Metal strip manufacturing facility, metal strip determination method, and metal strip manufacturing method

Abstract

Provided are a device for manufacturing a metal strip, a method for manufacturing the metal strip, and a method for determining whether or not the metal strip is qualified, with which it is possible to reliably ensure the quality of the warped shape of the metal strip. A device for manufacturing a metal strip is provided with: a heating unit (6) that continuously heats a conveyed metal strip; a cooling unit (8) that cools the metal strip heated by the heating unit; a shape correction unit (13) that corrects the shape of the metal strip cooled by the cooling unit; a first warpage shape measurement unit (14) that is disposed on the downstream side of the shape correction unit and that measures the warpage shape of the metal strip; and a warpage shape specifying unit (41) that specifies position information from the tip of the metal strip, and specifies the correspondence between the warpage shape of the metal strip measured by the first warpage shape measuring unit and the position information from the tip of the metal strip.

Description

Technical Field

[0001] The present disclosure relates to a metal strip manufacturing device, a metal strip quality determination method, and a metal strip manufacturing method. Background Art

[0002] In continuous annealing equipment for metal strips, it is important to control heat treatment conditions such as heating and cooling in order to give the treated metal strips the desired mechanical properties. In the manufacture of high-strength steel sheets, as a control of heat treatment conditions, the cooling rate of the metal strip is often increased, and a tempering treatment is performed by reheating the cooled metal strip from the viewpoint of improving stamping formability.

[0003] The continuous annealing equipment used to manufacture high-strength steel sheets is equipped with a heating zone, a soaking zone, and a cooling zone. The cooling methods in the cooling zone include liquid quenching, roll cooling, air-water mixed (water mist) cooling, gas jet cooling, etc. The appropriate cooling method is appropriately selected to control the material of the metal strip.

[0004] Among them, the liquid quenching method in which the metal strip is immersed in liquid has the fastest cooling speed and can reduce the addition of alloy elements for improving the strength of the metal strip, so it is suitable for the production of high-strength steel sheets. As a liquid quenching method, a general method is to immerse the heated metal strip in liquid and spray cooling liquid onto the metal strip from a slit nozzle set in the liquid to perform rapid cooling (quenching). The quenched metal strip is scraped off the remaining liquid by a pressed rubber roller or gas wiping based on gas jetting from the slit nozzle, and is heated again after a drying process.

[0005] When the metal strip is rapidly cooled, the shape of the metal strip is easily damaged due to the influence of the thermal contraction of the metal strip and the volume expansion accompanying the phase transformation of the metal structure. In addition, the yield stress of the rapidly cooled metal strip becomes very large, so even if a temper rolling mill arranged on the downstream side of the continuous annealing equipment is used, the elongation required for shape correction cannot be given to the metal strip, and there is a problem that the metal strip as a product is prone to residual shape defects.

[0006] In contrast, Patent Document 1 discloses a technique in which a metal strip undergoing rapid cooling and quenching is restrained by restraining rollers in a temperature range determined by the temperature at which the martensitic transformation of the metal strip starts and ends, thereby suppressing shape defects that may occur in the metal strip after rapid cooling.

[0007] Patent Document 2 describes a method for controlling the shape of a metal strip by a rolling mill such as a temper rolling mill, in which the shape of the metal strip is measured using a shape meter, and a shape control actuator of the rolling mill is operated based on the deviation between the measured shape and the target shape. The shape meter used in this case is a contact shape meter, and the shape meter, which is obtained by embedding a plurality of load cells inside a shape measuring roll, estimates the distribution of the elongation in the plate width direction of the metal strip based on the distribution of the contact load in the plate width direction.

[0008] Patent Document 3 discloses a technique of using work rolls having an average surface roughness exceeding 10.0 μm as a method of reducing the warpage height of a metal strip after the temper rolling when temper rolling a high-strength steel sheet.

[0009] Patent Document 1: Japanese Patent No. 6094722

[0010] Patent Document 2: Japanese Patent No. 6673285

[0011] Patent Document 3: Japanese Patent Application Publication No. 2013-176802

[0012] However, the method disclosed in Patent Document 1 requires determining the temperature region where phase change occurs in the metal strip and constraining the metal strip by the constraining roller in the temperature region. As the operating conditions of the continuous annealing equipment, if the conveying speed of the metal strip changes, the cooling start temperature also changes, and the shape of the metal strip after cooling also changes. There is room for improvement. In particular, when the strength level of the high-strength steel sheet is improved, there is still a case where the shape of the metal strip cannot be flattened, and sometimes a portion with a poor shape remains in the length direction of the metal strip.

[0013] On the other hand, the method disclosed in Patent Document 2 dynamically controls the shape of the metal strip based on the shape of the metal strip measured at the output side of the temper rolling mill, thereby stabilizing the shape of the metal strip in the longitudinal direction. However, the shape meter described in Patent Document 2 infers the distribution of the elongation in the plate width direction of the metal strip, and does not measure the warping shape of the metal strip. In particular, it is impossible to measure the cross-sectional shape in the plate width direction as a W-shaped or further high-order function-approximated buckling shape, such as a high-strength steel plate after rapid cooling, so it is difficult to perform quality assurance related to the warping height of the metal strip.

[0014] The method disclosed in Patent Document 3 is a shape correction mechanism for high-strength steel plates after quenching, and uses work rolls with specific surface roughness to perform temper rolling to reduce the warping height of the metal strip. However, the warping height of the metal strip after temper rolling is measured offline after a sample plate is cut from the metal strip. Therefore, it is impossible to determine whether the specifications for warping are met throughout the entire length of the metal strip. In addition, the metal strip after quenching has a variation in warping height in the length direction. If combined with the fact that the shape correction effect based on the temper rolling mill is not sufficient when the strength level of the high-strength steel plate is high, there is a problem that it is difficult to ensure that the product specifications for the warping shape are met throughout the length direction of the metal strip. Summary of the invention

[0015] The present disclosure aims to provide a manufacturing device and a manufacturing method for a metal strip that can reliably perform quality assurance for the warped shape of the metal strip in a manufacturing device for a metal strip that includes a cooling unit for cooling the metal strip and a shape correction unit for correcting the shape of the cooled metal strip. In addition, the present disclosure provides a method for determining whether the shape of the metal strip is related to the warping height in the manufacturing device for the metal strip.

[0016] (1) A metal strip manufacturing apparatus according to one embodiment of the present disclosure includes:

[0017] A heating section that continuously heats the conveyed metal strip;

[0018] a cooling section for cooling the metal strip heated by the heating section;

[0019] a shape correcting section that corrects the shape of the metal strip cooled by the cooling section;

[0020] a first warp shape measuring section disposed on a downstream side of the shape correcting section and configured to measure the warp shape of the metal strip; and

[0021] A warp shape specifying unit specifies position information from the front end of the metal strip, and specifies a correspondence between the warp shape of the metal strip measured by the first warp shape measuring unit and the position information from the front end of the metal strip.

[0022] (2) As one embodiment of the present disclosure, based on (1),

[0023] The manufacturing equipment of the metal strip is a continuous annealing equipment for the metal strip.

[0024] The cooling unit includes a cooling fluid spraying device including a plurality of nozzles for spraying a cooling fluid toward the metal strip from both sides of the metal strip, and at least a pair of restraining rollers for restraining the metal strip.

[0025] (3) As one embodiment of the present disclosure, based on (1) or (2),

[0026] The manufacturing equipment of the metal strip is a continuous annealing equipment for the metal strip.

[0027] The shape correcting section includes at least one shape correcting mechanism selected from a temper rolling mill, a tension leveler, and a roll leveler.

[0028] (4) As one embodiment of the present disclosure, in addition to any one of (1) to (3),

[0029] The metal strip manufacturing equipment includes a second warpage shape measuring unit for measuring the warpage shape of the metal strip between the cooling unit and the shape correcting unit.

[0030] The warp shape specifying unit specifies a correspondence relationship between the warp shape of the metal strip measured by the first warp shape measuring unit, the warp shape of the metal strip measured by the second warp shape measuring unit, and position information from a front end of the metal strip.

[0031] (5) As one embodiment of the present disclosure, in addition to any one of (1) to (3),

[0032] The metal strip manufacturing apparatus includes a third warpage shape measuring unit for measuring the warpage shape of the metal strip between the heating unit and the cooling unit.

[0033] The warp shape specifying unit specifies a correspondence relationship between the warp shape of the metal strip measured by the first warp shape measuring unit, the warp shape of the metal strip measured by the third warp shape measuring unit, and position information from a front end of the metal strip.

