JP2018135552A - Quenching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quenching apparatus for a metal plate capable of suppressing a reduction in cooling rate of a metal plate while suppressing shape defects occurring at the time of quenching of a high temperature metal plate.SOLUTION: A quenching apparatus 10 is equipped with: a water tank 13 for containing water 12 into which a steel plate 11 is immersed; a water injection device 14 provided so that at least a part thereof is disposed in the water 12 contained in the water tank 13 and provided with a plurality of nozzles 16 for spraying a cooling liquid on the metal plate 11 from both sides of the steel plate 11; and a pair of constraining rolls 20 provided between the nozzles 16 and a metal plate passing line through which the steel plate 11 passes, and constraining the steel plate 11. The constraining rolls 20 have a groove 22 through which the cooling liquid ejected from the water injection device 14 can pass.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rapid quenching apparatus that cools a high-temperature metal plate immersed in a liquid.

  When manufacturing a metal plate such as a steel plate, in the continuous annealing equipment, the metal plate is cooled after heating, and the material is formed by causing a phase transformation. In recent years, in the automobile industry, the application of high-tensile steel sheets (high tension) has been progressing for the purpose of reducing the weight of the vehicle body and collision safety, and it is advantageous for the production of high-tensile steel sheets to meet such demand trends. The importance of rapid cooling (rapid cooling) technology is increasing. As the water quenching method with the fastest cooling rate, a method of immersing a heated high-temperature steel sheet in water and simultaneously injecting cooling water into the steel sheet by a quench nozzle provided in the water and quenching is generally used. is there. However, during the rapid cooling, there is a problem that a defective shape due to out-of-plane deformation such as warpage or wave-like deformation occurs in the metal plate.

  With respect to such a problem, in Patent Document 1, in order to suppress the wave-like deformation of the metal plate that occurs at the time of rapid quenching in a continuous annealing furnace, the tension of the steel sheet subjected to the rapid quenching process can be changed. As a tension changing means, a method has been proposed in which bridle rolls are provided before and after the quenching and quenching portion.

  Further, in Patent Document 2, attention is paid to the fact that thermal stress in the compression direction is generated in the width direction of the metal plate at the quenching start point (cooling start point), and a defective shape is generated due to buckling of the metal plate. A method has been proposed in which out-of-plane deformation is suppressed by restraining from both sides of a metal plate in a region where compressive stress is generated in the plate width direction or in the vicinity thereof.

  And in patent document 3, the method of suppressing an out-of-plane deformation | transformation is arrange | positioned by arrange | positioning a pair of restraint roll in a quenching and quenching apparatus, and restraining a metal plate from both sides by this restraint roll.

JP 2011-184773 A JP 2003-277833 A WO2016 / 084283

  However, in the method described in Patent Document 1, there is a possibility that the steel sheet may be broken because a large tension is applied to the high-temperature steel sheet. In addition, since a large thermal crown is generated in the bridle roll before the quenching and quenching portion that contacts the hot steel plate, the bridle roll and the steel plate contact non-uniformly in the width direction of the bridle roll, and as a result, the steel plate buckles. There was a problem that wrinkles occurred and the shape of the steel sheet could not be improved.

  Moreover, as a result of verifying the method described in Patent Document 2, it was found that the method described in Patent Document 2 has a small shape correction effect on the metal plate.

  And if the rapid quenching apparatus of patent document 3 is used, although the deformation | transformation of the metal plate at the time of rapid quenching can be prevented, when a metal plate passes the injection device which injects cooling water, the cooling rate of a metal plate temporarily The problem that the characteristic of a metal plate fell by having fallen was discovered. Specifically, due to a decrease in the cooling rate of the metal plate, a metal plate having desired material characteristics of the metal plate, for example, a desired tensile strength, may not be obtained.

  The present invention has been completed in view of such circumstances, and a metal plate capable of suppressing a decrease in the cooling rate of the metal plate while suppressing a shape defect occurring in the metal plate during rapid quenching of a high-temperature metal plate. It is an object of the present invention to provide a rapid quenching apparatus.

