CN110565021A - optimization method of hot-rolled ribbed steel bar production process - Google Patents

optimization method of hot-rolled ribbed steel bar production process Download PDF

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Publication number
CN110565021A
CN110565021A CN201910960526.7A CN201910960526A CN110565021A CN 110565021 A CN110565021 A CN 110565021A CN 201910960526 A CN201910960526 A CN 201910960526A CN 110565021 A CN110565021 A CN 110565021A
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Prior art keywords
odd
rolling
racks
steel bar
percent
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CN201910960526.7A
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Inventor
樊尧桂
傅余东
李卫东
邓冰
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Yangchun New Iron and Steel Co Ltd
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Yangchun New Iron and Steel Co Ltd
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Priority to CN201910960526.7A priority Critical patent/CN110565021A/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B1/00Metal-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
    • B21B1/16Metal-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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B21B1/163Rolling or cold-forming of concrete reinforcement bars or wire ; Rolls therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B37/00Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Abstract

The invention discloses an optimization method of a production process of a hot-rolled ribbed steel bar, which improves the traditional rolling method from two aspects of billet material and preparation process, and can more effectively utilize equipment capacity and reduce rolling energy consumption under the same process conditions by adjusting billet components and reasonably distributing rough rolling load reduction, and the produced steel bar improves yield strength and tensile strength, has uniform steel bar texture, accurate section shape and qualified indexes.

