Method for controlling hot-rolled head imprint of interstitial-free steel and interstitial-free steel coil

Abstract

The invention provides a method for controlling imprint of a hot-rolled head of interstitial-free steel and an interstitial-free steel coil, and the method comprises the following steps: cooling a slab of the interstitial-free steel subjected to rolling treatment, and then coiling at a preset temperature by adopting a three-roller coiling machine to obtain a steel coil; in the coiling process, the coiling temperature of a head area which is located on the head of the plate blank and is 20 m long is lower than the preset temperature by 30 DEG C, and before wrapper rollers of the three-roller type coiling machine are completely opened and when pressure control is converted into position control, the KP value setting operation of a sectional type oil cylinder servo valve is carried out according to the following process. By means of the method, head imprint can be effectively controlled and reduced, and even IF steel coils with the thickness smaller than or equal to 3.0 mm can be effectively controlled.

Description

Technical Field

[0001] The present invention relates to the field of alloy technology, and in particular to a method for controlling hot-rolled head stamping of interstitial-free steel and an interstitial-free steel coil. Background Art

[0002] Interstitial-free atomic steel, also known as IF steel, has excellent deep drawing performance, high plastic strain ratio, high elongation, high hardening index, low yield strength ratio and excellent non-aging resistance. Therefore, it is known as the third generation of ultra-deep drawing steel. Its excellent performance makes it widely used in automobile production, but there are many problems to be solved in hot rolling production, especially when producing steel coils with a thickness of ≤3.0mm. There are often 1-3 circles of tongue stampings on the head with deep thickness fluctuations exceeding 10%, which cannot be removed even by cold rolling process. During high-speed cold rolling, the drastic thickness fluctuations at the stamping position can easily cause tearing and breaking of the strip, seriously affecting cold rolling production and causing serious cost and quality losses.

[0003] Some existing technologies have studied the tongue imprinting problem of hot-rolled strip steel, but there are no good control measures for the head imprinting of IF steel coils with a thickness of ≤3.0mm. In particular, there is no good way to solve the conflict between the various measures for controlling the head imprinting when the head coil must be tight and cannot be loosened.

[0004] Therefore, the traditional technology still needs to be improved. Summary of the invention

[0005] Based on this, the present application provides a method for controlling the hot rolling head imprint of interstitial atomic steel and an interstitial atomic steel coil, which can effectively control and reduce the hot rolling head imprint of interstitial atomic steel to obtain a steel coil with good performance.

[0006] The technical solution of this application is as follows.

[0007] In a first aspect of the present application, a method for controlling the hot rolling head imprint of interstitial-free atomic steel is provided, comprising the following steps:

[0008] The interstitial-free steel slab after rolling is cooled, and then coiled by a three-roller coiler at a preset temperature to obtain a steel coil;

[0009] During the coiling process, the coiling temperature of the head area of ​​the slab head with a length of 20 m is lower than the preset temperature by 30° C., and before the auxiliary coiling rolls of the three-roller coiler are fully opened and when the pressure control is switched to the position control, the following process is performed:

[0010] When the actual value of the head pressure of the auxiliary rolling roller is greater than the reference pressure value, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR1 is set to 20, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR2 is set to 22, and the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR3 is set to 24;

[0011] When the actual value of the head pressure of the auxiliary rolling roller is less than or equal to the reference pressure value, the KP value of the cylinder servo valve of the auxiliary rolling roller WR1 is set to 16, the KP value of the cylinder servo valve of the auxiliary rolling roller WR2 is set to 18, and the KP value of the cylinder servo valve of the auxiliary rolling roller WR3 is set to 20.

[0012] In the above method, the head winding temperature is lowered to increase the head yield strength, thereby affecting the pressure on the winding machine's auxiliary winding roller, and then the auxiliary winding roller cylinder servo valve response speed coefficient, that is, the KP value, is set according to different situations when the pressure control of the auxiliary winding roller of the winding machine is converted to position control. When it is greater than the reference pressure value, the KP value of the cylinder servo valve is controlled to make the auxiliary winding roller open quickly. When it is less than or equal to the reference pressure value, the KP value of the cylinder servo valve is controlled to make the auxiliary winding roller open at an appropriate speed, so as to solve the problem of head tongue imprinting caused by excessive pressure caused by slow response of pressure control to position control before the auxiliary winding roller is fully opened.

