Spring flat steel rolling production method considering high dimensional precision and high strength

Abstract

The invention belongs to the technical field of spring flat steel production in the ferrous metallurgical industry, relates to a spring flat steel rolling production method considering both high dimensional precision and high strength, and provides a rolling production line. The rolling production line comprises a heating unit, a rough rolling unit, an intermediate rolling unit, a finish rolling unit, a temperature control unit before forming rolling, a four-rack two-roller reducing sizing unit, a temperature control unit after forming rolling and a finished product finishing treatment unit which are sequentially arranged in the rolling production direction. The arrangement form of the four-rack two-roller reducing sizing unit is H-V-H-H, the four-rack two-roller reducing sizing unit comprises a first horizontal rolling mill, a vertical rolling mill, a second horizontal rolling mill and a third horizontal rolling mill which are sequentially arranged in the rolling production direction, and a first loop is arranged between the first horizontal rolling mill and the vertical rolling mill. And a second loop is arranged between the vertical rolling mill and the second horizontal rolling mill. By means of the rolling production method, spring flat steel products with the thickness ranging from 3 mm to 60 mm can be produced, and high dimensional precision and high strength of the spring flat steel are both considered.

Description

Technical Field

[0001] The invention belongs to the technical field of spring flat steel production in the iron and steel metallurgical industry, and relates to a rolling production method for spring flat steel with both high dimensional accuracy and high strength. Background Art

[0002] As an important material in the industrial field, spring steel has various product forms, mainly including bars, wires, plates and flat steel. Among them, flat steel has become the leader in spring steel due to its wide range of applications and large demand. Common flat steel grades include 60Si2Mn, 50CrV4, 51CrV4, 52CrMoV4, etc. They are widely used in many fields such as automobiles, railways, aviation, and national defense, playing a pivotal role. In recent years, with the continuous upgrading of production equipment of Chinese enterprises and the rapid development of the automobile industry, the demand for spring steel has shown a rapid growth trend. In particular, the market demand for spring flat steel continues to rise. It is predicted that by 2025, the annual demand for spring flat steel will reach 8 million tons, of which the demand for automobile spring flat steel will be about 3 million tons. This data fully illustrates the important position and development potential of spring flat steel in the market.

[0003] In the automotive industry, with the increasing requirements for environmental protection and energy conservation and emission reduction, the lightweighting of automobiles has become an irreversible development trend. As an important elastic element in the automobile shock absorption system, the leaf spring accounts for 7% to 9% of the total weight of the automobile. It is a high-tech, high-value-added steel material and is the most important elastic element in the shock absorption system of various commercial vehicles, buses and special automobiles. Therefore, the lightweighting of leaf springs is of great significance to the lightweighting of automobiles. High-strength and high-hardenability spring flat steel is an ideal material for manufacturing lightweight leaf springs. Due to the particularity of the service environment, spring flat steel is required to have good fatigue life, small load loss capacity, good wear resistance and other comprehensive properties. By increasing the design stress of spring flat steel, its weight can be significantly reduced. For example, if the design stress is increased by 20%, the weight of spring flat steel can be reduced by about 25%. In the future, heavy-duty vehicles will use high-strength leaf spring steel, which is expected to reduce the mass of the spring assembly itself by 30% to 50%. Therefore, it is an inevitable trend for spring flat steel to develop in the direction of high strength and high hardenability. Replacing ordinary spring flat steel with lower strength levels with high-strength spring flat steel has become an obvious trend in the development of the industry. The development trend of using high-strength spring flat steel to replace ordinary spring flat steel below 1200MPa or even 1500MPa is becoming more and more obvious.

[0004] Spring flat steel is mainly produced by rolling and subsequent heat treatment processes. However, there are still many problems in the current rolling production of spring flat steel. First, the product performance is unstable, and the tensile strength of the final product is often low, which is difficult to meet the requirements of high strength and high hardenability. Secondly, when rolling thicker spring flat steel, the microstructure of the core and the surface is quite different, making it difficult to take into account both the strength and plasticity indicators of the product. In addition, the product has low dimensional accuracy and poor passability, and can generally only meet lower precision standards (such as GB / T 702-2017 2 group accuracy), resulting in low metal yield. Finally, due to the limitations of the production line layout, low-temperature rolling cannot be achieved through controlled rolling and controlled cooling, which further increases production costs.

[0005] In view of the above problems, there is an urgent need to propose a spring flat steel rolling production method that takes into account both high dimensional accuracy and high strength, so as to improve the core and surface microstructure uniformity of spring flat steel products and improve product strength and dimensional accuracy by optimizing the rolling process and production line configuration. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a spring flat steel rolling production method that takes into account both high dimensional accuracy and high strength, so as to solve the problems existing in the background technology.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A rolling production method for spring flat steel with both high dimensional accuracy and high strength is provided, and a rolling production line is provided, wherein the rolling production line comprises a heating unit, a rough rolling unit, an intermediate rolling unit, a finishing rolling unit, a pre-forming rolling temperature control unit, a four-stand two-roller sizing unit, a post-forming rolling temperature control unit, and a finished product finishing unit, which are sequentially arranged along the rolling production direction;

[0009] The four-stand two-roller sizing unit is arranged in the form of HVHH, including a first horizontal rolling mill, a vertical rolling mill, a second horizontal rolling mill and a third horizontal rolling mill arranged in sequence along the rolling production direction, and a first looper is arranged between the first horizontal rolling mill and the vertical rolling mill, and a second looper is arranged between the vertical rolling mill and the second horizontal rolling mill;

[0010] The production method comprises the following steps:

[0011] Continuous casting billet heating: The continuous casting billet is heated to 900℃~1200℃ through the heating unit;

[0012] Rough rolling: The heated continuous casting billet is rolled through a rough rolling unit for 6 passes at a rolling temperature of 900°C to 1050°C;

[0013] Intermediate rolling: The rough rolled product is rolled through the intermediate rolling unit for 4 passes at a rolling temperature of 880°C to 1000°C.

