Manufacturing method of single-sided wedge-shaped longitudinal variable-thickness steel plate

Abstract

The invention provides a manufacturing method of a single-face wedge-shaped longitudinal variable-thickness steel plate, and relates to the field of steel plate manufacturing. Wherein the continuous casting slab comprises a first slab and a second slab; the first plate blank and the second plate blank are assembled, and an obtained combined blank is placed in a heating furnace to be evenly heated; the heated combined blank is fed into a rolling mill to be subjected to longitudinal variable-thickness rolling; and the combined blank subjected to longitudinal variable-thickness rolling is sequentially subjected to cooling, straightening, plate splitting and finishing treatment, and the single-face wedge-shaped longitudinal variable-thickness steel plate is obtained. The problem of plate shape bending caused by uneven stress distribution of the upper surface and the lower surface of the steel plate in a traditional manufacturing process can be solved, and production of the multi-wedge-section nonlinear transition single-face wedge-shaped longitudinal variable-thickness steel plate is achieved.

Description

Technical Field

[0001] The present application relates to the field of steel plate manufacturing, and in particular to a method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate. Background Art

[0002] Steel plates serve as the supporting structure for simply supported beams such as bridges and crane beams. The loads borne at different locations are not the same. However, the upper and lower flanges of the simply supported beams are made of steel plates of equal thickness. During use, there will inevitably be a situation where the strength margin of the steel plates is large at some locations along the length of the beam, resulting in material waste and the need to increase the length of welds in some structures. In order to achieve lightweight structures, reduce welds, and lower production costs, the existing technology has developed a longitudinally variable thickness steel plate (Longitudinal Profiled, hereinafter referred to as longitudinally variable thickness) and has achieved industrial production. The main types of longitudinally variable thickness steel plates currently available are shown in Figure 1 As shown in the figure, in addition to the bridge field, longitudinal variable thickness steel plates are also used in nonlinear load fields such as construction, shipbuilding, wind power, and chemical industry. Figure 1 It can be seen that the upper and lower surfaces of the currently commonly used longitudinal variable thickness steel plates are symmetrical single-segment or multi-segment wedge-shaped (i.e., double-sided wedge-shaped). However, in actual applications, some longitudinal variable thickness steel plates used as upper and lower flange plates require a single-sided wedge-shaped structure on their upper and lower surfaces (especially the upper surface), that is, one surface is wedge-shaped and the other surface is flat. The current symmetrical wedge-shaped longitudinal variable thickness steel plates cannot meet this requirement. Among them, Figure 1 The size identifications in the figures are for reference only, and the same symbols do not mean that they actually have the same size.

[0003] During the rolling process of symmetrical wedge-shaped longitudinally variable thickness steel plates, the target wedge shape can be achieved using conventional rectangular billets by dynamically adjusting process parameters such as mill opening and rolling speed. During this process, because the metal flow is symmetrically distributed during deformation of the symmetrical wedge-shaped longitudinally variable thickness steel plates, the finished product is less likely to exhibit asymmetric shapes. However, this production method cannot produce single-sided wedge-shaped longitudinally variable thickness steel plates with asymmetric top and bottom surfaces. Therefore, there is an urgent need to develop a production method for single-sided wedge-shaped longitudinally variable thickness steel plates. Summary of the Invention

[0004] In response to the problems in the existing technology, the present application provides a manufacturing method for a single-sided wedge-shaped longitudinally variable thickness steel plate, which can solve the plate bending problem caused by uneven stress distribution on the upper and lower surfaces of the steel plate in the traditional manufacturing process, and realize the production of multi-wedge-segment, nonlinear transition single-sided wedge-shaped longitudinally variable thickness steel plates.

[0005] To solve the above technical problems, this application provides the following technical solutions:

[0006] The present application provides a method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate, comprising:

[0007] Performing surface treatment on the continuously cast slab; wherein the continuously cast slab includes a first slab and a second slab;

[0008] Assembling the first slab and the second slab, and placing the obtained assembled slab in a heating furnace for uniform heating;

[0009] The heated composite billet is fed into a rolling mill for longitudinal variable thickness rolling; during the longitudinal variable thickness rolling, the number of rolling passes, the average roll gap in each rolling pass, and the wedge amount in each rolling pass are dynamically adjusted according to the thickness of the composite billet, the average thickness of the finished product, and the reduction in each rolling pass of the finished product;

[0010] The combined billet after the longitudinal variable thickness rolling is sequentially cooled, straightened, split and finished to obtain a single-sided wedge-shaped longitudinal variable thickness steel plate.

[0011] Furthermore, the dynamic adjustment of the number of rolling passes, the average roll gap of each rolling pass, and the wedge amount of each rolling pass according to the thickness of the combined billet, the average thickness of the finished product, and the preset reduction of each rolling pass of the finished product includes:

[0012] Determining the number of rolling passes according to the thickness of the combined billet, the average thickness of the finished product, and the preset reduction amount per rolling pass of the finished product;

[0013] Determining an average rolling reduction per pass based on the thickness of the combined billet, the average thickness of the finished product, a preset rolling reduction per pass of the finished product, and the number of rolling passes;

[0014] Determining the average roll gap of each rolling pass according to the average reduction of each rolling pass;

[0015] The wedge amount of each rolling pass is determined according to the target wedge amount of the finished product, the thickness of the combined billet, the average thickness of the finished product, the preset reduction amount of each rolling pass of the finished product and the number of rolling passes.

