 1.1). The curve expression for the transition section is: y = x / 200. The curve expressions for each transition section in the first pass are obtained in the same way.

[0088] The mathematical model expressions for each transition curve in the first pass are:

[0089]

[0090] Nominal lengths of each transition zone in the first pass:

[0091]

[0092] T (1,1) =T (1,2) =T (1,3) =T (1,4) =179.47mm

[0093] The required length of raw material plate for each equal thickness zone:

[0094]

[0095]

[0096]

[0097] The required length of raw material plates for each transition zone:

[0098]

[0099] The left and right clamps hold the reserved length of the sheet metal: l1 = l2 = 150mm

[0100] The total length of raw material plates required for differential thickness plates is:

[0101] (2) Right side loading: Open the roll gap, the right clamp clamps the right end of the workpiece, the right tension cylinder moves to the left, driving the workpiece through the roll gap, and the right tension cylinder automatically stops after moving to its left limit position. At this time, the workpiece is on the left side of the mill.

[0102] (3) Clamping and tensioning on the left side: The left clamp clamps the left end of the workpiece, the roll gap closes to the set value, and the tension on the left and right sides is established according to the tension set value;

[0103] (4) First pass of variable thickness rolling to the right: Roll to the right according to the first pass of variable thickness rolling procedure. Based on the exit length of the workpiece (measured by the displacement sensor inside the right tension cylinder), automatically control the roll gap, speed and tension. The first pass is rolled down to 4.6-3mm. The exit thickness of the thick zone is 4.6mm and the length is 73.04mm. The exit thickness of the thin zone is 3mm and the length is 53.33mm. The length of the transition zone is 179.47mm. The first pass of rolling ends.

[0104] (5) Return the rolled piece to its original position: Open the roll gap, and the tension cylinders on both sides drive the rolled piece to move synchronously to the left. The right tension cylinder stops automatically when it reaches its left limit position. At this time, the rolled piece is on the left side of the rolling mill. The position of the right tension cylinder coincides with the position after the material is loaded in step (2), so that the position offset caused by the rolling mill response time is consistent during the two rolling processes, effectively reducing the error caused by position offset during the rolling process.

[0105] (6) Second pass to right-side variable thickness rolling: The roll gap is closed, tension is established, and rolling is performed to the right according to the second pass variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the entry length of the workpiece (measured by the displacement sensor inside the left tension cylinder). The second pass is pressed down to 4.2-2mm. The thickness of the thick zone exit is 4.2mm and the length is 80mm. The thickness of the thin zone exit is 2mm and the length is 80mm. The length of the transition zone is 220mm.

[0106] (7) Unloading: Release the tension, open the roll gap, loosen the jaws on both sides, retract the tension cylinders on both sides, and remove the differential thickness plate. According to the preparation method of Example 1, a differential thickness plate with the required differential thickness ratio <1:2.0 and good plate shape is produced.

[0107] Example 2

[0108] A method for preparing differential thickness plates using a hydraulic tension cold and warm rolling mill, wherein a certain sample requires the following dimensions after rolling: Figure 7 As shown, the differential thickness plate includes 3 equal thickness zones and 2 transition zones. The transition curve is a linear dominant type. The origin of the mathematical model of the transition curve is the point connecting the thin zone and the transition zone. The thickness of the thick zone is 4.2 mm and the length is 11 mm. The thickness of the thin zone is 2 mm and the length is 50 mm. The length of the transition zone is 500 mm. The thickness of the raw material plate is 5 mm and the width is 80 mm. The diameter of the work roll is 150 mm. The rolling speed is 0.03 m / s and the tension is 8 kN. The single-sided zero-adjustment rolling force of the rolling mill is 200 kN. The material of the raw material plate is a certain aluminum alloy. The rolling method is two-pass variable thickness cold rolling.

[0109] (1) Rolling parameter setting: Based on the target size of the differential thickness plate and the nominal thickness h of each equal thickness zone in the first pass. (1,i) Calculate the outline dimensions of the rolled piece after the first pass and the required length of the raw material plate, set the rolling speed, roll gap and tension for each zone, and the roll gap action strategy for each pass.

