WO2020042924A1 - 连铸大方坯平辊和凸辊组合的轻压下方法 - Google Patents

连铸大方坯平辊和凸辊组合的轻压下方法 Download PDF

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Publication number
WO2020042924A1
WO2020042924A1 PCT/CN2019/101037 CN2019101037W WO2020042924A1 WO 2020042924 A1 WO2020042924 A1 WO 2020042924A1 CN 2019101037 W CN2019101037 W CN 2019101037W WO 2020042924 A1 WO2020042924 A1 WO 2020042924A1
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Prior art keywords
convex
roll
slab
reduction
rolls
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PCT/CN2019/101037
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English (en)
French (fr)
Inventor
徐荣军
刘俊江
万根节
李成斌
柳向椿
孟庆玉
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宝山钢铁股份有限公司
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Priority to EP19853592.4A priority Critical patent/EP3845330B1/en
Priority to JP2021510897A priority patent/JP7234347B2/ja
Priority to KR1020217008840A priority patent/KR102417154B1/ko
Priority to US17/271,041 priority patent/US11207729B2/en
Publication of WO2020042924A1 publication Critical patent/WO2020042924A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/20—Controlling or regulating processes or operations for removing cast stock
    • B22D11/201—Controlling or regulating processes or operations for removing cast stock responsive to molten metal level or slag level
    • B22D11/202—Controlling or regulating processes or operations for removing cast stock responsive to molten metal level or slag level by measuring temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
    • B22D11/1287—Rolls; Lubricating, cooling or heating rolls while in use
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/20—Controlling or regulating processes or operations for removing cast stock
    • B22D11/207—Controlling or regulating processes or operations for removing cast stock responsive to thickness of solidified shell

Definitions

  • the invention belongs to the field of metal casting, and particularly relates to a method for post-processing or post-processing a cast billet on site.
  • the application publication number is CN 105983668, and the Chinese invention patent application with an application publication date of 2016.10.05 discloses a "light reduction roll, a light reduction device with the same, and a method for manufacturing a cast slab", whose light reduction
  • the diameter of the end portion of the roller is smaller than the diameter of the middle portion.
  • a light reduction device is also disclosed.
  • the convex roller transition curve is composed of two segments of concave and convex arcs tangent to each other. The radius of the two arcs is different. The convex first arc radius is smaller than the concave second arc radius. The purpose is to reduce the folding defects caused by the depression of the cast slab during the subsequent rolling process.
  • the application publication number is CN 107377919, and the Chinese invention patent application on the application publication date 2017.11.24 discloses a "method for increasing the center density of bearing steel slabs".
  • This technical solution adopts the method of heavy-duty pressing at the solidification end.
  • the technical problem to be solved by the present invention is to provide a light-reduction method for a combination of continuous casting bloom billet flat rolls and convex rolls. It adopts the light reduction method of continuous casting of large billet flat rolls and convex rolls, which uses convex rolls to reduce the reduction force of the drawing straightener and reduce the drawing resistance. Its convex rollers on different drawing and straightening machines use different lengths of bosses.
  • the final indentation shape on the upper surface of the cast slab has wider openings, which can avoid folding defects in the subsequent rolling process, and is more conducive to reducing the pressing force. And it is more conducive to reducing the pressing force of the convex roller tension leveler.
  • the technical solution of the present invention is to provide a method for lightly reducing the combination of continuous casting of bloom billet flat rolls and convex rolls, which comprises successively setting a plurality of drawing and straightening machines on the continuous casting line to perform compression casting on the billet; its characteristics are:
  • model data of solidification heat transfer and liquid phase cavities in continuous bloom casting of billet is based on the continuous casting process and casting slab forming theory.
  • the liquid cavity is calculated by the model, and the three-dimensional temperature field distribution along the casting direction, the thickness of the two-phase region, the solid-phase region, and the solid-phase fraction are calculated according to different steel types, billet speed, cooling conditions, and superheat.
  • model data or model calculation determine the position of the start and end rollers, and associate the model data with each of the drawing and straightening machines on the continuous casting line, so that the Each drawing straightening machine corresponds to the corresponding three-dimensional temperature field distribution of the slab, the thickness of the two-phase region, the thickness of the solid phase region, and the solid phase fraction;
  • Embodiments include obtaining by empirical formula according to the casting conditions;
  • the reduction amount in% is, in one embodiment, a reduction amount of not more than 5 mm.
  • the solid phase fraction when the solid phase fraction is f s ⁇ 0.5, the flat slab is subjected to compression casting using a flat-roller pull straightening machine, and the solid phase fraction f s > 0.5 is adopted.
  • Convex roll tension leveler performs compression casting on the slab.
  • the reduction ratio is the reduction amount divided by the thickness of the slab.
  • the flat roll drawing straightening machine is still used for compression casting of the slab
  • the convex slab is used for compression casting of the slab
  • the light reduction method adopts a light reduction method of a combination of a flat roll drawing straightening machine and a convex roll drawing straightening machine to perform light reduction control on the solidified end of the cast slab to reduce the center looseness, shrinkage and Segregation to improve the internal quality of rolled materials;
  • the light reduction method can reduce the reduction force of the convex-roller stretch straightening machine; at the same time, it reduces the resistance of the slab during the continuous casting process of the slab.
  • the upper roller of the convex roller tensioner is a convex roller and can be raised and lowered to adjust the roll gap, and the convex roller is connected to a motor and a reducer;
  • the lower roller of the convex-roller straightening machine is a flat roller; the upper roller and the lower roller are connected by a frame, and a pressing force is applied to the intermediate casting slab through four pairs of driving hydraulic cylinders.
  • the upper roller is a convex roller and is a driving roller.
  • the lower roller is a flat roller and is a fixed passive roller.
  • the contour curve of the working portion of the convex roller body includes a first straight segment AB, a first transition curve segment BC, a second straight segment CD, and a second straight segment.