[0016] Furthermore, the step of feeding the heated composite billet into a rolling mill for longitudinal variable thickness rolling comprises:

[0017] Generate a rolling speed curve corresponding to each pass according to the combined billet thickness, the average thickness of the finished product, the wedge amount of each pass, and the average rolling reduction of each pass;

[0018] Determine the roll gap adjustment amount for each rolling pass based on the rolling speed curve corresponding to each pass and the target wedge shape of the finished product;

[0019] Determining the real-time rolling speed of each rolling pass according to the rolling speed when the wedge amount is zero, the wedge amount of each rolling pass, and the roll gap adjustment amount of each rolling pass;

[0020] According to the average roll gap of each rolling pass and the wedge amount of each rolling pass, the rolling mill is controlled to perform longitudinal variable thickness rolling on the combined billet at the real-time rolling speed of each rolling pass until the shape of the combined billet reaches the target wedge shape.

[0021] Furthermore, before performing surface treatment on the continuous casting slab, the method further includes:

[0022] The continuously cast slab is subjected to thinning rolling; wherein, the starting rolling temperature of the thinning rolling is ≥1020° C.; the continuously cast slab is rolled into an intermediate slab in a rectangular parallelepiped shape.

[0023] Furthermore, the surface treatment of the continuous casting slab comprises:

[0024] planing and milling the lower surface of the first slab;

[0025] planing and milling the upper surface of the second slab;

[0026] Chamfers are respectively turned around the periphery of the planed and milled surfaces of the first slab and the second slab; wherein the chamfer size is 10 mm to 50 mm.

[0027] Furthermore, a milling machine or a grinding machine is used to perform surface treatment on the continuous casting slab; wherein the roughness of the continuous casting slab after the surface treatment is Ra 2.0 μm to 4.0 μm, and the flatness is 0 mm to 2 mm.

[0028] Furthermore, when the grinding machine is used for surface treatment, the particle size of the abrasive of the grinding wheel is 60 mesh to 100 mesh.

[0029] Furthermore, before the first slab and the second slab are subjected to the assembly process, a release agent is coated on the treated surfaces of the first slab and the second slab; the release agent is graphite, carbide or metal coating.

[0030] Furthermore, the assembly method is rivet connection, spot welding, intermittent welding or vacuum sealing; wherein, the assembly method is determined according to the maximum reduction rate of the assembly; when the maximum reduction rate is less than 50%, rivet connection or spot welding is used; when the maximum reduction is greater than 50%, intermittent welding or vacuum sealing is used.

[0031] Furthermore, the vacuum sealing is performed in a vacuum chamber; wherein the vacuum degree of the vacuum chamber is ≤5×10 - 2 Pa; the welding method is electron beam sealing welding.

[0032] Furthermore, the surface of the composite billet is descaled before rolling.

[0033] Furthermore, the starting rolling temperature of the longitudinal variable thickness rolling is ≥950°C.

[0034] Furthermore, after the thinning rolling is completed, the intermediate billet is taken off the production line and subjected to billet assembly processing after being completely cooled.

[0035] Furthermore, the first pass of the longitudinal variable thickness rolling is performed by flat rolling, so that the intermediate billets corresponding to the first slab and the second slab are closely fitted together and the cross-sections remain horizontal.

[0036] Furthermore, the combined billet after the longitudinal variable thickness rolling is cooled by air cooling or accelerated cooling.

[0037] Furthermore, different cooling intensities are used at different positions and thicknesses of the combined blank; wherein the cooling intensity is dynamically adjusted during the movement of the combined blank.

[0038] Furthermore, the method is applicable to the production of 355MPa grade structural steel, whose composition is C: 0.05% to 0.20%, Mn: 0.80% to 1.80%, Si: 0.15% to 0.50%, Al: ≥0.01%, Nb: ≤0.08%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.30%, Ni: ≤0.01%, and Mo: ≤0.10%.

[0039] Furthermore, the method is suitable for the production of 420MPa grade high-strength structural steel, whose composition is C: 0.05% to 0.20%, Mn: 1.00% to 1.90%, Si: 0.15% to 0.55%, Al: ≥0.01%, Nb: ≤0.06%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.40%, and Ni: ≤0.70%.

[0040] In response to the problems in the prior art, the manufacturing method of a single-sided wedge-shaped longitudinally variable thickness steel plate provided by this application can dynamically adjust the mill opening (rolling roll gap) and dynamically track the position of the rolled piece, thereby producing a multi-segment wedge-shaped, nonlinear transition single-sided wedge-shaped longitudinally variable thickness steel plate, which has high production flexibility and thickness control accuracy, and can realize the production of single-sided wedge-shaped longitudinally variable thickness steel plates of different specifications and shapes. Compared with the traditional billet assembly and rolling method, it only performs surface milling and chamfering on the slab, and can then be sealed and rolled, without the need for other turning processes, and does not require the setting of auxiliary intermediate billets. It has the advantages of short production cycle, low production cost, and high material utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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 only 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.