[0034] (6) As one embodiment of the present disclosure, in addition to any one of (1) to (3),

[0035] The manufacturing equipment of the metal strip includes a second warping shape measuring unit for measuring the warping shape of the metal strip between the cooling unit and the shape correcting unit, and a third warping shape measuring unit for measuring the warping shape of the metal strip between the heating unit and the cooling unit.

[0036] The warping shape determination unit determines the correspondence between the warping shape of the metal strip measured by the first warping shape measuring unit, the warping shape of the metal strip measured by the second warping shape measuring unit, the warping shape of the metal strip measured by the third warping shape measuring unit, and position information from the front end of the metal strip.

[0037] (7) As one embodiment of the present disclosure, in addition to any one of (1) to (6),

[0038] The warping shape of the metal strip is measured using at least one warping shape measuring method selected from a distance measuring method, an image processing method, and a light sectioning method.

[0039] (8) A method for determining whether a metal strip is good or bad according to an embodiment of the present disclosure includes:

[0040] A heating process for continuously heating the conveyed metal strip;

[0041] a cooling step of cooling the metal strip heated in the heating step;

[0042] A shape correction step of correcting the shape of the metal strip cooled in the cooling step;

[0043] a first warpage shape measuring step of measuring the warpage shape of the metal strip after the shape correction step;

[0044] a warping shape determining step of determining position information from the front end of the metal strip and determining a correspondence between the warping shape of the metal strip measured in the first warping shape measuring step and the position information from the front end of the metal strip; and

[0045] A step of displaying a distribution state of warpage height in a manner capable of determining whether the metal strip is good or bad based on the correspondence between the warpage shape of the metal strip determined in the warpage shape determining step and position information from the front end of the metal strip.

[0046] (9) As one embodiment of the present disclosure, based on (8),

[0047] In the cooling step, while the metal strip is constrained by at least a pair of constraining rollers, liquid is sprayed onto the metal strip from both sides of the metal strip by a plurality of nozzles.

[0048] (10) As one embodiment of the present disclosure, based on (8) or (9),

[0049] In the shape correction step, the shape correction of the metal strip is performed using at least one shape correction mechanism selected from a temper rolling mill, a tension leveler, and a roll leveler.

[0050] (11) A method for producing a metal strip according to an embodiment of the present disclosure produces a metal strip that is judged as acceptable by the method for judging the acceptability of a metal strip according to any one of (8) to (10).

[0051] According to the present disclosure, it is possible to provide a metal strip manufacturing apparatus and a manufacturing method that can reliably perform quality assurance for the warped shape of the metal strip in a metal strip manufacturing apparatus including a cooling unit for cooling the metal strip and a shape correction unit for correcting the shape of the cooled metal strip. In addition, it is possible to provide a pass / fail determination method for the shape of the metal strip in the above-mentioned metal strip manufacturing apparatus that is related to the warping height. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram showing a configuration example of a metal strip manufacturing facility according to one embodiment of the present disclosure.

[0053] Figure 2 This is a diagram illustrating the thermal history of a metal strip.

[0054] Figure 3 It is a diagram showing the structure of a device for water cooling.

[0055] Figure 4 It is a diagram showing a structural example of a shape correcting unit.

[0056] Figure 5 It is a figure which shows the example of the warping shape of a metal strip.

[0057] Figure 6 This is a diagram showing an example in which a laser scanning distance meter is used as a warpage shape measuring mechanism.

[0058] Figure 7 This is a diagram showing an example in which a plurality of laser scanning distance meters are arranged in the plate width direction.

[0059] Figure 8 This is a diagram illustrating an example of the distribution state of the warpage height of the metal strip.

[0060] Fig. 9 This is a diagram illustrating an example of the distribution state of the warpage height of the metal strip. DETAILED DESCRIPTION

[0061] Hereinafter, a metal strip manufacturing device, a metal strip qualification determination method, and a metal strip manufacturing method according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same reference numerals are given to the same or corresponding parts. In the description of this embodiment, the description of the same or corresponding parts is appropriately omitted or simplified.

[0062] The manufacturing device of the metal strip in the present embodiment is a manufacturing device whose main purpose is to heat treat a steel plate whose thickness is reduced to a specified plate thickness through a hot rolling process, a pickling process, and a cold rolling process, and in particular, it constitutes a part of a continuous annealing device for continuously annealing the metal strip. At least after the hot rolling process, the metal plate is subjected to heat treatment after being wound into a coil, so in the present embodiment, the metal plate is recorded as a "metal strip". In addition, the manufacturing device of the metal strip in the present embodiment is mainly for equipment that heat treats steel plates. That is, the metal strip mainly means a steel strip. The plate thickness of the metal strip is, for example, 0.4 to 3.2 mm. The plate width of the metal strip is, for example, 700 to 1800 mm. The length of the metal strip is, for example, 600 to 4000 m.

[0063] <Manufacturing equipment>

[0064] The metal strip manufacturing equipment according to the embodiment of the present disclosure will be described by taking the continuous annealing equipment of the metal strip as an example. Figure 1 It is a schematic diagram showing an example of a facility of a continuous annealing facility for producing a cold-rolled steel sheet according to the present embodiment. Figure 1 The solid arrows in the figure indicate the direction of travel of the metal strip. The “upstream side” and “downstream side” below are determined based on the direction of travel of the metal strip. Figure 1 The dotted line represents sending and receiving information through communication.

[0065] The continuous annealing equipment is roughly divided into an input side equipment 120, a furnace body equipment 121 and an output side equipment 124. The input side equipment 120 has an uncoiler 2, a welding machine 3, and an input side looper 4. The furnace body equipment 121 is composed of an annealing device 122 and a reheating device 123. The annealing device 122 has a heating zone 6, a soaking zone 7 and a cooling zone 8, and there is a case where a preheating zone 5 is provided on the upstream side of the heating zone 6. The reheating device 123 has a reheating zone 9, an over-aging zone 10 and a final cooling zone 11, and an induction heating device is arranged in the reheating zone 9. The output side equipment 124 has an output side looper 12, a shape correction device (shape correction unit 13), a first warp shape measuring device (first warp shape measuring unit 14), and a tension coiler 15.

[0066] The annealing process of the metal strip performed by the continuous annealing equipment is a process of heating the metal strip from near room temperature, maintaining the temperature at a predetermined temperature, and then lowering the temperature to near room temperature. Figure 1 In the continuous annealing equipment shown, the annealing process is performed through the heating zone 6, the soaking zone 7 and the cooling zone 8. The reheating process is a process of performing an over-aging treatment on the metal strip that has passed through the cooling zone 8. Figure 1 In the continuous annealing apparatus shown, a reheating process is performed in a reheating zone 9 , an over-aging zone 10 and a final cooling zone 11 .

[0067] The heating zone 6 is equipped with a device for heating the metal strip, and the metal strip is heated to a preset temperature in the range of about 600 to 900°C according to the composition of the metal strip. In the heating zone 6, a direct fire or radiation burner is used. These heating devices have a large heating capacity and a relatively fast response, so it is easy to change the temperature rise history when the thermal cycle is changed. The soaking zone 7 is a device for maintaining the metal strip at a specified temperature, and is a device for supplementing the heating capacity of the furnace body heat dissipation, etc.

[0068] The cooling zone 8 is a device for cooling the metal strip to a specified temperature, and liquid cooling, gas jet cooling, roller cooling, spray cooling (gas-liquid mixed cooling), etc. are used as cooling mechanisms. Liquid cooling is mostly performed by water cooling (water quenching) using water. Here, water cooling (an example of liquid cooling) is a cooling mechanism for cooling the metal strip by immersing it in an immersion water tank 23 provided on the downstream side of the equalizing zone 7. Gas jet cooling is a cooling mechanism for blowing gas from a nozzle onto the surface of the metal strip. Roller cooling is a cooling mechanism for cooling the metal strip by bringing it into contact with a water-cooled roller. Spray cooling is a cooling mechanism for cooling by spraying water into a fine mist and utilizing the absorption of its heat of vaporization. In spray cooling, the size of the sprayed water droplets is mostly about 0.1 to 1 mm.

[0069] The reheating device 123 is arranged on the downstream side of the cooling zone 8. After the metal strip is cooled to a predetermined temperature in the cooling zone 8, it is reheated to a temperature of about 300 to 400°C using an induction heating device or the like arranged in the reheating zone 9. The overaging zone 10 is a device for performing an overaging treatment by holding the reheated metal strip for a predetermined time. The final cooling zone 11 is a device for finally cooling the overaged metal strip to near room temperature. However, the continuous annealing equipment may not be equipped with the reheating device 123.