  As a result of intensive studies to solve the above-described problems, the inventors have obtained the following knowledge. In the production of metal plates, there is a case where a structure control that causes martensitic transformation to occur in the metal plate during quenching of the hot metal plate by immersion in water and injection of cooling water is used, but martensitic transformation occurs. And the tissue rapidly expands in volume, resulting in a complicated and uneven uneven shape. A high-strength steel sheet (high-strength steel sheet) having a martensite structure is subjected to the greatest stress on the steel sheet in the vicinity of the Mf point from the Ms point where transformation expansion occurs during thermal shrinkage during rapid quenching, and the shape collapses. The Ms point is the temperature at which martensitic transformation starts, and the Mf point is the temperature at which martensitic transformation ends.

  Further, martensitic transformation occurs from the Ms point to the Mf point. However, when the cooling rate of the metal plate in this temperature range is lowered, the material properties (for example, tensile strength) of the metal plate are also lowered.

  According to the study by the present inventors, when the metal plate is restrained from both sides with restraining rolls as in Patent Document 3 in order to suppress deformation of the metal plate at the time of quenching and quenching, particularly the restraint that comes into contact with the high-temperature metal plate. In the vicinity of the roll, the cooling water sprayed from the nozzle toward the metal plate is blocked by the restraining roll, the flow velocity is lowered, and the cooling water is difficult to reach both surfaces of the metal plate. It has been found that a decrease in the cooling rate of the plate is likely to occur.

  The present invention has been completed based on the above findings, and the gist thereof is as follows.

[1] A quenching and quenching device for cooling by immersing a high-temperature metal plate in a liquid,
An immersion tank containing a liquid for immersing the metal plate;
A liquid ejecting apparatus provided with a plurality of nozzles that are provided so that at least a part thereof is located in the liquid accommodated in the immersion tank and that injects a coolant from both sides of the metal plate to the metal plate;
A pair of restraining rolls provided between the nozzle and the metal plate passing plate line through which the metal plate passes, and restraining the metal plate;
The quenching and quenching apparatus, wherein the restraining roll has a groove through which a cooling liquid ejected from the nozzle of the liquid ejecting apparatus can pass.

  [2] The quench quenching apparatus according to [1], wherein the groove has a groove width of 5 to 20 mm and a groove depth of 5 to 20 mm.

  [3] The rapid quenching apparatus according to [1] or [2], wherein the pitch of the groove is 6.5 to 35 mm, and is 1.3 to 2.0 times the groove width. .

  [4] Any of [1] to [3], wherein the restraining roll has a soft layer made of a material softer than the metal plate on an outer peripheral surface where the groove of the restraining roll is not provided. The quenching and quenching apparatus according to claim 1.

  According to the quenching and quenching apparatus of the present invention, by providing a restraining roll that restrains the metal plate from both sides, while suppressing a shape defect (deformation) that occurs in the metal plate during quenching and quenching of the high temperature metal plate, It can suppress that the cooling rate of a metal plate falls temporarily in the vicinity. Therefore, by using the rapid quenching apparatus of the present invention, a metal plate having a good shape and desired material properties such as tensile strength can be produced.

It is a schematic diagram which shows the rapid quenching apparatus of Embodiment 1. It is an enlarged view which shows the water injection apparatus vicinity of the rapid quenching apparatus of FIG. It is a schematic diagram explaining the restraint roll of a rapid quenching apparatus. It is sectional drawing of the restraint roll of the rapid quenching apparatus of Embodiment 1. It is sectional drawing which shows the other example of the restraint roll of the rapid quenching apparatus of Embodiment 1. FIG. It is sectional drawing of the restraint roll of the rapid quenching apparatus of Embodiment 2.

(Embodiment 1)
The rapid quenching apparatus of this embodiment is demonstrated using FIGS. FIG. 1 is a schematic diagram illustrating a quenching and quenching apparatus according to the first embodiment. FIG. 2 is an enlarged view showing the vicinity of the water injection device of the rapid quenching device of FIG. FIG. 3 is a schematic diagram illustrating a restraining roll of a rapid quenching apparatus, FIG. 3 (a) is a schematic view of a restraining roll of a rapid quenching apparatus according to the prior art, and FIG. 3 (b) is a diagram of the first embodiment. It is a schematic diagram explaining the restraint roll of a rapid quenching apparatus. FIG. 4 is a cross-sectional view of the restraining roll of the rapid quenching apparatus according to the first embodiment. This rapid quenching apparatus is applied to a cooling facility provided on the exit side of the soaking zone of a continuous annealing furnace.