[0042] Figure 1 Schematic diagram of various types of longitudinally variable thickness steel plates in the embodiments of this application;

[0043] Figure 2 Schematic diagram of the production process of a single-sided wedge-shaped longitudinally variable thickness steel plate in an embodiment of the present application;

[0044] Figure 3 Schematic diagram of the cross section of the longitudinally variable thickness steel plate in Example 1 of the present application;

[0045] Figure 4 Schematic diagram of the cross section of the longitudinally variable thickness steel plate in Example 2 of the present application;

[0046] Figure 5 Flow chart of the manufacturing method of the single-sided wedge-shaped longitudinally variable thickness steel plate provided in this application;

[0047] Figure 6 A flow chart for dynamic adjustment provided for this application;

[0048] Figure 7 A flow chart of longitudinal variable thickness rolling provided for this application;

[0049] Figure 8 Flow chart of surface treatment provided for this application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0051] In one embodiment, see Figure 1 and Figure 5 In order to solve the problem of plate bending caused by uneven stress distribution on the upper and lower surfaces of steel plates in traditional manufacturing processes and realize the production of multi-wedge-segment, nonlinear transition single-sided wedge-shaped longitudinally variable thickness steel plates, the present application provides a manufacturing method of single-sided wedge-shaped longitudinally variable thickness steel plates, comprising:

[0052] S101: performing surface treatment on a continuously cast slab; wherein the continuously cast slab includes a first slab and a second slab;

[0053] S102: Assembling the first slab and the second slab, and placing the obtained assembled slab in a heating furnace for uniform heating;

[0054] S103: feeding the heated composite billet into a rolling mill for longitudinal variable thickness rolling; wherein, during the longitudinal variable thickness rolling, dynamically adjusting the number of rolling passes, the average roll gap in each rolling pass, and the wedge amount in each rolling pass according to the thickness of the composite billet, the average thickness of the finished product, and the reduction in each rolling pass of the finished product;

[0055] S104: The combined billet after the longitudinal variable thickness rolling is sequentially cooled, straightened, split and finished to obtain a single-sided wedge-shaped longitudinal variable thickness steel plate.

[0056] It can be understood that the present application provides a method for producing a single-sided wedge-shaped longitudinally variable thickness steel plate. This method solves the problem of uneven stress distribution on the upper and lower surfaces of the steel plate, which leads to plate bending, when single-sided wedge-shaped longitudinally variable thickness steel plates are produced using traditional processes. This method uses a combination of two ingots for production, and places the stresses on the upper and lower surfaces of the steel plates on the wedge-shaped surfaces of the two steel plates during rolling, so that the stresses on the upper and lower surfaces of the combined ingot are symmetrically distributed, completely solving the problem of plate bending. Unlike the traditional single-sided wedge-shaped longitudinally variable thickness steel plate production that uses a flat surface as the rolling surface, this method uses the wedge surface as the rolling surface, which can realize the production of multi-wedge-segment, nonlinear transition single-sided wedge-shaped longitudinally variable thickness steel plates, and improves production flexibility and thickness control accuracy.

[0057] Specifically, the rolling production process is shown in Figure 2 As shown in the figure, the thick end thickness of the single-sided wedge-shaped longitudinally variable thickness steel plate can be ≤100mm. The production process may include: smelting → continuous casting → cutting → surface treatment → billet assembly → heating → rolling → cooling → straightening → shearing → plate separation → finishing.

[0058] ① Surface treatment: Surface treatment is performed on the continuous casting slabs. The lower surface of the first slab is planed and milled, and the upper surface of the second slab is planed and milled, and chamfers are turned around the planed and milled surfaces of the two slabs.

[0059] ② Assembly: Apply a release agent to the planed and milled surfaces of the two slabs and assemble them. Join the slab at the chamfered groove formed around the center of the assembled slab to complete the assembly. Connection methods include riveting, spot welding, intermittent welding, or vacuum sealing. For improved production efficiency, riveting and spot welding are preferred. When the assembly reduction is high, intermittent welding or vacuum sealing is preferred. For improved surface quality, vacuum sealing is preferred.

[0060] ③ Heating: Place the blank into the heating furnace for uniform heating.

[0061] ④ Rolling: The heated composite billet is fed into the rolling mill by conveyor rollers for rolling (lap rolling). During the rolling process, the mill opening and rolling speed are dynamically adjusted according to the target shape until the target wedge shape (contour) is achieved.

[0062] ⑤ Cooling: After rolling, cooling is carried out by air cooling or accelerated cooling. During accelerated cooling, the cooling intensity of each section of the cooling device needs to be dynamically adjusted according to the thickness change rate of the longitudinal variable thickness plate to avoid plate shape defects.

[0063] ⑥ Straightening: Use a hot straightening machine for straightening. During the straightening process, the opening of the straightening roller is dynamically adjusted according to the target shape to ensure that the steel plate is straight after straightening.

[0064] ⑦ Shearing and plate separation: The welded areas at the head, tail and edge of the laminated steel plate are cut off. The separated upper steel plate is lifted by the workshop crane to obtain two single-sided wedge-shaped longitudinally variable thickness steel plates.

[0065] ⑧Finishing: Check whether the shape of the separated longitudinally variable thickness steel plate meets the target requirements. If necessary, the steel plate can be subjected to finishing treatments such as surface grinding, cold straightening and manual flaw detection.

[0066] Furthermore, considering the smaller work roll diameters and reduced rolling thicknesses of some mills, the aforementioned production process can be adjusted to: smelting → continuous casting → cutting → heating → ironing → surface treatment → assembly → heating → forming rolling → cooling → straightening → shearing → plate separation → finishing. This method separates the ironing and forming rolling steps into two separate processes, effectively reducing the assembly thickness and rolling reduction, enabling some mills with smaller work roll diameters to produce single-sided wedge-shaped longitudinally variable thickness steel plates.

[0067] It can be seen that for single-sided wedge-shaped longitudinally variable thickness steel plates with different thickness at the thick end, or for rolling mills with smaller working roll diameters, the following processes can be used:

[0068] First, a method for producing single-sided wedge-shaped longitudinally variable thickness steel plates: The thick end thickness of the single-sided wedge-shaped longitudinally variable thickness steel plates is ≤100mm. The production process is smelting → continuous casting → cutting → surface treatment → billet assembly → heating → rolling → cooling → straightening → shearing → plate separation → finishing.