[0013] Furthermore, the above method for controlling the head imprint of hot-rolled interstitial-free atom steel can also effectively control and reduce the head imprint of IF steel coils with a thickness of ≤3.0mm, and can still play an effective role even under the condition of no step control, is easy to operate, and greatly improves production efficiency.

[0014] In some embodiments, the reference pressure value is 100KN.

[0015] In some of the embodiments, the thickness of the steel coil is ≤3.0 mm.

[0016] In some embodiments, the preset temperature is 600-700°C.

[0017] In some of these embodiments, the cooling process pack uses laminar flow cooling.

[0018] In some of the embodiments, the front section of the laminar cooling adopts a centralized cooling mode, and the back section adopts air cooling.

[0019] In some of the embodiments, the outlet temperature of the rolling process is 870°C to 1000°C.

[0020] In some of the embodiments, the interstitial-free steel comprises, by mass percentage, 0-0.009% C, 0-0.15% Cr, 0-0.09% Si, 0.03%-0.5% Mn, P≤0.02%, S≤0.005%, 0.03%-0.5% Alt, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B and the balance Fe.

[0021] In some of the embodiments, during the winding process, step control is not performed.

[0022] A second aspect of the present application provides an interstitial-free atom steel coil produced by the method for controlling the embossing of the hot-rolled head of interstitial-free atom steel according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture of the interstitial-free steel coil prepared in Example 1;

[0024] Figure 2 This is a physical picture of the interstitial-free atom steel coil prepared in Comparative Example 1;

[0025] Figure 3 This is a physical picture of the interstitial atom-free steel coil prepared in Comparative Example 2;

[0026] Figure 4 This is a physical picture of the interstitial atom-free steel coil prepared in Comparative Example 3. DETAILED DESCRIPTION

[0027] For ease of understanding of the present application, the present application will be described more fully below, and preferred embodiments of the present application are provided. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0030] The "range" disclosed in the present application can be defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of the end values, and any end value can be included or excluded independently, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a specific parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are also listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to listing the parameter as, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0031] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] In traditional technology, the head of the steel coil needs to be kept tight and not loose during the coiling process, which makes it impossible to effectively control the head embossing. Traditional technology only uses conventional auxiliary winding roller step control. Although it can reduce the pressure on the auxiliary winding roller, the control over the head embossing is limited, especially for the head embossing of IF steel coils with a thickness of ≤3.0mm.

[0034] During the long-term actual production and research process, the researchers of this application found that the cooling coiling temperature after rolling affects the yield strength of the steel strip during coiling, and the response speed of the coiler equipment affects the control of the tongue imprint on the head of the steel coil. When coiling, the auxiliary coil roller is not opened in time to squeeze the head of the strip, and the force on the steel coil exceeds the yield limit, resulting in the tongue imprint on the head.

[0035] Thus, after a lot of experimental exploration, the technical solution of the present application was obtained, and the researchers creatively proposed a method for controlling the hot-rolled head imprint of interstitial atomic steel in the present application.

[0036] An embodiment of the present application provides a method for controlling the stamping of a hot-rolled head of interstitial-free atomic steel, comprising the following steps:

[0037] The rolled interstitial-free steel slab is cooled and then coiled using a three-roller coiler at a preset temperature to obtain a steel coil.

[0038] During the coiling process, the coiling temperature of the head area of ​​the slab head with a length of 20 m is lower than the preset temperature by 30°C, and before the auxiliary coiling rolls of the three-roller coiler are fully opened and the pressure control is switched to the position control, the following process is performed:

[0039] When the actual value of the head pressure of the auxiliary rolling roller is greater than the reference pressure value, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR1 is set to 20, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR2 is set to 22, and the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR3 is set to 24;

[0040] When the actual value of the head pressure of the auxiliary winding roller is less than or equal to the reference pressure value, the KP value of the cylinder servo valve of the auxiliary winding roller WR1 is set to 16, the KP value of the cylinder servo valve of the auxiliary winding roller WR2 is set to 18, and the KP value of the cylinder servo valve of the auxiliary winding roller WR3 is set to 20.

