Induction quenching device and quenching method for concave roller

Abstract

The invention discloses an induction quenching device and quenching method for a concave roller, and belongs to the technical field of metal heat treatment, and the device comprises a quenching machine tool, a machine tool hanger for vertically mounting the concave roller, and a profiling inductor and a water spraying ring which are coaxially arranged. The longitudinal section of the profiling sensor is matched with the outer contour of the concave roller, the inner diameter and the length of the water spraying ring are larger than those of the concave roller, the tray drives the sensor and the water spraying ring to move in the vertical direction, and dynamic cooperation of heating and cooling is achieved. The method comprises the following steps: preheating the pit furnace and then integrally heating; the concave roller rotates and is heated to 880 DEG C in a lower-step liter power mode; the water spraying ring performs water pressure spraying and synchronously moves upwards for cooling; and air cooling is conducted after box-type furnace tempering. Through the design of the profiling inductor, dynamic cooling control and process parameter optimization, the surface hardness of the concave roller reaches HRC60-63 (the uniformity is smaller than or equal to 2 HRC), the hardening layer is larger than 30 mm, gradient transition is achieved, the heating efficiency is improved by 40%, the deformation is smaller than or equal to 0.5 mm / m, and the method is suitable for batch treatment of large alloy steel concave rollers.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal heat treatment, and specifically relates to an induction quenching device for a concave roll, and also relates to an induction quenching method for a concave roll. Background Art

[0002] A concave roll is a special roll with a concave middle on its surface. Its function is to stretch and extrude metal materials and is used to manufacture thin-walled products, which can make the surface of the processed material smoother during use. In order to ensure the strength, toughness and surface wear resistance during work, the surface hardness of the concave roll needs to reach HRC58 - 62 to meet the wear resistance first; secondly, the hardened layer depth must reach more than 30 mm to have a certain bending strength during work. Induction quenching is a surface heat treatment technology based on the principle of electromagnetic induction, which has advantages such as high heating efficiency, high quenching quality, small deformation and high precision, and has become a main heat treatment method for rolls. Existing induction quenching methods cannot uniformly heat the concave part of the concave roll, resulting in uneven heating of the concave roll during quenching. Summary of the Invention

[0003] The purpose of the present invention is to provide an induction quenching device for a concave roll.

[0004] The purpose of the present invention is also to provide an induction quenching method for a concave roll, which solves the technical problem that the inductor in the prior art cannot uniformly heat the concave part of the concave roll.

[0005] The first technical solution adopted by the present invention is an induction quenching device for a concave roll, including a quenching machine tool. A lower center is installed at the bottom of the quenching machine tool, and a machine tool sling is vertically installed on the lower center. The concave roll is installed on the machine tool sling. A tray is also installed on the quenching machine tool, and a quenching transformer is installed on the top of the tray. The inductor is installed on the quenching transformer and is connected with a power connection plate. A water spray ring is installed at the bottom of the tray, and the tray drives the inductor and the water spray ring to move along the vertical direction.

[0006] The characteristics of the first technical solution of the present invention are also as follows: The shape of the longitudinal section of the inductor is similar to the outer contour shape of the longitudinal section of the concave roll, and the minimum dimension of the cross section of the inductor is larger than the maximum dimension of the cross section of the concave roll; The inner diameter dimension of the water spray ring is larger than the maximum dimension of the cross section of the concave roll, the length dimension of the water spray ring is larger than the length dimension of the concave roll, and the water line direction of the water spray ring faces the concave roll; The concave roll, the inductor, the machine tool sling and the water spray ring are coaxially arranged.

[0007] The second technical solution adopted by the present invention is an induction quenching method for a concave roll, using the above-mentioned induction quenching device for a concave roll, and specifically implemented according to the following steps: S1: Place the concave roll in a heat treatment furnace for heating and insulation, and then conduct overall heating on a quenching machine tool. S2: Lift out the heated concave roll and transfer it to an inductor. Start the intermediate frequency power supply, set the initial power to heat the concave roll, and the lower center rotates synchronously to drive the concave roll to start rotating. S3: Observe the heating temperature of the concave roll, adjust the heating power of the inductor, move the inductor up and down to heat the concave roll. Stop heating after the concave roll is heated to 880 °C, open the water valve of the water spray ring, and the tray drives the water spray ring to move upward to cool the concave roll. S4: Unload the cooled concave roll from the quenching machine tool and load it into a box-type resistance furnace for tempering. After tempering, air-cool it to room temperature.

[0008] The characteristics of the second technical solution of the present invention also lie in: In S1: The heating temperature of the concave roll in the heat treatment furnace is 290 °C - 310 °C; The heating rate of the concave roll in the heat treatment furnace is 80 °C / h; The insulation time of the concave roll in the heat treatment furnace is 8h - 10h; The heat treatment furnace selects a pit-type resistance furnace, and the temperature uniformity of the pit-type resistance furnace is ±10 °C.