[0014] Finishing rolling: the rolled piece after intermediate rolling is passed through the finishing unit for finishing rolling or empty rolling, and the rolling temperature during finishing rolling is 850℃~980℃;

[0015] Temperature control before forming rolling: The rolled piece after finishing rolling is temperature controlled by the temperature control unit before forming rolling, and the temperature of the rolled piece after temperature control is made to be 730℃~920℃;

[0016] Sizing unit forming rolling: the rolled piece that has been temperature controlled before forming rolling is formed and rolled through a four-stand two-roller sizing unit, the rolling temperature is 750℃~900℃, and the exit speed is 0.5m / s~12m / s;

[0017] Temperature control after forming and rolling: The rolled piece after forming and rolling by the reducing and sizing mill is temperature controlled by the temperature control unit after forming and rolling, and the temperature of the rolled piece after temperature control is made to be 600℃~850℃;

[0018] Finishing of finished products: The rolled product after forming and rolling and temperature control is finished by a finishing unit to obtain a spring flat steel, and the thickness of the spring flat steel ranges from 3.0 mm to 60.0 mm.

[0019] Furthermore, the four-stand two-roller sizing unit is a prestressed rolling mill, and the first horizontal rolling mill and the vertical rolling mill are sizing units, and the second horizontal rolling mill and the third horizontal rolling mill are sizing units.

[0020] Furthermore, there is a compact arrangement between the second horizontal rolling mill and the third horizontal rolling mill.

[0021] Furthermore, the first looper and the second looper have the same structure, both comprising a looper body, a sensor group, a data processing module and a driving mechanism;

[0022] The sensor group is used to collect the cross-sectional area of ​​the rolled piece, the rolling mill spacing, the height, tension and speed of the looper body in real time during the rolling process;

[0023] The data processing module calculates the initial height H of the looper body; constructs a dynamic mathematical model of the looper height, and uses an adaptive control algorithm to iteratively optimize the dynamic mathematical model of the looper height, and outputs a looper height deviation Δh;

[0024] The looper body adjusts the height of the looper body according to the looper height deviation through the driving mechanism, that is, H'=H+Δh;

[0025] Among them, the initial height of the looper body is:

[0026] H=αsqrt(Q·A / L)

[0027] Among them, H is the initial height of the looper body, α is the looper height coefficient, which ranges from 0 to 100, Q is the looper amount, which ranges from 0 to 1000 mm, A is the cross-sectional area of ​​the rolled piece, and L is the mill spacing, which ranges from 1000 to 5000 mm;

[0028] The dynamic mathematical model of the looper height is Δh=K f (ΔV·K t +δV+α 1 ΔF+β(TT 0 )-γμ), where Δh is the loop height deviation; ΔV is the speed adjustment; K f K is the rolling force correction coefficient, ranging from 0.1 to 20; t is the tension adjustment coefficient, ranging from 0 to 5; α 1 is the tension influence coefficient, ranging from 0 to 20; ΔF is the rolling force deviation, δV is the speed fluctuation noise, ranging from 0 to 10 mm; β is the temperature sensitivity coefficient, ranging from 0 to 10; T is the real-time temperature of the rolled piece, ℃; T 0 The reference temperature is set for the rolling process, ℃; μ is the friction coefficient between the looper roller and the strip, which is 0.6; γ is the friction attenuation coefficient, which ranges from 0 to 1.

[0029] Furthermore, the adaptive control algorithm is used to iteratively optimize the looper height dynamic mathematical model, specifically:

[0030] When the rolled piece bites into the first horizontal rolling mill in the four-stand two-roller sizing unit, the current value of the first horizontal rolling mill collected by the sensor unit is recorded as I 1目标值 When the rolled piece bites into the vertical rolling mill, the current of the vertical rolling mill collected by the sensor unit is recorded as I 2目标值 ;

[0031] Within 0.1s after the workpiece bites into the vertical rolling mill, the first looper is set up. After the first looper is set up, the sensor unit collects the data of the first horizontal rolling mill I 1实时值 ;

[0032] If I 1实时值 ∈[1.02I 1目标值 , 1.05I 1目标值 ], then calculate the first looper height deviation Δh of the first looper 11 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 11 =H 1 +Δh 11 ;

[0033] The first looper height adjustment is completed, and the sensor unit collects the first horizontal rolling mill I again. 1实时值 , if I 1实时值 ∈[1.02i 1目标值 , 1.05i 1目标值 ], then calculate the second loop height deviation Δh of the first loop 12 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 12 =H' 11 +Δh 12 ;

[0034] And so on, until I 1实时值 ∈[I 1目标值 , 1.02I 1目标值 ];

[0035] If I 1实时值 ∈[0.95I 1目标值 , I 1目标值 ], it is judged that there is steel between the first horizontal rolling mill and the vertical rolling mill, and the first looper cannot be released, and the speed of the vertical rolling mill biting into the rolled piece is adjusted to I 1实时值 >I 1目标值 Finally, the first looper is started and dynamically adjusted;

[0036] Within 0.1s after the rolled piece bites into the second horizontal rolling mill, the second looper is set up. After the second looper is set up, the vertical rolling mill I is collected by the sensor unit. 2实时值 ;

[0037] If I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the first loop height deviation Δh of the second loop 21 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 21 =H 2 +Δh 21 ;

[0038] The first looper height adjustment is completed, and the sensor unit collects the vertical rolling mill I again. 2实时值 , if I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the second looper height deviation Δh of the second looper 22 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 22 =H' 21 +Δh 22 ;

[0039] And so on, until I 2实时值 ∈[I 2目标值 , 1.02I 2目标值 ];

[0040] If I 2实时值 ∈[0.95I 2目标值 , I 2目标值 ], it is judged that there is steel between the vertical rolling mill and the second horizontal rolling mill, and the second looper cannot be released, and the speed of the second horizontal rolling mill biting into the rolled piece is adjusted to I 2实时值 >I 2目标值 Finally, start the second loop and make dynamic adjustments.