[0041] During the long-term actual production and research process, the researchers of this application found that the cooling coiling temperature after rolling affects the yield strength of the steel strip during coiling, and the response speed of the coiler equipment affects the control of the tongue imprint on the head of the steel coil. When coiling, the auxiliary coil roller is not opened in time to squeeze the head of the strip, and the force on the steel coil exceeds the yield limit, resulting in the tongue imprint on the head.

[0042] Therefore, it is creatively proposed to increase the head yield strength by lowering the head winding temperature, thereby affecting the pressure on the winding machine's auxiliary winding roller, and then setting the auxiliary winding roller cylinder servo valve response speed coefficient, i.e., KP value, when the pressure control of the auxiliary winding roller of the winding machine is converted to position control, according to different situations. When it is greater than the reference pressure value, the cylinder servo valve KP value is controlled to make the auxiliary winding roller open quickly. When it is less than or equal to the reference pressure value, the cylinder servo valve KP value is controlled to make the auxiliary winding roller open at an appropriate speed, so as to solve the problem of tongue imprint on the head caused by excessive pressure due to slow response of pressure control to position control before the auxiliary winding roller is fully opened. The technical solution of this application was obtained after a lot of experimental exploration.

[0043] Furthermore, the above method for controlling the head imprint of hot-rolled interstitial-free atom steel can also effectively control and reduce the head imprint of IF steel coils with a thickness of ≤3.0mm, and can still play an effective role even under the condition of no step control, is easy to operate, and greatly improves production efficiency.

[0044] It can be understood that: the preset temperature during coiling is the coiling temperature commonly used for interstitial-free atom steel, which can be selected according to the model of interstitial-free atom steel; the head area located at the 20m long head of the slab refers to the head area formed by extending 20m in a straight line from the starting point of the head end of the slab away from the head end.

[0045] It should be noted that the three-roller winder includes three auxiliary winding rollers: auxiliary winding roller WR1, auxiliary winding roller WR2, and auxiliary winding roller WR3, which are all common knowledge in the field. The KP values ​​of the cylinder servo valves of auxiliary winding roller WR1, auxiliary winding roller WR2 and auxiliary winding roller WR3 can be pre-set through the program.

[0046] Specifically, the method flow of controlling the head stamping of the interstitial-free atomic steel hot rolling process includes the following:

[0047] S1: Load the cooled slab through the clamping roller of the three-roller coiler; S2: Switch the loading of the auxiliary coiling roller from position control to pressure control; S3: When the coiling length of the slab reaches the 20m long head area of ​​the slab head, trigger the auxiliary coiling roller to switch from pressure control to position control before fully opening; S41: When the actual value of the head pressure of the auxiliary coiling roller is greater than the preset reference pressure value, the following settings are made S42: Set the KP value of the oil cylinder servo valve of the auxiliary coiling roller WR1 to 20, and the KP value of the oil cylinder servo valve of the auxiliary coiling roller WR2 to 22, The KP value of the oil cylinder servo valve of the auxiliary winding roller WR3 is 24, so the auxiliary winding roller can be opened quickly; S51: when the actual value of the head pressure of the auxiliary winding roller is less than or equal to the preset reference pressure value, the following settings are made S52: the KP value of the oil cylinder servo valve of the auxiliary winding roller WR1 is 16, the KP value of the oil cylinder servo valve of the auxiliary winding roller WR2 is 18, and the KP value of the oil cylinder servo valve of the auxiliary winding roller WR3 is 20; in this way, the auxiliary winding roller is opened at a normal speed, and finally S6 can be achieved: the auxiliary winding roller is fully opened and disengaged from the steel strip, and winding is achieved without causing head tongue pressure.

[0048] In some embodiments, the reference pressure value is 100 KN.

[0049] In some of the embodiments, the thickness of the steel coil is ≤3.0 mm.

