Method for roll bonding of sheets of a difficult-to-deform metal

Abstract

The application discloses a method for splicing and rolling of thin sheets of difficult-to-deform metal, wherein a sheet blank with a thickness of 2 mm or above is subjected to 5-13 passes of initial rough rolling on a four-roller or six-roller rough rolling mill by adopting a block method process, and after the thickness is reduced to less than 0.5 mm, the sheet material is not cut at the edge portion, the head and tail are each cut by 50-100 mm, and then the head and tail of a plurality of sheets are spliced and welded, the spliced and welded strip is subjected to one pass of fine rough rolling on a six-roller or twelve-roller or fourteen-roller or twenty-roller finishing mill by adopting a strip method process. The method can realize the processes of one pass of fine rough rolling, on-line edge cutting (welding seam cutting), and multi-pass fine rolling of the spliced and welded strip coil on the finishing mill under a constant roll gap; the double-side scrap edges and the welding seams do not participate in deformation, there are no welding points and welding seams in the overlapping section, and the length of the overlapping section after the rolling and composite connection can be directly used as part of the finished product without the need for post-cutting, thereby simplifying the processing flow, reducing raw material waste, and improving the yield.

Description

Technical Field

[0001] This invention relates to the field of metal sheet and strip production technology, specifically a method for welding and rolling thin metal sheets that are difficult to deform. Background Technology

[0002] Difficult-to-deform metals generally include tungsten (W), molybdenum (Mo), titanium (Ti), nickel (Ni), magnesium (Mg), tantalum (Ta), as well as high-temperature alloys and functional materials. During rolling production, these metals typically exhibit high deformation resistance, making it difficult to control the performance, dimensions, and sheet quality of the products. The addition of microalloying elements increases the strength and hardness of difficult-to-deform metal strips such as titanium alloy TC4, tantalum alloy Ta-W, magnesium alloy ZK60, and molybdenum alloy Mo-La, further increasing the difficulty of rolling. Especially when the thickness of these metal sheets exceeds 0.5-2.0 mm, they are prone to cracking during coiling, making high-quality, high-efficiency rolling under tension impossible in coil form. Only energy-intensive, low-efficiency block rolling methods are used. When difficult-to-deform metal sheets are continuously thinned using block rolling, reaching a thickness of 0.01-0.5 mm, the sheets become too thin and light to be automatically transported and rolled using equipment such as roller conveyors. Only manual transport and a "two-person operation" production method can be used, resulting in low product quality and production efficiency.

[0003] In recent years, in order to improve production efficiency and product quality, some companies have adopted a method of continuous production under tension by welding together several thin sheets obtained from rough rolling to a thickness of less than 0.5 mm and then rolling them into coils, which has improved product quality and production efficiency.

[0004] However, in the continuous rolling process of welding together several difficult-to-deform metal sheets into a coil, the industry currently faces the following technical problems:

[0005] Problem 1: Using a butt welding method with sections facing each other is difficult to join, and the sections are prone to breakage during production. When cutting the finished product, all welded sections and the parts before and after them need to be removed, which makes the processing steps cumbersome and results in a low yield.

[0006] When the sheet metal is 2-3mm or thicker, it is suitable to butt-weld the tail section of the previous sheet metal to the head section of the next sheet metal. However, for difficult-to-deform metal sections with a thickness of 0.01-0.5mm, butt welding is extremely difficult due to their thinness. Furthermore, to ensure that the entire width direction of the sheet metal participates in deformation and shape control, traditional rolling processes employ a structure where the roll width is greater than the sheet metal width (as shown in the attached diagram). Figure 9The width of one side in the weld is greater than the difference a = 15-75mm. Therefore, regardless of whether spot welding or continuous welding is used at the joint, the weld point or weld seam will be damaged after contact deformation of various components of the rolling mill, especially after multiple rolling passes. The connection strength will decrease sharply, and fracture under tensile stress will frequently occur (the metal matrix is ​​not rolled together, and the strength relies only on the welding), making it difficult to achieve continuous and stable production. At the same time, the weld seam at the butt weld of each plate and its associated areas before and after it need to be cut off in the later stages, which not only reduces the yield but also hinders the continuous use of the coiled strip in downstream processes. The aforementioned existing technical solution is attached. Figure 1 , 2 As shown in 7 and 9.