[0070] The output side sleever 12 is a device for temporarily storing the metal strip in order to adjust the conveying speed of the metal strip in the furnace body device 121 and the processing speed in the output side device 124. The shape correction section 13 is a device for flattening the shape of the metal strip, and is equipped with any one or more devices of a temper rolling mill, a tension straightening machine, and a roller straightening machine. The first warping shape measuring section 14 is a device arranged on the downstream side of the shape correction section 13, and measures the warping shape of the metal strip. The tension coiler 15 is a device for winding the metal strip into a coil. The metal strip wound into a coil is sometimes shipped as a product coil. In addition, the metal strip wound into a coil is sometimes transported to a recoil line to adjust the size or weight of the metal strip, collect samples for quality assurance, check the shape or size, rewind the coil, etc. In addition, there is a case where the metal strip wound into a coil is transported to a surface treatment device for plating the metal strip for surface treatment.

[0071] in addition, Figure 1 The continuous annealing equipment shown is equipped with a control computer 40, which manages the operation of the continuous annealing equipment. The control computer 40 sets the processing conditions of the metal strip in the input side equipment 120, the furnace body equipment 121, and the output side equipment 124 of the continuous annealing equipment, and collects sensor information obtained from the control controller to obtain various information related to the operation performance of the metal strip. In addition, the control computer 40 tracks the welded portion of the preceding metal strip and the succeeding metal strip connected by the welding machine 3, and determines the current position of the welded portion in the continuous annealing equipment.

[0072] Figure 2 This is a graph showing the thermal history of the metal strip in the annealing process and the reheating process. The horizontal axis represents time and the vertical axis represents the metal strip temperature. The metal strip temperature is, for example, the surface temperature of the metal strip. The annealing process is performed by the heating zone 6, the soaking zone 7 and the cooling zone 8, and then the reheating process is performed by the reheating zone 9, the over-aging zone 10 and the final cooling zone 11. In order to prevent material deviation caused by the position of the metal strip in the longitudinal direction, the conveying speed of the metal strip in the annealing process is kept constant within the possible range. However, when metal strips with different plate thickness, plate width, steel type, etc. are welded and continuously conveyed, there is a case where the production line speed changes before and after the weld.

[0073] <Heating section>

[0074] The heating section in this embodiment refers to a device or a section that continuously heats the conveyed metal strip, and the process performed by the heating section is called a heating process. That is, in the heating section, a heating process is performed to continuously heat the conveyed metal strip. Figure 1 In the continuous annealing apparatus shown, the heating section is the heating zone 6 or the reheating zone 9. However, the heating section is preferably the heating zone 6. This is because the metal strip is heated to a temperature above the recrystallization temperature or the austenite transformation start temperature (A C3 ), therefore, by cooling the metal strip which has become high temperature, the shape of the metal strip is easily disturbed, and the effect of the method based on the present disclosure is easily exerted.

[0075] <Cooling section>

[0076] The cooling section in this embodiment refers to a device or a section for cooling the metal strip heated by the heating section, and the process performed by the cooling section is called a cooling process. That is, the cooling section performs a cooling process for cooling the metal strip heated in the heating process. Figure 1In the continuous annealing equipment shown, the cooling section corresponds to the cooling zone 8 or the final cooling zone 11. However, the cooling section may also be a device or a division in a part of the cooling zone 8 for rapidly cooling the metal strip. In addition, the cooling section is preferably a cooling device that performs liquid cooling using water as a refrigerant, that is, water cooling (water quenching) as a cooling method in the cooling zone 8. This is because the shape of the metal strip after cooling is likely to be disturbed due to the cooling of the metal strip heated by the heating section to a temperature lower than the martensitic transformation start temperature (Ms) or the bainitic transformation start temperature (Bf), so that the effect of the method disclosed in the present invention is easily exerted.

[0077] Figure 3 2 shows the structure of a device for water cooling as a cooling method. The cooling device of the water cooling method is composed of a cooling fluid injection device 21 having a water injection nozzle, an immersion water tank 23, and guide rollers 26 and 27. In addition, in the cooling device of the water cooling method, a device for preventing the metal strip (in Figure 3 The metal strip having passed through the immersion water tank 23 is dewatered by the water removal roller 28, and then is dried by the drying furnace 29 and transported to the reheating zone 9. In the case of a water-cooling cooling device, Figure 1 In the continuous annealing equipment shown, the immersion water tank 23 serves as a cooling section. This is because the immersion water tank 23 is the zone where the metal strip is rapidly cooled.

[0078] The immersion water tank 23 is formed into a container shape so as to be able to store cooling water 24 for immersion cooling of the metal strip. In order to suppress the temperature rise of the cooling water 24 stored in the immersion water tank 23 and control the water temperature of the cooling water 24 within a predetermined range, a cooling machine (not shown) for circulating the cooling water 24 in the immersion water tank 23 to cool the cooling water 24 may also be provided.

[0079] The cooling fluid spraying device 21 is a water cooling nozzle unit, and sprays cooling water 24 to the metal strip for cooling. In the cooling fluid spraying device 21, a pair of water spraying nozzles are arranged in multiple stages on both sides of the running metal strip in order to spray the cooling water 24 to the front and back sides of the running metal strip. And by spraying the cooling water 24 from these multiple stages of water spraying nozzles to both the front and back sides of the metal strip, the metal strip passing through the soaking zone 7 can be cooled.

[0080] The cooling fluid injection device 21 may also be configured to include a pair of constraint rollers 22, which are used to suppress deformation of the metal strip and prevent the shape of the metal strip from deteriorating. The constraint rollers 22 may also be configured to clamp the metal strip from the front and back sides, and be arranged staggered on the front and back sides of the metal strip relative to the direction of travel of the metal strip. In addition, at least one of the constraint rollers 22 arranged on the front and back sides may also have a position adjustment function, which allows the constraint roller 22 to be displaced toward the metal surface so that the amount of pressure pressed into the metal strip is variable. In addition, the constraint rollers 22 may also be configured in the cooling fluid injection device 21 in the direction of travel of the metal strip.

[0081] By configuring the restraining roller 22 together with the cooling fluid injection device 21, the deformation of the metal strip can be restrained between the martensitic transformation start temperature (Ms) and the end temperature (Mf) of the metal strip. As a result, the shape defects of the metal strip caused by the thermal contraction and volume change caused by the phase transformation when the metal strip is rapidly cooled can be reduced.

[0082] The guide rollers 26 and 27 apply a predetermined tension to the metal strip and change the conveying direction of the metal strip. Thus, the metal strip immersed in the cooling water 24 stored in the immersion water tank 23 is guided upward from the liquid surface of the cooling water 24. In this case, at least one of the guide rollers 26 and 27 is arranged to be immersed in the cooling water 24 in the immersion water tank 23.

[0083] <Shape Correction Department>

[0084] The shape correction section 13 in this embodiment refers to a device or a section for correcting the shape of the metal strip cooled by the cooling section, and the process performed by the shape correction section 13 is called a shape correction process. That is, the shape correction process for correcting the shape of the metal strip cooled in the cooling process is performed in the shape correction section 13. The shape correction section 13 preferably uses at least one shape correction mechanism selected from a temper rolling mill, a tension leveler, and a roller leveler. The temper rolling mill is a device that uses a pair of upper and lower working rolls to press the metal strip up and down in the plate thickness direction, and flattens the shape of the metal strip by giving the metal strip an elongation of about 0.1 to 3.0%. The tension leveler is a device that uses at least a pair of upper and lower correction rolls arranged in a staggered manner to correct the shape by applying tension to the metal strip while giving it bending deformation. The roller leveler is a device that uses multiple pairs of correction rolls arranged in a staggered manner to correct the shape by repeatedly giving bending and bending recovery deformation to the metal strip. The shape correction mechanism disposed in the shape correction section 13 may also be composed of two or more of them. For example, the shape correction section 13 may also include a temper rolling mill and a tension leveler located downstream thereof. This is because by combining a plurality of shape correction mechanisms, the shape of the high-strength steel plate can be effectively corrected.

[0085] When the shape correction section 13 uses the temper rolling mill 30, as an operating condition of the temper rolling mill 30, the warping shape of the metal strip can be changed by changing the plastic strain imparted to the metal strip such as the elongation. When the shape correction section 13 uses the tension straightening machine, as an operating condition of the tension straightening machine, the warping shape of the metal strip can be changed by changing the plastic strain imparted to the metal strip such as the elongation. In addition, when the shape correction section 13 uses the roller straightening machine, the plastic strain imparted to the metal strip is changed by changing the amount of pressure of the correction roller, thereby changing the warping shape. The operating conditions of the shape correction section are set by the control computer 40 in consideration of the constraints on the equipment, etc.