  As shown in FIG. 1, a rapid quenching apparatus 10 of the present embodiment includes a water tank (immersion tank) 13 that contains water 12 in which a steel plate (steel strip) 11 is immersed, and a water injection device that injects cooling water onto the steel plate 11. 14 is provided. Moreover, the rapid quenching apparatus 10 is provided so as to be positioned in the water 12 accommodated in the water tank 13, and includes a sink roll 15 that changes the conveying direction (the passing plate direction) of the steel plate 11.

  And the water-injection apparatus 14 is provided so that the part may be located in the water 12 accommodated in the water tank 13, and in FIG. 1, it opposes on both sides of the steel plate passage line through which the steel plate 11 passes, and is predetermined. It is installed through the gap. Further, the water injection device 14 has a plurality of nozzles 16 that extend in the width direction of the steel plate 11 and inject cooling water from both sides of the steel plate 11. In FIG. 1, eight nozzles 16 are arranged on both sides of a steel plate passing line through which the steel plates 11 pass through a predetermined gap in the conveying direction of the steel plates 11. Further, in FIG. 1, all the nozzles 16 are provided so as to be located in the water 12 accommodated in the water tank 13.

  The rapid quenching apparatus 10 includes a pair of restraining rolls 20 that restrain the steel plate 11 from both sides thereof. In FIG. 1, the constraining roll 20 is arranged so that its central axis is perpendicular to the conveying direction of the steel plate 11. And the restraint roll 20 is provided between the steel plate passage line and the nozzle 16, that is, the restraint roll 20 has cooling water sprayed from the nozzle 16 of the water injection device 14 to the steel plate 11 to the steel plate 11. It is provided on the facing channel. In FIG. 1, the restraining roll 20 is provided so as to be disposed in the water 12 accommodated in the water tank 13.

  In such a rapid quenching apparatus 10, the water 12 is stored in the water tank 13 so that at least a part of the water injection apparatus 14 is located in the water 12, and heating, soaking, while continuously passing the steel plate 11, The hot steel plate 11 discharged from the soaking zone of the continuous annealing furnace that performs cooling and reheating is conveyed into the water 12 from above the water tank 13. Then, cooling water is jetted from the nozzle 16 of the water jet device 14 onto both surfaces of the steel plate 11, and the steel plate 11 is rapidly cooled. Thus, the steel plate 11 cooled to, for example, the temperature of the cooling water by being immersed in the water 12 and jetting of the cooling water is discharged from the outlet 19 of the water tank 13 and conveyed to the next step.

  Here, the steel plate 11 is thermally contracted by being rapidly cooled by the cooling water injected from the nozzle 16 of the water injection device 14 in the water 12 accommodated in the water tank 13, that is, below the water surface of the water tank 13. In particular, when the steel plate 11 is a material that causes martensitic transformation, the temperature of the steel plate 11 changes from the Ms point, which is the temperature at which martensitic transformation starts, to the Mf point, which is the temperature at which martensitic transformation ends. In addition, rapid thermal contraction and transformation expansion occur simultaneously in the steel plate 11, the stress acting on the steel plate 11 becomes the largest, and the shape collapses.

  In order to suppress the deformation of the steel plate 11, in this embodiment, a pair of restraining rolls 20 that restrain the steel plate 11 are disposed in the water 12 in a region where martensitic transformation occurs. That is, a pair of restraining rolls 20 are arranged between the nozzle 16 of the water injection device 14 and the steel plate passage line in a predetermined steel plate conveying direction, and the steel plates 11 are restrained from both sides by the restraining rolls 20. Thus, deformation that occurs in the steel plate 11 when the steel plate 11 is rapidly cooled is suppressed. Since the steel plate 11 expands between the Ms point and the Mf point, and the martensitic transformation of the steel plate 11 proceeds and becomes difficult to deform as it approaches the Mf point, immediately after the temperature at which the steel plate 11 reaches the Ms point. It is desirable to arrange the restraining roll 20 on the surface. Note that the temperatures at the Ms point and the Mf point can be calculated from the component composition of the steel plate 11. Further, the position where the steel plate 11 reaches the Ms point can be determined by a method such as quenching by attaching a thermocouple to the steel plate 11.