[0007] Question 2: Using a method of overlapping and welding two plates of a certain length for splicing and welding is beneficial to improve the connection strength and prevent breakage. However, the two wide weld protrusions at the front and back of the overlap section bring production difficulties to the rolling process (damage to the rolls or the need for the rolls to be lifted and pressed down multiple times). In addition, the entire overlap section, including the weld, needs to be removed afterward, making the processing steps cumbersome and the yield rate low.

[0008] To address the problems associated with butt welding of thin metal sheets: Lap welding (overlap welding) is used, where the tail of one sheet overlaps the head of the next, and then the front and rear ends of the overlapping section are welded in the width direction. Lap welding improves the connection strength (after rolling, the metal matrix of the lap section achieves a rolling bond), making it less prone to breakage under tensile stress. However, because the thickness of the lap section is twice that of the single sheet, a bulge in the welding area occurs. To avoid damage to the rolling mill roll system from this bulge, an automatic weld detection device needs to be installed on the production line. Before the lap section enters the roll gap, the rolling mill slows down and the roll system is raised; after the lap section passes through the roll gap, the rolling mill roll system is pressed down and accelerated again. Each lap section involves a process of acceleration-deceleration-(stop)-(start)-acceleration, reducing production efficiency and resulting in low consistency in product dimensions and mechanical properties. Furthermore, since the lap section, including the weld, does not participate in rolling deformation, it needs to be removed later (including uneven deformation sections caused by acceleration and deceleration), making production cumbersome and resulting in a very low yield. The aforementioned existing technical solutions are attached. Figure 3 , 4 As shown in Figures 8 and 9.

[0009] To address problems 1 and 2 mentioned above, this invention provides a method for welding and rolling thin metal sheets that are difficult to deform, thereby solving the aforementioned problems. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the existing defects and provide a method for welding and rolling difficult-to-deform metal thin sheets. This method enables the finishing mill to perform one pass of roughing rolling, online edge trimming (weld cutting), and multi-pass finishing rolling on the welded strip coil under constant roll gap. Since the waste edges on both sides and their welds do not participate in deformation, there are no weld points or welds in the overlapping section. The length of the overlapping section after rolling and composite connection can be directly used as part of the finished product without subsequent cutting, which simplifies the processing flow, reduces raw material waste, and improves the yield. This method can effectively solve the problems in the background art.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a method for welding and rolling difficult-to-deform metal sheet, characterized in that: metal sheet blanks with a thickness of 2mm or more are first roughed in 5-13 passes using a block method on a four-roll or six-roll roughing mill. After rolling to a thickness of less than 0.5mm, the metal sheet is not trimmed at the edges, but 50-100mm is trimmed at both ends. Several metal sheets are then joined together by overlapping the ends and welding them into a metal strip. After the metal sheets are welded into a strip, they are then roughed in one pass using a strip method on a six-roll, twelve-roll, fourteen-roll, or twenty-roll finishing mill. At the same time as the roughing is being rolled, the edges are trimmed online on the finishing mill.

[0012] Between the 5-13 passes of rough rolling and the 1 pass of strip finishing rolling, several metal sheets are welded into coils as follows:

[0013] S1. After rough rolling, cut off 50-100mm from each end of several metal plates with single-sided crack defects of 5-20mm in width, i.e., double-sided crack defects with a total width of 10-40mm. Then, overlap them in pairs, with an overlap length s=30-150mm.

[0014] S2. After the overlap, the two sides of the metal strip overlap section are subjected to laser welding under argon protection in the rolling direction. The width of the continuous welding area of ​​the single-sided crack defect edge is not greater than the width of the defect edge formed by the crack on the single-sided crack defect edge.

[0015] S3. Several metal plates are welded together into a metal strip by continuous longitudinal welding at the overlapping edges of two metal plates, which is then used in the subsequent production processes of the strip method.

[0016] During single-pass finishing rolling, the double-sided crack defect edge in S1 and the laser-welded weld defect edge in S2 are controlled to be outside the roll surface width range and do not participate in rolling deformation. At the same time, the two metal plates that participate in deformation within the overlap section s length range and the roll surface width range achieve rolling composite and uniform thickness. The online edge trimming device of the finishing mill symmetrically and completely removes the waste edges on both sides of the metal strip and the laser-welded weld of the overlap section. The single-sided removal amount c≥b and c≥10mm. The width of the metal strip after removal is smaller than the roll surface width of the finishing mill.