[0009] In S2: The initial power is 50KW; the rotation speed of the concave roll is 10r / min - 12r / min.

[0010] In S3, the specific adjustment of the heating power of the inductor is: according to the heating temperature of the concave roll, gradually increase the heating power from 50KW to 255KW; the heating time of the concave roll in the inductor is 30min.

[0011] In S3, the water pressure of the water spray ring is 0.1MPa, and the cooling time of the water spray ring for the concave roll is 40min.

[0012] In S4, after the concave roll is unloaded from the quenching machine tool, it is horizontally placed in a box-type tempering furnace, heated to 210 °C at a rate of 80 °C / h and insulated. The insulation time depends on the effective cross-section of the concave roll, and the insulation is 8 - 12min / mm; the temperature uniformity of the box-type resistance furnace is ±5 °C.

[0013] Compared with the prior art, the beneficial effects of the present invention are: The present invention uses a profiling inductor induction hardening method to perform induction hardening on a concave roll made of 60CrMoV material. The surface can reach a hardness of HRC60 - 63, the surface hardness uniformity is ≤2HRC, and a hardened layer depth of >30 mm is obtained. The hardness below the hardened layer depth does not drop suddenly but gradually decreases to the matrix hardness, enabling the concave roll to have sufficient wear resistance and strength during use. At the same time, since a profiling inductor is used, the workpiece can be better heated simultaneously during the heating process, enabling it to reach the quenching temperature faster and having better heating efficiency than other types of inductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of the induction hardening device for the concave roll of the present invention; Figure 2 is a schematic structural diagram of the concave roll in the induction hardening device for the concave roll of the present invention.

[0015] In the figure, 1. concave roll, 2. inductor, 3. machine tool sling, 4. water spray ring, 5. water line, 6. lower center, 7. power connection plate, 8. quenching machine tool, 9. flange. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0017] Embodiment 1 As Figure 1 and Figure 2 shown, the induction hardening device for the concave roll disclosed in this embodiment includes a quenching machine tool 8. A lower center 6 is installed at the bottom of the quenching machine tool 8. A machine tool sling 3 is vertically installed on the lower center 6. The concave roll 1 is installed on the machine tool sling 3. A tray is also installed on the quenching machine tool 8. A quenching transformer is installed on the top of the tray. The inductor 2 is installed on the quenching transformer and is connected to a power connection plate 7. A water spray ring 4 is installed at the bottom of the tray. The tray drives the inductor 2 and the water spray ring 4 to move along the vertical direction.

[0018] In this embodiment, the machine tool sling 3 is vertically installed by the lower center point 6 to ensure the stability of the concave roll 1 during the processing. The machine tool sling 3 realizes the vertical installation and rapid hoisting and transfer of the concave roll 1, and adapts to the clamping requirements of different sizes of the concave roll 1. In the specific installation, the machine tool sling 3 includes a mandrel that passes through the concave roll 1 and is connected to the lower center point 6. Two flanges 9 are sleeved on the outer periphery of the mandrel. The flange 9 at the bottom is welded to the mandrel, and the flange 9 at the top is sleeved on the mandrel and clamped with the concave roll 1. The two flanges 9 are respectively installed at the top and bottom of the concave roll 1. The inductor 2 and the quenching transformer are powered by the power connection plate 7 to generate a high-frequency electromagnetic field to heat the concave roll 1 to achieve surface quenching. The water spray ring 4 provides uniform cooling, and the tray drives the inductor 2 and the water spray ring 4 to move in the vertical direction to realize the dynamic matching of the heating and cooling processes.

[0019] Embodiment 2 On the basis of Embodiment 1, the shape of the longitudinal section of the inductor 2 is similar to the outer contour shape of the longitudinal section of the concave roll 1, and the minimum dimension of the cross section of the inductor 2 is greater than the maximum dimension of the cross section of the concave roll 1; The inner diameter dimension of the water spray ring 4 is greater than the maximum dimension of the cross section of the concave roll 1, the length dimension of the water spray ring 4 is greater than the length dimension of the concave roll 1, and the direction of the water line 5 of the water spray ring 4 faces the concave roll 1; The concave roll 1, the inductor 2, the machine tool sling 3 and the water spray ring 4 are coaxially arranged.