  In the present invention, the constraining roll 20 included in the quenching and quenching apparatus 10 has at least one groove through which cooling water ejected from the nozzle 16 of the water injection apparatus 14 can pass. Specifically, the constraining roll 20 included in the rapid quenching apparatus 10 is provided with, for example, a circumferential groove on the outer periphery of a cylindrical constraining roll 40 included in the conventional rapid quenching apparatus illustrated in FIG. Has a shape. In other words, as shown in FIGS. 3B and 4, the restraining roll 20 includes a groove portion 22 that is recessed toward the central axis side and a non-groove portion 23 that maintains the outer peripheral portion of the conventional cylindrical restraining roll 40. Have. Thus, since the constraining roll 20 has the groove part 22, the cooling water ejected from the water injection device 14 can pass through the groove part 22, so that the cooling rate of the steel plate 11 is prevented from decreasing near the constraining roll 20. it can.

  More specifically, as indicated by arrows in FIG. 2, the cooling water sprayed from the nozzle 16 of the water spray device 14 hits both surfaces of the steel plate 11 inside the water spray device 14. At this time, the cooling water from the nozzle 16a located on the upstream side in the conveying direction of the steel plate 11 relative to the restraining roll 20 and the cooling water sprayed from the nozzle 16c located on the downstream side in the conveying direction of the steel plate 11 hit the steel plate 11. Exhibits sufficient cooling capacity. On the other hand, the cooling water sprayed from the nozzle 16b in a position overlapping with the restraining roll and the conveying direction of the steel plate 11 is blocked by the restraining roll in the rapid quenching apparatus according to the conventional technique, The flow velocity decreases and it becomes difficult to reach the steel plate 11. For this reason, in the rapid quenching apparatus concerning a prior art, it was discovered that a cooling rate becomes easy to fall in the vicinity of a restraint roll.

  Since the restraint roll is in contact with the steel plate 11, the position where the flow velocity is the lowest is in the vicinity of the contact point between the restraint roll and the steel plate 11. Therefore, in order to suppress a decrease in the cooling rate of the steel plate 11, it is only necessary to suppress a decrease in the flow rate of the cooling water generated by the constraining roll in the vicinity of the contact point between the constraining roll and the steel plate 11. Based on such knowledge, in the present invention, the restraining roll 20 having a groove through which the cooling water ejected from the water ejection device 14 can pass is used. By providing a groove in the restraint roll 20, it is possible to make it difficult to inhibit the flow of cooling water at the contact point between the restraint roll 20 and the steel plate 11. It is possible to suppress the decrease and allow the cooling water to reach the steel plate 11. Thereby, in this invention, ensuring the cooling rate required for the steel plate 11 (for example, high-tensile steel plate) which has a desired material characteristic, suppressing the shape defect which generate | occur | produces in the steel plate 11 at the time of rapid quenching by the restraint roll 20. Can do. 3B and 4 exemplify the case where the plurality of groove portions 22 are provided, the constraining roll 20 only needs to have at least one groove portion 22. However, the restraining roll 20 preferably has a plurality of groove portions 22 because the effect of suppressing the decrease in the cooling rate is increased. Moreover, the shape of the groove part 22 should just be the cooling water sprayed from the nozzle 16, and is not limited to the shape of FIG.3 (b) and FIG. 4, For example, it is helical on the outer periphery of a cylindrical roll. May be provided.

  5-20 mm is suitable for the width | variety (groove width w) which the restraint roll 20 has. If the groove width is within this range, it is difficult to inhibit the flow of cooling water caused by the groove width being too narrow, the cooling capacity at the time of rolling is not reduced, and the restraint roll due to the groove width being too wide. A decrease in shape control capability is suppressed. Moreover, 5-20 mm is suitable for the depth (groove depth d) of the groove | channel which the constraining roll 20 has. If the groove depth is within this range, it is difficult to inhibit the flow of cooling water caused by the groove depth being too shallow, and the cooling capacity at the time of rolling is not reduced, and the groove depth is too deep. A reduction in the rigidity of the constraining roll and a reduction in shape control capability are suppressed. Moreover, 6.5-35 mm is suitable for the pitch (space | interval p of a groove | channel between grooves) of the groove | channel which the restraining roll 20 has. If the groove pitch is within this range, it will be difficult for the shape control ability to decrease due to the groove pitch being too small (too small), and the cooling ability due to the groove pitch being too coarse (too large). Generation | occurrence | production of a fall is suppressed. The pitch p of the grooves of the restraining roll 20 is preferably 1.3 times or more and 2.0 times or less of the groove width w. FIG. 5 shows an example of a constraining roll in which the ratio of the groove pitch p to the groove width w is smaller than that of the constraining roll of FIG. FIG. 5 is a cross-sectional view showing another example of the restraining roll of the rapid quenching apparatus of the first embodiment. In the restraining roll 20A of FIG. 5, the groove pitch p is 1.3 times the groove width w.