[0017] As a preferred embodiment of the present invention, the initial roughing reduction rate before metal sheet welding accounts for 85%-95% of the total roughing reduction rate, and the rolling speed is 10-30m / min; the finishing roughing reduction rate after metal sheet welding accounts for 5%-15% of the total roughing reduction rate, and the rolling speed is 30-60m / min.

[0018] As a preferred embodiment of the present invention, the roll width of the roughing mill is greater than the width of the metal sheet, with a single-sided difference of a = 15-75 mm, and both sides are symmetrical along the longitudinal centerline of the roll with a total difference of 2a = 30-150 mm; the roll width of the finishing mill is less than the width of the metal sheet before trimming after roughing, with a single-sided difference of b = 5-10 mm, and both sides are symmetrical along the longitudinal centerline of the roll with a total difference of 2b = 10-20 mm.

[0019] As a preferred embodiment of the present invention, the edge trimming device is installed on the finishing mill production line, located between the main mill and the exit coiler; the edge trimming device participates in production during the first pass of finishing and roughing rolling, but does not participate in production during subsequent multi-pass reversible finishing rolling.

[0020] As a preferred technical solution of the present invention, after the waste edges on both sides of the metal strip and the weld seam of the laser-welded lap section are symmetrically and completely removed, the lap section after the composite connection by fine and rough rolling is directly used as part of the product without being removed. After the entire metal strip is finely rolled, it goes off the line for subsequent strip annealing and strip cleaning, and then goes back on the finishing mill for multi-pass continuous strip reversible finishing rolling according to process requirements until the final finished product thickness is reached. The finishing rolling speed is 90-300m / min.

[0021] As a preferred technical solution of the present invention, the following production process is adopted for several difficult-to-deform metal thin plates with a target thickness of 0.01-0.5mm before precision rolling: rolling thick slab - surface cleaning - block method rough rolling - overlapping double-sided longitudinal welding and coiling - strip method fine rolling - online strip method edge trimming - strip method annealing - strip method cleaning - precision rolling.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The method for welding and rolling difficult-to-deform metal sheets exemplified by this invention can realize the processes of roughing, trimming (cutting welds) and multi-pass finishing rolling of welded strip coils under constant roll gap on a finishing mill. Since the waste edges on both sides and their welds do not participate in deformation, there are no weld points or welds in the overlapping section. The length of the overlapping section after rolling and composite connection can be directly used as part of the finished product without subsequent cutting, which simplifies the processing flow, reduces raw material waste, and improves the yield. Attached Figure Description

[0024] Figure 1 Schematic diagram of a wide-direction spot weld for butt joint of difficult-to-roll thin metal sheets;

[0025] Figure 2 for Figure 1 A top-view structural diagram;

[0026] Figure 3 A schematic diagram of a wide-direction continuous weld for overlapping thin metal sheets that are difficult to roll;

[0027] Figure 4 for Figure 3 A top-view structural diagram;

[0028] Figure 5 A schematic diagram of longitudinal continuous welding at the edge of overlapping difficult-to-roll thin metal sheets;

[0029] Figure 6 for Figure 5 A top-view structural diagram;

[0030] Figure 7 This is a schematic diagram of conventional strip rolling and welding methods.

[0031] Figure 8 for Figure 7 A top-view structural diagram;

[0032] Figure 9 for Figure 7 Schematic diagram showing the relationship between the roll width of the intermediate rolling mill and the strip width;

[0033] Figure 10 This is a schematic diagram of the structure of the present invention;

[0034] Figure 11 This is a schematic diagram showing the relationship between the roll surface width and the strip width of 10 finishing mills;

[0035] Figure 12 This is a schematic diagram of the plan layout of the finishing mill for the lap-joint edge welding of the strip and plate according to the present invention;

[0036] Figure 13 for Figure 12 Elevation diagram;

[0037] Figure 14 This is a schematic diagram showing the welded strip before and after rough rolling and trimming.

