TW528808B - Method for manufacturing a steel plate and apparatus thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing a steel plate comprising the steps of: hot rolling a steel slab; quenching or accelerated cooling the hot rolled steel plate; and tempering the quenched or accelerated cooled steel plate using a solenoid-type induction heater; wherein the steel plate is intermittently and in at least two parts heated up to the aimed temperature in the tempering treatment. By the method, it is possible to conduct an on-line tempering treatment without impeding the productivity and also to temper the steel plate homogeneously in a thickness direction without overheating the surface of the steel plate over the aimed temperature.

Description

528808 V. Description of the invention (1) Mandibular jaw field The present invention relates to a method for manufacturing a thick steel plate, and more particularly to a manufacturing method and equipment for in-line tempering treatment. BACKGROUND ART In order to obtain a high-strength steel sheet with a plate thickness of 8 or more, a high-strength and high-knife-shaped steel sheet can be obtained. :: After the hot-rolled steel sheet is quenched by quenching and accelerated cooling, the following: In case of fire treatment method. —In recent years, quenching and accelerated cooling have gradually begun to be used on the wire ^: However, because the tempering process is still not on the line, but the use of a gas burner for the process takes a long time, which significantly hinders the production of thick steel plates Sex. ^ In order to improve its productivity, Japanese Patent Laid-Open No. 4-3 58 022 discloses the production line of the f-thick steel plate by using a quenching device or accelerated cooling, and heating by electric current, induction heating, and infrared radiation. The rapid tempering device of heating methods such as heating and peripheral air makeup heating works. 0 5〜? 〇 / sec above the heating speed directly heat the sweat or accelerated cooling of the steel plate to a specified temperature, immediately 0. 0 5 ~? The method of cooling and tempering at a cooling rate of z u C / sec. But 2: In the method described in Japanese Patent Laid-Open No. 1358022, because a short time tempering treatment by rapid heating by gas is performed, the surface temperature of the steel plate exceeds the target temperature, or the thickness of the steel plate There is a problem that a large temperature difference occurs in the direction, and it is not possible to temper the steel sheet in all directions. Invention Revealed C: \ 2D-C0DE \ 91-03 \ 90131315.ptd Page 5

528808 V. Description of the invention (2) The purpose of plate t = is to provide a thick steel plate that does not hinder its productivity, and the steel return temperature does not exceed the target temperature, and can be evenly advanced in the plate thickness direction. Method and equipment. Or Z: ϋ lies in the step of becoming a steel plate with a hot-rolled steel slab, the step of quenching the hot-rolled steel plate, and the treatment of Φ by 卞 / beaming or accelerated cooling by electromagnetic induction and tempering The step of performing the steel plate and the temperature ^ P ^ are achieved by a method of manufacturing the target steel plate to the target / plate thick steel plate by intermittently heating the steel plate twice or more. In addition, there is an I! Method, which is performed in the order from the upstream side to the downstream side of the manufacturing process. ^ Force ^ furnace: hot rolling mill, flame device or accelerated cooling device, and two. Manufacturing equipment for thick steel plates of electromagnetic induction heating device to realize the shape of the bears> One of the embodiments of the manufacturing equipment for thick steel plates which is not simplified and clarified: The steel plate 2 is hot rolled by the rolling mill 1, and the quenching device is 3 Then, the quenched type II salt r 'is subjected to a flattening treatment by a slab rolling mill 4, and then six electric units are provided. U tempering device 6 ~ 1 to 6-6 in the tempering treatment of the tempering unit to reduce the surface temperature of the steel plate does not exceed the target temperature, can be driven in the thickness direction β, door into the uniform heating, Six or more electromagnetic induction sensors T 2. To 6 6 are used to heat the steel plate at a target temperature of 2 to 650 t intermittently. Figure 2A, 2B shows the split! And 2 times of 8-plate thickness