Description

Optimization method of hot-rolled ribbed steel bar production process
Technical Field
the invention relates to a control method of a wire rolling process, in particular to a hot-rolled ribbed steel bar rolling process, and belongs to the technical field of steel bar rolling.
Background
The reinforcing steel bars are important building materials, and are widely applied and used in large quantities. With the rapid development of the construction industry, the performance requirements on the ribbed steel bars are higher and higher. The production process of the common hot-rolled ribbed steel bar is mature, the production process mainly comprises the working procedures of uncoiling, paying off, descaling, hot-rolling forming, heat treatment, wire take-up and the like, the load distribution of each machine frame pass is easy to be inconsistent, and the tension of a wire rod generates severe fluctuation, so that the stability of the production process is influenced, and the productivity is influenced due to the quality defect of the finished wire rod when the production process is serious. In the prior art, each control subsystem adopts an independent operation mode and cannot meet the high-precision control requirement. The press reduction control effect based on the traditional control theory is near the limit, the unit yield is low, the cost is high, and the key problem of how to reasonably distribute the rack load so as to control the size stability of the finished reinforcing steel bar is urgently needed to be solved.
Disclosure of Invention
Aiming at the problems, the invention provides an optimization method of a production process of a hot-rolled ribbed steel bar, which improves the traditional process in two aspects of billet material optimization and rolling process, improves the yield strength and the tensile strength by material improvement, and ensures that the produced steel bar has uniform texture and accurate section shape by optimization of a control method.
carbon is the most important component in steel, and the pearlite amount in the steel is increased along with the increase of the carbon content, so that the impact absorption work is reduced, and the carbon is a harmful element influencing the impact absorption work. Manganese lowers the austenite to ferrite transformation temperature, thereby making the grain finer. The impact absorption work of ferrite-pearlite steel can be improved by adding manganese. Silicon increases the yield point of the material and simultaneously increases the brittle transition temperature. The increase in nickel content results in an improvement in the notch toughness of the carbon steel. Phosphorus and sulfur are inevitable elements in steel and are detrimental to fracture toughness. Phosphorus has a strong solid solution strengthening effect, so that the strength and the hardness of the steel are increased, but the plasticity and the toughness are obviously reduced. In the process of crystallization, because of the generation of intragranular segregation, the phosphorus content in a local area is higher, and the brittle transition temperature is increased to cause cold brittleness.
In order to improve the strength of the steel bar, a certain amount of VN alloy is added into the steel billet, vanadium can form VN with nitrogen, the strength of the steel can be improved, austenite recrystallization is prevented, and grains are slightly refined. In addition, the Mn content in the steel is increased correspondingly. Because the content of manganese is higher, Mn is segregated in steel due to large capacity in the smelting process, Mn has the effect of improving the stability of the supercooled austenite, the pearlite transformation part in the isothermal transformation process of the supercooled austenite is obviously shifted to the right, and the bainite structure can be generated under the air cooling condition after the steel is austenitized by Mn segregation in the core of a steel billet. And the normal structure of the steel bar is ferrite plus pearlite, and the core part of the steel bar has a granular bainite abnormal structure due to Mn segregation, so that the uniformity of the structure is damaged, the toughness of the steel bar is reduced, and the risk of brittle fracture is increased. Therefore, the microalloyed steel has an obvious yield platform by adding Nb element, and the necessary condition is that the Mn weight percentage is less than 1.6 percent, and the bainite content is less than 10 percent by controlled cooling.
The rough rolling is an important part in the whole steel rolling process, is a very key factor for ensuring the stability, good continuity and high product precision of the whole production process, and more scientific load distribution is more key for improving the precision and production performance of products and eliminating the problem rate. The optimization method can eliminate the quality problem caused by alternating stress, further improve the obdurability of the reinforcing steel bar, ensure that the internal distribution of the whole tissue is uniform, and reduce the probability of generating the quality problem.
The technical scheme of the invention is as follows: an optimization method of a production process of hot-rolled ribbed steel bars sequentially comprises the following steps: heating a steel billet, rough rolling, cutting the head and the tail, intermediate rolling, finish rolling, heat treatment, derusting, straightening, segmenting by flying shears, sizing, bundling, inspecting and warehousing. The steel billet comprises the following chemical components in percentage by weight: c: 0.21 to 0.25%, Si: 0.25 to 0.36%, Mn: 1.33% -1.43%, Nb: 0.025% 5-0.04%, V: 0.04 to 0.06 percent, less than or equal to 0.05 percent of P, less than or equal to 0.05 percent of S, and the balance of Fe and inevitable impurities; the rough rolling is performed with reduction load distribution control, and the specific control method comprises the following steps:
1) Initializing the reduction rate epsilon of the odd-number group stand according to the average distribution principle by the square billet size and the rough rolling target sizeoddAnd even number of sets of frame reduction rate epsiloneven(ii) a Then there are: epsilon1=ε3=ε5=…=εodd,ε2=ε4=ε6=…=εeven(ii) a When the initial reduction rate is distributed, the broadening is calculated according to the following formula;
In the formula: Δ b is spread; delta h is the reduction; h is the inlet thickness; r is the roller radius; h isj-1the thickness of the rolled piece inlet of the 1 st pass is obtained; h isiThe thickness of the outlet of the rolled piece of the ith pass is; epsiloniThe i-th pass reduction rate.
Odd number group frame outlet height hiAnd outlet width biRespectively as follows:
hi=hi-1(1-εodd)
Height h of even number group rack outletjand width bjRespectively as follows:
bj=bj-1(1-εeven)
2) determining an initial rolling speed by taking the size of a finished steel bar as a target size, and then initializing the rolling speed of each rack according to the principle of second flow equality by using the outlet size of each rack;
3) Solving the complex load function f of each racki(hi-1,h1)、fj(bi-1,b1);
4) Respectively searching the maximum value and the minimum value f of the comprehensive load function of the frames of the odd groupsk1、fk2And the maximum value and the minimum value f of the even number group frame comprehensive load functionk3、fk4