[0038] In the figure: 1. nth metal sheet, 2. n+1th metal sheet, 3. continuous edge weld, 4. roll, 5. uncoiler, 6. inlet side coiler, 7. main machine, 8. outlet side coiler, 9. pinch guide roller, 10. edge trimming device. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1-14 This invention provides a technical solution: a method for welding and rolling difficult-to-deform thin metal sheets, employing the following production process: rolling thick slabs - surface cleaning - rough rolling - overlapping double-sided longitudinal welding and coiling - strip rough rolling - online strip trimming - strip annealing - strip cleaning - finish rolling, specifically:

[0041] For metal sheet blanks with a thickness of 2mm or more, the primary roughing process is carried out on a four-roll or six-roll roughing mill using a block method for 5-13 passes. The primary roughing reduction rate before the metal sheets are welded accounts for 85%-95% of the total roughing reduction rate.

[0042] After rolling to a thickness of less than 0.5mm, the edges of the sheet are not removed. 50-100mm is removed from both the head and tail. Several sheets are then joined together by overlapping the head and tail. After being joined into a metal strip, it is subjected to one pass of roughing and finishing rolling using a strip mill with a six-roll, twelve-roll, fourteen-roll, or twenty-roll design. The reduction rate of the roughing and finishing rolling after joining the metal sheets accounts for 5%-15% of the total reduction rate of the roughing rolling. At the same time as the roughing and finishing rolling, the edges are removed online on the finishing mill.

[0043] like Figure 7 , 8 As shown in Figure 9, the function of the roughing mill is to perform block-type roughing rolling of a single metal sheet. The width of the roll surface of the roughing mill is greater than the width of the metal sheet. The difference on one side is a = 15-75 mm, and the difference on both sides is symmetrical along the longitudinal center line of the roll and the total difference is 2a = 30-150 mm. The rolling speed of the roughing mill is V = 10-30 m / min.

[0044] like Figure 10 , 11As shown, the function of the finishing mill is to perform one pass of strip roughing, online trimming, and all subsequent strip finishing processes (after annealing and cleaning) on ​​the strip welded into coils. The width of the finishing roll is smaller than the width of the metal strip before trimming after roughing, with a single-sided difference of b = 5-10 mm. The difference is symmetrical along the longitudinal centerline of the roll on both sides and the total difference is 2b = 10-20 mm. The rolling speed for one pass of roughing is V = 30-60 m / min, and the finishing rolling speed after annealing and cleaning is V = 90-300 m / min.

[0045] like Figure 5 , 6 As shown in Figures 10 and 11, after initial rough rolling of a single sheet metal plate using the block method, certain rolling edge defects such as cracks and uneven thickness differences appear on both sides. The width of the defective edge on one side is 5-20 mm, and the width of both sides is symmetrical along the longitudinal centerline of the metal plate, with a total width of 10-40 mm. Edge trimming is not performed immediately after initial rough rolling. Several metal plates after initial rough rolling are connected into a coil as follows: the tail of the nth metal plate 1 and the head of the (n+1)th metal plate 2 are overlapped, with an overlap length s = 30-150 mm. After overlapping, the defective edges on both sides of the symmetrical overlap section are continuously longitudinally welded in the rolling direction to form a coil. The width of the continuous weld 3 on one side is not greater than the width of the defective edge formed by cracks, etc. Several metal plates are welded into a coil by continuous longitudinal welding of the overlapped edges for subsequent strip production.

[0046] like Figure 12 and 13 As shown, the edge trimming device 10 is installed online on the finishing mill production line. The finishing mill is arranged along the rolling direction as follows: uncoiler 5, pinch guide roller 9, inlet-side coiler 6, main machine 7, edge trimming device 10, and outlet-side coiler 8. The edge trimming device 10 is located between the main machine 7 and the outlet-side coiler 8. The edge trimming device 10 consists of a frame, upper and lower cutter shafts, a lifting turbine box, a gear reducer, an AC variable frequency motor, a universal coupling, a machine base, and a power gearbox. The edge trimming device 10 is controlled by the gearbox driven by the AC variable frequency motor, and drives the circular cutter spindle to rotate through the universal coupling. The overlap of the upper and lower cutters is controlled by a displacement sensor. The lower cutter shaft is fixed, and the upper cutter shaft moves up and down to adjust the gap and overlap between the two cutters.