[0041] Furthermore, the looper body is a vertical looper or a side looper.

[0042] Furthermore, the reduction amount of a single pass of the reducing unit is in the range of 15% to 30%, and the reduction amount of a single pass of the sizing unit is in the range of 2% to 8%.

[0043] Furthermore, the number of groups of the temperature control units before forming and rolling and the temperature control units after forming and rolling are 1-10 groups, and all are water-cooled temperature control units. The temperature reduction range of each group of water-cooled temperature control units is 10°C to 200°C, and the cooling water pressure is 0.1MPa to 2.0MPa.

[0044] Furthermore, when the forming size thickness of the spring flat steel is less than or equal to 10 mm, a heat preservation device is arranged between the finishing unit and the four-stand two-roller sizing unit, and the heat preservation device is arranged in parallel with the temperature control unit before forming rolling, and they are not turned on at the same time.

[0045] Furthermore, a head-off device after the rough rolling unit is provided between the rough rolling unit and the intermediate rolling unit to perform head-off rolling;

[0046] Flying shears are arranged between the head stripping device after the rough rolling unit and the intermediate rolling unit, between the intermediate rolling unit and the finishing rolling unit, between the temperature control unit before forming rolling and the four-stand two-roller sizing unit, and between the temperature control unit after forming rolling and the finished product finishing unit.

[0047] The beneficial effects of the present invention are:

[0048] 1. The present invention adopts a four-stand two-roller sizing unit (using HVHH structure) for forming rolling, which innovatively realizes the precise control of the flat spring steel production process. The four-stand two-roller sizing unit adopts a sizing unit and a sizing unit in combination, wherein the sizing unit is designed with a large single-pass reduction and cumulative reduction (15% to 30%), ensuring that the deformation fully penetrates into the core, significantly improving the core surface organization of the product; the sizing unit uniformly adopts a smaller reduction (2% to 8%), and combined with the pre-rolling mill design, the mill bounce is effectively reduced by pre-setting when unloaded, thereby ensuring the high dimensional accuracy of the mill and ensuring the high dimensional accuracy of the final product. This unique mill configuration and control method not only improves the product quality stability, but also supports the production of spring flat steel with a wide thickness range (2mm to 60mm), meets the market nutrition needs, and reflects the high practicality of the solution. The final product has a tensile strength deviation of less than 20MPa, a yield strength deviation of less than 20MPa, an elongation deviation of less than 4%, and a cross-sectional shrinkage deviation of less than 5%. It is more than 20% higher than the normal level.

[0049] 2. This rolling production method is equipped with a looper between the first three rolling mills of the four-stand two-roller sizing unit to achieve tension-free rolling, effectively reducing the dimensional deviation of the head and tail of the rolled piece; the third to fourth rolling mills adopt a compact structure layout, with a small spacing between the rolling mills and a short distance between the head and tail where no tension is established, which can effectively reduce the head and tail dimensional deviation caused by the falling of the loop, and the rolled piece has good smoothness. This rolling production method controls the temperature of the whole rolling process of the rolled piece, avoids the rapid and drastic temperature, limits the growth of austenite grains, and provides a fine initial organization for the subsequent phase transformation. Through fine grain strengthening, the product finally obtains a uniform and fine grain strength structure, with high, high plasticity, high endurance and extreme fatigue performance. This technical design ensures the consistency of the temperature, deformation and dimensional accuracy between the head and tail and the middle position of the rolled piece.

[0050] 3. The present invention significantly improves the economic benefits and production stability by optimizing the process. The use of a lower continuous casting billet heating temperature (≤1200°C) reduces the depth of the decarburization layer and improves the metal yield; the stabilization of the rolling process further reduces material losses. In addition, 1-10 groups of water-cooled temperature control units are synchronously set up for forming and rolling to ensure the temperature of the rolled piece. These measures jointly guarantee the stability of the efficient rolling process, minimize the head and tail dimensional deviations, and improve the smoothness of the bars, providing reliable support for industrial production. On the whole, this rolling production method takes into account both economy and safety while improving product quality, and has significant industrial application value.

[0051] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0053] Figure 1 It is a process flow chart of a rolling production method of spring flat steel with both high dimensional accuracy and high strength in the embodiment;

[0054] Figure 2 It is a schematic diagram of the arrangement of a four-stand two-roller reducing sizing rolling unit in the embodiment;

[0055] Figure 3 Schematic diagram of the control principle of the first looper in the embodiment.