  • the transition curve segment DE and the third straight line segment EF are sequentially connected; wherein the first straight line segment AB and the third straight line segment EF are arranged coaxially or in the same plane, and the second straight line segment CD and the first straight line segment AB or the third straight line are formed.
  • the segments EF are arranged in parallel; the first curved segment BC and the second curved segment DE are respectively composed of a sine curve, or are formed by two concave and convex arcs tangent to each other, and the radii of the two arcs are equal or different.
  • the first transition curve section BC, the second straight section CD, and the second transition curve section DE form a convex structure in the form of a boss on the surface of the convex roller.
  • the indentation shape opening on the upper surface of the cast slab is widened, which can avoid folding defects in the subsequent rolling process, and is beneficial to reduce the pressing force and to reduce the convex roll tensioner. Pressing force.
  • the sine curve equation of the BC curve of the first transition curve section of the boss is:
  • the second transition curve DE is mirror-symmetrical to the first transition curve BC; a mirror-symmetric centerline thereof passes through a midpoint of the second straight line CD and is symmetrical to the first
  • the two straight segments CD are straight lines perpendicular to each other.
  • an indentation shape opening generated on the upper surface of the slab It is equal to the length of the second straight segment CD of the convex roller body.
  • the length of the second straight segment CD of the convex roll roll body on each drawing straightening machine depends on the unset point when the continuous casting slab reaches the position of each drawing straightening machine.
  • the width D of the two-phase region depends on the unset point when the continuous casting slab reaches the position of each drawing straightening machine.
  • the length of the second straight segment CD of the convex roller roll body on each of the drawing and straightening machines is ⁇ D + 40 mm.
  • the soft reduction control at the solidification end is used and comprehensively used to reduce the center looseness, shrinkage and segregation of the billet, and improve the rolling material.
  • avoiding the deformation resistance of the slab that has solidified on both sides to avoid large deformation resistance which can reduce the pressing force of the convex roller stretch straightening machine; the friction force is reduced, so the slab casting process Resistance is also reduced;
  • the light reduction is dispersed, and the bosses of different lengths are rolled down. After the light reduction is finished, it is finally cast.
  • the opening of the indentation shape on the upper surface of the billet has a wider opening, which can avoid folding defects in the subsequent rolling process, and is more conducive to reducing the pressing force of the convex roller tensioner.
  • FIG. 1 is a schematic diagram of a calculation process of solidification heat transfer in continuous casting in the present technical scheme
  • FIG. 2 is a schematic diagram of the installation position of the bloom according to the present invention for a light-pressure drawdown straightening machine
  • FIG. 3 is a schematic diagram of the width of the two-phase region at the solidified end of the bloom according to the present invention.
  • FIG. 4 is a schematic view of pressing down of a convex roll of a bloom billet straightening machine according to the present invention
  • FIG. 5 is a schematic diagram of the outline shape of a convex roll
  • FIG. 6 is a schematic diagram of an indentation shape on an upper surface of a cast slab.
  • finite element calculations can be used to simulate the three-dimensional temperature field distribution, the thickness of the two-phase region, and the solid-phase region of different steel grades, drawing speeds, cooling conditions, and superheat degrees when casting slabs to each drawing and straightening machine. And solid phase fraction.
  • Fig. 1 is a flow block diagram of the calculation of solidification heat transfer in continuous casting.
  • start is the start of calculation
  • input parameter is the input of the physical parameters of the steel, steel type, billet speed, superheat degree, etc .
  • Finding the water volume database is to find the cooling water volume of each cooling circuit in each cooling zone
  • Initial slice is the initialization of the slice at the beginning of the finite element slice calculation
  • Record (update) slice time and position is the record (update) slice formation time and arrival position
  • “Judgment point position” is to judge the cut The point is in the crystallizer or in the second cooling zone.
  • the crystallizer calculates the heat flow of the crystallizer; for example, in the "second cold zone”, calculate the heat flow of the second cooling zone. If the "second cold zone” is not water-cooled, then Air-cooled zone, calculate the heat flow of air-cooled zone; "Judging node phase zone”, judging whether the node is in "Liquid phase zone”, “Two-phase zone”, “Solid-phase zone”; "Center”, “Inner” and “Surface” of the slab; "Calculate the temperature of the slice” is to calculate the temperature value of each slice; "Output result” is the output, the three-dimensional temperature distribution of the slab, the thickness of the two-phase region, and the solid-phase region thick Degree, solid phase fraction and other calculation results.
  • n the total number of drawing straightening machines on a continuous casting line
  • the arrows in the figure indicate the direction of the continuous casting process route, that is, the forward direction of the slab.
  • the hatched part in the figure is the schematic of the solid phase region
  • the blank region is the schematic of the two phase region
  • D is the width of the two phase region
  • the arrow indicates the continuous casting process.
  • the direction of the route that is, the forward direction of the slab.
  • the drawing straightening machine that is far from the solidification end (that is, the front drawing straightening machine, whose number i is small, can be selected as an i value between 1-4). High, the required light reduction force is small, which can meet the requirements of light reduction.
  • the drawing straightening machine that is closer to the solidification end (that is, the rear drawing straightening machine, whose number i is larger, can be selected as the value of i in 5- Between 8) Due to the thickness of the shell, the temperature of the cast slab is low, and the required light reduction force is large, which cannot meet the requirements of light reduction.
  • the technical solution of the present invention adopts a light reduction method of a combination of a flat roll and a convex roll, and a flat roll solution is still adopted for the front-end drawing and straightening machine, and a convex roll solution is adopted for the rear-end drawing and straightening machine.
  • a convex roll solution is adopted for the rear-end drawing and straightening machine.
  • the boundary between the front-end draw straightening machine and the rear-end draw straightening machine is usually related to f s .
  • the inventor recommends that when the solid phase fraction of the slab is f s ⁇ 0.5, the flat slab is used for compression casting of the slab.