[0047] Between the multi-pass block-type roughing rolling and the single-pass strip-type finish rolling processes, several thin metal sheets are welded into coils using the following method:

[0048] S1. After rough rolling, cut off 50-100mm from the head and tail of several metal plates with defects such as single-sided edge cracks with a width of 5-20mm or double-sided edge cracks with a total width of 10-40mm. Then, overlap the plates in pairs, with an overlap length s=30-150mm.

[0049] S2. After the overlap, laser welding is carried out on the edges of the metal plate overlap section with cracks and other defects on both sides under argon protection in the rolling direction. The width of the continuous welding area on one side is not greater than the width of the edge of the defect formed by cracks on one side.

[0050] S3. Several metal sheets are welded together into a strip by continuous longitudinal welding at the overlapping edges, which is then used in subsequent strip production processes.

[0051] Furthermore, by utilizing the finishing mill during single-pass finishing and roughing rolling, defects such as double-sided cracks in S1 and welds in S2 are controlled to be outside the width range of the roll surface and do not participate in rolling deformation. At the same time, the two metal plates that participate in deformation within the overlap section s length range and the roll surface width range achieve rolling composite and uniform thickness.

[0052] Furthermore, the trimming device is installed on the finishing mill production line, located between the main mill and the exit coiler; the trimming device participates in production during the first pass of finishing rolling, but does not participate in production during subsequent multi-pass reversible finishing rolling.

[0053] The above method is as follows: the metal strip that has been rough rolled and lapped and welded into a coil is uncoiled in the uncoiler 5 of the finishing mill, and then passes through the main machine 7, the edge trimming device 10 and the exit side coiler 8 in sequence under the pinching and deflection drive of the pinching guide roller 7. After being wound 2-3 turns on the exit side coiler 8, the metal strip establishes tension between the uncoiler 5 and the exit side coiler 8.

[0054] The main unit 7 is started and pressed down, and the edge cutting device 10 is put into use at the same time;

[0055] In the first pass, the upper and lower working rolls 4 of the main machine 7 perform a fine rolling of the metal strip with a reduction rate of 5%-15%. The metal substrate within the overlap length s of the nth metal sheet 1 and the (n+1)th metal sheet 2 achieves a composite connection between the two after being rolled by the upper and lower working rolls 4 of the main machine 7.

[0056] Meanwhile, during rolling, the strip and the upper and lower rolls 4 are symmetrically arranged along the width centerline of the rolling direction. The continuous edge welds 3 on the longitudinal side of the strip and the uncut defect edges are always kept outside the working range of the roll surface, so they do not participate in the rolling deformation, do not damage or reduce the connection strength of the welded area, and do not damage the upper and lower rolls 4.

[0057] The edge trimming device 10 symmetrically and completely removes the waste edges on both sides of the metal strip and the continuous weld seam 3 at the edge of the overlapping section, ensuring that the metal strip in the width direction participates in deformation and that the shape can be controlled by the bending rolls of the upper and lower rolls 4 in subsequent multi-pass finishing rolling processes. The width of the metal strip after trimming is smaller than the width of the roll surface of the upper and lower rolls 4 of the finishing mill.

[0058] Furthermore, such as Figure 14 As shown, the online edge trimming device of the finishing mill symmetrically and completely removes the waste edges on both sides of the metal strip and the weld seam of the overlapping section. The range of single-sided edge trimming amount c of the metal strip after one pass of finishing rolling is: single-sided trimming amount c≥b, and c≥10mm; the width of the metal strip after trimming is less than the width of the finishing mill roll surface.

[0059] Furthermore, after the sides and welds are removed, the overlapping section after the composite connection by rough rolling is directly used as part of the product without further removal. The entire strip is rough rolled and then removed from the line for subsequent strip annealing and strip cleaning. It is then put back on the finishing mill for multi-pass continuous strip reversible finishing rolling according to process requirements until the final finished product thickness is achieved.

[0060] During multi-pass finishing rolling, the upper and lower cutter shafts of the edge trimming device 10 are in the open state and do not participate in the work. Except for the first pass uncoiler 5, which participates in the work, only the inlet-side coiler 6, the main machine 7, and the outlet-side coiler 8 participate in the work in the other passes.

[0061] The following production process is used before finishing rolling for several difficult-to-deform metal sheets with a target thickness of 0.01-0.5mm: rolling thick slab - surface cleaning - block method rough rolling - overlapping double-sided longitudinal welding and splicing - strip method finish rolling - online strip method edge trimming - strip method annealing - strip method cleaning - finish rolling.