[0056] Reference numerals: heating unit 1, rough rolling unit 2, head stripping device after rough rolling unit 3, intermediate rolling unit 4, finishing unit 5, temperature control unit before forming rolling 6, four-stand two-roller sizing unit 7, temperature control unit after forming rolling 8, finished product finishing unit 9, flying shear 10;

[0057] The four-stand two-roller sizing unit 7 includes: the first horizontal rolling mill 7-1, the first looper 7-2, the vertical rolling mill 7-3, the second looper 7-4, the second horizontal rolling mill 7-5, and the third horizontal rolling mill 7-6. DETAILED DESCRIPTION

[0058] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0059] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0060] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0061] See also Figure 1 to Figure 3 , a rolling production method for spring flat steel with both high dimensional accuracy and high strength is provided, and a rolling production line is provided, the rolling production line comprises a heating unit 1, a rough rolling unit 2, an intermediate rolling unit 4, a finishing rolling unit 5, a pre-forming rolling temperature control unit 6, a four-stand two-roller sizing unit 7, a post-forming rolling temperature control unit 8 and a finished product finishing unit 9 which are sequentially arranged along the rolling production direction;

[0062] The four-stand two-roller sizing unit 7 is arranged in the form of HVHH, including a first horizontal rolling mill 7-1, a vertical rolling mill 7-3, a second horizontal rolling mill 7-5 and a third horizontal rolling mill 7-6 which are sequentially arranged along the rolling production direction, and a first looper 7-2 is arranged between the first horizontal rolling mill 7-1 and the vertical rolling mill 7-3, and a second looper 7-4 is arranged between the vertical rolling mill 7-3 and the second horizontal rolling mill 7-5;

[0063] The production method comprises the following steps:

[0064] Continuous casting billet heating: The continuous casting billet is heated to 900℃~1200℃ through the heating unit;

[0065] Rough rolling: The heated continuous casting billet is rolled through a rough rolling unit for 6 passes at a rolling temperature of 900°C to 1050°C;

[0066] Intermediate rolling: The rough rolled product is rolled through the intermediate rolling unit for 4 passes at a rolling temperature of 880°C to 1000°C.

[0067] Finishing rolling: the rolled piece after intermediate rolling is passed through the finishing unit for finishing rolling or empty rolling, and the rolling temperature during finishing rolling is 850℃~980℃;

[0068] Temperature control before forming rolling: The rolled piece after finishing rolling is temperature controlled by the temperature control unit before forming rolling, and the temperature of the rolled piece after temperature control is made to be 730℃~920℃;

[0069] Sizing unit forming rolling: the rolled piece that has been temperature controlled before forming rolling is formed and rolled through a four-stand two-roller sizing unit, the rolling temperature is 750℃~900℃, and the exit speed is 0.5m / s~12m / s;

[0070] Temperature control after forming and rolling: The rolled piece after forming and rolling by the reducing and sizing mill is temperature controlled by the temperature control unit after forming and rolling, and the temperature of the rolled piece after temperature control is made to be 600℃~850℃;

[0071] Finishing of finished products: The rolled product after forming and rolling and temperature control is finished by a finishing unit to obtain a spring flat steel, and the thickness of the spring flat steel ranges from 3.0 mm to 60.0 mm.

[0072] Furthermore, the four-stand two-roller sizing unit 7 is a prestressed rolling mill, and the first horizontal rolling mill and the vertical rolling mill are sizing units, and the second horizontal rolling mill and the third horizontal rolling mill are sizing units.

[0073] Furthermore, the second horizontal rolling mill and the third horizontal rolling mill are compactly arranged without a loop.

[0074] Furthermore, the first looper and the second looper have the same structure, both comprising a looper body, a sensor group, a data processing module and a driving mechanism;

[0075] The sensor group is used to collect the cross-sectional area of ​​the rolled piece, the rolling mill spacing, the height, tension and speed of the looper body in real time during the rolling process;

[0076] The data processing module calculates the initial height H of the looper body; constructs a dynamic mathematical model of the looper height, and uses an adaptive control algorithm to iteratively optimize the dynamic mathematical model of the looper height, and outputs a looper height deviation Δh;

[0077] The looper body adjusts the height of the looper body according to the looper height deviation through the driving mechanism, that is, H'=H+Δh;

[0078] Among them, the initial height of the looper body is:

[0079] H=αsqrt(Q·A / L)

[0080] Among them, H is the initial height of the looper body, α is the looper height coefficient, which ranges from 0 to 100, Q is the total length of the looper, which ranges from 0 to 1000 mm, A is the cross-sectional area of ​​the rolled piece, and L is the mill spacing, which ranges from 1000 to 5000 mm;

[0081] The dynamic mathematical model of the looper height is Δh=K f (ΔV·K t +δV+α1 ΔF+β(TT 0 )-γμ), where Δh is the loop height deviation; ΔV is the speed adjustment; K f K is the rolling force correction coefficient, ranging from 0.1 to 20; t is the tension adjustment coefficient, ranging from 0 to 5; α 1 is the tension influence coefficient, ranging from 0 to 20; ΔF is the rolling force deviation, δV is the speed fluctuation noise, ranging from 0 to 10 mm; β is the temperature sensitivity coefficient, ranging from 0 to 10; T is the real-time temperature of the rolled piece, ℃; T 0 The reference temperature is set for the rolling process, ℃; μ is the friction coefficient between the looper roller and the strip, which is 0.6; γ is the friction attenuation coefficient, which ranges from 0 to 1.

[0082] Two examples are provided here to illustrate the parameter calculation values ​​of the looper height deviation under different conditions, as shown in Table 1.

[0083] Table 1

[0084] ΔV <![CDATA[K f ]]> <![CDATA[K t ]]> <![CDATA[α 1 ]]> ΔF δV β γ Δh Calculation example 1 3 0.1 5 6.25 10 6 0.2 0.6 9.35 Calculation example 2 0.5 20 0.2 0.5 2 0.5 0.2 0.6 152.5

[0085] See also Figure 3 , further, the adaptive control algorithm is used to iteratively optimize the highly dynamic mathematical model of the looper, specifically:

[0086] When the rolled piece bites into the first horizontal rolling mill in the four-stand two-roller sizing unit, the current value of the first horizontal rolling mill collected by the sensor unit is recorded as I 1目标值 When the rolled piece bites into the vertical rolling mill, the current of the vertical rolling mill collected by the sensor unit is recorded as I 2目标值 ;