  • the phase fraction f s > 0.5 is used for compression casting of the slab by using a convex roll tensioner.
  • FIG 4 shows a schematic diagram of a convex roller tension leveler.
  • the upper roller 1 is a convex roller, which is a driving roller, and can be raised and lowered to adjust the roll gap, which is connected to the motor and the reducer.
  • the lower roller 3 is a flat roller.
  • the passive rollers are fixed, the upper and lower rollers are connected by a frame, and the middle casting slab is pressed by four pairs of driving hydraulic cylinders.
  • the cast slab 2 Located between the upper and lower rolls is the cast slab 2.
  • FIG. 5 is a schematic structural diagram of a convex roller shape of a convex roller drawing straightener in the present technical solution.
  • the contour curve of the working part of the convex roller (referred to as a convex roller) is defined by a first straight line segment. AB, a first transition curve section BC, a second straight section CD, a second transition curve section DE, and a third straight section EF.
  • the first transition curve segment BC and the second transition curve segment DE are composed of a sine curve, or are two concave and convex arc lines tangent to each other and adjacent straight line segments, and the radii of the two arcs Equal or unequal.
  • first transition curve section BC, the second straight section CD and the second transition curve section DE form a protrusion in the form of a boss on the surface of the convex roller.
  • point B is used as a coordinate origin
  • the x-axis is parallel to the central axis of the roller
  • the y-axis is perpendicular to the central axis of the roller.
  • the sine curve equation of the first transition curve segment BC is:
  • H is the height of the boss.
  • n is the projected length of the first transition curve section BC of the boss on the axis.
  • n is a multiple of the height H of the boss, that is, the projection length of the first transition curve section BC of the boss on the axis is nH.
  • the second transition curve DE can be formed by mirroring the first transition curve BC along the midpoint of the line segment CD as the center line.
  • the length of the second straight segment CD in the middle of the convex roll body depends on the width D of the uncondensed two-phase region when the continuous casting slab in FIG. 3 reaches the position of each drawing straightener.
  • the length of the second straight section (also called the middle straight section) CD of each convex roller is also different according to the position of the drawing and straightening machine. different.
  • the length of the second straight segment CDi of the convex roller corresponding to each drawing straightening machine should be greater than or equal to the casting billet to each drawing straightening
  • the length of the second straight section CDi of the corresponding convex roller should be greater than the uncondensed two-phase area when the billet reaches the position of each drawing straightening machine Width Di.
  • the casting slab will deviate from the center of the casting flow (referred to as deflection) during the downward drawing of the slab, the smaller deflection does not have much impact on the flat-roller drawing and straightening machine.
  • the uncondensed two-phase region portion in the center of the slab but it is required that the protruding portion of the convex roller (that is, the aforementioned boss) can also be pressed on the uncondensed two-phase region portion in the center of the slab.
  • the height H of the boss is determined based on the total shrinkage and linear shrinkage of the solidification volume in all the stretcher-reduction sections. Considering the generality, it is 30% larger than the theoretical calculation.
  • FIG. 6 shows the shape of the indentation on the upper surface of the slab after the light reduction is finished by using the boss reduction rollers of different lengths.
  • the opening of the indentation T becomes wider (to be precise, it should be upward from the bottom of the opening and gradually widen, which is approximately an inverted equilateral trapezoid), which can avoid folding defects in the subsequent rolling process, and is more conducive to Reduce the pressing force of the convex roller tensioner.
  • the light reduction method of continuous casting of large billet flat rolls and convex rolls is used to perform soft reduction control at the solidification end to comprehensively reduce the looseness, shrinkage and segregation of the center of the cast billet, and improve the interior of the rolled material. quality.
  • the slab has a large volume shrinkage during the slab solidification process, so a larger reduction is required to compensate for the slab volume shrinkage.
  • the slab will have deformation resistance, which is mainly concentrated on both sides On the solidified shell.
  • the light-reduction method of the combination of continuous-casting square billet flat rolls and convex rolls avoids the large deformation resistance of the solidified blank shells on both sides, and can reduce the pressing force of the convex-roller straightening machine.
  • the contact area between the convex roller and the slab is small, the friction force is reduced, so the slab continuous casting process is drawn. Billet resistance is also reduced.
  • the light reduction method of the combination of the flat roll and the convex roll of the present invention is not to complete the light reduction on a single convex roll using a large reduction amount, but to disperse the reduction.
  • the opening of the indentation shape finally formed on the upper surface of the cast slab has a wider opening, which can avoid folding defects in the subsequent rolling process, and is more conducive to reducing the pressing force of the convex roller tensioner.
  • the model calculates the solidification heat transfer and liquid phase cavities of the continuous bloom casting, and calculates the slab to each unit according to different steel types, drawing speed, cooling conditions and superheat.
  • the three-dimensional temperature field distribution, the thickness of the two-phase region, the thickness of the solid phase region, and the solid-phase fraction when pulling the straightening machine part Then, based on the model calculation, determine the position of the start and end rollers, and compare them with the continuous casting line. Corresponding to each pull straightening machine, the following results were obtained:
  • Pull straightening machine No. 1-5 install flat roll, roll work roll length is 500mm, roll diameter is 500mm.
  • the stretch straightening machine No. 6 is a convex roller.
  • the length of the roll work roll is 500 mm
  • the roll diameter is 500 mm
  • the straight ends of the two ends ie, the first and third straight sections described above are the same below.
  • the middle straight section ie the aforementioned second straight section, the same below
  • the transition curves BC and DE ie the aforementioned first transition curve BC and the second transition curve DE, the same below
  • the projection length is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • Pull straightening machine No. 1-5 install flat roll, roll work roll length is 500mm, roll diameter is 500mm.
  • the draw straightening machine No. 6 is a convex roll.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the drawing straightening machine No. 9 is a convex roll.
  • the length of the roll work roll is 500mm
  • the roll diameter is 500mm
  • the length of the middle straight line is 190mm
  • the transition curves are BC and DE.