[0110] Set the nominal thickness of each equal-thickness zone in the first pass:

[0111] h (1,1) =3mm

[0112] h (1,2) =4.6mm

[0113] h (1,3) =3mm

[0114] Nominal length of each equal-thickness zone in the first pass:

[0115]

[0116]

[0117]

[0118] Since the two transition zones have the same size, the mathematical model expression for calculating the transition curve of the differential thickness plate is as follows:

[0119]

[0120] The mathematical model expressions for each transition curve in the first pass are:

[0121]

[0122] Nominal lengths of each transition zone in the first pass:

[0123]

[0124] T (1,1) =T(1,2) =407.89mm

[0125] The required length of raw material plate for each equal thickness zone:

[0126]

[0127]

[0128]

[0129] The required length of raw material plates for each transition zone:

[0130]

[0131] The left and right clamps hold the reserved length of the sheet metal: l1 = l2 = 150mm

[0132] The total length of raw material plates required for differential thickness plates is:

[0133] (2) Left side loading: Open the roll gap, the left clamp clamps the left end of the workpiece, the left tension cylinder moves to the right, driving the workpiece through the roll gap, and the left tension cylinder automatically stops after moving to its right limit position. At this time, the workpiece is on the right side of the mill.

[0134] (3) Clamping and tensioning on the right side: The right clamp clamps the right end of the workpiece, the roll gap closes to the set value, and the tension on the left and right sides is established according to the tension set value;

[0135] (4) First pass left-side variable thickness rolling: Roll to the left according to the first pass variable thickness rolling procedure. Based on the exit length of the workpiece (measured by the displacement sensor inside the left tension cylinder), automatically control the roll gap, speed and tension. The first pass is pressed down to 4.6-3mm. The exit thickness of the thick zone is 4.6mm and the length is 10.04mm. The exit thickness of the thin zone is 3mm and the length is 33.33mm. The length of the transition zone is 407.89mm. The first pass rolling ends.

[0136] (5) Return the rolled piece to its original position: Open the roll gap, and the tension cylinders on both sides drive the rolled piece to move synchronously to the right. The left tension cylinder stops automatically when it reaches its right limit position. At this time, the rolled piece is on the right side of the rolling mill. The position of the left tension cylinder coincides with that of the material loading in step (2), so that the position offset caused by the rolling mill response time is consistent during the two rolling processes, effectively reducing the error caused by position offset during the rolling process.

[0137] (6) Second pass left-to-left variable thickness rolling: The roll gap is closed, tension is established, and rolling is performed to the left according to the second pass variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the entry length of the workpiece (measured by the displacement sensor inside the right tension cylinder). The second pass is pressed down to 4.2-2mm. The thickness of the thick zone exit is 4.2mm and the length is 80mm. The thickness of the thin zone exit is 2mm and the length is 50mm. The length of the transition zone is 500mm.

[0138] (7) Unloading: Release the tension, open the roll gap, loosen the jaws on both sides, retract the tension cylinders on both sides, and remove the differential thickness plate. For example... Figures 8-10 As shown, according to the preparation method of Example 2, a thickness plate with the required thickness difference ratio <1:2.0 was produced, and the plate shape was good.

[0139] Example 3

[0140] A method for preparing differential thickness plates using a hydraulic tension cold and warm rolling mill, wherein a certain sample requires the following dimensions after rolling: Figure 11 As shown, the differential thickness plate includes 3 equal thickness zones and 2 transition zones. The transition curve is a linear dominant type. The origin of the mathematical model of the transition curve is the point connecting the thin zone and the transition zone. The thickness of the thick zone is 2.5 mm and the length is 100 mm. The thickness of the thin zone is 1.5 mm and the length is 200 mm. The length of the transition zone is 100 mm. The thickness of the raw material plate is 3 mm and the width is 80 mm. The diameter of the work roll is 150 mm. The rolling speed is 0.05 m / s. The tension is 2 kN. The single-sided zero-adjustment rolling force of the mill is 80 kN. The material of the raw material plate is AZ31B magnesium alloy. The rolling method is one-pass variable thickness warm rolling. The rolls are heated to 150°C.

[0141] (1) Rolling parameter setting: Based on the target size of the differential thickness plate, calculate the required length of the raw material plate, set the rolling speed, roll gap and tension of each zone, and the roll gap action strategy during rolling;

[0142] The required length of raw material plate for each equal thickness zone:

[0143]

[0144]

[0145]

[0146] Since the two transition zones have the same size, the mathematical model expression for calculating the transition curve of the differential thickness plate is as follows:

[0147]

[0148] Because AZ31B magnesium alloy is produced using a single-stage variable thickness warm rolling process, f here... (1,j)(x) is the mathematical model expression for the j-th transition curve of the differential thickness plate.

[0149] The required length of raw material plates for each transition zone:

[0150]

[0151] The left and right clamps hold the reserved length of the sheet metal: l1 = l2 = 150mm

[0152] The total length of raw material plates required for differential thickness plates is:

[0153] (2) Roll heating: The AZ31B magnesium alloy differential thickness plate is rolled by one-pass variable thickness warm rolling. The rolls are preheated to 150°C and the roll gap is reset to zero to eliminate the thermal expansion of the rolls.