[0069] Surface treatment: Surface treatment is performed on the continuous casting slabs obtained by continuous casting production, wherein the lower surface of the first slab is surface treated, and the upper surface of the second slab is surface planed and milled, and chamfering is performed on the periphery of the processed surfaces of the two slabs.

[0070] Assembly: Apply an isolation agent to the planed and milled surfaces of the two slabs and combine them. Chamfer the edges to form a groove, connect them, and complete the assembly.

[0071] Heating: Place the billet into the heating furnace for uniform heating.

[0072] Rolling: The heated composite billet is fed by conveyor rollers into the rolling mill for rolling (lap rolling). During the rolling process, the mill opening and rolling speed are dynamically adjusted according to the target shape until the target wedge shape (contour) is achieved.

[0073] Cooling: After rolling, cooling is carried out by air cooling or accelerated cooling. During accelerated cooling, the cooling intensity of each section of the cooling device needs to be dynamically adjusted according to the thickness change rate of the longitudinally variable thickness plate to avoid plate shape defects.

[0074] Straightening: Use a hot straightening machine for straightening. During the straightening process, the opening of the straightening roller is dynamically adjusted according to the target shape to ensure that the steel plate is straight after straightening.

[0075] Shearing and plate separation: The welded parts of the head, tail and edge of the laminated steel plate are cut off, and the separated upper steel plate is lifted by the workshop crane to obtain two single-sided wedge-shaped longitudinally variable thickness steel plates.

[0076] Finishing: Check whether the shape of the separated single longitudinal variable thickness steel plate meets the target requirements. If necessary, the steel plate can be subjected to finishing treatments such as surface grinding, cold straightening and manual flaw detection.

[0077] Second, a method for producing single-sided wedge-shaped longitudinally variable thickness steel plates. Taking into account the higher requirements for the opening of the rolling mill after billet assembly, which some rolling mills cannot meet, the above method can be adjusted to: smelting → continuous casting → cutting → heating → thinning rolling → surface treatment → billet assembly → heating → forming rolling → cooling → straightening → shearing → plate separation → finishing.

[0078] Heating: The continuous casting billet is sent into the heating furnace using hot charging and hot delivery technology for uniform heating.

[0079] Thinning rolling: The heated continuous casting billet is sent by the conveyor roller to the descaling machine before the rolling mill for descaling, and then rolled.

[0080] Surface treatment: Surface treatment is performed on the intermediate blank after thinning, wherein the lower surface of the first slab is surface treated, and the upper surface of the second slab is surface planed and milled, and chamfering is performed on the periphery of the processed surfaces of the two slabs.

[0081] Assembly: Apply an isolation agent to the planed and milled surfaces of the two slabs and combine them. Chamfer the edges to form a groove, connect them, and complete the assembly.

[0082] Heating: Place the billet into the heating furnace for uniform heating.

[0083] Forming rolling: After heating, the combined billet is fed by conveyor rollers to the mill where it is first descaled by the descaling machine before rolling (lap rolling). During the rolling process, the mill opening and rolling speed are dynamically adjusted according to the target shape until the target wedge shape (contour) is achieved.

[0084] Cooling: After rolling, cooling is carried out by air cooling or accelerated cooling. During accelerated cooling, the cooling intensity of each section of the cooling device needs to be dynamically adjusted according to the thickness change rate of the longitudinally variable thickness plate to avoid plate shape defects.

[0085] Straightening: Use a hot straightening machine for straightening. During the straightening process, the opening of the straightening roller is dynamically adjusted according to the target shape to ensure that the steel plate is straight after straightening.

[0086] Shearing and plate separation: The welded parts of the head, tail and edge of the laminated steel plate are cut off, and the separated upper steel plate is lifted by the workshop crane to obtain two single-sided wedge-shaped longitudinally variable thickness steel plates.

[0087] Finishing: Check whether the shape of the separated single longitudinal variable thickness steel plate meets the target requirements. If necessary, the steel plate can be subjected to finishing treatments such as surface grinding, cold straightening and manual flaw detection.

[0088] From the above description, it can be seen that the manufacturing method of the single-sided wedge-shaped longitudinally variable thickness steel plate provided by the present application can dynamically adjust the mill opening (rolling roll gap) and dynamically track the position of the rolled piece, thereby producing a multi-segment wedge-shaped, nonlinear transition single-sided wedge-shaped longitudinally variable thickness steel plate, which has high production flexibility and thickness control accuracy, and can realize the production of single-sided wedge-shaped longitudinally variable thickness steel plates of different specifications and shapes. Compared with the traditional billet assembly and rolling method, it only performs surface milling and chamfering processing on the slab, and can then be sealed and rolled, without the need for other turning processing, and does not require the setting of auxiliary intermediate billets. It has the advantages of short production cycle, low production cost, and high material utilization rate.

[0089] In one embodiment, see Figure 6 The method of dynamically adjusting the number of rolling passes, the average roll gap of each rolling pass, and the wedge amount of each rolling pass according to the combined billet thickness H, the average thickness of the finished product h, and the preset reduction of each rolling pass of the finished product includes:

[0090] S201: According to the thickness H of the combined billet, the average thickness h of the finished product, and the preset reduction H of each pass of the finished product rolling i0 Determining the number of rolling passes n;

[0091] S202: According to the thickness H of the combined billet, the average thickness h of the finished product, and the preset reduction H of each pass of the finished product rolling i0 The average reduction H of each rolling pass is determined by the number of rolling passes n.i ;

[0092] S203: Determine the average roll gap of each rolling pass according to the average reduction of each rolling pass; for example, the combined billet thickness - the average reduction of the first rolling pass = the average roll gap of the first rolling pass; the average roll gap of the first rolling pass - the average reduction of the second rolling pass = the average roll gap of the second rolling pass; and so on, the average roll gap of the i-th rolling pass - the average reduction of the i+1-th rolling pass = the average roll gap of the i+1-th rolling pass; wherein i+1≤the number of rolling passes n;

[0093] S204: According to the target wedge shape of the finished product w, the thickness of the combined billet H, the average thickness of the finished product h, the preset reduction amount H of each pass of the finished product rolling i0 The number of rolling passes n determines the wedge amount of each rolling pass.