  • the projection length in the horizontal direction is 40mm.
  • the rest is the same as in the first embodiment.
  • Pull straightening machine No. 1-5 install flat roll, roll work roll length is 500mm, roll diameter is 500mm.
  • the draw straightening machine No. 6 is a convex roll.
  • the length of the roll work roll is 500 mm
  • the roll diameter is 500 mm
  • the length of the middle straight section is 240 mm
  • the transition curve BC and The projection length of DE in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the straightening machine No. 9 is equipped with a flat roll.
  • the length of the roll work roll is 500mm and the roll diameter is 500mm.
  • the rest is the same as in the first embodiment.
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • Pull straightening machine No. 1-4 install flat roll, roll work roll length is 500mm, roll diameter is 500mm.
  • the drawing straightening machine No. 5 is a convex roll.
  • the length of the roll work roll is 500mm
  • the roll diameter is 500mm
  • the length of the middle straight line is 250mm
  • the transition curves are BC and DE.
  • the projection length in the horizontal direction is 40mm.
  • the draw straightening machine No. 6 is a convex roll.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the projection length in the horizontal direction is 40mm.
  • the straightening machine No. 9 is equipped with a flat roll.
  • the length of the roll work roll is 500mm and the roll diameter is 500mm.
  • the rest is the same as in the first embodiment.
  • the three-dimensional temperature field distribution and two-phase area of the slab to each drawing and straightening machine part are calculated.
  • the technical solution of the present invention adopts a light reduction method of a combination of continuous casting of bloom billet flat rolls and convex rolls, which avoids the large deformation resistance of the solidified blank shells on both sides, and can reduce the reduction of the convex roll tensioner. force.
  • f s 0.9-1.0
  • the invention can be widely used in the field of metal casting.

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Abstract

一种连铸大方坯平辊和凸辊组合的轻压下方法，首先获得铸坯的三维温度场分布、两相区、固相区厚度和固相分率，确定压下起始和结束辊子的位置，根据铸坯的体积收缩量，制定每个拉矫机辊子的压下量；在铸坯固相分率f s＝0.9-1.0区间，实施重压下工作模式；在铸坯固相分率f s＝0.25-0.80区间，实施轻压下工作模式。

Description

连铸大方坯平辊和凸辊组合的轻压下方法 技术领域
本发明属于金属铸造领域，尤其涉及一种用于在现场对铸造坯料进行后处理或后加工的方法。
背景技术
钢的连铸过程中，由于外部冷却的原因，铸坯表面比内部先凝固，因此表面比内部有更大的收缩，随着凝固结晶结束，某些局部区两边柱状晶搭桥，当桥下面包围的液体凝固时，阻止了液相穴内桥上部的钢水补充，如此桥下面钢水凝固时缩孔和疏松就产生了，伴随着缩孔和疏松的形成，真空的缩孔会抽吸枝晶间富集溶质的液体向中心流动，同时宏观偏析就产生了。
由于轻压下相当于压缩铸造，它有同时消除缩孔、疏松和宏观偏析的作用，因此铸坯的平辊轻压下技术在连铸领域得到了广泛应用。
因为铸坯表面比内部先凝固，越接近凝固末端铸坯坯壳越厚、温度越低，由于坯壳的两侧已经全部凝固，压下过程越接近凝固末端变形抗力越大，现有的技术都是采用一对平辊进行压缩，由于拉矫机互换的缘故，都做成一样的，那么压下力也是一样的，这造成前端拉矫机压力富裕后端拉矫机压力不足。随着高合金钢的生产越来越多，这一矛盾越发突出。采用凸辊进行在未凝固的部位进行更有效的轻压下技术被提出了。