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IC: \ 2D-C0DH \ 91-03 \ 90131315.ptd 528808 V. Description of the invention (3) The measured surface temperature of the central part in the width direction of the steel plate and the thickness obtained by calculation when the steel plate is around 650 ° C Changes in the core temperature over time. At this time, the second heating uses an electromagnetic induction heating device, with a power input of 750 MW and a frequency of 1 500 Hz, and the second heating uses an electromagnetic induction heating device 6-i and 6-2, with an electric power input of 3 MW. (6_2), proceed. Also, 'the conveying speed of the steel plate is in any case; β': the force is hot, and the surface temperature is overheated when the surface temperature exceeds the target temperature, but when heating is performed, the surface temperature will not be overheated, and two = Surface temperature and plate thickness center temperature to the wrong eye The method of the present invention will not hinder productivity, and the average hooking degree will not exceed the target temperature. The percentage expansion of the center can be performed in the thickness direction. J: If the thickness of the steel plate To increase the thickness of the temple, it must spread to the thickness of the plate I :: Expansion "It takes a long time and there is an increase in the number of heating times according to the plate thickness as a heating device. Using φ for rapid heating can increase the principle. It is easier to control heating conditions due to temperature. "After the heat is concentrated on the surface of the steel plate and the surface is heated for each time, as long as the average temperature is below the temperature, the next step is performed: the flatness of the surface temperature of the plate will not exceed the target temperature in the thickness direction and 5 === hot, can be more Make sure that the average temperature of the surface temperature is heating for a certain temperature. The temperature is calculated at the thickness of 4 daggers. The heating method in Figure 3 翮 /, B off ^ is calculated in advance by 58 (TC example, but 1 = For 60 times, the steel plate with a thickness of 40_plate thickness is below the average temperature, and the surface temperature of the steel plate will be the next time it becomes thicker, so its surface temperature is C: \ 2D-OODE \ 91-O3 \ 90131315.ptd Page 7

528808 V. Description of the invention (4) In excess of 600. (: Is overheated. As shown in Fig. 1, when processed by Fuer, the %% rolling mill 4 flattens the steel plate before tempering: you can enter more uniform heating. $ 力 成 数Intermittently; 隹 / The power of the heating device and the frequency J 仃 force: "'Make the two-in electromagnetic induction induction points into the pole * If the goat is a 疋, but who is at least in the direction of the second half ^^ It is best to make the reducing side not exceed the target temperature when the distance between the thickness and the thickness is Ϊ: ΪΪYes, when the tempering efficiency is set to Λ 匕 士士 + 丄, take it in the range that does not exceed the target temperature Make the most of your investment:… 'It's best to use the electricity that you put in the first half

Second, Muda reduced power in the number of times performed in the second half. W ^ When the frequency of the electromagnetic induction heating device is 2000 Hz or more, uniform heating can be formed in a wide range of plate thicknesses from thin steel plates to thick steel plates. f It is that when the number and frequency are low, the penetration depth of the induced current changes in order to form a more uniform heating in the direction of the plate. In fact, the penetration depth at a frequency of 200 Hz is about 2 mm. However, in the case of heating a steel plate with a thickness of 8 mm, when the penetration depth exceeds 2 mm, temperature control in the thickness direction becomes impossible. Therefore, it is necessary to make the frequency above 2000 Hz, and the maximum value of the commercial frequency currently used is 2000 Hz.

As long as the following formula (1) is used to determine the full electric power P of the electromagnetic induction heating device, tempering treatment can be performed at an efficiency greater than the rolling pitch, and higher productivity can be obtained. P ^ (l / ??)-pH-L-Cp- (ΔΤ / Δΐ) · [(Lc + Lw) / Lc] · [1 / (Ν · Μ)] (1) Here, each element is numbered separately It means the following. That is, β •• heating