[0050] In some embodiments, the preset temperature is 600-700°C.

[0051] In some of these embodiments, the cooling process pack employs laminar flow cooling.

[0052] In some of the embodiments, the front section of laminar cooling adopts a centralized cooling mode, and the rear section adopts air cooling.

[0053] It can be understood that by presetting the laminar cooling conditions, the temperature of each part of the slab can be controlled, thereby controlling the temperature during coiling.

[0054] In some of the embodiments, the outlet temperature of the rolling process is 870°C to 1000°C.

[0055] The interstitial-free steel may be any type of interstitial-free steel known in the art.

[0056] In some of the embodiments, the interstitial-free steel comprises, by mass percentage, 0-0.009% C, 0-0.15% Cr, 0-0.09% Si, 0.03%-0.5% Mn, P≤0.02%, S≤0.005%, 0.03%-0.5% Alt, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B, and the balance Fe.

[0057] In some of the embodiments, the interstitial-free steel comprises, by mass percentage, 0.001% to 0.009% C, 0.001% to 0.15% Cr, 0.001% to 0.09% Si, 0.03% to 0.5% Mn, 0≤P≤0.02%, 0≤S≤0.005%, 0.03% to 0.5% Alt, N≤0.005%, 0.02% to 0.09% Ti, 0 to 0.009% B, and the balance Fe.

[0058] It can be understood that "Alt" is acid-soluble aluminum.

[0059] In some of the embodiments, during the winding process, step control is not performed.

[0060] Another embodiment of the present application provides an interstitial-free steel coil produced by the method for controlling the embossing of the hot-rolled head of interstitial-free steel according to the first aspect.

[0061] The above method can produce a steel coil without head imprint and with perfect performance.

[0062] The present application will be described below in conjunction with specific embodiments, but the present application is not limited to the following embodiments. It should be understood that the attached claims summarize the scope of the present application. Under the guidance of the concept of the present application, technical personnel in the field should realize that certain changes made to the various embodiments of the present application will be covered by the spirit and scope of the claims of the present application.

[0063] The following are specific embodiments.

[0064] Example 1

[0065] (1) A conventional interstitial atomic steel slab was selected and rolled using a hot rolling mill. The finishing outlet temperature was controlled to be 870-1000°C, and then the slab entered laminar cooling: the front section concentrated cooling mode and the rear section area were used to air cool the steel plate to control the coiling temperature to 600°C, and the head 20m coiling temperature was made 570°C. The slab entered the three-roller coiler for coiling. Before the auxiliary coiling roller was fully opened, when the pressure control was switched to position control, the actual value of the head pressure of the auxiliary coiling roller was greater than 100KN. The KP value of the cylinder servo valve of the auxiliary coiling roller WR1 was set to 20, the KP value of the cylinder servo valve of the auxiliary coiling roller WR2 was set to 22, and the KP value of the cylinder servo valve of the auxiliary coiling roller WR3 was set to 24. The auxiliary coiling rollers were opened quickly until the auxiliary coiling rollers were fully opened and separated from the steel strip, and a steel coil with a thickness of 3.0 mm was obtained.

[0066] The actual picture of the steel coil is as follows Figure 1 As shown, there is no tongue impression on the head.

[0067] Example 2

[0068] Example 2 is basically the same as Example 1, except that: (1) another different type of interstitial atomic steel slab is selected, the actual value of the head pressure of the auxiliary winding roller is less than 100 KN, and the following settings are made: the KP value of the cylinder servo valve of the auxiliary winding roller WR1 is 16, the KP value of the cylinder servo valve of the auxiliary winding roller WR2 is 18, and the KP value of the cylinder servo valve of the auxiliary winding roller WR3 is 20, until the auxiliary winding rollers are fully opened and separated from the steel strip, thereby obtaining a steel coil with a thickness of 3.0 mm.

[0069] The other steps are the same as those in Example 1. There is no tongue imprint on the head of the steel coil.

[0070] Comparative Example 1

[0071] Comparative Example 1 is substantially the same as Example 1, except that the KP value of the cylinder servo valve of the auxiliary winding roller WR1 is 16, the KP value of the cylinder servo valve of the auxiliary winding roller WR2 is 18, and the KP value of the cylinder servo valve of the auxiliary winding roller WR3 is 20.