申请公布号为CN 105983668 A，申请公布日为2016.10.05的中国发明专利申请，公开了一种“轻压下辊、具有其的轻压下装置及铸坯的制造方法”，其轻压下辊的端部的直径比中间部的直径小，其中，在观察轻压下辊的包含旋转轴线的截面时，中间部与端部之间的外周在端部侧具有朝向旋转轴线鼓出的第1圆弧、在中间部侧具有朝向与第1圆弧的鼓出方向相反的方向鼓出的第2圆弧，与第1圆弧和第2圆弧这两者相切的切线和旋转轴线所成的角度为40°以下。该技术方案采用恒定曲率无凸台凸型辊(鼓型辊)安装在固相率0.2的位置实施大的压下量，渐变曲率有凸台凸型辊处在凝固终点的位置，仅在中心固相率0.2的位置点与 凝固终点两个位置依次采用大变形量压下用以解决化学成分偏析与凝固中心缩孔及严重疏松质量缺陷。但是，根据铸坯的凝固原理，轻压下相当于压缩铸造，其压下量用于弥补当前钢水的收缩量，用以限制枝晶间富集低熔点杂质的钢水向中心流动，过大的压下量并不利于凝固偏析的改善。
在上述中国发明专利申请中，还公开了一种轻压下装置，其凸辊过渡曲线由彼此相切的两段内凹外凸的圆弧线构成，两个圆弧的半径不等，通常外凸的第1圆弧半径小于内凹的的第2圆弧半径，其目的为了减少后工序轧钢过程中铸坯凹陷出产生折叠缺陷。
申请公布号为CN 107377919 A，申请公布日2017.11.24的中国发明专利申请，公开了一种“提高轴承钢铸坯中心致密度的方法”，其在连铸过程中，控制铸机拉速为0.50m/min～0.65m/min，控制中间包钢液的过热度20℃～30℃，采用凝固末端重压下方式，轻压下与重压下按分配固相率进行，重压下从fs＝0.9时开始，在fs＝l.0时使用凸型辊进行重压下。本技术方案采用凝固末端重压下方式，在fs＝0.9-1.0时使用单个凸型辊进行重压下，用以减少缩孔。但是其未涉及到如何进行轻压下的问题。
发明内容
本发明所要解决的技术问题是提供一种连铸大方坯平辊和凸辊组合的轻压下方法。其通过连铸大方坯平辊和凸辊组合的轻压下方法，使用凸辊部分减低了拉矫机的压下力，减少拉坯阻力。其在不同拉矫机上凸辊采用不同长度的凸台，最终在铸坯上表面产生的压痕形状其开口变宽，可避免后工序轧钢过程产生折叠缺陷，且更有利于减轻压下力，且更有利于减轻凸辊拉矫机的压下力。
本发明的技术方案是：提供一种连铸大方坯平辊和凸辊组合的轻压下方法，包括在连铸线上依次设置多台拉矫机对铸坯进行压缩铸造；其特征是：
1)获取铸坯的大方坯连铸凝固传热与液相穴的模型数据，获取该模型数据的一种实施方式是根据连铸工艺、铸坯成型理论，对大方坯连铸凝固传热与液相穴进行模型计算，根据不同钢种、拉坯速度、冷却条件、过热度下，计算出沿浇铸方向的三维温度场分布、两相区、固相区厚度和固相分率；
2)根据所述模型数据或者模型计算，确定压下起始和结束辊子的位置，并将所述模型数据与位于连铸线上的各台拉矫机对应起来，以使连铸线上的各台拉矫机对应铸坯相应的三维温度场分布、两相区、固相区厚度和固相分率；
3)获取铸坯的体积收缩量，根据该体积收缩量，制定每个拉矫机辊子的压下量，获取铸坯的体积收缩量的实施方式包括根据铸造条件通过经验公式获取；
并且在步骤3)中，在铸坯的固相分率f s＝0.9到1.0区间，对铸坯实施重压下工作模式，即当固相分率在f s＝0.9-1.0时，采用凸辊拉矫机对铸坯进行压缩铸造，各台拉矫机进行单辊压下率为1％-10％的压下量，在一个实施方式中，为最大单辊10mm的压下量；此外，在步骤3)中，在铸坯的固相分率f s＝0.25到0.80区间，对铸坯实施轻压下工作模式，相应的各台拉矫机进行单辊压下率为不大于2％的压下量，在一个实施方式中其不大于5mm的压下量。
在所述轻压下方法的一个或多个实施方式中，当固相分率在f s≤0.5时，采用平辊拉矫机对铸坯进行压缩铸造，固相分率f s>0.5采用凸辊拉矫机对铸坯进行压缩铸造。
压下率为压下量除以铸坯厚度。
根据前述方案，对于距离凝固末端较远的前端拉矫机，仍采用平辊拉矫机对铸坯进行压缩铸造；
对于距离凝固末端较近的后端拉矫机，采用凸辊拉矫机对铸坯进行压缩铸造；
所述的轻压下方法，采用平辊拉矫机和凸辊拉矫机组合的轻压下方法，对铸坯进行凝固末端的轻压下控制，以降低铸坯的中心疏松、缩孔与偏析，改善轧材内部质量；
所述的轻压下方法，能减轻凸辊拉矫机的压下力；同时减少铸坯连铸过程的拉坯阻力。
在所述轻压下方法的一个或多个实施方式中，所述凸辊拉矫机的上辊为凸辊，并可升降来调节辊缝，所述的凸辊与电机和减速机相连；所述凸辊拉矫机的下辊为平辊；所述的上辊、下辊由框架相连，通过四对驱动液压油缸对中间铸坯施加压下力。
在所述轻压下方法的一个或多个实施方式中，所述的上辊为凸辊，且为驱动辊。所述的下辊为平辊，且为固定不动的被动辊。
在所述轻压下方法的一个或多个实施方式中，所述凸辊辊身工作部分的轮廓曲线，由第一直线段AB、第一过渡曲线段BC、第二直线段CD、第二过渡曲线段DE和第三直线段EF依次连接构成；其中，第一直线段AB和第三直线段EF同轴线或同平面设置，第二直线段CD与第一直线段AB或第三直线段EF平行设置；第一曲线段BC和第二曲线段DE分别由正弦曲线构成，或为彼此相切的两段内凹外凸的圆弧线构成，两个圆弧的半径相等或不等；对于凸辊轴长方向的截面而言，第一过渡曲线段BC、第二直线段CD和第二过渡曲线段DE，在凸辊的表面构成一个凸台形式的凸起结构。
采用所述的轻压下方法，使得铸坯上表面产生的压痕形状开口变宽，能避免后工序轧钢过程产生折叠缺陷，且有利于减轻压下力，更有利于减轻凸辊拉矫机的压下力。
在所述轻压下方法的一个或多个实施方式中，所述凸台的第一过渡曲线段BC曲线正弦曲线方程为：
y＝H sin(x*π/2nH)；
式中：H为凸台高度；n为凸台的第一过渡曲线段BC在轴上的投影长度。
在所述轻压下方法的一个或多个实施方式中，所述第二过渡曲线DE与第一过渡曲线BC镜像对称；其镜像对称中心线为通过第二直线段CD的中点且与第二直线段CD相垂直的直线。
在所述轻压下方法的一个或多个实施方式中，在铸坯的固相分率＝0.25到0.80区间内，对每台拉矫机而言，铸坯上表面产生的压痕形状开口等于凸辊辊身第二直线段CD的长度。
在所述轻压下方法的一个或多个实施方式中，所述每台拉矫机上凸辊辊身第二直线段CD的长度，取决于连铸坯到每台拉矫机位置时未凝两相区的宽度D。