[0086] Figure 4 The structure of the temper rolling mill 30 that can be used in the shape correction section 13 is shown. The temper rolling mill 30 includes: a pair of working rolls 32a, 32b that directly contact the metal strip as the rolled material and apply downward pressure; and support rolls 33a, 33b that support the pair of working rolls 32a, 32b from above and below and suppress the deflection of the working rolls 32a, 32b. At least one of the working rolls 32a, 32b and the support rolls 33a, 33b is connected to a driving motor via a coupling or a speed reducer at one end, and the roller is rotated by the driving motor. The support rolls 33a, 33b are supported by a bearing box (support roll bearing seat) at the end of the shaft, and the bearing box is displaced up and down by a downward pressure device, thereby adjusting the gap (roll gap) between the working rolls 32a and 32b.

[0087] An input side tension roller 34, an input side tension meter 36, an output side tension meter 37, and an output side tension roller 35 are arranged before and after the temper rolling mill 30. The input side tension roller 34 and the output side tension roller 35 are rollers for applying appropriate tension to the metal strip. The input side tension meter 36 and the output side tension meter 37 are respectively arranged between the temper rolling mill 30 and the input side tension roller 34, and between the temper rolling mill 30 and the output side tension roller 35, and measure the tension of the metal strip on the input side and the output side of the temper rolling mill 30. In addition, there is a case where a shape meter for measuring the shape of the metal strip is arranged between the temper rolling mill 30 and the output side tension roller 35. The shape meter in this case is a contact type shape meter. It is also possible to infer the distribution of the elongation of the metal strip from the distribution of the contact load in the plate width direction by using a shape meter in which a plurality of load cells are embedded inside a shape measuring roller.

[0088] In the temper rolling process of the metal strip using the temper rolling mill 30, the metal strip that has passed through the cooling section is rolled at a predetermined elongation. The elongation refers to the elongation of the metal strip before and after the temper rolling, and is defined by the increase rate of the length of the metal strip before and after the temper rolling process. The elongation is measured by the difference in peripheral speed between the input side tension roller 34 and the output side tension roller 35. In this case, the controller for controlling the temper rolling mill 30 changes the setting of the pressing device of the temper rolling mill 30, and controls in a manner that the measured elongation is consistent with the target elongation. However, in the case where the metal strip is a high-strength steel plate with a tensile strength of more than 1180 MPa, the rolling load becomes high, so sometimes the elongation required for shape correction of the metal strip (for example, 0.2%) cannot be ensured, and the shape defects of the metal strip generated in the cooling section cannot be fully flattened. In contrast, Patent Document 3 describes a method for performing temper rolling using work rolls having a specific surface roughness. Alternatively, a method of reducing the rolling load by using superhard rolls to which cobalt, tungsten carbide, etc. are added instead of steel as the work rolls 32a and 32b may be applied. However, when the shape of the metal strip is greatly disturbed, there may be a case where the warping of the metal strip remains even after these shape correction mechanisms.

[0089] <Warp shape measurement unit>

[0090] In the present embodiment, the warping shape of the metal strip that has undergone the shape correction process is measured using the first warping shape measuring unit 14 disposed on the downstream side of the shape correction unit 13. In other words, in the first warping shape measuring unit 14, the first warping shape measuring process of measuring the warping shape of the metal strip is performed after the shape correction process. The warping shape refers to the height distribution of the metal strip in the plate width direction of the metal strip. As the warping of the metal strip, L warping (length warping) and C warping (width warping) are known. The warping shape in the present embodiment includes C warping, but does not include L warping. This is because when the metal strip is continuously conveyed, L warping is constrained by the tension of the production line, and it is difficult to measure L warping online. That is, the warping shape in the present embodiment includes C warping in the plate width direction of the metal strip that can be approximated by a second-order function, and includes a height distribution in the plate width direction that can be approximated by a function of a third order or higher. Here, being able to approximate a curve by a function of a third order or higher means that the height distribution of the metal strip in the plate width direction has two or more inflection points.

[0091] Since the stress in the plane generated in the plate width direction of the metal strip after the cooling process and the shape correction process are completed cannot be maintained in the plane of the metal strip, it is displaced out of the plane due to buckling, thereby generating a height distribution in the plate width direction of the metal strip. As the shape defect of the metal strip, there is a case where a wave-shaped shape defect called the so-called edge wave or intermediate corrugation occurs. Since the elongation in the length direction of the metal strip is distributed in the plate width direction, the stress in the plane generated in the length direction of the metal strip cannot be maintained in the plane of the metal strip, and it is displaced out of the plane due to buckling, thereby generating a wave-shaped shape defect. The above-mentioned warping shape and wave shape have the same point that they are out-of-plane deformations caused by buckling, but they are different in that the direction of the stress that causes the buckling is the plate width direction or the length direction.

[0092] Therefore, in the case of a corrugated shape, if tension is applied in the longitudinal direction of the metal strip, the difference in elongation in the plate width direction (difference in elongation in the plate width direction) is absorbed, and the shape defect of the metal strip is latent. That is, the shape defect of the corrugated shape is often changed to a flat shape in appearance by applying tension in the longitudinal direction of the metal strip. In contrast, in the case of a warped shape, there is a difference that even if tension is applied in the longitudinal direction of the metal strip, the stress in the plate width direction is not greatly affected, so even if tension is applied, the change in the warped shape of the metal strip is small. As in the shape meter described in Patent Document 2, a contact shape meter is sometimes arranged between the temper rolling mill 30 and the output side tension roller 35. The contact shape meter arranged in this way applies a large tension (for example, 100 to 200 MPa) between the temper rolling mill 30 and the output side tension roller 35 to make the shape defect of the metal strip latent, and measures the contact load distribution in the plate width direction. That is, although the contact shape meter can measure the corrugated shape generated in the metal strip, it does not measure the warped shape. In addition, there is the following difference: the displacement of the metal strip in the height direction of the metal strip relative to the length direction of the metal strip changes periodically, while the warp shape is not easy to produce periodic displacement in the length direction of the metal strip. Here, the wave shape of the metal strip is often a periodic shape with a pitch of about 0.5 to 5m in the length direction of the metal strip. Therefore, when the displacement of the metal strip in the height direction does not change at such a pitch, it can also be regarded as a warp shape.

[0093] In this embodiment, the warping shape of the metal strip is determined by measuring the height distribution of the metal strip in the plate width direction by the first warping shape measuring unit 14. The warping shape of the metal strip can be determined using data indicating the warping height at each position in the plate width direction or information indicating the warping height relative to the position in the plate width direction using a curve. Figure 5 An example of the warped shape of a metal strip is shown. Figure 5An example is the case where a high-strength steel plate is rapidly cooled by water quenching. If a high-strength steel plate is rapidly cooled by water quenching, the cross-section of the metal strip in the plate width direction often becomes a shape that can be approximated by a high-order function curve. Here, Figure 5 This is an example of measuring a high-strength steel plate with a plate thickness of 1.2 mm and a plate width of 1200 mm after the cooling process and the temper rolling process are completed. The average value of the height distribution measured at 20 positions with a pitch of 100 mm in the length direction of the metal strip is calculated, and the height distribution normalized according to the maximum height in the plate width direction is shown. As the warp shape in this embodiment, in addition to Figure 5 In addition to the curve showing the relationship between the position in the plate width direction and the warping height, it is also possible to use parameters such as the average value, maximum height, and standard deviation of the warping height in the plate width direction that can determine the warping shape of the metal strip. In this case, the warping shape can also be calculated by averaging the warping height at each position in the plate width direction in the range of about 1 to 5 m in the length direction of the metal strip. This is because, even if the measured height distribution of the metal strip includes both the warping shape and the wave shape, the warping shape can be determined by excluding the periodically changing wave shape. In addition, the curve showing the relationship between the position in the plate width direction and the warping height can be approximated by a function, and the parameters representing the approximated function can be used as the warping shape.

[0094] As for the measurement of the warping shape of the metal strip, any means can be selected as long as the height distribution in the plate width direction of the metal strip can be measured. The measurement of the warping shape of the metal strip can also use at least one warping shape measurement method selected from the distance measurement method, the image processing method and the light cutting method. The image processing method is a method of measuring the warping shape based on the captured image of the surface of the metal strip. In the image processing method, the warping shape can be measured based on the image projected onto the surface of the metal strip using a grating projection method or a moiré fringe method. In addition, the distance measurement method is a method using a rangefinder. As a warping shape measuring mechanism, a plurality of laser rangefinders that measure the distance in a specific direction in a non-contact manner in the plate width direction of the conveyed metal strip can also be arranged to measure the warping height at each position. In this case, the number of rangefinders arranged in the plate width direction of the metal strip is preferably greater than 3 and less than 100. This is because if there are less than 3, it is difficult to determine the warping shape of the metal strip, and even if it exceeds 100, the measurement accuracy related to the distribution of the warping height will not be improved.