[0087] Within 0.1s after the workpiece bites into the vertical rolling mill, the first looper is set up. After the first looper is set up, the sensor unit collects the data of the first horizontal rolling mill I 1实时值 ;

[0088] If I 1实时值 ∈[1.02I 1目标值 , 1.05I 1目标值 ], then calculate the first looper height deviation Δh of the first looper 11 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 11 =H 1 +Δh 11 ;

[0089] The first looper height adjustment is completed, and the sensor unit collects the first horizontal rolling mill I again. 1实时值 , if I 1实时值 ∈[1.02I 1目标值 , 1.05I1目标值 ], then calculate the second loop height deviation Δh of the first loop 12 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 12 =H' 11 +Δh 12 ;

[0090] And so on, until I 1实时值 ∈[I 1目标值 , 1.02I 1目标值 ];

[0091] If I 1实时值 ∈[0.95I 1目标值 , I 1目标值 ], it is judged that there is steel between the first horizontal rolling mill and the vertical rolling mill, and the first looper cannot be released, and the speed of the vertical rolling mill biting into the rolled piece is adjusted to I 1实时值 >I 1目标值 Finally, the first looper is started and dynamically adjusted;

[0092] Within 0.1s after the rolled piece bites into the second horizontal rolling mill, the second looper is set up. After the second looper is set up, the vertical rolling mill I is collected by the sensor unit. 2实时值 ;

[0093] If I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the first loop height deviation Δh of the second loop 21 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 21 =h 2 +Δh 21 ;

[0094] The first looper height adjustment is completed, and the sensor unit collects the vertical rolling mill I again. 2实时值 , if I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the second looper height deviation Δh of the second looper 22 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 22 =H' 21 +Δh 22 ;

[0095] And so on, until I 2实时值 ∈[I 2目标值 , 1.02I 2目标值 ];

[0096] If I2实时值 ∈[0.95I 2目标值 , I 2目标值 ], it is judged that there is steel between the vertical rolling mill and the second horizontal rolling mill, and the second looper cannot be released, and the speed of the second horizontal rolling mill biting into the rolled piece is adjusted to I 2实时值 >I 2目标值 Finally, start the second loop and make dynamic adjustments.

[0097] Specifically, the H 1 and H 2 are the initial heights of the first and second loopers, respectively. It should also be noted that under normal production conditions, or 2实时值 ∈[0.95I 2目标值 , 1.05I 2目标值 ] working conditions. When the above working conditions occur, they are usually fault conditions (such as serious steel piling or steel pulling, etc.), and the machine needs to be shut down for processing, so there is no need to adjust the loop.

[0098] Furthermore, the looper body is a vertical looper or a side looper.

[0099] Furthermore, the reduction amount of a single pass of the reducing unit is in the range of 15% to 30%, and the reduction amount of a single pass of the sizing unit is in the range of 2% to 8%.

[0100] Furthermore, the number of groups of the temperature control units before forming and rolling and the temperature control units after forming and rolling are 1-10 groups, and all are water-cooled temperature control units. The temperature reduction range of each group of water-cooled temperature control units is 10°C to 200°C, and the cooling water pressure is 0.1MPa to 2.0MPa.

[0101] Furthermore, when the forming size thickness of the spring flat steel is less than or equal to 10 mm, a heat preservation device is arranged between the finishing unit and the four-stand two-roller sizing unit, and the heat preservation device is arranged in parallel with the temperature control unit before forming rolling, and they are not turned on at the same time.

[0102] Furthermore, a head-removing device 3 after the rough rolling unit is provided between the rough rolling unit and the intermediate rolling unit to perform head-removing rolling;

[0103] A flying shear 10 is provided between the head stripping device after the rough rolling unit and the intermediate rolling unit, between the intermediate rolling unit and the finishing rolling unit, between the temperature control unit before forming rolling and the four-stand two-roller sizing unit, and between the temperature control unit after forming rolling and the finished product finishing unit.

[0104] Example 1 (Spring flat steel - 8mm×90mm)

[0105] The production method comprises the following steps:

[0106] (1) Continuous casting billet heating: a heating unit 1 (a walking beam type heating unit) is used to heat a billet with a cross-sectional size of 150 mm × 150 mm to 900°C to 1100°C;

[0107] (2) Rough rolling: After descaling by high-pressure water, the billet heated by the continuous casting billet in step (1) is rolled in 6 passes by a rough rolling unit 2. Guides are provided before and after each rolling mill. A flying shear 10 is provided after the rough rolling unit. The average compression ratio of each pass deformation during the rolling process is 1.220. The thickness × width of the rolled piece after rolling is 68 mm × 108 mm. The running speed of the rolled piece is 0.92 m / s. The rolling temperature of the rough rolling unit is 900° C. to 1050° C.

[0108] (3) Intermediate rolling: the intermediate rolling unit 4 is used to transport the rolled piece subjected to the rough rolling in step (2) through the continuous rolling roller after the rough rolling unit 2 or the head removal device 3 after the rough rolling unit, and then continues to be rolled for 6 passes. Guides are provided before and after each rolling mill, and a flying shear is provided after the intermediate rolling unit 4. The average compression ratio of the pass deformation during the rolling process is 1.189. The thickness × width of the rolled piece after rolling is 29 mm × 94 mm. The running speed of the rolled piece is 2.47 m / s. The rolling temperature of the intermediate rolling unit is 880°C to 1000°C.

[0109] (4) Finishing rolling: The finished product rolled in step (3) is further rolled for 4 passes by a finishing rolling unit 5. A guide is provided before and after each rolling mill. The average compression ratio of each pass during the rolling process is 1.169. The thickness × width of the rolled product after rolling is 16 mm × 91 mm. The running speed of the rolled product is 4.01 m / s. The rolling temperature of the finishing rolling unit is 850° C. to 980° C.