在所述轻压下方法的一个或多个实施方式中，所述每台拉矫机上凸辊辊身第二直线段CD的长度≥D+40mm。
与现有技术比较，本发明的优点是：
1.根据一些实施方式，通过连铸大方坯平辊和凸辊组合的轻压下方法，进行凝固末端轻压下控制、综合运用来降低铸坯的中心疏松、缩孔与偏析，改善轧材内部质量；
2.根据一些实施方式，避开了两侧已经凝固的坯壳产生较大的变形抗力，可减轻凸辊拉矫机的压下力；摩擦力减小，因此铸坯连铸过程的拉坯阻力也减少；
3.根据一些实施方式，不是把轻压下在单一凸辊上使用大的压下量完成，而是分散压下，并且不同长度凸台压下辊，在轻压下结束后，最终在铸坯上表面产生的压痕形状其开口变宽，可避免后工序轧钢过程产生折叠缺陷，且更有利于减轻凸辊拉矫机的压下力。
附图说明
图1是本技术方案中连铸凝固传热计算流程示意图；
图2是本发明大方坯用于轻压下拉矫机的安装位置示意图；
图3是本发明大方坯凝固末端两相区宽度示意图；
图4是本发明大方坯拉矫机凸辊压下示意图；
图5是凸型轧辊的轮廓形状示意图；
图6是铸坯上表面的压痕形状示意图。
具体实施方式
下面结合附图和实施例对本发明做进一步说明。
图1中，首先，根据目前现有的连铸工艺、铸坯成型理论对大方坯连铸凝固传热与液相穴进行模型计算：
根据凝固传热方程：
Figure PCTCN2019101037-appb-000001
给定初始条件：
T| 0＝T(x,y,z,0)     (2)
边界条件：
一类边界条件：
T| w＝T w＝T w(t)       (3)
二类边界条件：
Figure PCTCN2019101037-appb-000002
三类边界条件：
Figure PCTCN2019101037-appb-000003
代入钢的物性参数，可用有限元计算模拟出不同钢种、拉坯速度、冷却条件、过热度下铸坯到每台拉矫机部位时的三维温度场分布、两相区、固相区厚度和固相分率。
图1为连铸凝固传热计算的流程框图。其中，“开始”为计算开始；“输入参数”，为输入钢的物性参数，钢种、拉坯速度、过热度等；“查找水量数据库”，为查找各冷却区各冷却回路的冷却水量；“初始化切片”为有限元切片计算开始时对切片初始化；“记录(更新)切片的时间和位置”为记录(更新)切片形成的时间和到达的位置；“判断切点位置”，为判断切点是在结晶器内或是在二冷区；如在“结晶器”内，计算结晶器的热流；如在“二冷区”计算二冷各区的热流，如果“二冷区”没有水冷即空冷区，计算空冷区的的热流；“判断节点相区”，判断节点是在“液相区”、“两相区”、“固相区”；“判断切点位置”同时判断节点是在铸坯“中心”、“内部”、“表面”；“求切片的温度”为计算各切片的温度值；“输出结果”为输出、铸坯三维温度分布、两相区的厚度、固相区厚度、固相分率等计算结果。
图2中，给出了每台拉矫机(i＝1至n，n为一条连铸线上拉矫机的总数量)在连铸线上的部位或位置。
图中箭头表示连铸工艺路线的方向，亦即铸坯的前进方向。
图3中，给出了铸坯的两相区及固相区厚度。
图中阴影线填充的部分为固相区的示意，空白区为两相区的示意，D为两相区的宽度示意，P为f s＝0.25到0.80的压下区间，箭头表示连铸工艺路线的方向， 亦即铸坯的前进方向。
根据图3的计算结果，距离凝固末端较远的拉矫机(即前端拉矫机，其编号i较小，可选定为i值在1-4之间)由于坯壳薄，铸坯温度高，需要的轻压下力小，可满足轻压下的要求，距离凝固末端较近的拉矫机(即后端拉矫机，其编号i较大，可选定为i值在5-8之间)由于坯壳厚，铸坯温度低，需要的轻压下力大，无法满足轻压下的要求。
因此本发明的技术方案采用平辊和凸辊组合的轻压下方法，对于前端拉矫机仍采用平辊方案，而对于后端拉矫机，则采用凸辊方案。尤其对已有的连铸机由于后端拉矫机压下能力不足，采用这种组合方案进行轻压下是非常合适的。前端拉矫机和后端拉矫机的界限通常与f s有关，发明人推荐当铸坯的固相分率在f s≤0.5时，采用平辊拉矫机对铸坯进行压缩铸造，固相分率f s>0.5采用凸辊拉矫机对铸坯进行压缩铸造。
图4中，给出了凸辊拉矫机的示意图，上辊1为凸辊，且为驱动辊，并可升降来调节辊缝，与电机和减速机相连；下辊3为平辊，为固定不动的被动辊，上下辊由框架相连，通过四对驱动液压油缸对中间铸坯施加压下力。
位于上辊和下辊之间的即为铸坯2。
图5中，给出了本技术方案中凸辊拉矫机凸辊形状的结构示意图，由图可知，所述凸形辊(简称凸辊)辊身工作部分的轮廓曲线，由第一直线段AB、第一过渡曲线段BC、第二直线段CD、第二过渡曲线段DE和第三直线段EF构成。
其中，第一过渡曲线段BC和第二过渡曲线段DE由正弦曲线构成，或为彼此与相邻的直线段相切的两段内凹外凸的圆弧线构成，两个圆弧的半径相等或不等。
明显的，对于每个凸辊轴长方向的纵向截面而言，第一过渡曲线段BC、第二直线段CD和第二过渡曲线段DE，在凸辊的表面构成一个凸台形式的凸起结构4。
图5的坐标系中以B点为坐标原点，x轴平行于辊子中心轴，y轴垂直于辊子中心轴线。
所述第一过渡曲线段BC的正弦曲线方程为：
y＝Hsin(x*π/2nH)
式中：H为凸台高度。n为凸台的第一过渡曲线段BC在轴上的投影长度。
n是凸台高度H的倍数，即凸台的第一过渡曲线段BC在轴上的投影长度为nH。
第二过渡曲线DE可用第一过渡曲线BC沿着线段CD的中点作为中心线镜像形成。
特别指出的是，凸辊辊身中间的第二直线段CD的长度取决于图3中连铸坯到每台拉矫机位置时的未凝两相区宽度D。
由于铸坯到各台拉矫机位置时的未凝两相区宽度D不相同，因此根据拉矫机位置的不同，各个凸辊的第二直线段(亦称中间直线段)CD的长度也不同。
理论上各台拉矫机所对应的凸辊的第二直线段的长度CDi(其中的i＝各台拉矫机在连铸线上的位置编号)，应大于等于铸坯到每台拉矫机位置时的未凝两相区宽度Di(其中的i＝各台拉矫机在连铸线上的位置编号)，由于不同铸造速度、钢种、过热度、冷却强度，其Di值会发生变化，考虑到通用性的原因，实际上对每台拉矫机而言，其对应凸辊的第二直线段CDi的长应大于铸坯到每台拉矫机位置时的未凝两相区宽度Di。再考虑到铸坯在向下拉坯过程中，铸坯会偏离铸流中心线(称之为偏流)，较小的偏流对平辊拉矫机没有太大影响，由于平辊总能压到铸坯中心的未凝两相区部分，但要求凸辊的突出部分(即前述的凸台)也能压在铸坯中心的未凝两相区部分。
综合考虑，对每台拉矫机i而言，对应凸辊推荐的第二直线段CDi的长度≥Di+40mm(其中的i＝各台拉矫机在连铸线上的位置编号)。