[0154] (3) Right side loading: Open the roll gap, clamp the right end of the workpiece with the right clamp, move the right tension cylinder to the left, and drive the workpiece through the roll gap. The right tension cylinder will automatically stop after moving to its left limit position. At this time, the workpiece is on the left side of the mill.

[0155] (4) Clamping and tensioning on the left side: The left clamp clamps the left end of the workpiece, the roll gap closes to the set value, and the tension on the left and right sides is established according to the tension set value;

[0156] (5) Heating of the rolled piece: The rolled piece is heated to 290°C using an online heating device, and then heating is stopped;

[0157] (6) One-pass right-side variable thickness rolling: Roll to the right according to the variable thickness rolling procedure. Based on the exit length of the workpiece (measured by the displacement sensor inside the right tension cylinder), automatically control the roll gap, speed and tension to reduce to 2.5~1.5mm. The exit thickness of the thick zone is 2.5mm and the length is 100mm. The exit thickness of the thin zone is 1.5mm and the length is 200mm. The length of the transition zone is 100mm.

[0158] (7) Unloading: Release the tension, open the roll gap, loosen the jaws on both sides, retract the tension cylinders on both sides, and remove the differential thickness plate. For example... Figure 12 and Figure 13 As shown, according to the preparation method of Example 3, a differential thickness plate with the required dimensions and good plate shape was produced, and the edge cracking problem of the AZ31B magnesium alloy differential thickness plate was greatly improved.

Claims

1. A rolling method for preparing differential thickness plates using a hydraulic tension cold and warm rolling mill, characterized in that, This is a unidirectional rolling process, which includes the following steps: (1) Rolling parameter setting: Based on the target size of the differential thickness plate and the set reduction amount of each pass, calculate the outline size of the rolled piece after the first pass and the required length of the raw material plate, set the rolling speed, roll gap and tension of each zone, and the roll gap action strategy during each pass rolling. The reduction amount in each cold rolling pass must meet the following requirements: ; The reduction in each pass of warm rolling must meet the following requirements: The reduction amount in each pass of warm rolling is related to the heating temperature; the higher the heating temperature, the greater the allowable reduction amount. The target dimensions of the differential thickness plate include the nominal lengths and thicknesses of n equal-thickness zones, and the nominal lengths and curve types of m transition zones. The origin of the transition curve mathematical model is the point connecting the thin zone and the transition zone. The contour dimensions of the rolled piece after the first pass and the required length of the raw material plate are calculated as follows: The nominal length of the i-th equal-thickness zone in the first pass: The nominal length of the j-th transition zone in the first pass: The length of the raw material plate required for the i-th equal thickness zone: The length of the raw material plate required for the j-th transition zone: The total length of raw material plates required for differential thickness plates is: Where i = 1, 2, ..., n; j = 1, 2, ..., m; Let be the nominal thickness of the i-th equal thickness zone of the differential thickness plate, in mm; Let be the nominal length of the i-th equal-thickness zone of the differential-thickness plate, in mm; Let J be the minimum thickness of the j-th transition zone of the differential thickness plate, in mm; Let J be the nominal length of the j-th transition zone of the differential thickness plate, in mm; The nominal thickness of the i-th uniform thickness zone in the first pass, in mm; Let be the nominal length of the i-th equal-thickness zone in the first pass, in mm; The minimum thickness of the j-th transition zone in the first pass, in mm; The nominal length of the j-th transition zone in the first pass, in mm; The thickness of the raw material plate is in mm; Let be the length of the raw material plate required for the i-th equal thickness zone of the differential thickness plate, in mm; Let be the length of the raw material plate required for the j-th transition zone of the differential thickness plate, in mm; Here is the mathematical model expression for the j-th transition zone of the differential thickness plate; This is the mathematical model expression for the j-th transition zone in the first pass; l1 and l2 represent the reserved lengths of sheet metal to be held by the left and right clamps, in mm; (2) Roll heating: If warm rolling is to be performed, the rolls should be heated to the required temperature in advance and the roll gap should be reset to zero to eliminate the thermal expansion of the rolls; if cold rolling is to be performed, roll heating is not required. (3) Feeding: Open the roll gap, clamp the workpiece, move the tension cylinder to drive the workpiece through the roll gap; (4) Clamping and tensioning: Clamp the workpiece, close the roll gap to the set value, and establish the left and right tensions according to the tension set value; (5) Heating of rolled parts: If the material needs to be warm rolled, an online heating device is used to heat the rolled parts to the set temperature; if it is cold rolled, no heating of rolled parts is required. (6) First pass variable thickness rolling: Rolling is carried out according to the first pass variable thickness rolling procedure, with the exit length of the rolled piece as the reference, and the roll gap, speed and tension are automatically controlled; (7) Return the workpiece to its original position: If the workpiece needs to undergo a second pass of variable thickness rolling, the roll gap is opened, and the tension cylinders on both sides drive the workpiece to move synchronously. The tension cylinder on the feeding side stops automatically when it reaches its extension limit position. If the workpiece does not need to undergo a second pass of variable thickness rolling, skip directly to step (9). (8) Second pass variable thickness rolling: The roll gap is closed, tension is established, and rolling is carried out according to the second pass variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the entry length of the workpiece. (9) Unloading: Release the tension, open the roll gap, loosen the jaws on both sides, retract the tension cylinders on both sides, and take out the differential thickness plate rolled piece.