[0110] (5) Temperature control before forming and rolling: The temperature of the rolled piece after the finish rolling in step (4) is controlled by the temperature control unit 6 before forming and rolling, and the temperature of the rolled piece after temperature control is 730°C to 920°C;

[0111] (6) Forming rolling: the temperature-controlled rolled piece after finishing rolling in step (5) is further rolled by a four-stand two-roller sizing unit 7, guides are provided before and after each rolling mill, the average pass deformation compression ratio during the rolling process is 1.196, the thickness × width of the rolled piece after rolling is 8 mm × 90 mm, the running speed of the rolled piece is 8 m / s, and the rolling temperature of the four-stand two-roller sizing unit is 750° C. to 900° C.;

[0112] (7) Temperature control after forming and rolling: The temperature of the rolled piece after forming and rolling in step (6) is controlled by a temperature control unit 8 after forming and rolling, and the temperature of the rolled piece after temperature control is 700° C. to 900° C.;

[0113] (8) Finishing of finished products: The rolled product after temperature control after forming rolling in step (7) is subjected to double-length processing and then air-cooled on a cooling bed, wherein the temperature range of the cooling bed on the rolled product is 700°C to 900°C; the rolled product after air-cooling on the cooling bed is cold sheared to a fixed length, and after passing through a cross-inspection platform, it is weighed and collected to obtain a spring flat steel with a thickness × width of 8 mm × 90 mm.

[0114] Example 2 (Spring flat steel - 13mm×89mm)

[0115] (1) Continuous casting billet heating: a walking beam heating unit is used to heat the billet with a cross-sectional size of 150 mm × 150 mm to 900°C to 1100°C;

[0116] (2) Rough rolling: After descaling by high-pressure water, the billet heated by the continuous casting billet in step (1) is rolled in 6 passes by a rough rolling unit 2. Guides are provided before and after each rolling mill. A flying shear is provided after the rough rolling unit. The average compression ratio of each pass deformation during the rolling process is 1.220. The thickness × width of the rolled piece after rolling is 68 mm × 108 mm. The running speed of the rolled piece is 1.02 m / s. The rolling temperature of the rough rolling unit is 900° C. to 1050° C.

[0117] (3) Intermediate rolling: the intermediate rolling unit 4 is used to transport the rolled piece after the rough rolling in step (2) through the continuous rolling roller or the head-removing device 3 after the rough rolling unit 2, and then continues to be rolled for 6 passes. Each rolling mill is provided with a guide before and after, and a flying shear is provided after the intermediate rolling unit. The average compression ratio of the pass deformation during the rolling process is 1.189. The thickness × width of the rolled piece after rolling is 29 mm × 94 mm. The running speed of the rolled piece is 2.74 m / s. The rolling temperature of the intermediate rolling unit is 880°C to 1000°C.

[0118] (4) Finishing rolling: The finished product rolled in step (3) is further rolled by a finishing rolling unit 5. Guides are provided before and after each rolling mill. The average compression ratio of each pass during rolling is 1.225. The thickness × width of the rolled product after rolling is 22 mm × 98 mm. The running speed of the rolled product is 3.36 m / s. The rolling temperature of the finishing rolling unit is 850° C. to 980° C.

[0119] (5) Temperature control before forming and rolling: The temperature of the rolled piece after the finish rolling in step (4) is controlled by the temperature control unit 6 before forming and rolling, and the temperature of the rolled piece after temperature control is 730° C. to 920° C.;

[0120] (6) Forming rolling: the rolled piece after temperature control before forming rolling in step (5) is further rolled by using a four-stand two-roller sizing unit 7, and each rolling mill is provided with guides before and after. The average pass deformation compression ratio during the rolling process is 1.196, and the thickness × width of the rolled piece after rolling is 13 mm × 90 mm. The running speed of the rolled piece is 8 m / s, and the rolling temperature of the four-stand two-roller sizing unit is 750° C. to 900° C.;

[0121] (7) Temperature control after forming and rolling: The temperature of the rolled piece after forming and rolling in step (6) is controlled by a temperature control unit 8 after forming and rolling, and the temperature of the rolled piece after temperature control is 700° C. to 900° C.;

[0122] (8) Finishing of finished products: The rolled product after temperature control after forming rolling in step (7) is subjected to double-length processing and then air-cooled on a cooling bed, wherein the temperature range of the cooling bed on the rolled product is 700°C to 900°C; the rolled product after air-cooling on the cooling bed is cold sheared to a fixed length, and after passing through a cross-inspection platform, it is weighed and collected to obtain a spring flat steel with a thickness × width of 13 mm × 90 mm.

[0123] Example 3 (Spring flat steel 60mm×180mm)

[0124] (1) Continuous casting billet heating: a walking beam heating unit is used to heat the billet with a cross-sectional size of 220 mm × 220 mm to 900°C to 1100°C;

[0125] (2) Rough rolling: After descaling by high-pressure water, the billet heated by the continuous casting billet in step (1) is rolled for 6 passes by a rough rolling unit 2. Guides are provided before and after each rolling mill. A flying shear is provided after the rough rolling unit. The average compression ratio of each pass deformation during the rolling process is 1.147. The thickness × width of the rolled piece after rolling is 109 mm × 206 mm. The running speed of the rolled piece is 0.71 m / s. The rolling temperature of the rough rolling unit is 900° C. to 1050° C.

[0126] (3) Intermediate rolling: the intermediate rolling unit 4 is used to transport the rolled piece after the rough rolling in step (2) through the continuous rolling roller or the head-removing device 3 after the rough rolling unit 2, and then continues to roll for 4 passes. Each rolling mill is provided with guides before and after, and a flying shear is provided after the intermediate rolling unit. The average compression ratio of the pass deformation during the rolling process is 1.113. The thickness × width of the rolled piece after rolling is 75 mm × 190 mm. The running speed of the rolled piece is 1.12 m / s. The rolling temperature of the intermediate rolling unit is 880°C to 1000°C.