\\ 312 \ 2d-code \ 91-03 \ 90131315.ptd Page 8 528808 ι * »(* · k ^ 1 V. Description of the invention (5) Efficiency, p: steel density (Kg / m3), H: steel plate Thickness (m), w: width of steel plate (m), L: length of steel plate (m), Cp: specific heat (J / kg ° C), ΔT · necessary temperature rise (° C), △ t: rolling of steel plate Pressure interval (seconds), lc: coil length (m), Lw: distance between electromagnetic induction heating devices (m), n: number of electromagnetic induction heating devices, M: number of heating times. For example, heating a plate with a thickness of 40 mm In the case of a steel plate (weight is i200 000 kg), where ?? = 0.7, Cp = 60 0 J / kg ° C, ΔT 2 600 ° C, ^ 1: = 180 seconds, Lc = lm, Lw = lm, when two electromagnetic induction heating devices are moved in one direction for heating, each one requires more than 34MW of power. In addition, three electromagnetic induction heating devices are used to heat the steel plate by one and a half moving back and forth. In this case, it is necessary to have a power of 7.6 MW or more. In this way, in order to perform the tempering treatment at an efficiency higher than the rolling pitch, the formula (丨) can be used and the number of electromagnetic induction heating devices can be used. In the case of heating a thick steel plate with an electromagnetic induction heating device, not only the upper and lower surfaces of the steel plate but also the cross-section in the width direction are also heated. Therefore, the widthwise end of the steel plate is overheated than the center of the plate width. In the process of reviewing the surface temperature in the visibility direction of the steel sheet, the present inventors learned that in a width corresponding to the thickness of the steel sheet, it was approximately overheated by about 5 times the central portion. Therefore, during tempering, During the treatment, if the tempering treatment is performed while cooling the widthwise end portion of the steel plate, it is easy to prevent overheating of the widthwise end portion of the steel plate. In the apparatus of FIG. 1, in order to make the tempering treatment uniform, it is flattened. The rolling mill 4 performs a flattening treatment before the steel sheet is processed. However, if a flattening mill is installed after the treatment, a steel sheet having excellent flatness can be produced.

\\ 312 \ 2d-code \ 91-03 \ 90131315.ptd Page 9 528808: V. Description of the invention (6): Induction heating system puts energy from the surface of the steel plate, and it is not easy to form a uniform sentence in the thickness direction. Achieve heating due to long. However, since the length of the coils that can be supported by the rollers is separated as much as possible, the coils of the electromagnetic induction heating device are made between the lepton cells taking into account the distortion of the steel plate K = reverse; 5: 5; 0 Therefore, it is best that the plate is between: m :; j to the next-time heating period, although there is cooling steel, = ί will generate thermal expansion from the surface of the steel plate toward the center of the thickness of the plate. Into. In order to make the temperature of the steel plate uniform: = almost the same as the rod temple, as long as each electromagnetic induction plate is made longer than the coil length, uniform heating can be performed in a wide range of thin steel plates to thick steel plates. , Figure, 1 = In the device, set the temperature on the inlet side and the outlet side of the tempering treatment device ^ By this, the electric power input to the electromagnetic induction heating device and the old one can be controlled; In particular, in the heat treatment of thick steel plates, since it is necessary to accurately understand the surface temperature of the steel plate from a quality point of view, it is best to use a two-dimensional scanning type thermometer that can simultaneously measure the temperature distribution in the length and width directions. . 3, Right Inside the electromagnetic induction heating device or at the outlet side, a cooling mechanism for the I-degree end of the cold section steel plate can be installed to prevent excessive force and heat at the end. Reference numeral 7 denotes a cooling mechanism. Examples of the cooling mechanism include an air jet pipe shown in Fig. 4, a water jet nozzle shown in Fig. 5, and a water cooling roller shown in Fig. 6.