[0020] In this embodiment, the longitudinal section of the inductor 2 is similar to the outer contour of the concave roll 1, ensuring that the heating area is consistent with the geometric shape of the concave roll 1 and avoiding local overheating or underheating. The inner diameter of the water spray ring 4 is larger than the maximum cross section of the concave roll 1, and the length covers the entire length of the concave roll 1, ensuring that the cooling medium uniformly covers the surface of the concave roll 1 and improving the uniformity of the hardened layer. The concave roll 1, the inductor 2, the machine tool sling 3 and the water spray ring 4 are coaxially arranged, reducing the uneven heating or cooling deviation caused by eccentricity and improving the process stability.

[0021] Embodiment 3 The present invention also discloses an induction quenching method for a concave roll, using the induction quenching device for a concave roll as described in Embodiment 2, which is specifically implemented according to the following steps: S1: Place the concave roll 1 in a heat treatment furnace and heat it to 290°C - 310°C at an efficiency of 80°C / h and hold for 8h - 10h, and then perform overall heating on the quenching machine tool 8; The material of the concave roll 1 is 60CrMoV, and the heat treatment furnace is a pit resistance furnace, and the temperature uniformity of the pit resistance furnace is ±10°C.

[0022] S2: Lift out the heated concave roll 1 and transfer it to the inductor 2, start the medium-frequency power supply, set the initial power to 50KW to heat the concave roll 1, and the lower center point 6 rotates synchronously to drive the concave roll 1 to start rotating at a rotation speed of 10r / min - 12r / min; S3: Observe the heating temperature of the concave roll 1, adjust the heating power of the inductor 2, gradually increase the heating power from 50 KW to 255 KW, move the inductor 2 up and down to heat the concave roll 1 for 30 min, stop heating after the concave roll 1 is heated to 880 °C, open the water valve of the water spray ring 4, drive the water spray ring 4 to move upward by the tray, and cool the concave roll 1 with the water pressure of 0.1 Mpa by the water spray ring 4 for 40 min; S4: Remove the cooled concave roll 1 from the quenching machine tool 8, horizontally place it in a box-type resistance furnace with a furnace temperature uniformity of ±5 °C, heat it to 210 °C at a rate of 80 °C / h and hold for tempering, and the holding time is determined according to the effective cross-section of the concave roll, hold for 8 - 12 min / mm, and air-cool to room temperature after tempering.

[0023] Example 4 In this example, a concave roll 1 made of 60CrMoV (an existing part in the art) is used, and its product external dimensions are: length 640 mm, maximum diameter 570 mm, minimum diameter 480 mm, center hole diameter 270 mm, wall thickness (effective cross-section) 150 mm, and there are 4 M16 screw holes at each of the upper and lower ends, and the external shape is as Figure 2 shown. The technical requirement for quenching hardness is HRC58 - 62, and the layer depth > 30 mm. Its material composition table is shown in Table 1, Table 1

[0024] The quenching machine tool 8 used for the 60CrMoV concave roll 1 is an intermediate frequency induction machine tool, and its parameters are shown in Table 2: Table 2

[0025] Adopt the induction quenching method of the concave roll described in Example 3, and the specific process is as follows: 1. Preheating of the concave roll 1: The concave roll 1 has a large size. During the process of heating to the quenching temperature, due to the large temperature difference and long time, it is necessary to preheat the concave roll 1 before induction quenching. Place the concave roll 1 in a pit-type resistance furnace, close the furnace door, and heat the concave roll at a heating rate of 80 °C / h to 300 °C, and hold for 10 h.

[0026] 2. Installation of the inductor 2 and the water spray ring 4: According to the external dimensions of the concave roll 1, a special-shaped inductor 2 is made, with a maximum diameter of 640 mm and a minimum diameter of 590 mm, and the diameter of the water spray ring 4 is selected as 720 mm. During installation, install the water spray ring 4 under the lower tray of the quenching machine tool 8, install the inductor 2 above the tray, and both the inductor 2 and the water spray ring 4 can move with the up and down movement of the tray. Ensure that the centers of the two are on the same vertical line during installation.

[0027] 3. Quenching of the concave roll 1: Use the machine tool sling 3 to lift the preheated concave roll 1, and suspend it vertically on the quenching machine tool 8. The lower end of the machine tool sling 3 is a locating pin, which can be fixed on the lower center point 6 of the quenching machine tool 8, and make the center lines of the concave roll 1, the inductor 2, and the water spray ring 4 in a straight line. Then start the intermediate frequency power supply button. First, make the intermediate frequency power very low (about 50KW), and the intermediate frequency inductor 2 starts to heat slightly. Then slowly increase the intermediate frequency power until it increases to 255KW. When the intermediate frequency starts to heat, start the rotation button of the quenching machine tool 8 to make the rotation speed of the 60CrMoV concave roll 1 between 10r / min - 12r / min. Move the inductor 2 up and down during the heating process of the concave roll 1 to make the concave roll 1 heat evenly, and heat the concave roll 1 for about 30 minutes. After heating to the quenching temperature, perform cooling. Before the concave roll 1 cools, open the water valve, and the spray quenching water pressure is about 0.1Mpa. Then the water spray ring 4 quickly rises outside the concave roll 1 to make the water line completely submerge the concave roll 1, and start to cool the concave roll 1. The cooling time is about 40 minutes. The process parameters of the concave roll 1 during quenching are shown in Table 3.