凸台高度H的确定根据所有拉矫机压下区间的凝固体积总收缩和线收缩来决定，考虑到通用性，它比理论计算值大30％。
图6为采用不同长度凸台压下辊，在轻压下结束后，最终在铸坯上表面产生的压痕形状。
明显地，压痕T的开口变宽(准确地说应该是自开口底部向上，呈渐宽趋势，近似是一个倒置的等边梯形)，可避免后工序轧钢过程产生折叠缺陷，且更有利于减轻凸辊拉矫机的压下力。
本发明的技术方案，通过连铸大方坯平辊和凸辊组合的轻压下方法，进行凝 固末端轻压下控制、综合运用来降低铸坯的中心疏松、缩孔与偏析，改善轧材内部质量。
铸坯在铸坯凝固过程中会产生很大的体积收缩，所以需要更大的压下量来补偿铸坯体积收缩，在压下过程中，铸坯会产生变形抗力，其主要集中在两侧已经凝固的坯壳上。
本发明连铸大方坯平辊和凸辊组合的轻压下方法，避开了两侧已经凝固的坯壳产生较大的变形抗力，可减轻凸辊拉矫机的压下力。能够对铸坯的凝固末端当f s＝0.9-1.0实施重压下，提高铸坯中心致密度，同时由于凸辊与铸坯接触面积小，摩擦力减小，因此铸坯连铸过程的拉坯阻力也减少。
同时，本发明的平辊和凸辊组合的轻压下方法不是把轻压下在单一凸辊上使用大的压下量完成而是分散压下，并且不同长度凸台压下辊，在轻压下结束后，最终在铸坯上表面产生的压痕形状其开口变宽，可避免后工序轧钢过程产生折叠缺陷，且更有利于减轻凸辊拉矫机的压下力。
实施例：
实施例一：
沿连铸线工艺前进方向上，依次设置有9台拉矫机，各台拉矫机的编号依次为1号至9号。
首先根据连铸工艺、铸坯成型理论，对大方坯连铸凝固传热与液相穴进行模型计算，根据不同钢种、拉坯速度、冷却条件、过热度下，计算出铸坯到每台拉矫机部位时的三维温度场分布、两相区、固相区厚度和固相分率；然后，根据模型计算，确定压下起始和结束辊子的位置，并与位于连铸线上的各台拉矫机对应起来，得到如下结果：
1-5号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
6号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段(即前述的第一和第三直线段，下同)长度AB＝EF＝90mm，中间直线段(即前述的第二直线段，下同)CD长度240mm，过渡曲线BC和DE(即前述的第一过渡曲线BC和第二过渡曲线DE，下同)在水平方向上的投影长 40mm。
7号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝105mm，中间直线段CD长度210mm，过渡曲线BC和DE在水平方向上的投影长40mm。
8号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝120mm，中间直线段CD长度180mm，过渡曲线BC和DE在水平方向上的投影长40mm。
9号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝135mm，中间直线段CD长度150mm，过渡曲线BC和DE在水平方向上的投影长40mm。
实施例二：
1-5号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
6号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝85mm，中间直线段CD长度250mm，过渡曲线BC和DE在水平方向上的投影长40mm。
7号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝95mm，中间直线段CD长度230mm，过渡曲线BC和DE在水平方向上的投影长40mm。
8号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝105mm，中间直线段CD长度210mm，过渡曲线BC和DE在水平方向上的投影长40mm。
9号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝115mm，中间直线段CD长度190mm，过渡曲线BC和DE在水平方向上的投影长40mm。
其余同实施例一。
实施例三：
1-5号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
6号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20 mm，两端直线段长度AB＝EF＝90mm，中间直线段CD长度240mm，过渡曲线BC和DE在水平方向上的投影长40mm。
7号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝105mm，中间直线段CD长度210mm，过渡曲线BC和DE在水平方向上的投影长40mm。
8号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝120mm，中间直线段CD长度180mm，过渡曲线BC和DE在水平方向上的投影长40mm。
9号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
其余同实施例一。
实施例四：
1-4号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
5号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝85mm，中间直线段CD长度250mm，过渡曲线BC和DE在水平方向上的投影长40mm。
6号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝95mm，中间直线段CD长度230mm，过渡曲线BC和DE在水平方向上的投影长40mm。
7号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝105mm，中间直线段CD长度210mm，过渡曲线BC和DE在水平方向上的投影长40mm。
8号拉矫机为凸辊，轧辊工作辊身长度500mm，辊径500mm，凸台高度H＝20mm，两端直线段长度AB＝EF＝115mm，中间直线段CD长度190mm，过渡曲线BC和DE在水平方向上的投影长40mm。
9号拉矫机，安装平辊，轧辊工作辊身长度500mm，辊径500mm。
其余同实施例一。