[0062] The following describes a production example using a specific metal alloy: Example

[0063] The incoming material is a titanium alloy plate with a thickness of 2.0mm and a width of 550mm. The target finished product thickness is 0.03mm.

[0064] (1) According to the production process requirements, rough rolling completes the rolling from 2.0mm to 0.4mm, and finish rolling completes the rolling from 0.4mm to 0.03mm.

[0065] (2) A square titanium alloy slab with a billet size of 2.0×550×550mm (thickness×width×length) is roughed on a block-type roughing mill. The rolling mill has a four-roll system, with the upper and lower working rolls having a roll surface width of 700mm and a diameter of Φ360mm. The rolling process is carried out using the block method. The rough rolling process accounts for 90% of the total compression ratio of the rough rolling, and consists of 8 passes: 2.0→1.8→1.6→1.36→1.15→0.95→0.78→0.64→0.56 (unit: mm). The corresponding reduction rates for each pass are 20%, 20%, 24%, 21%, 20%, 17%, 14%, and 8%, respectively. The rolling speeds for each pass are 12 m / min, 12 m / min, 15 m / min, 18 m / min, 24 m / min, 30 m / min, 24 m / min, and 12 m / min. The dimensions of a single sheet after rough rolling are 0.56×555×1945 mm. Cracks and edge defects are not removed initially; only 50 mm is removed from the beginning and end of irregular sheets, resulting in a sheet size of 0.56×555×1845 mm.

[0066] (3) Two of the 150 titanium alloy thin plates with dimensions of 0.56×555×1845mm that have undergone rough rolling are joined end to end, with a joint length of 90mm. The symmetrical double-sided defective edges of the joint are continuously welded by laser welding under argon protection. The welding width on each side is 5mm, and the total welding width on both sides is 10mm.

[0067] (4) The total length of the 150 titanium alloy strips continuously welded together longitudinally on both sides is approximately 249m. This strip, with dimensions of 0.56×555×249000mm, was subjected to a second stage of roughing and finishing rolling using a finishing mill. The finishing mill has a six-roll system, with the upper and lower work rolls having a roll width of 540mm and a diameter of Φ110mm. The strip rolling process was employed. The roughing and finishing rolling accounted for 10% of the total reduction ratio of the roughing rolling, and consisted of one pass: 0.56mm → 0.4mm, corresponding to a reduction rate of 28.6%, and a rolling speed of 45m / min. The dimensions of the titanium alloy strip after roughing and finishing rolling were 0.4×557×347000mm. During this rolling pass, a trimming device located between the finishing mill coiler and the main rolling mill is used to symmetrically remove both sides of the titanium alloy strip, thereby removing cracks, continuous weld seams in lap joints, and defective edges. The single-side removal amount is 18.5 mm, and the dimensions of the titanium alloy strip after double trimming are 0.4 × 520 × 347000 mm.

[0068] (5) After the titanium alloy strip coils that have completed roughing and trimming are removed from the finishing mill, they are transported to relevant equipment for strip annealing, strip cleaning and other processes, and then transported to the finishing mill for multi-pass reversible finishing rolling using the strip rolling process. The finishing rolling is performed from 0.4mm to 0.03mm, with a total reduction ratio of 92.5%, and a total of 7 passes are performed: 0.4→0.35→0.26→0.18→0.12→0.07→0.04→0.03, in mm. The corresponding reduction rates for each pass are 12.5%, 25.7%, 30.8%, 33.3%, 41.7%, 42.9%, and 25.0%, respectively. The rolling speeds for each pass are 120m / min, 150m / min, 180m / min, 200m / min, 240m / min, 240m / min, and 150m / min. The titanium alloy strip, after seven passes of precision rolling, measures 0.03×520×4626000mm. The overlapping sections at both ends of the final rolled titanium alloy sheets are rolled together to form a single unit, becoming part of the strip matrix. There are no weld points or seams within the strip, resulting in uniform dimensions and performance. This eliminates the need for trimming, effectively improving production efficiency and yield, and ensuring the strip can be used in subsequent coil production. Example

[0069] The incoming material is a molybdenum alloy plate with a thickness of 1.2mm and a width of 430mm. The target finished product thickness is 0.01mm.