2. The rolling method for preparing differential thickness plates using a hydraulic tension cold rolling mill according to claim 1, characterized in that, For rolling to the right, steps (3) to (8) specifically involve: (3) Right side loading: Open the roll gap, clamp the right end of the workpiece with the right clamp, move the right tension cylinder to the left, and drive the workpiece through the roll gap. The right tension cylinder will automatically stop after moving to its left limit position. At this time, the workpiece is on the left side of the mill. (4) Clamping and tensioning on the left side: The left clamp clamps the left end of the rolled piece, the roll gap closes to the set value, and the tension on the left and right sides is established according to the tension set value; (5) Heating of rolled parts: If the material needs to be warm rolled, an online heating device is used to heat the rolled parts to the set temperature; if it is cold rolled, no heating of rolled parts is required. (6) First pass variable thickness rolling to the right: Roll to the right according to the first pass variable thickness rolling procedure, with the exit length of the rolled piece as the reference, and automatically control the roll gap, speed and tension; (7) Return the rolled piece to its original position: If the rolled piece needs to undergo a second pass of variable thickness rolling, the roll gap is opened, and the tension cylinders on both sides drive the rolled piece to move synchronously to the left. The right tension cylinder stops automatically when it reaches its left limit position. At this time, the rolled piece is on the left side of the mill, and the right tension cylinder coincides with the position after the material is loaded in step (3). If the rolled piece does not need to undergo a second pass of variable thickness rolling, then skip directly to step (9). (8) Second pass to the right variable thickness rolling: The roll gap is closed, tension is established, and rolling is carried out to the right according to the second pass variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the entry length of the workpiece.

3. The rolling method for preparing differential thickness plates using a hydraulic tension cold rolling mill according to claim 1, characterized in that, For rolling to the left, steps (3) to (8) specifically involve: (3) Left side loading: Open the roll gap, the left clamp clamps the left end of the rolled piece, and the left tension cylinder moves to the right, driving the rolled piece through the roll gap; (4) Clamping and tensioning on the right side: The right clamp clamps the right end of the workpiece, the roll gap closes to the set value, and the tension on the left and right sides is established according to the tension set value; (5) Heating of rolled parts: If the material needs to be warm rolled, an online heating device is used to heat the rolled parts to the set temperature; if it is cold rolled, no heating of rolled parts is required. (6) First pass leftward variable thickness rolling: Roll to the left according to the first pass variable thickness rolling procedure, with the roll gap, speed and tension automatically controlled based on the exit length of the rolled piece; (7) Return the workpiece to its original position: If the workpiece needs to undergo a second pass of variable thickness rolling, the roll gap is opened, and the tension cylinders on both sides drive the workpiece to move synchronously to the right. The left tension cylinder stops automatically when it reaches its right limit position. At this time, the workpiece is on the right side of the mill, and the position of the left tension cylinder coincides with the position after the material is loaded in step (3). If the workpiece does not need to undergo a second pass of variable thickness rolling, skip directly to step (9). (8) Second pass of variable thickness rolling to the left: The roll gap is closed, tension is established, and rolling is performed to the left according to the second pass of variable thickness rolling procedure. The roll gap, speed and tension are automatically controlled based on the length of the workpiece entry.

4. The rolling method for preparing differential thickness plates using a hydraulic tension cold and warm rolling mill according to claim 2, characterized in that, In steps (6) and (8), the starting positions of the right tension cylinder coincide during the two rolling processes.

5. The rolling method for preparing differential thickness plates using a hydraulic tension cold rolling mill according to claim 1, characterized in that, A differential thickness plate rolled product with a differential thickness ratio of <1:2.0 is prepared, wherein the differential thickness ratio refers to the ratio of the minimum thickness to the maximum thickness of the differential thickness plate.

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