[0094] It is understood that during the rolling process, the heated composite billet is fed into the rolling mill by the conveyor rollers for rolling (lap rolling). During the rolling process, the mill opening and rolling speed are dynamically adjusted according to the target shape until the target wedge shape (contour) is achieved.

[0095] In fact, the rolling process can be divided into two processes: ironing rolling and forming rolling. Each pass can be represented as the i-th pass.

[0096] During forming rolling, the number of passes can be calculated based on the following conditions:

[0097]

[0098] Among them, n is the number of rolling passes, H is the thickness of the batch, h is the average thickness of the finished product, H i0 The preset reduction for the i-th pass of the finished product rolling can be calculated using the following formula:

[0099] After determining the number of passes, the average reduction of the i-th pass is:

[0100]

[0101] The target wedge volume of the finished product is known to be w = T max -T min , which is the thickest part T of the target plate shape max With the thinnest point T min The difference between the two, the wedge amount of the i-th pass

[0102] The preset reduction H for the i-th pass of finished product rolling i0 It can be understood as the preset standard reduction of the i-th pass; the average reduction of the i-th pass H iIt can be understood as the average reduction of the i-th pass adjusted according to the combined slab thickness H and the average thickness of the finished product h during actual rolling; the average reduction of the i-th pass H i and the wedge amount w of the i-th pass i The sum is the actual pressing amount at each moment of the i-th pass.

[0103] From the above description, it can be seen that the manufacturing method of single-sided wedge-shaped longitudinal variable thickness steel plate provided in this application can dynamically adjust the number of rolling passes, the average roll gap in each rolling pass and the wedge amount in each rolling pass according to the combined billet thickness H, the average thickness h of the finished product and the preset reduction amount in each rolling pass of the finished product.

[0104] In one embodiment, see Figure 7 The step of feeding the heated composite billet into a rolling mill for longitudinal variable thickness rolling comprises:

[0105] S301: Based on the combined blank thickness H, the average thickness of the finished product h, and the wedge amount w of each pass i , average reduction per rolling pass H i Generate a rolling speed curve corresponding to each pass; wherein the rolling speed curve is a function curve related to time;

[0106] S302: Determine the roll gap adjustment Δh for each rolling pass based on the rolling speed curve corresponding to each pass and the target wedge shape of the finished product. i (t);

[0107] S303: According to the rolling speed v0 when the wedge amount is zero, the wedge amount w of each rolling pass i , the roll gap adjustment amount Δh for each rolling pass i (t) determining the real-time rolling speed v of each rolling pass;

[0108] S304: According to the average roll gap of each rolling pass and the wedge amount w of each rolling pass i The rolling mill is controlled to perform longitudinal variable thickness rolling on the combined billet according to the real-time rolling speed v of each rolling pass until the shape of the combined billet reaches a target wedge shape.

[0109] It can be understood that in a single-pass rolling process, the rolling speed v decreases with the increase of rolling reduction, which can be expressed as:

[0110]

[0111] Where Δh i (t) is the roll gap adjustment amount during a single-pass rolling process, which changes with the rolling time; v0 is the rolling speed when the wedge amount is zero.

[0112] Among them, the roll gap adjustment amount Δh during each rolling process is i (t) + average roll gap per rolling pass = real-time roll gap per rolling pass.

[0113] It can be seen from the above description that the manufacturing method of the single-sided wedge-shaped longitudinally variable thickness steel plate provided in the present application can feed the heated combined billet into the rolling mill for longitudinal variable thickness rolling.

[0114] In one embodiment, before performing surface treatment on the continuously cast slab, the method further comprises:

[0115] The continuously cast slab is subjected to thinning rolling; wherein, the starting rolling temperature of the thinning rolling is ≥1020° C.; the continuously cast slab is rolled into an intermediate slab in a rectangular parallelepiped shape.

[0116] In one embodiment, see Figure 8 The surface treatment of the continuous casting slab comprises:

[0117] S401: milling the lower surface of the first slab;

[0118] S402: planing and milling the upper surface of the second slab;

[0119] S403: turning chamfers around the planed and milled surfaces of the first slab and the second slab respectively; wherein the chamfer size is 10 mm to 50 mm.

[0120] Among them, in the surface treatment process, it is necessary to chamfer the four sides of the treated surface, and the chamfer size is 10 to 50 mm. The greater the rolling reduction rate, the larger the chamfer size.

[0121] In one embodiment, a milling machine or a grinding machine is used to perform surface treatment on the continuous casting slab; wherein the roughness of the continuous casting slab after the surface treatment is Ra 2.0 μm to 4.0 μm, and the flatness is 0 mm to 2 mm.

[0122] Among them, when processing the surface of the slab, a milling machine or a grinder can be used for processing. After the surface treatment, the roughness is Ra2.0~4.0μm and the flatness is 0~2mm.

[0123] In one embodiment, when the grinding machine is used for surface treatment, the particle size of the abrasive on the grinding wheel is 60 mesh to 100 mesh.