[0070] (1) According to the production process requirements, rough rolling completes the rolling from 1.2mm to 0.12mm, and finish rolling completes the rolling from 0.12mm to 0.01mm.

[0071] (2) A square molybdenum alloy thick slab with a billet size of 1.2×430×430mm (thickness×width×length) is roughed on a block-type roughing mill. The rolling mill has a four-roll system, with the upper and lower work rolls having a roll surface width of 680mm and a diameter of Φ280mm. The rolling process is carried out using the block method. The roughing mill accounts for 88.3% of the total compression ratio of the roughing mill and is rolled in 9 passes: 1.2→1.05→0.9→0.74→0.58→0.45→0.34→0.25→0.18→0.14 (unit: mm). The corresponding reduction rates for each pass are 12.5%, 14.3%, 17.8%, 21.6%, 22.5%, 24.5%, 26.5%, 28%, and 22.2%, respectively. The rolling speeds for each pass are 12 m / min, 12 m / min, 15 m / min, 18 m / min, 18 m / min, 24 m / min, 24 m / min, 18 m / min, and 12 m / min, respectively. The dimensions of a single sheet after rough rolling are 0.14×435×3643mm. Cracks and other edge defects are not removed temporarily. Only 30mm is cut off from the head and tail of the irregular sheet. The dimensions of the sheet after cutting are 0.14×435×3583mm.

[0072] (3) Two of the 90 molybdenum alloy thin plates with dimensions of 0.14×435×3583mm that have undergone rough rolling are overlapped end to end, with an overlap length of 75mm. The symmetrical double-sided defective edges of the overlap are continuously welded by laser welding under argon protection. The welding width on each side is 5mm, and the total welding width on both sides is 10mm.

[0073] (4) A total length of 315m was obtained from 90 molybdenum alloy strips continuously welded longitudinally on both sides. The strip coils with dimensions of 0.14×435×315000mm were subjected to a second stage of roughing and finishing rolling using a finishing mill. The finishing mill had a 14-roll system, with upper and lower work rolls having a roll face width of 420mm and a diameter of Φ90mm. Strip rolling was employed. The roughing and finishing rolling accounted for 11.7% of the total compression ratio of the roughing rolling, and consisted of one pass: 0.14mm→0.12mm, corresponding to a pass reduction rate of 14.3%, and a rolling speed of 48m / min. The dimensions of the molybdenum alloy strip after roughing and finishing were 0.12×437×365000mm. During this rolling pass, a trimming device located between the finishing mill coiler and the main rolling mill is used to symmetrically remove both sides of the molybdenum alloy strip, thereby removing cracks, continuous weld seams in lap sections, and defective edges. The single-side removal amount is 13.5 mm, and the dimensions of the trimmed molybdenum alloy strip are 0.12 × 410 × 365000 mm.

[0074] (5) After the molybdenum alloy strip coils that have completed roughing and trimming are removed from the finishing mill, they are transported to relevant equipment for strip annealing, strip cleaning and other processes, and then transported to the finishing mill for multi-pass reversible finishing rolling using the strip rolling process. The finishing rolling is performed from 0.12mm to 0.01mm, with a total reduction ratio of 91.7%, and a total of 6 passes are performed: 0.12→0.09→0.065→0.042→0.026→0.015→0.01, in mm. The corresponding reduction rates for each pass are 25.0%, 27.8%, 35.3%, 38.1%, 42.3%, and 33.3%, respectively. The rolling speeds for each pass are 150m / min, 180m / min, 200m / min, 240m / min, 240m / min, and 180m / min, respectively. After six passes of precision rolling, the molybdenum alloy strip measures 0.01×410×4380000mm. The overlapping sections at both ends of the final rolled molybdenum alloy sheets are rolled together to form a single unit, becoming part of the strip matrix. There are no weld points or seams within the strip, resulting in uniform dimensions and performance. This eliminates the need for trimming, effectively improving production efficiency and yield, and ensuring the strip can be used in subsequent coil production.

[0075] This invention enables a finishing mill to perform one pass of roughing, online edge trimming (weld trimming), and multi-pass finishing rolling on welded strip coils under constant roll gap. Since the waste edges and welds on both sides do not participate in deformation, there are no weld points or welds in the overlap section. The length of the overlap section after rolling and composite connection can be directly used as part of the finished product without subsequent trimming, which simplifies the processing flow, reduces raw material waste, and improves the yield.