  The pair of restraining rolls 20 may be arranged with their central axes shifted from each other in the conveying direction of the steel plate 11, but in the vicinity of the restraining roll 20, the cooling capacity changes, and the temperature difference between the front and back surfaces of the steel plate 11 (on both sides) Therefore, as shown in FIG. 1 and the like, it is desirable to arrange the central axes without shifting each other in the conveying direction of the steel plate 11. In addition, although the material of the restraint roll 20 is not specifically limited, For example, it is metal.

  In the above description, the quenching and quenching apparatus that performs cooling that causes martensitic transformation has been described. However, the present invention is not limited thereto, and cooling that causes other transformation may be performed.

  Moreover, in the above, although the rapid quenching apparatus provided in the soaking | tropical exit side of the continuous annealing furnace was described, it is not limited to this, You may provide in the exit side of another heating furnace.

  Moreover, although the quench quenching apparatus in which a part of the water injection device 14 is disposed in the water 12 is described above, the entire water injection device 14 may be immersed in the water 12.

  In the above description, the quench quenching apparatus in which eight nozzles 16 are provided as the nozzles 16 on both sides of the steel plate passage line is described. However, it is only necessary that the steel plate 11 can be cooled from both sides, one on each side of the steel plate passage line. One or more may be provided.

  Moreover, although the example which water-cools a steel plate was demonstrated above, it is not necessarily limited to this. The technical idea of the present invention is wide and can be applied to cooling of all metal plates other than steel plates, and can also be applied to general quenching and quenching devices that are cooled by a liquid other than water.

(Embodiment 2)
FIG. 6 is a sectional view of the restraining roll of the rapid quenching apparatus according to the second embodiment of the present invention. The rapid quenching apparatus of the present embodiment is the same as that of the first embodiment except that the restraining roll 20B having a soft layer is used as the restraining roll, and redundant description is omitted.

  As shown in FIG. 6, the restraint roll 20B included in the rapid quenching apparatus of the present embodiment is formed from the steel plate 11 on the outer peripheral surface where the groove (groove portion 22) of the restraint roll 20B is not provided, that is, on the surface of the non-groove portion 23. It has a soft layer 31 made of a soft material. In this invention, what provided the groove | channel as a restraining roll is used, However, If the non-groove part 23 has an angle | corner, this angle | corner may contact with the steel plate 11, and it may become a cause of generating a flaw. Therefore, in this embodiment, the soft layer 31 which consists of a raw material softer than the steel plate 11 is provided in the surface of the non-groove part 23 of the restraint roll 20B (lining). The soft layer 31 may not be provided in the groove portion 22. The heat resistant temperature of a material (lining material) softer than the steel plate 11 constituting the soft layer 31 is preferably Ms point or higher, and preferably 400 ° C. or higher. The thickness (lining thickness) a of the soft layer 31 should just be a grade which does not contact the metal location of the restraining roll 20B, and the steel plate 11, for example, is 5 mm or more. Moreover, the hardness (Hs) of a lining material should just be 50 or more and 100 or less, for example.

  Hereinafter, the present invention will be described by way of examples for further understanding of the present invention. However, the examples do not limit the present invention.

  A high-tensile cold-rolled steel sheet having a plate thickness of 1.0 mm, a plate width of 1 m, and a tensile strength of 1470 MPa was manufactured at a plate speed of 100 mpm using the rapid quenching apparatus 10 of FIG. The steel plate 11 was cooled to a quenching start temperature (immersion start temperature in the water tank 13) of 750 ° C. and a water temperature of 30 ° C. A pair of restraining rolls 20 was installed at a position where the temperature of the steel plate 11 was 400 ° C.