[0095] The distance meter may be a laser scanning distance meter 44 that scans laser light in a fan shape to measure the warpage height at each position in the sheet width direction of the metal strip. Figure 6 The example of using a laser scanning distance meter 44 as a warp shape measuring mechanism is shown. Figure 6The distance to each position in the width direction of the metal strip is measured by scanning in a fan-shaped manner above the strip (indicated by 1 in the figure) in the width direction to measure the warpage height. Figure 7 As shown, it is also possible to use a metal strip (in Figure 7 A plurality of laser scanning distance meters 44 are arranged in the plate width direction (indicated by 1 in FIG. 1 ), and the warping height at each position in the plate width direction of the metal strip is measured for each division in the plate width direction of the metal strip.

[0096] As a measurement of the warping shape of the metal strip, the warping height at each position in the plate width direction of the metal strip can also be measured by the light section method. The measurement of the warping height using the light section method is exemplified by the LJ-X8000 series manufactured by KEYENCE or the Gocator manufactured by LMT Technologies. The light section method is a method of measuring the displacement of the metal strip in the height direction by photographing the reflected light of the laser beam from the metal strip that expands in a fan shape from the top of the metal strip relative to the plate width direction using an image sensor, and performing image processing on the photographed image.

[0097] The measurement accuracy of the warp height by the warp shape measuring mechanism is preferably 1 mm or less, and more preferably 0.5 mm or less. This is because the upper limit of the warp height of the metal strip manufactured in the continuous annealing equipment is set to about 5 to 10 mm, and quality assurance can be reliably performed in such a case.

[0098] The measurement of the warp height based on the warp shape measuring mechanism is preferably configured to be able to collect at intervals of less than 1m in the length direction of the metal strip. For the continuously conveyed metal strip, the measurement frequency of the warp height is preferably 10Hz or more, and more preferably 20Hz or more. That is because, in the output side equipment of the continuous annealing equipment, the metal strip is sometimes conveyed at a speed of more than 600m / min, so that it can be collected at intervals of less than 1m in the length direction of the metal strip. In this case, the measurement of the warp shape of the metal strip is preferably performed using a laser scanning distance measurement method or a light cutting method. This is because, in the laser scanning distance measurement method and the light cutting method, the warp height at each position in the width direction of the metal strip can be measured at a measurement frequency of more than 10Hz. On the other hand, in a method in which a plurality of distance meters are arranged in which a distance in a specific direction is measured using a laser instead of a laser scanning distance meter 44, the measurement accuracy of the warp height near the plate width end of the metal strip is sometimes reduced due to the interval between adjacent distance meters. In addition, if the warping height of the plate width end of the metal strip is measured by a mechanism that moves a distance meter along the plate width direction of the metal strip, it is sometimes difficult to set the measurement frequency to 10 Hz or more. Here, the warping height measured by the warping shape measuring mechanism can also be averaged in the range of about 1 to 5 m in the length direction of the metal strip as the warping shape. Thus, even if the metal strip includes both a warping shape and a wave shape, the warping shape can be determined by excluding the wave shape.

[0099] The first warpage shape measuring unit 14 is Figure 1 In the continuous annealing equipment shown, the first warp shape measuring unit 14 can be arranged at any position as long as it is on the downstream side of the shape correction unit 13 and before the metal strip is wound by the tension coiler 15. In a conventional continuous annealing equipment, an inspection station for inspecting surface defects of the metal strip is often provided on the downstream side of the shape correction unit 13. Therefore, the first warp shape measuring unit 14 is preferably provided near the inspection station on the output side of the continuous annealing equipment. This is to enable correspondence with quality inspection information other than the warp height of the metal strip.

[0100] <Warp shape determination section>

[0101] The manufacturing equipment of the metal strip of the present embodiment includes a warping shape determining unit 41, which determines the position information from the front end of the metal strip, and determines the correspondence between the warping shape of the metal strip measured by the first warping shape measuring unit 14 and the position information from the front end of the metal strip as described above. That is, the warping shape determining unit 41 generates information on the warping height distribution of the metal strip corresponding to the position information from the front end of the metal strip as a warping shape determining step.

[0102] The position information from the front end of the metal strip refers to the distance in the length direction of the metal strip from the welded portion which becomes the front end of the metal strip. Figure 1 The control computer 40 for the operation of the continuous annealing equipment shown generates tracking information of the welded portion. By using information related to the conveying speed of the metal strip passing through the first warp shape measuring unit 14, the position information from the front end of the metal strip passing through the first warp shape measuring unit 14 can be determined through internal calculations of the control computer 40. In addition, the warp shape determination unit 41 can also obtain the tracking information of the welded portion and the conveying speed of the metal strip passing through the first warp shape measuring unit 14 from the control computer 40 to determine the position information from the front end of the metal strip. In addition, the warp shape determination unit 41 can determine the correspondence between the warp shape of the metal strip measured by the first warp shape measuring unit 14 and the position information from the front end of the metal strip by acquiring the height distribution information of the metal strip in the plate width direction collected by the first warp shape measuring unit 14.

[0103] The information of the warpage height distribution of the metal strip associated with the position information from the front end of the metal strip determined by the warpage shape determination unit 41 is, for example, Figure 5 The curve showing the relationship between the position in the plate width direction and the warp height is associated with the position information from the front end of the metal strip. The cooling conditions of the metal strip in the cooling section or the correction conditions in the shape correction section 13 vary in the length direction of the metal strip, so that the warp height of the metal strip that has undergone the shape correction process varies in the length direction. Therefore, by determining the warp height at a specific position rather than a representative value of the warp height of the metal strip as a product, quality management becomes easy. The warp shape determination section 41 preferably determines the position information at a plurality of positions at different distances from the front end of the metal strip and the warp height distribution at each position. The warp shape determination section 41 determines the warp height distribution at a predetermined position, such as the front end (e.g., within 20 m from the welding section), the stabilizing section, and the tail end (e.g., within 20 m from the welding section of the tail end) of the metal strip. This is because there is a case where the quality assurance of metal products is usually performed by inspecting the front end, the stabilizing section, and the tail end to determine whether the product is qualified or not. In addition, when using a warping shape in which the warping height measured by a warping shape measuring mechanism is averaged within a range of about 1 to 5 m in the length direction of the metal strip as the warping shape, the range in the length direction of the metal strip averaged from the front end of the metal strip can also be used as the corresponding position information.

[0104] In addition, the warping shape determination unit 41 preferably generates information on the warping height distribution of the metal strip corresponding to the position information from the front end at a predetermined interval throughout the entire length of the metal strip. In this case, the interval of the position information can also be set to about 5 to 20 meters. This is because, by determining the warping height distribution at each position in the length direction of the metal strip, it is possible to determine whether the metal strip meets the warping height benchmark set as the product specification throughout the entire length, thereby achieving reliable quality assurance. For example, in a part of the length direction of the metal strip, even if there is a part that does not meet the product specification related to the warping height, it is possible to cut off the part with a poor warping height on the downstream side of the continuous annealing equipment or the recoil production line, and only the part that meets the product specification is shipped as a product.

[0105] The warping shape determination unit 41 can also generate information on the warping height distribution of the metal strip corresponding to the position information from the front end at a specified interval throughout the entire length of the metal strip, and illustrate it by color-differentiating the contour lines or warping heights within the surface of the metal strip. Figure 8 This is an example of an image representation in which the warpage height in the plane with the position in the length direction and the position in the width direction from the front end of the metal strip as coordinates is distinguished by grayscale. By displaying the distribution state of the warpage height in the plane of the metal strip, it is possible to identify the area where the quality defect of the warpage height occurs, so that the judge who makes the pass / fail judgment of the product can easily identify whether the product specifications are met and the position in the plane that does not meet the product specifications. Here, the judge can be, for example, the control computer 40 or a person.

[0106] In addition, if the warp shape determination unit 41 obtains the information of the warp height distribution of the metal strip corresponding to the position information from the front end of the metal strip, it is easy to determine the operating condition that increases the warp height by comparing it with the change of the operating condition in the longitudinal direction of the metal strip manufacturing equipment. For example, based on the correspondence between the conveying speed of the metal strip in the cooling unit and the warp height information, it is possible to perform an operation that restricts the conveying speed of the metal strip in the cooling unit, which helps to optimize the operating conditions.