[0124] In one embodiment, before the first slab and the second slab are assembled, a release agent is coated on the treated surfaces of the first slab and the second slab; the release agent is graphite, carbide or metal coating.

[0125] In one embodiment, the assembly method is rivet connection, spot welding, intermittent welding or vacuum sealing; wherein, the assembly method is determined according to the maximum reduction rate of the assembly; when the maximum reduction rate is less than 50%, rivet connection or spot welding is used; when the maximum reduction is greater than 50%, intermittent welding or vacuum sealing is used; when the surface quality requirements are high, vacuum sealing is used.

[0126] In one embodiment, the vacuum sealing is performed in a vacuum chamber; wherein the vacuum degree of the vacuum chamber is ≤5×10 - 2 Pa; the welding method is electron beam sealing welding.

[0127] In one embodiment, the surface of the composite billet is descaled before rolling.

[0128] In one embodiment, the starting rolling temperature for longitudinal variable thickness rolling is ≥ 950°C. Specifically, the rolling is performed in two stages: the first stage is thinning rolling, and the second stage is forming rolling. The first stage starts at a temperature ≥ 1050°C, using a large reduction to rapidly thin the steel plate. The second stage starts at a temperature ≥ 950°C.

[0129] In one embodiment, after the ironing rolling is completed, the intermediate billet is taken off the production line and subjected to billet assembly after being completely cooled.

[0130] In one embodiment, the first pass of the longitudinal variable thickness rolling is performed by flat rolling, so that the intermediate billets corresponding to the first slab and the second slab are closely fitted together and the cross-sections remain horizontal.

[0131] In one embodiment, air cooling or accelerated cooling is used to cool the combined billet after longitudinal variable thickness rolling. Specifically, post-rolling cooling is performed using air cooling or accelerated cooling. If the thickness of the slab after rolling varies significantly, a combination of cooling methods can be used to avoid shape defects.

[0132] In one embodiment, different cooling intensities are used at different positions and thicknesses of the combined blank; wherein the cooling intensity is dynamically adjusted during the movement of the combined blank.

[0133] In one embodiment, when shearing, the slab edge should first be calibrated to confirm the position of the finished product, and all edges of the slab should be cut off.

[0134] In one embodiment, during the finishing process, the steel plate may be subjected to surface grinding, cold straightening, manual flaw detection and other finishing treatments if necessary.

[0135] In one embodiment, the method is applicable to the production of 355 MPa grade structural steel, whose composition is C: 0.05% to 0.20%, Mn: 0.80% to 1.80%, Si: 0.15% to 0.50%, Al: ≥0.01%, Nb: ≤0.08%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.30%, Ni: ≤0.01%, and Mo: ≤0.10%.

[0136] In one embodiment, the method is applicable to the production of 420 MPa grade high-strength structural steel, whose composition is C: 0.05% to 0.20%, Mn: 1.00% to 1.90%, Si: 0.15% to 0.55%, Al: ≥0.01%, Nb: ≤0.06%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.40%, and Ni: ≤0.70%.

[0137] In order to better illustrate the method provided by this application, two embodiments are used for illustration below.

[0138] Example 1:

[0139] The single-sided wedge-shaped longitudinally variable thickness steel plate production method of the present invention is used to produce 355MPa grade longitudinally variable thickness steel plates. The dimensions are shown in FIG. Figure 3 As shown. 11 =1000mm, L 12 =20000mm, L 13 =1000mm,h 11 =20mm,h 12 =45mm, width is 3000mm.

[0140] The specific production process is as follows:

[0141] Steelmaking: The molten iron is pretreated and smelted in a top-blown or top-bottom combined blowing converter, followed by refining. The target composition is C: 0.05%-0.20%, Mn: 0.80%-1.80%, Si: 0.15%-0.50%, Al: ≥0.01%, Nb: ≤0.08%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.30%, Ni: ≤0.01%, Mo: ≤0.10%.

[0142] Continuous casting: Electromagnetic stirring is used during the continuous casting process. After continuous casting, the continuous casting billet is cut into pieces with a size of 2500mm×230mm×4000mm.

[0143] Heating: The continuous casting billet is sent into the heating furnace using hot charging and hot delivery technology for uniform heating at a temperature of 1200-1250°C for 4-5 hours.

[0144] Thinning rolling: After heating, the continuous casting billet is sent to the descaling machine before the rolling mill by the conveyor roller for descaling, and then rolled. The starting rolling temperature is ≥1020℃. The continuous casting billet is rolled into an intermediate billet with a specification of 3000mm×60mm×11820mm for billet assembly. The rolling procedure is shown in Table 1 below.

[0145] Table 1 Thinning rolling procedures

[0146] Rolling passes Rolling method Roll gap / mm 1 T+CM 202.7 2 CM+T 190.2 3 RM 156.4 4 RM 129.0 5 RM 108.9 6 RM 92.4 7 RM 79.1 8 RM 68.5 9 RM 60.0

[0147] Surface treatment: The surface of the intermediate blank is treated using a grinder with a grinding wheel of 60 mesh abrasive particle size, and C20 chamfers are ground around the treated surface.

[0148] Welding assembly: two intermediate billets of the same size and specifications are processed and coated with graphite isolation agent and assembled. The four sides are chamfered to form a groove, and spot welding is performed. The distance between the welding points is 100 to 120 mm, and the length of the welding points is ≥25 mm to complete the assembly.

[0149] Heating: Place the billet into a heating furnace for heating at a temperature of 1200-1250°C for 2-4 hours.