[0072] The other steps are the same as those in Example 1. There is an obvious tongue imprint on the head of the steel coil, as shown in the actual picture. Figure 2 shown.

[0073] Comparative Example 2

[0074] Comparative Example 2 is substantially the same as Example 1, except that the coiling temperature of the first 20 m is also 600°C.

[0075] The other steps are the same as those in Example 1. There is an obvious tongue imprint on the head of the steel coil, as shown in the actual picture. Figure 3 shown.

[0076] Comparative Example 3

[0077] Comparative Example 3 is substantially the same as Comparative Example 1, except that the coiling temperature in the first 20 m is also 600°C.

[0078] The other steps are the same as those in comparative example 1. The tongue imprint on the head of the steel coil is more obvious than that in comparative example 1. Figure 4 shown.

[0079] Comparative Example 4

[0080] Comparative Example 4 is substantially the same as Example 2, except that the coiling temperature in the first 20 m is also 600°C.

[0081] The other steps are the same as those in Example 1. There is a slight tongue imprint on the head of the steel coil.

[0082] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of this patent shall be subject to the attached claims.

Claims

1. A method for controlling the stamping of the hot-rolled head of interstitial-free atomic steel, characterized in that: The steps include: The interstitial-free steel slab after rolling is cooled, and then coiled by a three-roller coiler at a preset temperature to obtain a steel coil; During the coiling process, the coiling temperature of the head area of ​​the slab head with a length of 20 m is lower than the preset temperature by 30° C., and before the auxiliary coiling rolls of the three-roller coiler are fully opened and when the pressure control is switched to the position control, the following process is performed: When the actual value of the head pressure of the auxiliary rolling roller is greater than the reference pressure value, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR1 is set to 20, the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR2 is set to 22, and the KP value of the oil cylinder servo valve of the auxiliary rolling roller WR3 is set to 24; When the actual value of the head pressure of the auxiliary rolling roller is less than or equal to the reference pressure value, the KP value of the cylinder servo valve of the auxiliary rolling roller WR1 is set to 16, the KP value of the cylinder servo valve of the auxiliary rolling roller WR2 is set to 18, and the KP value of the cylinder servo valve of the auxiliary rolling roller WR3 is set to 20.

2. The method for controlling the stamping of the hot rolling head of interstitial-free steel according to claim 1, characterized in that: The reference pressure value is 100KN.

3. The method for controlling the stamping of the hot rolling head of interstitial-free steel according to claim 2, characterized in that: The thickness of the steel coil is ≤3.0 mm.

4. The method for controlling the stamping of the hot rolling head of interstitial-free steel according to claim 2, characterized in that: The preset temperature is 600-700°C.

5. The method for controlling the stamping of the hot-rolled head of interstitial-free steel according to any one of claims 1 to 3, characterized in that: The cooling process package adopts laminar flow cooling.

6. The method for controlling the stamping of the hot rolling head of interstitial-free steel according to claim 5, characterized in that: The front section of the laminar cooling adopts a centralized cooling mode, and the rear section adopts air cooling.

7. The method for controlling the stamping of the hot-rolled head of interstitial-free steel according to any one of claims 1 to 3, characterized in that: The outlet temperature of the rolling process is 870°C to 1000°C.

8. The method for controlling the stamping of the hot-rolled head of interstitial-free steel according to any one of claims 1 to 3, characterized in that: The components of the interstitial-free steel include, by mass percentage, 0-0.009% C, 0-0.15% Cr, 0-0.09% Si, 0.03%-0.5% Mn, P≤0.02%, S≤0.005%, 0.03%-0.5% Alt, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B and the balance Fe.

9. The method for controlling the stamping of the hot-rolled head of interstitial-free steel according to any one of claims 1 to 3, characterized in that: During the coiling process, no step control is performed.

10. A gapless atomic steel coil, characterized in that: The method for controlling the hot-rolled head stamping of interstitial-free steel is used to make the steel.

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