\\ 312 \ 2d- c〇de \ 9l.〇3 \ 9〇13i315.ptd Page 10 528808 V. Description of the invention (7) In Figure 4, 'in the electromagnetic induction heating device 6 and between nests, there are The ceramic nozzle air injection pipes 12a and 12b are provided at the two ends of the steel plate with holes with a diameter of 0.3mm. Air is supplied from the air supply pipe 14 to the spray pipes 12a and 12b, and the cooling air is blown uniformly from the holes 13 toward the end of the steel plate. The air flow is controlled by a flow adjustment valve, and its cooling capacity is controlled. In Fig. 5, in the electromagnetic induction heating device 6, a pair of upper and lower water spray nozzles 6 are provided near both ends of the steel plate 2. In addition, an air jet nozzle 17 and a water cutting roller 18 are provided to cut off water so that the cooling water sprayed from the water jet nozzle 16 does not flow into the vicinity of the coil. The water-powered Λ-type induction heating device includes a plurality of water cooling rollers 19 inside. The end of the steel plate is cooled by abutting the water-cooled ladles 19 on the end of the steel plate 2. The cooling conditions at the ends of such cooling mechanisms are calculated in advance based on the steel plate width, plate thickness, and steel plate conveying speed. Calculate the heating temperature curvature near the central portion in the width direction. , To find the temperature-increasing curvature at the end of the end = to control the corner temperature of the end below the target. In the tempering treatment device 5 shown in FIG. 1, the plate 2 may be intermittently heated along one direction. However, in the tempering treatment device 5, the same heating can be performed by shifting the plate. In particular, in the case of thick steel plates, it is necessary to intermittently heat the steel plates in fractions, but the number of electromagnetic induction heating devices can also be reduced by moving back and forth. There are 6 electromagnetic induction heating devices on the fire treatment device 5. However, as long as

C: \ 2D-CODE \ 9l-03 \ 90131315.ptd Page 11 528808 5. Description of the invention (8) If there are at least two or more units, it can correspond to a wide range of plate thicknesses from thin steel plates to thick steel plates. In particular, in the case of a thin steel plate, the temperature drop between heating rooms is large '. Two or more electromagnetic induction heating devices are required. (Example 1) Using the manufacturing equipment for the thick steel plate shown in FIG. 1, the steel plate 2 having a thickness of 50 mm after being hot-rolled by the hot rolling mill 1 through the water-cooling section of the quenching device 3 is up to 50 mm. After the rolling mill 4 is subjected to the flattening treatment, the tempering device 5 composed of six electromagnetic induction heating devices 6-1 to 6-6 is subjected to a tempering treatment at 65 ° C under the conditions shown in Table 1. The frequency of each electromagnetic induction heating device is 100 Hz. The comparative example is an example in which only the electromagnetic induction heating device 6-1 is used and the steel sheet surface / la degree is heated to 6 50 ° C at a time. As shown in FIG. 7, using only 30 seconds, the surface f degree becomes 6 50, and the temperature at the center of the plate thickness at this time is 400 ° C. With f ′, both the surface and the center of the plate thickness become 50. 〇Temperature around it 'but will not reach β 5 of the target temperature. Invention Example 1 is an example in which an electromagnetic type induction heating device 6-1 to 6-4 is used, and the surface temperature of the steel sheet is heated to 6500C in 4 times. As shown in FIG. 8, the surface temperature becomes 65 ° after 2 ^ 00 seconds. 〇, the degree at the center of the plate thickness at this time is 63 0. . Therefore, the target temperature can be uniformly heated in the thickness direction. Inventive Example 2 uses an electromagnetic induction heating device 6 — i to 6 to 6, and divides the steel plate surface temperature to β 5 00 plant in 6 times. Example of bbU C. As shown in Fig. Θ, the two-surface temperature becomes 650. ° ’At this time, the plate thickness at the center of the plate thickness is 640 C, so that it can be evenly heated to the target temperature in the thickness direction.