[0107] <Second embodiment>

[0108] The second embodiment of the present disclosure is based on the above-mentioned metal strip manufacturing equipment, and includes a second warp shape measuring device (second warp shape measuring unit 42) that measures the warp shape of the metal strip between the cooling unit and the shape correcting unit 13. The warp shape determining unit 41 determines the correspondence between the warp shape of the metal strip measured by the first warp shape measuring unit 14, the warp shape of the metal strip measured by the second warp shape measuring unit 42, and the position information from the front end of the metal strip.

[0109] The second warped shape measuring unit 42 Figure 1 The second warp shape measuring unit 42 is configured between the cooling zone 8 and the shape correcting unit 13 in the continuous annealing equipment. Thus, the second warp shape measuring unit 42 measures the warp height after the metal strip is rapidly cooled and before the shape is corrected. The warp height measurement method of the second warp shape measuring unit 42 can also be the same as the first warp shape measuring device (first warp shape measuring unit 14).

[0110] As described above, the warp shape determination unit 41 in this embodiment determines the correspondence between the warp shape of the metal strip measured by the first warp shape measurement unit 14 and the position information from the front end of the metal strip, and also determines the warp shape of the metal strip measured by the second warp shape measurement unit 42. That is, the warp shape of the metal strip measured by the first warp shape measurement unit 14 and the warp shape of the metal strip measured by the second warp shape measurement unit 42 are determined to be comparable with respect to the position information from the front end of the metal strip. In this case, since the control computer 40 generates tracking information of the welded portion, the position information from the front end of the metal strip can be determined using information related to the conveying speed of the metal strip passing through the second warp shape measurement unit 42. As a result, the warp shape of the metal strip on the downstream side of the cooling unit and the warp shape on the downstream side of the shape correction unit 13 are associated with each other by the position information from the front end of the metal strip. That is, the warp height after the cooling process and the warp height after the shape correction process at the same position in the longitudinal direction of the metal strip can be compared.

[0111] The warping shape of the metal strip measured by the first warping shape measuring unit 14 is caused by the fact that the stress in the plane generated in the plate width direction of the metal strip cannot be maintained in the plane of the metal strip at the stage when the cooling process and the shape correction process are completed, and it is displaced out of the plane due to buckling. However, even in the state where the metal strip is buckled, the stress in the plane of the metal strip is not completely released, and a certain amount of stress often remains in the plane. Therefore, if the metal strip shipped as a product is cut into plates for component processing, etc., the residual stress in the plane is released, and sometimes the warping shape of the metal strip is deteriorated.

[0112] On the other hand, the magnitude of the residual stress formed in the surface of the metal strip that has undergone the shape correction process is correlated with the amount of change from the warping shape of the metal strip after the cooling process to the warping shape after the shape correction process. That is, the metal strip before the cooling process is heated by the heating unit, thereby releasing the internal residual stress. However, warping occurs in the metal strip due to thermal contraction and phase change in the cooling process. Thereafter, if the shape of the metal strip is changed in the shape correction process, residual stress is generated according to the amount of change. In this embodiment, the warping height after the cooling process at the same position in the length direction of the metal strip can be compared with the warping height after the shape correction process is completed, so it can be inferred that the greater the change in the warping height at the same position, the greater the residual stress of the metal strip.

[0113] Therefore, in the quality inspection of the product as the metal strip, H1 is set as the warpage height corresponding to the prescribed quality standard. Generally, the pass / fail judgment of the shape quality can be performed based on the warpage shape measured by the first warpage shape measuring unit 14, by determining whether the warpage height of the metal strip satisfies the standard of H1 at each position in the length direction of the metal strip. However, according to the present embodiment, when the change in the warpage height between the second warpage shape measuring unit 42 and the first warpage shape measuring unit 14 is large, it is inferred that residual stress is retained inside the metal strip. Therefore, the pass / fail judgment of the shape quality of the metal strip can be performed by applying H2 (where H1>H2), which is a stricter standard than H1, which is the standard of the warpage shape measured by the first warpage shape measuring unit 14. As a result, when the metal strip is shipped and cut into a plate for component processing, the deterioration of the warpage shape of the metal strip can be suppressed.

[0114] Fig. 9 This figure shows an example of information on the warpage height distribution of the metal strip generated by the warpage shape determination unit 41. The warpage height distribution of the metal strip measured by the first warpage shape measurement unit 14 can be compared with the warpage height distribution of the metal strip measured by the second warpage shape measurement unit 42. Fig. 9 In the example of FIG. 1 , the region with a large warp height measured by the first warp shape measuring unit 14 is substantially consistent with the region with a large warp height measured by the second warp shape measuring unit 42 after the cooling process. Therefore, it can be determined that in order to improve the warp shape of the metal strip measured by the first warp shape measuring unit 14, it is only necessary to reset the operating conditions of the cooling process.

[0115] <Third Embodiment>

[0116] The third embodiment of the present disclosure includes a third warp shape measuring device (third warp shape measuring unit 43) for measuring the warp shape of the metal strip between the heating unit and the cooling unit, based on the above-mentioned metal strip manufacturing equipment. The warp shape determination unit 41 determines the correspondence between the warp shape of the metal strip measured by the first warp shape measurement unit 14, the warp shape of the metal strip measured by the third warp shape measurement unit 43, and the position information from the front end of the metal strip. The third warp shape measurement unit 43 can also obtain the warp shape of the metal strip by the same method as the first warp shape measurement unit 14. In addition, the method of obtaining the position information from the front end of the metal strip passing through the third warp shape measurement unit 43 from the control computer 40 is also the same.

[0117] The warping shape determination unit 41 in the present embodiment determines the correspondence between the warping shape of the metal strip measured by the first warping shape measurement unit 14 and the position information from the front end of the metal strip, and also determines the warping shape of the metal strip measured by the third warping shape measurement unit 43. That is, the warping shape of the metal strip measured by the first warping shape measurement unit 14 and the warping shape of the metal strip measured by the third warping shape measurement unit 43 are established in correspondence with respect to the position information from the front end of the metal strip, and are determined to be comparable. In this case, the third warping shape measurement unit 43 can be arranged at any position as long as it is on the downstream side of the heating zone 6 and the upstream side of the cooling zone 8 (in the case of a cooling device with a water cooling method, it is an immersion water tank 23). This is because the shape change of the metal strip in the soaking zone 7 is relatively small, and therefore can be ignored in practical application.

[0118] In this embodiment, the warping shape of the metal strip on the upstream side of the cooling section is associated with the warping shape on the downstream side of the shape correction section 13 by means of position information from the front end of the metal strip. That is, the warping height before the cooling process and the warping height after the cooling process and the shape correction process at the same position in the length direction of the metal strip can be compared.

[0119] In the above-mentioned metal strip manufacturing equipment, a third warp shape measuring unit 43 may be disposed between the heating unit and the cooling unit, and a second warp shape measuring unit 42 may be disposed between the cooling unit and the shape correcting unit 13. The warp shape determining unit 41 may determine the correspondence between the warp shape of the metal strip measured by the first warp shape measuring unit 14, the warp shape of the metal strip measured by the second warp shape measuring unit 42, the warp shape of the metal strip measured by the third warp shape measuring unit 43, and the position information from the front end of the metal strip.

[0120] As described above, the metal strip before the cooling process is heated by the heated portion to release the internal residual stress. However, even in the state where the internal residual stress is released, in the case where the metal strip has warping, residual stress corresponding to the warping is generated in the cooling process and the shape correction process. That is, the residual stress corresponding to the change from the warping shape of the metal strip before the cooling process to the warping shape after the shape correction process is formed at the moment of passing through the first warping shape measuring unit 14. In this embodiment, the warping height before the cooling process and the warping height after the shape correction process at the same position in the longitudinal direction of the metal strip can be compared, so it can be inferred that the greater the change in the warping height at the same position, the greater the residual stress of the metal strip.

[0121] In addition, the second warp shape measuring unit 42 determines the warp shape between the cooling process and the shape correction process in advance, thereby being able to estimate the change in the residual stress generated in the plane of the metal strip. The residual stress generated in the cooling process is caused by the thermal contraction and phase change of the metal strip, and is therefore generated isotropically in the plane of the metal strip. In contrast, the residual stress generated in the shape correction process is caused by the plastic deformation of the metal strip in the length direction or the plate width direction, and therefore has a difference in the length direction and the plate width direction generated in the plane of the metal strip. Therefore, it is estimated that an isotropic residual stress corresponding to the difference between the warp shape of the metal strip measured by the third warp shape measuring unit 43 and the warp shape of the metal strip measured by the second warp shape measuring unit 42 is generated in the metal strip after the shape correction process. In addition, it is estimated that a residual stress in the length direction or the plate width direction corresponding to the difference between the warp shape of the metal strip measured by the second warp shape measuring unit 42 and the warp shape of the metal strip measured by the first warp shape measuring unit 14 is generated. In this way, by using the second warpage shape measuring unit 42, it is possible to separate and evaluate the characteristics of the residual stress generated in the metal strip after the shape correction step.