[0127] (4) Finish rolling: the finished product after the middle rolling in step (3) is further subjected to empty rolling by the finishing rolling unit 5;

[0128] (5) Temperature control before forming and rolling: The temperature of the rolled piece after the finish rolling in step (4) is controlled by the temperature control unit 6 before forming and rolling, and the temperature of the rolled piece after temperature control is 730° C. to 920° C.;

[0129] (6) Forming rolling: the temperature-controlled rolled piece after finishing rolling in step (5) is further rolled by a four-stand two-roller sizing unit 7, and each rolling mill is provided with a guide before and after. The average pass deformation compression ratio during the rolling process is 1.058, and the thickness × width of the rolled piece after rolling is 60 mm × 180 mm. The running speed of the rolled piece is 1.4 m / s, and the rolling temperature of the four-stand two-roller sizing unit is 750° C. to 900° C.;

[0130] (7) Temperature control after forming and rolling: The temperature of the rolled piece after forming and rolling in step (6) is controlled by a temperature control unit 8 after forming and rolling, and the temperature of the rolled piece after temperature control is 700° C. to 900° C.;

[0131] (8) Finishing of finished products: The rolled product after temperature control after forming rolling in step (7) is subjected to double-length processing and then air-cooled on a cooling bed, wherein the temperature range of the cooling bed on the rolled product is 700°C to 900°C; the rolled product after air-cooling on the cooling bed is cold sheared to a fixed length, and after passing through a cross-inspection platform, it is weighed and collected to obtain a spring flat steel with a thickness × width of 60 mm × 180 mm.

[0132] Table 1 Table of rolling reduction of spring flat steel in Example 1 to Example 3

[0133]

[0134]

[0135] Table 2 Dimensional accuracy of spring flat steel in Example 1 to Example 3

[0136]

[0137] Table 3 Mechanical properties of spring flat steel in Examples 1 to 3

[0138]

[0139]

[0140] According to the contents of Table 1 and Table 3, it can be seen that the spring flat steel produced by the rolling production method has a head and tail dimensional accuracy deviation of only 1 / 3 to 1 / 4 of the national standard deviation, high dimensional accuracy, and good product smoothness. The product has excellent mechanical properties, with a tensile strength deviation of less than 20MPa, a yield strength deviation of less than 20MPa, an elongation deviation of less than 4%, and a cross-sectional shrinkage deviation of less than 5%. Compared with the conventional level, it has increased by more than 20%.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for rolling spring flat steel with both high dimensional accuracy and high strength, characterized in that: A rolling production line is provided, which includes a heating unit, a rough rolling unit, an intermediate rolling unit, a finishing unit, a pre-forming rolling temperature control unit, a four-stand two-roller sizing unit, a post-forming rolling temperature control unit, and a finished product finishing unit, which are sequentially arranged along the rolling production direction; The four-stand two-roller sizing unit is arranged in the form of HVHH, including a first horizontal rolling mill, a vertical rolling mill, a second horizontal rolling mill and a third horizontal rolling mill arranged in sequence along the rolling production direction, and a first looper is arranged between the first horizontal rolling mill and the vertical rolling mill, and a second looper is arranged between the vertical rolling mill and the second horizontal rolling mill; The production method comprises the following steps: Continuous casting billet heating: The continuous casting billet is heated to 900℃~1200℃ through the heating unit; Rough rolling: The heated continuous casting billet is rolled through a rough rolling unit for 6 passes at a rolling temperature of 900°C to 1050°C; Intermediate rolling: The rough rolled product is rolled through the intermediate rolling unit for 4 passes at a rolling temperature of 880°C to 1000°C. Finishing rolling: the rolled piece after intermediate rolling is passed through the finishing unit for finishing rolling or empty rolling, and the rolling temperature during finishing rolling is 850℃~980℃; Temperature control before forming rolling: The rolled piece after finishing rolling is temperature controlled by the temperature control unit before forming rolling, and the temperature of the rolled piece after temperature control is made to be 730℃~920℃; Sizing unit forming rolling: the rolled piece that has been temperature controlled before forming rolling is formed and rolled through a four-stand two-roller sizing unit, the rolling temperature is 750℃~900℃, and the exit speed is 0.5m / s~12m / s; Temperature control after forming and rolling: The rolled piece after forming and rolling by the reducing and sizing mill is temperature controlled by the temperature control unit after forming and rolling, and the temperature of the rolled piece after temperature control is made to be 600℃~850℃; Finishing of finished products: The rolled product after forming and rolling and temperature control is finished by a finishing unit to obtain a spring flat steel, and the thickness of the spring flat steel ranges from 3.0 mm to 60.0 mm.

2. The method for rolling spring flat steel according to claim 1, characterized in that: The four-stand two-roller sizing unit is a prestressed rolling mill, wherein the first horizontal rolling mill and the vertical rolling mill are sizing units, and the second horizontal rolling mill and the third horizontal rolling mill are sizing units.

3. The method for rolling spring flat steel according to claim 1, characterized in that: A compact arrangement is provided between the second horizontal rolling mill and the third horizontal rolling mill.