528808 V. Description of invention (9) Degree. Table 1 Transfer Speed Induction Heating Device: Input Power (MW) (m / s) 6-1 6-2 6-3 6-4 6-5 6-6 Comparative Example 0.53 10-----Invention Example 1 1.56 10 5 β 3--Invention Example 2 2.76 10 10 8 8 6 4 (Embodiment 2) The same as Invention Example 2 of Embodiment 1, an electromagnetic induction heating device 6 -1 to 6-6 was used, as shown in Table 2 The input power and frequency of each electromagnetic induction heating device were changed as shown, and the surface temperature of the steel plate with a thickness of 50 mm was heated to 650 ° C in 6 times. The conveying speed of the steel plate is set at a fixed value of 2.76 m / s. In this case, the same result as that of Fig. 9 can be obtained, so that the target temperature can be uniformly heated in the thickness direction. Table 2 ____ Induction heating device 6-1 6-2 6-3 6-4 6-5 6-6 Input power (MW) 10 10 8 8 8 6 Frequency (Hz) 2000 1000 200 200 200 200 (Example 3)

C: \ 2D-C0DE \ 91-03 \ 90131315.ptd Page 13 528808 V. Description of invention (ίο) " The manufacturing equipment using the thick steel plate shown in Fig. 1 is cooled by a quenching device 3 by a hot rolling mill 1 After hot rolling, the steel plate with a thickness of 20 mm and a length of 10 mm is 2 to 30 C. After being flattened by the flat rolling mill 4, it is moved from the electromagnetic induction heating device 6-1 to 6-6 Semi-reciprocating, that is, heating is divided into 9 times for tempering treatment at 650 ° C. The input power of each time is shown in Table 2. In addition, the conveying speed of the steel plate was moved back and forth one by one, respectively, 17, 17, 0, 30 m / s, and the frequency of each electromagnetic induction heating device was set to 1000 Hz. During the back-and-forth movement, the movement is reversed after stopping for 3 seconds. Fig. 10 shows changes in the surface temperature and the thickness center temperature of the steel sheet over time in the front end position in the longitudinal direction. The surface temperature of the steel plate and the center temperature of the plate thickness are approximately 6 5 0 X plus rail. · ', Table 3 Input power of induction heating device (KW) 6] 6-2 6-3 6-4 6-5 6-6 Outbound 4000 3800 3000-One-Circuit 1800 2200 2500 One Out-1000 600 200 One I- Using the thick steel sheet manufacturing equipment shown in Figure 1, water quenched by the hot rolling mill 1 with a quenching device 3 to cool the steel sheet with a plate thickness of 40 mm 2 to 30 ° C, and flattened by the flat rolling mill 4 After processing, adopt 6 electromagnetic induction heating

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provincial judge. The tempering device 5 composed of 1 to 6 to 6 is subjected to a tempering treatment of 65 0 C according to the conditions shown in Table 4. In addition, the conveying speed of the steel sheet is 0, and the frequency of the electromagnetic induction heating I is set to 1000 Hz. In the device of electromagnetic plastic induction heating I and the device to 6_5, set the air jet tube shown in Figure 4, Pei, Sheng ,, ^ ^ Asia to spray the air to the end of the steel plate under the conditions shown in Table 4 . FIG. 11 shows the surface of the central portion ① in the width direction and the center of the plate thickness center at the position 10m away from the long end of the steel plate, and the thickness end of the end of the plate. ^ ^ ^ The temperature at the corners ⑨ and the plate thickness center ④ changes over time at four points. At the corners in the widthwise direction, heat that does not exceed 65.0 t is generated, and the steel plates can be heated for 6 0 t each in a short time of about 200 seconds. Heart, dish