[0122] Therefore, in the quality inspection of the product as the metal strip, H1 is set as the warp height corresponding to the predetermined quality standard, and when the change in the warp height between the third warp shape measuring section 43 and the first warp shape measuring section 14 is large, it is estimated that residual stress remains inside the metal strip. Therefore, H3 (where H1>H3), which is a stricter standard than H1, which is the standard of the warp shape measured by the first warp shape measuring section 14, can be used to determine whether the shape quality of the metal strip is acceptable or not. In addition, H1 can also be changed according to the change in the warp height between the second warp shape measuring section 42 and the first warp shape measuring section 14 and the change in the warp height between the third warp shape measuring section 43 and the first warp shape measuring section 14. This is because the metal strip as a product is subjected to various secondary processes, but according to the characteristics of the residual stress generated inside the metal strip, by setting the quality standard of the product more finely, reliable quality assurance can be achieved.

[0123] (Example)

[0124] Hereinafter, the effects of the present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples.

[0125] (Example 1)

[0126] As a first embodiment of the present disclosure, Figure 1 The continuous annealing equipment shown in the figure is used to perform an example of judging whether a metal strip is good or bad in terms of its warping shape. Figure 1 In the continuous annealing equipment shown, the heating zone 6 is used as a heating section, the immersion water tank 23 is used as a cooling section, and a first warpage shape measuring section 14 is arranged on an inspection table for quality inspection arranged on the output side of the continuous annealing equipment.

[0127] The cooling unit uses Figure 3 The cooling device of the water cooling method shown in the figure. The cooling device includes: a cooling fluid injection device 21, which has a plurality of nozzles for injecting water as a cooling fluid (liquid) from both sides of the metal strip to the metal strip; and a pair of restraining rollers 22, which restrain the metal strip. The diameter of the restraining roller 22 is 150 mm, and the pair of restraining rollers 22 are structured so that the front and back sides of the metal strip are offset by 80 mm relative to the traveling direction of the metal strip. In addition, the restraining roller 22 arranged on the back side of the metal strip can be pressed into the metal strip, and the maximum amount of pressing is 20 mm. The amount of pressing is set according to the strength and size of the metal strip to be manufactured.

[0128] The shape correction section 13 uses a 4-stage temper rolling mill 30, and sets the roll gap of the work rolls so that the elongation of the metal strip is in the range of 0.1 to 0.2%. However, the maximum load of the temper rolling mill 30 is 8000 kN, so for a metal strip with a tensile strength of 1320 MPa or more, the above elongation may not be achieved.

[0129] The first warp shape measuring unit 14 measures the warp shape of the metal strip using a laser scanning range finder. The first warp shape measuring unit 14 measures the height distribution in the width direction of the metal strip by scanning the laser in the width direction of the metal strip. The warp height measurement frequency of the first warp shape measuring unit 14 is 20 Hz, and under the condition of the maximum speed of 600 m / min of the output side equipment of the continuous annealing equipment, it is possible to collect actual data of the warp shape at intervals of 1 m in the length direction of the metal strip.

[0130] Furthermore, the warping shape determination unit 41 in this embodiment obtains tracking information of the welded portion, which is the front end of the metal strip, from the control computer 40 at any time. In addition, the warping shape determination unit 41 uses information on the conveying speed of the metal strip in the output side device 124 to determine the position information from the front end of the metal strip, and determines the correspondence between the warping shape of the metal strip measured by the first warping shape measurement unit 14 and the position information from the front end of the metal strip. The correspondence between the warping shape of the metal strip determined by the warping shape determination unit 41 and the position information from the front end of the metal strip is as follows: Figure 8 The image in which the warpage height distribution is differentiated by color is displayed on the monitor screen in the operator's cab where the product acceptance or rejection judgment is performed.

[0131] In this embodiment, a high-strength steel plate with a plate thickness of 1.0 to 1.8 mm, a plate width of 800 to 1250 mm, and a tensile strength of 1310 to 1470 MPa is manufactured using the above manufacturing equipment. In this embodiment, the conveying speed of the metal strip passing through the cooling zone 8 is set to 40 to 120 m / min, the target temperature of the metal strip at the start of cooling is set to 740°C, and the target temperature at the end of cooling is set to 30°C.

[0132] Moreover, in this embodiment, the judge who makes the pass / fail judgment of the product makes the pass / fail judgment of the metal strip based on the image showing the correspondence between the warping shape of the metal strip and the position information from the front end of the metal strip displayed on the monitor screen. The criterion for judging the pass / fail of the metal strip is that the maximum value of the warping height of the metal strip in the entire surface of the plate width direction and the length direction of the metal strip is set as pass, and the case of exceeding 10 mm is set as fail. In addition, the metal strip wound into a coil by the tension coiler 15 of the continuous annealing equipment is conveyed to the recoil line for detailed product inspection, and the warping shape of the metal strip is re-inspected. In the recoil line, the metal strip is conveyed at a low speed of less than 50m / min, and the conveyance of the metal strip is stopped at any time, and the warping height of the metal strip is inspected over the entire length. As a result, as described above, the metal strips of the 24 coils judged as pass by the judge at the inspection station of the continuous annealing equipment were all judged as pass in the recoil line. In addition, all the metal strips of the 13 coils that were judged as unqualified by the judges at the inspection station of the continuous annealing equipment were also judged as unqualified in the recoil line. That is, the accuracy rate at the inspection station of the continuous annealing equipment was 100%.

[0133] On the other hand, the pass / fail judgment related to the warpage height of the metal strip was performed based on the size of the elongation difference of the metal strip measured by the contact type shape meter arranged on the output side of the temper rolling mill 30. Among the metal strips of the 16 coils judged as pass by the contact type shape meter, the proportion judged as pass in the back-punching line was 75.0%. In addition, for the metal strips of the 22 coils judged as unqualified by the contact type shape meter, the proportion judged as unqualified in the back-punching line was 63.6%.

[0134] (Example 2)

[0135] As a second embodiment of the present disclosure, Figure 1 The continuous annealing equipment shown in the figure is used to perform an example of judging whether a metal strip is good or bad in terms of its warping shape. Figure 1 In the continuous annealing equipment shown, the heating zone 6 is used as a heating section, the immersion water tank 23 is used as a cooling section, and the temper rolling mill 30 is used as a shape correction section. In addition, a first warp shape measuring section 14 is arranged on the inspection table for quality inspection arranged on the output side of the continuous annealing equipment, and a second warp shape measuring section 42 is arranged between the cooling section and the shape correction section.

[0136] The cooling unit, the shape correcting unit 13 and the first warp shape measuring unit 14 are the same as those in Example 1. In the second warp shape measuring unit 42, similarly to the first warp shape measuring unit 14, a laser scanning distance meter is used to measure the warp shape of the metal strip before the shape correcting step.

[0137] Furthermore, the warp shape determination unit 41 in this embodiment obtains tracking information of the welded portion, which is the front end of the metal strip, from the control computer 40 at any time. The warp shape determination unit 41 determines the position information from the front end of the metal strip using the information of the conveying speed of the metal strip passing through the furnace device 121, and determines the correspondence between the warp shape of the metal strip measured by the second warp shape measurement unit 42 and the position information from the front end of the metal strip. In addition, the warp shape determination unit 41 determines the position information from the front end of the metal strip using the information of the conveying speed of the metal strip in the output side device 124, and determines the correspondence between the warp shape of the metal strip measured by the first warp shape measurement unit 14 and the position information from the front end of the metal strip. As a result, the warp height after the cooling process and the warp height after the shape correction process at the same position in the longitudinal direction of the metal strip are corresponded by the position information from the front end of the metal strip.

[0138] In this embodiment, a high-strength steel plate with a plate thickness of 1.6 to 2.0 mm, a plate width of 800 to 1250 mm, and a tensile strength of 1470 MPa is manufactured using the above manufacturing equipment. In this embodiment, the conveying speed of the metal strip passing through the cooling zone 8 is set to 40 to 80 m / min, the target temperature of the metal strip at the start of cooling is set to 740°C, and the target temperature at the end of cooling is set to 30°C.