[0150] Forming Rolling: The heated slab is conveyed by a conveyor roller to the rolling mill where it is first descaled by a descaling machine. Rolling then proceeds, with the starting rolling temperature ≥ 920°C, to form the intermediate slab into a longitudinally variable thickness plate of the target shape. Rolling is performed in seven passes, the first of which is flat rolling with a roll gap of 105mm to ensure close compression between the two slabs. See Table 2 for the rolling schedule.

[0151] Table 2 Forming rolling procedures

[0152] Rolling passes Rolling method Average roll gap / mm Wedge amount / mm 1 Flat rolling 105.00 0.00 2 Longitudinal variable thickness rolling 95.06 6.20 3 Longitudinal variable thickness rolling 86.83 11.35 4 Longitudinal variable thickness rolling 79.96 15.64 5 Longitudinal variable thickness rolling 74.17 19.26 6 Longitudinal variable thickness rolling 69.24 22.34 7 Longitudinal variable thickness rolling 65.00 25

[0153] Cooling: After rolling, cooling is carried out by air cooling, and the steel plate temperature is cooled to 720℃.

[0154] Straightening: Use a hot straightening machine to straighten longitudinal variable thickness steel plates. The "thick end" or "thin end" of the steel plate can be "entered" into the straightening machine first, and the straightening speed is 0.1-0.6m / s. During the straightening process, the upper and lower straightening rollers are linearly adjusted in the vertical direction to adapt to the straightening requirements of the continuous change in thickness of the longitudinal variable thickness steel plate.

[0155] Shearing and splitting: The edges of the billet are completely cut off and separated to obtain two single-sided wedge-shaped longitudinally variable thickness steel plates.

[0156] Finishing: Check whether the external dimensions of the separated single longitudinal variable thickness steel plate meet the target requirements: wedge segment taper and length, parallel segment thickness and length, etc. If necessary, the steel plate can be subjected to surface grinding, cold straightening, manual flaw detection and other finishing treatments.

[0157] Example 2:

[0158] The invention discloses a method for producing a single-sided wedge-shaped longitudinally variable thickness steel plate to produce a 420MPa grade longitudinally variable thickness steel plate. Figure 4 As shown. 21 =1000mm, L 22 =8000mm, L 23 =2000mm, L 24 =8000mm, L 25 =1000mm,h 21 =20mm,h 22 =32mm,h 23 =20mm, width is 3000mm.

[0159] Steelmaking: The molten iron is pretreated and smelted in a top-blown or top-bottom combined blowing converter, followed by refining. The target composition is C: 0.05%-0.20%, Mn: 1.00%-1.90%, Si: 0.15%-0.55%, Al: ≥0.01%, Nb: ≤0.06%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.40%, Ni: ≤0.70%.

[0160] Continuous casting: Electromagnetic stirring is used during the continuous casting process. After continuous casting, the continuous casting billet is cut into dimensions of 2500mm×230mm×2750mm.

[0161] Surface treatment: The surface of the continuous casting billet is treated with a planer. The surface roughness reaches Ra2.0mm after processing, and C20 chamfers are ground around the treated surface.

[0162] Welding assembly: Two slabs of the same size are processed and coated with graphite isolation agent, and then assembled. The four sides are chamfered to form a groove, and then welded. The welding is carried out in a vacuum chamber with a vacuum degree of ≤10 -2 Pa, perform sealing welding to complete the assembly.

[0163] Heating: Place the billet into a heating furnace for heating at a temperature of 1200-1250°C for 4-5 hours.

[0164] Rolling: The rolling process consists of two stages: the first stage is ironing rolling, and the second stage is forming rolling. The heated continuous casting slab is fed by a conveyor roller to a descaling machine before the rolling mill for descaling. Rolling then proceeds, with a starting temperature of ≥1020°C, to form intermediate slabs measuring 3000 mm × 80 mm × 13100 mm. The rolling process is shown in Table 3.

[0165] Table 3 Thinning rolling procedures

[0166] Rolling passes Rolling method Roll gap / mm 1 T+CM 398.9 2 CM+T 370.9 3 RM 295.2 4 RM 233.9 5 RM 188.9 6 RM 152.0 7 RM 122.2 8 RM 98.5 9 RM 80.0

[0167] After the thinning rolling is completed, the temperature is supplemented to 980℃ in a tunnel heating furnace for descaling, and then forming rolling is carried out. The rolling is carried out in 5 passes. The rolling procedure is shown in Table 4.

[0168] Table 4 Forming rolling procedures

[0169]

[0170]

[0171] Cooling: After rolling, cooling is carried out by air cooling, and the steel plate temperature is cooled to 720℃.

[0172] Straightening: Use a hot straightening machine to straighten longitudinal variable thickness steel plates. The "thick end" or "thin end" of the steel plate can be "entered" into the straightening machine first, and the straightening speed is 0.1-0.6m / s. During the straightening process, the upper and lower straightening rollers are linearly adjusted in the vertical direction to adapt to the straightening requirements of the continuous change in thickness of the longitudinal variable thickness steel plate.

[0173] Shearing and splitting: All edges of the billet are cut off to obtain two single-sided wedge-shaped longitudinally variable thickness steel plates.

[0174] Finishing: Check whether the external dimensions of the separated single longitudinal variable thickness steel plate meet the target requirements: wedge segment taper and length, parallel segment thickness and length, etc. If necessary, the steel plate can be subjected to surface grinding, cold straightening, manual flaw detection and other finishing treatments.