2 steel plate

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528808 Brief Description of Drawings Fig. 1 is a diagram showing an example of an embodiment of a manufacturing apparatus for a thick steel plate according to the present invention. Figures 2A and 2B are graphs showing the change over time of the surface temperature and the center temperature of the plate thickness when the steel plate with an 8 mm plate thickness is divided into 1, and heated to 650 ° C before and after. Fig. 3 is a graph showing the change over time of the surface temperature of a steel plate having a plate thickness of 40 mm divided into six heating steps to 580 ° C. Fig. 4 is a view showing an example of an air jet pipe for cooling an end portion in the width direction of a steel plate. Fig. 5 is a view showing an example of a water jet nozzle for cooling the end portion in the width direction of a steel plate. Fig. 6 is a view showing an example of a water-cooled roller for cooling an end portion in the width direction of a steel plate. Fig. 7 is a graph showing the change with time of the surface temperature and the center temperature of the plate thickness when the steel plate having a plate thickness of 50 mm was heated up to about 650 ° C at one time. Fig. 8 is a graph showing the change over time of the surface temperature and the center temperature of the plate thickness when the steel plate having a plate thickness of 50 mm is heated up and down to 650 ° C in 4 times. Fig. 9 is a graph showing the change over time of the surface temperature and the center temperature of the plate thickness when the steel plate having a plate thickness of 50 mm is heated up to 650 ° C before and after being divided into six times. Fig. 10 is a graph showing the change over time of the surface temperature and the center temperature of the plate thickness when the steel plate with a thickness of 20 mm is heated up and down to 650 ° C before and after the reciprocating movement of the induction heating device is divided into nine times. Fig. 11 is a graph showing the change over time of the temperature of each part of the steel plate when the steel plate with a thickness of 40 mm is heated up to about 65 ° while the end portion of the steel plate is cooled while cooling.

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Claims (1)

528808 VI. Scope of patent application1. A method for manufacturing a thick steel plate, which includes the steps of turning a hot-rolled steel slab into a steel plate, quenching or accelerating the cooling of the hot-rolled steel plate, and returning it by an electromagnetic induction heating device. A step of heat-treating a steel sheet after quenching or accelerated cooling, and 'in the tempering process, the steel sheet is intermittently heated to a target temperature at least twice. 2. The method for manufacturing a thick steel plate according to item 1 of the scope of patent application, wherein in the tempering process, the surface temperature of the steel plate after each heating becomes thick After the average temperature in the degree direction is below, the next heating is performed. 3. The method for manufacturing a thick steel plate according to item 1 of the scope of patent application, wherein a step of flattening the steel plate is provided between the step of annealing or accelerated cooling and the tempering treatment step. 4 · The manufacturing method of thick steel plate according to item 丨 of the patent application scope, wherein, in the tempering process, to the main part of ΦYougu eight ^ ^ ^ ^ v makes electromagnetic induction in the number of times of Houfeng 4 knives ;! The input power of thermal installations is reduced. 5. If the scope of the patent application is complicated, the households are in the tempering process to the half of the part; the manufacturing method of the eight steel plates, in which the frequency of the heating device is reduced. Electromagnetic induction during the number of times of the knife;! 6 · If the thick steel soil in the scope of the patent application applies to the tempering treatment, the magnetic field of the thunder and magnetic field will be worn. Electric route ^ • The frequency of induction heating device is 200Hz 528808 Six applications for patent scope You 1 5 ΐ Steel plate manufacturing equipment, which includes:% of manufacturing steps above 1 亍 to the downstream side with heating furnace, hot rolling mill, wide: device or accelerated cooling device, and The above electromagnetic induction heating device. Quenching in ”: Equipment for manufacturing thick steel plates in item 8 of the scope, among which, there are ° flat =: = set and 2 or more electromagnetic plastic induction heating installed at 2 ° ::: The manufacturing equipment, including the machine. The downstream side of the raw induction heating device has a flat rolling11. As in the patent application scope No. 8 of the electromagnetic type induction heating device, the manufacturing equipment of the phase-transmitting steel plate, among them, is placed. The above intervals are provided with 12. As in the electromagnetic induction heating device of item 8 of the scope of the patent application: the cooling mechanism for the end of the direction in which the board manufacturing equipment is used. Σ or the width of the cooling steel plate on the exit side 13. As in item 12 of the scope of application for a patent, the cooling mechanism is an equipment for manufacturing a thick steel plate by air spray, and one of them is optional. 'S, water cooling roller, water spray nozzle \\ 312 \ 2d-code \ 91-03 \ 901313l5.ptd Page 19