[0076] All parts not disclosed in this invention are prior art, and their specific structures, materials, and working principles will not be described in detail. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for welding and rolling difficult-to-deform thin metal sheets, characterized in that: For metal sheet billets with a thickness of 2mm or more, a 5-13 pass roughing process is first performed on a four-high or six-high roughing mill using a block method. After rolling to a thickness of less than 0.5mm, the metal sheet is not trimmed at the edges, but 50-100mm is trimmed from both ends. Several metal sheets are then lapped and welded together to form a metal strip. This strip is then subjected to a single pass roughing process on a six-high, twelve-high, fourteen-high, or twenty-high finishing mill using a strip method. Simultaneously, edge trimming is performed online on the finishing mill. The roll width of the roughing mill is greater than the width of the metal sheet, with a single-sided difference of a = 15-75 mm, symmetrical on both sides along the longitudinal centerline of the roll, and a total difference of 2a = 30-150 mm. The roll width of the finishing mill is less than the width of the metal sheet before edge trimming after roughing, with a single-sided difference of b = 5-10 mm, symmetrical on both sides along the longitudinal centerline of the roll, and a total difference of 2b = 10-20 mm. Between the 5-13 passes of rough rolling and the 1 pass of strip finishing rolling, several metal sheets are welded into coils as follows: S1. After rough rolling, cut off 50-100mm from each end of several metal plates with single-sided crack defects of 5-20mm in width, i.e., double-sided crack defects with a total width of 10-40mm. Then, overlap them in pairs, with an overlap length s=30-150mm. S2. After the overlap, the two sides of the metal strip overlap section are subjected to laser welding under argon protection in the rolling direction. The width of the continuous welding area of ​​the single-sided crack defect edge is not greater than the width of the defect edge formed by the crack on the single-sided crack defect edge. S3. Several metal plates are welded together into a metal strip by continuous longitudinal welding at the overlapping edges of two metal plates, which is then used in the subsequent production processes of the strip method. During single-pass finishing rolling, the double-sided crack defect edge in S1 and the laser-welded weld defect edge in S2 are controlled to be outside the roll surface width range and do not participate in rolling deformation. At the same time, the two metal plates that participate in deformation within the overlap section s length range and the roll surface width range achieve rolling composite and uniform thickness. The online edge trimming device of the finishing mill symmetrically and completely removes the waste edges on both sides of the metal strip and the laser-welded weld of the overlap section. The single-sided removal amount c≥b and c≥10mm. The width of the metal strip after removal is smaller than the roll surface width of the finishing mill.

2. The method for welding and rolling difficult-to-deform metal thin sheets according to claim 1, characterized in that: Before the metal plates are welded together, the initial roughing reduction rate accounts for 85%-95% of the total roughing reduction rate, and the rolling speed is 10-30m / min; after the metal plates are welded together, the finishing roughing reduction rate accounts for 5%-15% of the total roughing reduction rate, and the rolling speed is 30-60m / min.

3. The method for welding and rolling difficult-to-deform metal thin sheets according to claim 1, characterized in that: The trimming device is installed on the finishing mill production line, located between the main mill and the exit coiler. The trimming device participates in production during the first pass of finishing and roughing rolling, but does not participate in production during subsequent multi-pass reversible finishing rolling.

4. The method for welding and rolling difficult-to-deform metal thin sheets according to claim 1, characterized in that: After the waste edges on both sides of the metal strip and the weld seam of the laser-welded lap section are symmetrically and completely removed, the lap section after composite connection by fine and rough rolling is directly used as part of the product without being removed. The entire metal strip is finely rolled and then goes off the line for subsequent strip annealing and strip cleaning. Then it is put back on the finishing mill for multi-pass continuous strip reversible finishing rolling according to process requirements until the final finished product thickness is reached. The finishing rolling speed is 90-300m / min.

5. The method for welding and rolling difficult-to-deform metal thin sheets according to any one of claims 1-4, characterized in that: The following production process is used before finishing rolling for several difficult-to-deform metal sheets with a target thickness of 0.01-0.5mm: rolling thick slab - surface cleaning - block method rough rolling - overlapping double-sided longitudinal welding and splicing - strip method finish rolling - online strip method edge trimming - strip method annealing - strip method cleaning - finish rolling.

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