[0175] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0176] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0177] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0178] The above description is merely an example of the embodiments of this specification and is not intended to limit the embodiments of this specification. For those skilled in the art, various modifications and variations of the embodiments of this specification are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. A method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate, characterized in that: include: Performing surface treatment on the continuously cast slab; wherein the continuously cast slab includes a first slab and a second slab; Assembling the first slab and the second slab, and uniformly heating the resulting assembled slab; The number of rolling passes, the average roll gap of each rolling pass and the wedge amount of each rolling pass are dynamically adjusted according to the thickness of the combined billet, the average thickness of the finished product and the reduction of each rolling pass of the finished product, so as to feed the heated combined billet into the rolling mill for longitudinal variable thickness rolling; The combined billet after the longitudinal variable thickness rolling is sequentially cooled, straightened, split and finished to obtain a single-sided wedge-shaped longitudinal variable thickness steel plate.

2. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The method of dynamically adjusting the number of rolling passes, the average roll gap of each rolling pass, and the wedge amount of each rolling pass according to the thickness of the combined billet, the average thickness of the finished product, and the preset reduction amount of each rolling pass of the finished product includes: Determining the number of rolling passes according to the thickness of the combined billet, the average thickness of the finished product, and the preset reduction amount per rolling pass of the finished product; Determining an average rolling reduction per pass based on the thickness of the combined billet, the average thickness of the finished product, a preset rolling reduction per pass of the finished product, and the number of rolling passes; Determining the average roll gap of each rolling pass according to the average reduction of each rolling pass; The wedge amount of each rolling pass is determined according to the target wedge amount of the finished product, the thickness of the combined billet, the average thickness of the finished product, the preset reduction amount of each rolling pass of the finished product and the number of rolling passes.

3. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 2, characterized in that: The step of feeding the heated composite billet into a rolling mill for longitudinal variable thickness rolling comprises: Generate a rolling speed curve corresponding to each pass according to the combined billet thickness, the average thickness of the finished product, the wedge amount of each pass, and the average rolling reduction of each pass; Determine the roll gap adjustment amount for each rolling pass based on the rolling speed curve corresponding to each pass and the target wedge shape of the finished product; Determining the real-time rolling speed of each rolling pass according to the rolling speed when the wedge amount is zero, the wedge amount of each rolling pass, and the roll gap adjustment amount of each rolling pass; According to the average roll gap of each rolling pass and the wedge amount of each rolling pass, the rolling mill is controlled to perform longitudinal variable thickness rolling on the combined billet at the real-time rolling speed of each rolling pass until the shape of the combined billet reaches the target wedge shape.

4. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: Before the surface treatment of the continuous casting slab, it also includes: The continuously cast slab is subjected to thinning rolling; wherein, the starting rolling temperature of the thinning rolling is ≥1020° C.; the continuously cast slab is rolled into an intermediate slab in a rectangular parallelepiped shape.

5. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The surface treatment of the continuous casting slab comprises: planing and milling the lower surface of the first slab; planing and milling the upper surface of the second slab; Chamfers are respectively turned around the periphery of the planed and milled surfaces of the first slab and the second slab; wherein the chamfer size is 10 mm to 50 mm.

6. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The continuous casting slab is surface treated using a milling machine or a grinder; wherein the roughness of the continuous casting slab after the surface treatment is Ra 2.0 μm to 4.0 μm, and the flatness is 0 mm to 2 mm.

7. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 6, characterized in that: When the grinding machine is used for surface treatment, the particle size of the abrasive of the grinding wheel is 60 mesh to 100 mesh.

8. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: Before the first slab and the second slab are subjected to assembly processing, a release agent is coated on the processed surfaces of the first slab and the second slab; the release agent is graphite, carbide or metal coating.

9. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The assembly method is rivet connection, spot welding, intermittent welding or vacuum sealing; wherein, the assembly method is determined according to the maximum reduction rate of the assembly; when the maximum reduction rate is less than 50%, rivet connection or spot welding is used; when the maximum reduction rate is greater than 50%, intermittent welding or vacuum sealing is used.

10. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 9, characterized in that: The vacuum sealing is carried out in a vacuum chamber; wherein the vacuum degree of the vacuum chamber is ≤5×10 -2 Pa; the welding method is electron beam sealing welding.

11. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The surface of the composite billet is descaled before rolling.

12. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The starting rolling temperature of longitudinal variable thickness rolling is ≥950℃.

13. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 4, characterized in that: After the thinning rolling is completed, the intermediate billet is taken off the production line and subjected to billet assembly processing after being completely cooled.

14. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 4, characterized in that: The first pass of the longitudinal variable thickness rolling is performed by flat rolling so that the intermediate billets corresponding to the first slab and the second slab are closely fitted and the cross sections remain horizontal.

15. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The combined billet after longitudinal variable thickness rolling is cooled by air cooling or accelerated cooling.

16. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: Different cooling intensities are used at different positions and thicknesses of the combined blank; wherein the cooling intensity is dynamically adjusted during the movement of the combined blank.

17. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The method is suitable for the production of 355MPa grade structural steel, the composition of which is C: 0.05% to 0.20%, Mn: 0.80% to 1.80%, Si: 0.15% to 0.50%, Al: ≥ 0.01%, Nb: ≤ 0.08%, V: ≤ 0.18%, Ti: ≤ 0.20%, Cr: ≤ 0.30%, Ni: ≤ 0.01%, and Mo: ≤ 0.10%.

18. The method for manufacturing a single-sided wedge-shaped longitudinally variable thickness steel plate according to claim 1, characterized in that: The method is applicable to the production of 420MPa grade high-strength structural steel, the composition of which is C: 0.05%~0.20%, Mn: 1.00%~1.90%, Si: 0.15%~0.55%, Al: ≥0.01%, Nb: ≤0.06%, V: ≤0.18%, Ti: ≤0.20%, Cr: ≤0.40%, Ni: ≤0.70%.

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