4. The method for rolling spring flat steel according to claim 1, characterized in that: The first looper and the second looper have the same structure, and both include a looper body, a sensor group, a data processing module and a driving mechanism; The sensor group is used to collect the cross-sectional area of ​​the rolled piece, the rolling mill spacing, the height, tension and speed of the looper body in real time during the rolling process; The data processing module calculates the initial height H of the looper body; constructs a dynamic mathematical model of the looper height, and uses an adaptive control algorithm to iteratively optimize the dynamic mathematical model of the looper height, and outputs a looper height deviation Δh; The looper body adjusts the height of the looper body according to the looper height deviation through the driving mechanism, that is, H'=H+Δh; Among them, the initial height of the looper body is: H=αsqrt(Q·A / L) Among them, H is the initial height of the looper body, α is the looper height coefficient, which ranges from 0 to 100, Q is the looper amount, which ranges from 0 to 1000 mm, A is the cross-sectional area of ​​the rolled piece, and L is the mill spacing, which ranges from 1000 to 5000 mm; The dynamic mathematical model of the looper height is Δh=K f (ΔV·K t +δV+α1ΔF+β(T-T0)-γμ), where Δh is the loop height deviation; ΔV is the speed adjustment; K f K is the rolling force correction coefficient, ranging from 0.1 to 20; t is the tension adjustment coefficient, ranging from 0 to 5; α1 is the tension influence coefficient, ranging from 0 to 20; ΔF is the rolling force deviation, δV is the speed fluctuation noise, ranging from 0 to 10mm; β is the temperature sensitivity coefficient, ranging from 0 to 10; T is the real-time temperature of the rolled piece, ℃; T0 is the reference temperature set for the rolling process, ℃; μ is the friction coefficient between the looper roller and the strip, with a value of 0.6; γ is the friction attenuation coefficient, ranging from 0 to 1.

5. The method for rolling spring flat steel according to claim 4, characterized in that: The adaptive control algorithm is used to iteratively optimize the highly dynamic mathematical model of the looper, specifically: When the rolled piece bites into the first horizontal rolling mill in the four-stand two-roller sizing unit, the current value of the first horizontal rolling mill collected by the sensor unit is recorded as I 1目标值 When the rolled piece bites into the vertical rolling mill, the current of the vertical rolling mill collected by the sensor unit is recorded as I 2目标值 ; Within 0.1s after the workpiece bites into the vertical rolling mill, the first looper is set up. After the first looper is set up, the sensor unit collects the data of the first horizontal rolling mill I 1实时值 ; If I 1实时值 ∈[1.02I 1目标值 , 1.05I 1目标值 ], then calculate the first looper height deviation Δh of the first looper 11 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 11 =H1+Δh 11 ; The first looper height adjustment is completed, and the sensor unit collects the first horizontal rolling mill I again. 1实时值 , if I 1实时值 ∈[1.02I 1目标值 , 1.05I 1目标值 ], then calculate the second loop height deviation Δh of the first loop 12 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 12 =H' 11 +Δh 12 ; And so on, until I 1实时值 ∈[I 1目标值 , 1.02I 1目标值 ]; If I 1实时值 ∈[0.95I 1目标值 , I 1目标值 ], it is judged that there is steel between the first horizontal rolling mill and the vertical rolling mill, and the first looper cannot be released, and the speed of the vertical rolling mill biting into the rolled piece is adjusted to I 1实时值 >I 1目标值 Finally, the first looper is started and dynamically adjusted; Within 0.1s after the rolled piece bites into the second horizontal rolling mill, the second looper is set up. After the second looper is set up, the vertical rolling mill I is collected by the sensor unit. 2实时值 ; If I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the first loop height deviation Δh of the second loop 21 , and complete the first looper height adjustment of the first looper, adjusting the height to H' 21 =H2+Δh 21 ; The first looper height adjustment is completed, and the sensor unit collects the vertical rolling mill I again. 2实时值 , if I 2实时值 ∈[1.02I 2目标值 , 1.05I 2目标值 ], then calculate the second looper height deviation Δh of the second looper 22 , and complete the second looper height adjustment of the first looper, adjusting the height to H' 22 =H' 21 +Δh 22 ; And so on, until I 2实时值 ∈[I 2目标值 , 1.02I 2目标值 ]; If I 2实时值 ∈[0.95I 2目标值 , I 2目标值 ], it is judged that there is steel between the vertical rolling mill and the second horizontal rolling mill, and the second looper cannot be released, and the speed of the second horizontal rolling mill biting into the rolled piece is adjusted to I 2实时值 >I 2目标值 Finally, start the second loop and make dynamic adjustments.

6. The method for rolling spring flat steel according to claim 4, characterized in that: The looper body is a vertical looper or a side looper.

7. The method for rolling spring flat steel according to claim 2, characterized in that: The single-pass reduction amount of the diameter reducing unit ranges from 15% to 30%, and the single-pass reduction amount of the sizing unit ranges from 2% to 8%.

8. The method for rolling spring flat steel according to claim 1, characterized in that: The number of groups of the temperature control units before forming and rolling and the temperature control units after forming and rolling are both 1-10 groups, and all are water-cooled temperature control units. The temperature reduction range of each group of water-cooled temperature control units is 10°C to 200°C, and the cooling water pressure is 0.1MPa to 2.0MPa.

9. The method for rolling spring flat steel according to claim 1, characterized in that: When the forming size thickness of the spring flat steel is less than or equal to 10 mm, a heat preservation device is arranged between the finishing unit and the four-stand two-roller sizing unit, and the heat preservation device is arranged in parallel with the temperature control unit before forming rolling, and they are not turned on at the same time.

10. The method for rolling spring flat steel according to claim 1, characterized in that: A head-off device after the rough rolling unit is also provided between the rough rolling unit and the intermediate rolling unit to perform head-off rolling; Flying shears are arranged between the head stripping device after the rough rolling unit and the intermediate rolling unit, between the intermediate rolling unit and the finishing rolling unit, between the temperature control unit before forming rolling and the four-stand two-roller sizing unit, and between the temperature control unit after forming rolling and the finished product finishing unit.

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