5) For an odd-number group frame, two machines of k1 and k2 are adjusted by adopting a dichotomythe reduction rate of the frames is reduced, the reduction rate of k1 is reduced, and the reduction rate of k2 is increased, so that the comprehensive load function values of the two frames are equal; since the integrated load function is monotonous with respect to the reduction rate, the function C ═ f is definedk1(hk1-1,hk1)-fk2(hk2-1,hk2) C is a monotonous function, and when C is 0, the comprehensive load functions of the two racks are equal; for the even-numbered groups of racks, the adjustment mode is the same as that of the odd-numbered groups of racks;
6) At fk1=fk2and f isk3=fk4Then, returning to the step (4) to search the next rack with the largest difference value of the comprehensive load functions for adjustment until the difference of the comprehensive load function values of all the racks is smaller than a given error; but the comprehensive load function values of the final odd-number group stand and the even-number group stand are not necessarily in the same level, which is determined by the size of the square billet and the size of the rough rolling target;
7) Judging whether the comprehensive load function values of all the racks are lower than the lower limit, if so, reducing the rolling speed by 1 percent on the whole, and then returning to the step (3); if not, the result is output.
the invention has the beneficial effects that:
(1) The material and the preparation process of the steel bar improve the traditional hot-rolled steel bar, the product quality is improved, the performance of the produced steel bar is more excellent, the mechanical property and the like can reach and exceed the national standard, and the product quality is more stable.
(2) according to the characteristics of the slotless rolling of the roughing mill group, a process method which is suitable for the material of the steel bar is designed, and guidance is provided for optimizing and distributing the load of the roughing mill group. The produced steel bar improves the yield strength and the tensile strength, the steel bar is uniform in texture, the section shape is accurate, and all indexes are qualified.
Drawings
Fig. 1 is a flow chart of calculation of load distribution of a steel bar roughing mill group according to the present invention.
Detailed Description
embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Example (b):
Taking a new on-line 500MPA phi 18mm ribbed steel bar as an example, the optimization method of the hot rolling ribbed steel bar production process is explained, and the square billet size is 190 multiplied by 100 mm: rough rolling target size 30 × 60 mm: the rough rolling adopts 10 stands, and the finish rolling adopts 6 stands, includes the following steps in proper order: heating a steel billet, rough rolling, medium rolling, finish rolling, heat treatment, derusting, straightening, segmenting by flying shears, sizing, bundling, inspecting and warehousing. The steel billet comprises the following chemical components in percentage by weight: c: 0.21 to 0.25%, Si: 0.25 to 0.36%, Mn: 1.33% -1.43%, Nb: 0.025% 5-0.04%, V: 0.04 to 0.06 percent, less than or equal to 0.05 percent of P, less than or equal to 0.05 percent of S, and the balance of Fe and inevitable impurities; the rough rolling is performed with reduction load distribution control, and the specific control method comprises the following steps:
Step 1) the square billet size is 190 multiplied by 100 mm: rough rolling target size is 30 multiplied by 60mm, roller radius is 550mm, and the reduction rate epsilon of the odd-number group stand is initialized according to the average distribution principleoddAnd even number of sets of frame reduction rate epsiloneven(ii) a Then there are: epsilon1=ε3=ε5=…=εodd,ε2=ε4=ε6=…=εeven(ii) a When the initial reduction rate is distributed, the broadening is calculated according to the following formula;
In the formula: Δ b is spread; delta h is the reduction; h is the inlet thickness; r is the roller radius; odd number group frame outlet height hiAnd outlet width biRespectively as follows:
hi=hi-1(1-εodd)
height h of even number group rack outletjand width bjRespectively as follows:
bj=bj-1(1-εeven)
Step 2) determining the initial rolling speed to be 0.281m/s by taking the dimension phi 18mm of the finished steel bar as a target dimension, and then initializing the rolling speed of each rough rolling stand according to the principle of equal second flow by the outlet dimension of each stand, wherein the rolling speed is respectively 0.337, 0.469, 0.657m/s, 0.977m/s, 1.315m/s, 1.967m/s, 2.350m/s, 3.052m/s and 3.867 m/s;
Step 3) solving the comprehensive load function f of each racki(hi-1,h1)、fj(bi-1,b1);
Step 4) respectively searching the maximum value and the minimum value f of the comprehensive load function of the odd-number group of racksk1、fk2And the maximum value and the minimum value f of the even number group frame comprehensive load functionk3、fk4
step 5) for the odd-number group of racks, adjusting the pressing rates of the two racks before k1 and k2 by adopting a dichotomy, reducing the pressing rate of k1, and increasing the pressing rate of k2 so as to enable the comprehensive load function values of the two racks to be equal; since the integrated load function is monotonous with respect to the reduction rate, the function C ═ f is definedk1(hk1-1,hk1)-fk2(hk2-1,hk2) C is a monotonous function, and when C is 0, the comprehensive load functions of the two racks are equal; for the even-numbered groups of racks, the adjustment mode is the same as that of the odd-numbered groups of racks;
step 6) at fk1=fk2And f isk3=fk4then, returning to the step (4) to search the next rack with the largest difference value of the comprehensive load functions for adjustment until the difference of the comprehensive load function values of all the racks is smaller than a given error; but the comprehensive load function values of the final odd-number group stand and the even-number group stand are not necessarily in the same level, which is determined by the size of the square billet and the size of the rough rolling target;
Step 7) judging whether the comprehensive load function values of all the rough rolling frames are lower than the lower limit, if so, reducing the rolling speed by 1 percent on the whole, and then returning to the step 3; and continuously adjusting until the comprehensive load function value is not lower than the lower limit, and outputting a result, namely the finally determined comprehensive composite function value of each rough rolling stand.
Through a field rolling experiment, the racks with higher load rates are all concentrated on a roughing mill group, and the load rates are all over 90 percent and are close to the upper limit of the motor capacity. Through the field practice in a hot rolling plant, the rough rolling reduction load setting calculation is stable and accurate, the full-length diameter fluctuation is stably controlled within 0.15mm, the comprehensive mechanical property and the size stability of the steel bar are rapidly improved, the comprehensive mechanical property meets the requirements, the yield is improved to 97 percent, the yield quality and the product grade are improved, the market competitiveness of the steel bar products of the plant is enhanced, and good economic benefits are created.
The above-mentioned embodiments only express the specific embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims (1)