综上，实施本发明时，首先按照本发明的方法根据不同钢种、拉坯速度、冷 却条件、过热度下，计算出铸坯到每台拉矫机部位的三维温度场分布、两相区、固相区厚度和固相分率f s，轻压下区间从f s＝0.25到0.80结束，根据模型计算确定压下起始和结束辊子的位置，根据体积收缩量，制定每个辊子的压下量，当铸坯进入压下区间后，进行单辊不大于5mm的压下量，当f s＝0.9-1.0时可进行最大单辊10mm的压下量。
本发明的技术方案，采用连铸大方坯平辊和凸辊组合的轻压下方法，避开了两侧已经凝固的坯壳产生较大的变形抗力，可减轻凸辊拉矫机的压下力。能够对铸坯的凝固末端当f s＝0.9-1.0实施重压下，提高铸坯中心致密度，同时由于凸辊与铸坯接触面积小，摩擦力减小，因此铸坯连铸过程的拉坯阻力也减少。
本发明可广泛用于金属铸造领域。

Claims (13)

  1. 一种连铸大方坯平辊和凸辊组合的轻压下方法，包括在连铸线上依次设置多台拉矫机对铸坯进行压缩铸造；其特征是：
    根据铸坯成型的钢种种类、拉坯速度、冷却条件、过热度，获取铸坯的大方坯连铸凝固传热与液相穴的模型数据，包括沿浇铸方向的三维温度场分布、两相区、固相区厚度和固相分率f s；
    根据所述模型数据，确定压下起始和结束辊子的位置，并将所述模型数据与位于连铸线上的各台拉矫机对应起来；
    获取根据铸坯的体积收缩量，根据所述体积收缩量，制定每个拉矫机辊子的压下量，并且当铸坯的固相分率在f s＝0.9到1.0区间，对铸坯实施重压下工作模式，相应的各台拉矫机进行单辊压下率为1％到10％的压下量；
    当铸坯的固相分率在f s＝0.25到0.80区间，对铸坯实施轻压下工作模式，相应的各台拉矫机进行单辊压下率不大于2％的压下量；
    其中，所述多台拉矫机分为前端拉矫机和后端拉矫机，所述后端拉矫机相对于所述前端拉矫机更靠近铸坯的凝固末端，所述后端拉矫机为凸辊拉矫机，所述前端拉矫机为平辊拉矫机。
  2. 按照权利要求1所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是，当铸坯的固相分率在f s≤0.5时，采用平辊拉矫机对铸坯进行压缩铸造，固相分率f s>0.5采用凸辊拉矫机对铸坯进行压缩铸造。
  3. 按照权利要求1所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述凸辊拉矫机的上辊为凸辊，并可升降来调节辊缝，所述凸辊与电机和减速机相连；
    所述凸辊拉矫机的下辊为平辊；
    所述上辊、所述下辊由框架相连，通过四对驱动液压油缸对中间铸坯施加压下力。
  4. 按照权利要求3所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述上辊为凸辊，且为驱动辊。
  5. 按照权利要求3所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征 是所述下辊为平辊，且为固定不动的被动辊。
  6. 按照权利要求3所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述凸辊的辊身工作部分的轮廓曲线，由第一直线段(AB)、第一过渡曲线段(BC)、第二直线段(CD)、第二过渡曲线段(DE)和第三直线段(EF)依次连接构成；
    其中，第一直线段(AB)和第三直线段(EF)同轴线或同平面设置，第二直线段(CD)与第一直线段(AB)或第三直线段(EF)平行设置；
    第一过渡曲线段(BC)和第二过渡曲线段(DE)分别由正弦曲线构成，或为两段内凹外凸的圆弧线构成，两个圆弧的半径相等或不等；
    对于凸辊轴长方向的截面而言，第一过渡曲线段(BC)、第二直线段(CD)和第二过渡曲线段(DE)，在凸辊的表面构成一个凸台形式的凸起结构。
  7. 按照权利要求6所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述凸台的所述第一过渡曲线段(BC)为由正弦曲线构成时，正弦曲线方程为：
    y＝Hsin(x*π/2nH)；
    式中：H为凸台高度；n为凸台的第一过渡曲线段(BC)在x轴上的投影长度。
  8. 按照权利要求6或7所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述第二过渡曲线(DE)与第一过渡曲线(BC)镜像对称；其镜像对称中心线为通过所述第二直线段(CD)的中点且与所述第二直线段(CD)相垂直的直线。
  9. 按照权利要求6所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是在铸坯的固相分率f s＝0.25到0.80区间内，对每台拉矫机而言，铸坯上表面产生的压痕形状开口等于凸辊辊身第二直线段(CD)的长度。
  10. 按照权利要求6所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是每台所述拉矫机的所述凸辊的辊身第二直线段(CD)的长度，取决于铸坯到每台拉矫机位置时未凝两相区的宽度(D)。
  11. 按照权利要求10所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是所述每台拉矫机的所述凸辊的辊身第二直线段(CD)的长度≥D+40mm。
  12. 按照权利要求1所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特征是，所述模型数据的获取是根据连铸工艺、铸坯成型理论，对大方坯连铸凝固传热与液相穴进行模型计算，根据不同钢种、拉坯速度、冷却条件、过热度下，计算出铸坯到每台拉矫机部位时的三维温度场分布、两相区、固相区厚度和固相分率f s。
  13. 按照权利要求1所述的连铸大方坯平辊和凸辊组合的轻压下方法，其特 征是，对铸坯实施重压下工作模式的各台拉矫机进行最大单辊10mm的压下量；对铸坯实施轻压下工作模式的各台拉矫机进行单辊不大于5mm的压下量。
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CN110871265A (zh) 2020-03-10
US20210323052A1 (en) 2021-10-21
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