[0139] Moreover, in the present embodiment, as a criterion for determining whether a product is acceptable or not, the acceptable range of the warp height measured by the first warp shape measuring unit 14 is determined as follows. When the difference between the warp height measured by the first warp shape measuring unit 14 and the warp height measured by the second warp shape measuring unit 42 (hereinafter referred to as "difference in warp height") is 10 mm or more at the same position from the front end of the metal strip, the acceptable range is set to 4 mm or less. In addition, when the difference in warp height is less than 10 mm at the same position from the front end of the metal strip, the acceptable range is set to 5 mm or less. That is, the acceptable or unacceptable determination of the metal strip in the present embodiment determines that the above two criteria are satisfied in the entire surface of the metal strip in the plate width direction and the length direction, and determines that the above two criteria are not satisfied. That is, the entire surface of the metal strip is qualified only if the conditions that the warp height measured by the first warp shape measuring unit 14 is 4 mm or less when the difference in warp height is 10 mm or more, and the warp height measured by the first warp shape measuring unit 14 is 5 mm or less when the difference in warp height is less than 10 mm are met. Thus, stricter pass / fail criteria are set compared to the above-mentioned first embodiment, and the pass / fail judgment of the metal strip is performed.

[0140] On the other hand, in order to evaluate the appropriateness of the pass / fail judgment using the above-mentioned method, the metal strip wound into a coil by the tension coiler 15 of the continuous annealing equipment was transported to the recoil line for detailed product inspection, and the warping shape of the metal strip was re-inspected. In the recoil line, the metal strip was appropriately cut in the length direction so that the weight of the metal strip met the product specifications. In addition, in the recoil line, the metal strip was transported at a low speed of less than 50m / min, and the transportation of the metal strip was stopped at any time, and the warping height of the metal strip was inspected over the entire length. As a result, as described above, the metal strips of the 12 coils that were judged to be qualified in the inspection station of the continuous annealing equipment were all judged to be qualified in the recoil line.

[0141] Furthermore, all the metal strips of the 20 coils judged as unqualified in the inspection station of the continuous annealing equipment were also judged as unqualified in the recoil line. That is, the accuracy rate in the inspection station of the continuous annealing equipment was 100%.

[0142] On the other hand, the 32 coils were subjected to pass / fail determination with the pass range of the warp height measured by the first warp shape measuring unit 14 being set to 5 mm or less, regardless of the warp height measured by the second warp shape measuring unit 42. In the case of this pass / fail determination, although 13 coils were determined to be pass, one coil among them was determined to be fail in the backwash line.

[0143] Although the embodiments of the present disclosure are described based on the drawings and embodiments, it should be noted that it is easy for those skilled in the art to make various deformations or modifications based on the present disclosure. Therefore, it should be noted that these deformations or modifications are also included in the scope of the present disclosure. For example, the functions included in each structural part or each step can be reconfigured in a logically non-contradictory manner, and multiple structural parts or steps can be combined into one, or divided. The embodiments of the present disclosure can also be implemented as a program executed by a processor possessed by the device or a storage medium having a program recorded thereon. It should be understood that these are also included in the scope of the present disclosure.

[0144] Description of Reference Numerals

[0145] 2… Uncoiler; 3… Welding machine; 4… Input side sleever; 5… Preheating zone; 6… Heating zone; 7… Soaking zone; 8… Cooling zone; 9… Reheating zone; 10… Over-aging zone; 11… Final cooling zone; 12… Output side sleever; 13… Shape correction section; 14… First warp shape measuring section; 15… Tension coiler; 21… Cooling fluid injection device; 22… Constraint roller; 23… Immersion water tank; 24… Cooling water; 25… Pressing roller; 26… Guide roller; 28… Dewatering roller; 29… Drying furnace; 30… Quenched and tempered rolling mill ; 32a…working roller; 32b…working roller; 33a…support roller; 33b…support roller; 34…input side tensioning roller; 35…output side tensioning roller; 36…input side tension meter; 37…output side tension meter; 40…control computer; 41…warping shape determining unit; 42…second warping shape measuring unit; 43…third warping shape measuring unit; 44…laser scanning rangefinder; 120…input side equipment; 121…furnace body equipment; 122…annealing equipment; 123…reheating equipment; 124…output side equipment.

Claims

1. A metal strip manufacturing device, characterized in that: include: A heating unit, which continuously heats the conveyed metal strip; a cooling unit configured to cool the metal strip heated by the heating unit; a shape correcting section that corrects the shape of the metal strip cooled by the cooling section; a first warping shape measuring unit, which is disposed on a downstream side of the shape correcting unit and measures a warping shape of the metal strip; as well as A warping shape specifying unit specifies position information from a front end of the metal strip and specifies a correspondence between the warping shape of the metal strip measured by the first warping shape measuring unit and the position information from the front end of the metal strip.

2. The metal strip manufacturing equipment according to claim 1, characterized in that: The metal strip manufacturing equipment is a continuous annealing equipment for metal strips. The cooling unit includes a cooling fluid spraying device including a plurality of nozzles for spraying a cooling fluid toward the metal strip from both sides of the metal strip, and at least a pair of restraining rollers for restraining the metal strip.

3. The metal strip manufacturing equipment according to claim 1 or 2, characterized in that: The metal strip manufacturing equipment is a continuous annealing equipment for metal strips. The shape correcting section includes at least one shape correcting mechanism selected from a temper rolling mill, a tension leveler, and a roll leveler.

4. The metal strip manufacturing equipment according to any one of claims 1 to 3, characterized in that: The metal strip manufacturing equipment includes a second warpage shape measuring unit for measuring the warpage shape of the metal strip between the cooling unit and the shape correcting unit. The warp shape specifying unit specifies a correspondence relationship between the warp shape of the metal strip measured by the first warp shape measuring unit, the warp shape of the metal strip measured by the second warp shape measuring unit, and position information from a front end of the metal strip.

5. The metal strip manufacturing equipment according to any one of claims 1 to 3, characterized in that: The metal strip manufacturing equipment includes a third warpage shape measuring unit for measuring a warpage shape of the metal strip between the heating unit and the cooling unit. The warp shape specifying unit specifies a correspondence relationship among the warp shape of the metal strip measured by the first warp shape measuring unit, the warp shape of the metal strip measured by the third warp shape measuring unit, and position information from a front end of the metal strip.

6. The metal strip manufacturing equipment according to any one of claims 1 to 3, characterized in that: The metal strip manufacturing equipment includes a second warp shape measuring unit for measuring the warp shape of the metal strip between the cooling unit and the shape correcting unit, and a third warp shape measuring unit for measuring the warp shape of the metal strip between the heating unit and the cooling unit. The warping shape determination unit determines the correspondence between the warping shape of the metal strip measured by the first warping shape measuring unit, the warping shape of the metal strip measured by the second warping shape measuring unit, the warping shape of the metal strip measured by the third warping shape measuring unit, and position information from the front end of the metal strip.

7. The metal strip manufacturing equipment according to any one of claims 1 to 6, characterized in that: The warping shape of the metal strip is measured using at least one warping shape measuring method selected from a distance measuring method, an image processing method, and a light sectioning method.

8. A method for determining whether a metal strip is qualified or not, characterized in that: include: A heating process for continuously heating the conveyed metal strip; a cooling step of cooling the metal strip heated in the heating step; A shape correction step of correcting the shape of the metal strip cooled in the cooling step; a first warpage shape measuring step of measuring the warpage shape of the metal strip after the shape correction step; a warping shape determining step of determining position information from the front end of the metal strip and determining a correspondence between the warping shape of the metal strip measured in the first warping shape measuring step and the position information from the front end of the metal strip; as well as A step of displaying a distribution state of warpage height in a manner that enables acceptance or rejection of the metal strip based on the correspondence between the warpage shape of the metal strip determined in the warpage shape determining step and position information from the front end of the metal strip.

9. The method for determining whether a metal strip is acceptable or not according to claim 8, characterized in that: In the cooling step, while the metal strip is constrained by at least a pair of constraining rollers, liquid is sprayed toward the metal strip from both sides of the metal strip by a plurality of nozzles.

10. The method for determining whether a metal strip is acceptable or not according to claim 8 or 9, characterized in that: In the shape correction step, the shape of the metal strip is corrected using at least one shape correction mechanism selected from a temper rolling mill, a tension leveler, and a roll leveler.

11. A method for manufacturing a metal strip, characterized in that: A metal strip judged as being acceptable by the metal strip acceptance judging method according to any one of claims 8 to 10 is manufactured.

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