1. An optimization method of a production process of hot-rolled ribbed steel bars sequentially comprises the following steps: heating a steel billet, rough rolling, head and tail cutting, intermediate rolling, finish rolling, heat treatment, rust removal, straightening, flying shear segmentation, sizing, bundling, inspection and warehousing, and is characterized in that: the steel billet comprises the following chemical components in percentage by weight: c: 0.21 to 0.25%, Si: 0.25 to 0.36%, Mn: 1.33% -1.43%, Nb: 0.025 to 0.04 percent, V: 0.04 to 0.06 percent, less than or equal to 0.05 percent of P, less than or equal to 0.05 percent of S, and the balance of Fe and inevitable impurities; the rough rolling is performed with reduction load distribution control, and the specific control method comprises the following steps:
1) Initializing the reduction rate epsilon of the odd-number group stand according to the average distribution principle by the square billet size and the rough rolling target sizeoddAnd even number of sets of frame reduction rate epsiloneven(ii) a Then there are: epsilon1=ε3=ε5=…=εodd,ε2=ε4=ε6=…=εeven(ii) a At the time of dispensing the initial depression rate,And calculating the spread according to the following formula;
in the formula: Δ b is spread; delta h is the reduction; h is the inlet thickness; r is the roller radius; odd number group frame outlet height hiAnd outlet width birespectively as follows:
hi=hi-1(1-εodd)
Height h of even number group rack outletjand width bjRespectively as follows:
bj=bj-1(1-εeven)
2) Determining an initial rolling speed by taking the size of a finished steel bar as a target size, and then initializing the rolling speed of each rack according to the principle of second flow equality by using the outlet size of each rack;
3) Solving the complex load function f of each racki(hi-1,h1)、fj(bi-1,b1);
4) respectively searching the maximum value and the minimum value f of the comprehensive load function of the frames of the odd groupsk1、fk2and the maximum value and the minimum value f of the even number group frame comprehensive load functionk3、fk4
5) For the odd-number groups of racks, the pressing rates of the two racks k1 and k2 are adjusted by adopting a dichotomy, the pressing rate k1 is reduced, and the pressing rate k2 is increased, so that the comprehensive load function values of the two racks are equal; since the integrated load function is monotonous with respect to the reduction rate, the function C ═ f is definedk1(hk1-1,hk1)-fk2(hk2-1,hk2) C is a monotonic function, which indicates when C is 0The comprehensive load functions of the two racks are equal; for the even-numbered groups of racks, the adjustment mode is the same as that of the odd-numbered groups of racks;
6) At fk1=fk2and f isk3=fk4then, returning to the step (4) to search the next rack with the largest difference value of the comprehensive load functions for adjustment until the difference of the comprehensive load function values of all the racks is smaller than a given error;
7) Judging whether the comprehensive load function values of all the racks are lower than the lower limit, if so, reducing the rolling speed by 1 percent on the whole, and then returning to the step (3); if not, the result is output.
CN201910960526.7A 2019-10-10 2019-10-10 optimization method of hot-rolled ribbed steel bar production process Pending CN110565021A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103831304A (en) * 2012-11-23 2014-06-04 攀钢集团攀枝花钢钒有限公司 Method and system for calculating target width of hot continuous rolling intermediate billet
CN105543667A (en) * 2016-01-20 2016-05-04 广西丛欣实业有限公司 Corrosion-resistant reinforcing bar
CN106048419A (en) * 2016-07-14 2016-10-26 山西建邦集团有限公司 HRB400E high-strength low alloy coiled reinforced bar and production method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103831304A (en) * 2012-11-23 2014-06-04 攀钢集团攀枝花钢钒有限公司 Method and system for calculating target width of hot continuous rolling intermediate billet
CN105543667A (en) * 2016-01-20 2016-05-04 广西丛欣实业有限公司 Corrosion-resistant reinforcing bar
CN106048419A (en) * 2016-07-14 2016-10-26 山西建邦集团有限公司 HRB400E high-strength low alloy coiled reinforced bar and production method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
陈庆安等: "棒线材粗轧机组负荷裕量优化分配算法", 《钢铁》 *

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Application publication date: 20191213