  In Examples 1-13, the restraint roll 20 which provided the groove | channel of the dimension described in Table 1 as a restraint roll was used. Moreover, about Examples 14-21, it has a groove | channel of the dimension described in Table 1 as a restraint roll, and lining by heat-resistant rubber (Oidaka Rubber Co., Ltd. Himax I) is provided in parts other than a groove | channel (non-groove part 23). The constraining roll 20B of FIG. 6 provided with a rubber layer (soft layer 31) was used. Table 1 shows the rubber layer thickness and rubber hardness. The rubber hardness Hs was measured using a durometer in accordance with JIS K 6253.

  About the steel plate manufactured by the Example and the comparative example, the tensile strength, the steel plate shape, and the wrinkle area rate were evaluated. The evaluation results are shown in Table 1. The tensile strength is obtained by collecting a JIS No. 5 tensile test piece so that the tensile direction is the rolling direction, and performing a tensile test in accordance with the provisions of JIS Z 2241. When the tensile strength is less than 1470 MPa, In the case of 1470 MPa or more and less than 1500 MPa, it was evaluated as ◯, and in the case of 1500 MPa or more, it was evaluated as ◎. Regarding the steel plate shape determination, ◎ was given when the warpage of the steel plate was 7 mm or less, ○ when the warpage of the steel plate was more than 7 mm and 10 mm or less, and x when the warpage of the steel plate was more than 10 mm. Regarding the wrinkles, Table 2 shows the area ratio of the wrinkles due to the restraining rolls on the steel sheet surface to the entire outer peripheral surface of the restraining rolls.

  In Examples 1 to 21 having grooves in which the cooling water sprayed from the nozzle 16 can pass through the restraint roll, it is confirmed that the shape of the steel plate is good, the tensile strength is high, and the cooling rate reduction is suppressed. It was. A constraining roll having a groove satisfying a groove width of 5 to 20 mm, a groove depth of 5 to 20 mm, a groove pitch of 6.5 to 35 mm, and a groove pitch of 1.3 to 2.0 times the groove width was used. In Examples 2 to 4, 7 to 8, 11, 12, and 14 to 21, the tensile strength was higher, the effect of suppressing the decrease in cooling rate was higher, and the steel plate shape was also better. Moreover, in Examples 14-21 which provided the rubber layer, generation | occurrence | production of the wrinkle by a restraint roll was also suppressed. On the other hand, in Comparative Example 1 using a constraining roll having no grooves, although the shape of the steel sheet was good, the tensile strength did not reach a predetermined value, and the cooling rate was lower than in the Examples. .

DESCRIPTION OF SYMBOLS 10 Rapid quenching apparatus 11 Steel plate 12 Water 13 Water tank 14 Water injection apparatus 15 Sink roll 16 Nozzle 19 Outlet 20, 20A, 20B Restraint roll 22 Groove part 23 Non-groove part 31 Soft layer

Claims (4)

A quench quenching device that cools a hot metal plate by immersing it in a liquid,
An immersion tank containing a liquid for immersing the metal plate;
A liquid ejecting apparatus provided with a plurality of nozzles that are provided so that at least a part thereof is located in the liquid accommodated in the immersion tank and that injects a coolant from both sides of the metal plate to the metal plate;
A pair of restraining rolls provided between the nozzle and the metal plate passing plate line through which the metal plate passes, and restraining the metal plate;
The quenching and quenching apparatus, wherein the restraining roll has a groove through which a cooling liquid ejected from the nozzle of the liquid ejecting apparatus can pass.   The quenching and quenching apparatus according to claim 1, wherein the groove has a groove width of 5 to 20 mm and a groove depth of 5 to 20 mm.   The rapid quenching apparatus according to claim 1 or 2, wherein a pitch of the groove is 6.5 to 35 mm and is 1.3 times or more and 2.0 times or less of a groove width.   The said restraint roll has a soft layer which consists of a raw material softer than the said metal plate in the outer peripheral surface in which the said groove | channel of the said restraint roll is not provided, The any one of Claims 1-3 characterized by the above-mentioned. Rapid quenching and quenching equipment.

Images