[0028] Table 3

[0029] 4. Tempering and hardness testing: After the concave roll 1 is removed from the quenching machine tool 8, it is placed horizontally in a box-type tempering furnace, and then heated to 210°C at a temperature of 80°C / h and held for 30h.

[0030] After tempering, the hardness of each part of the outer cylindrical surface of the concave roll 1 is detected as shown in Table 4 below. At the same time, the layer depth of the concave roll 1 is detected by cutting samples, and the detection results are shown in Table 5: Table 4

[0031] Table 5

[0032] Result analysis: First, the outer shape of the concave roll 1 is intact, and no cracks are found after being detected with a coloring agent. Second, the hardness test shows HC59 - 62, meeting the required HRC58 - 62. In addition, according to the layer depth detected by cutting samples, HRC58 can be achieved within 30mm, the hardness gradually decreases to HRC55 at 35mm, and continues to decrease to the matrix hardness as it goes deeper, and the layer depth also meets the requirements. It is proved that after the 60CrMoV material concave roll 1 undergoes the quenching method of the present invention, the concave roll 1 reaches a high hardness, has a relatively deep hardened layer, and good wear resistance.

[0033] The concave roll 1 made of 60CrMoV material is first preheated at 300°C for 10 hours, and then heated by a special profiling inductor 2 to reach the quenching temperature. When cooling, the intermediate frequency heating is turned off, and it is quickly lowered so that it all enters the water line for cooling. After cooling, it quickly enters the heat treatment furnace for tempering treatment to prevent the concave roll 1 from cracking due to large stress. A box-type tempering furnace is used for low-temperature tempering at 210°C to ensure that the workpiece reaches high hardness.

[0034] Example 5 In this example, a concave roll 1 made of 60CrMoV (an existing part in the art) is used, and its product external dimensions are: length 580 mm, maximum diameter 460 mm, minimum diameter 380 mm, center hole diameter 180 mm, and wall thickness (effective cross-section) 140 mm. The technical requirement for quenching hardness is HRC58 - 62, and the layer depth > 30 mm. The quenching machine tool 8 used is an intermediate frequency induction machine tool, with the same parameters as in Example 4.

[0035] The induction quenching method for the concave roll described in Example 3 is adopted, and the specific process is as follows: 1. Preheating of the concave roll 1: Place the concave roll 1 in a pit-type resistance furnace, close the furnace door tightly, and heat the concave roll 1 to 320°C at a heating rate of 80°C / h and hold for 8 hours.

[0036] 2. Installation of the inductor 2 and the water spray ring 4: The installation of the inductor 2 and the water spray ring 4 is the same as in Example 4, except that the size of the specially made inductor 2 for the concave roll 1 is maximum diameter 550 mm and minimum diameter 500 mm, and the diameter of the selected water spray ring 4 is 580 mm.

[0037] 3. Quenching of the concave roll 1: Use the machine tool sling 3 to lift the preheated concave roll 1 and hang it vertically on the quenching machine tool 8. The lower end of the machine tool sling 3 is a positioning pin, which can be fixed on the lower center point 6 of the quenching machine tool 8, and make the center lines of the concave roll 1, the inductor 2, and the water spray ring 4 in a straight line. Then press the intermediate frequency power button. First, make the intermediate frequency power very low (about 50 KW), and the intermediate frequency inductor 2 starts to heat slightly. Then slowly increase the intermediate frequency power until it increases to 250 KW. While the intermediate frequency starts to heat, start the rotation button of the quenching machine tool 8 to make the rotation speed of the 60CrMoV concave roll between 10 r / min - 12 r / min. During the process of heating the concave roll 1, move the inductor 2 up and down to make the concave roll 1 heat evenly. Heat the concave roll 1 for about 25 minutes. After heating to the quenching temperature, start cooling. Before the concave roll 1 cools, open the water valve, and the spray quenching water pressure is about 0.1 Mpa. Then the water spray ring 4 quickly rises outside the concave roll 1 so that the water line can completely submerge the concave roll, and start cooling the concave roll. The cooling time is about 30 minutes. The process parameters during the quenching process of the concave roll 1 are shown in Table 6.

[0038] Table 6

[0039] 4. Tempering and Hardness Detection: After the concave roll 1 is removed from the quenching machine tool 8, it is horizontally placed in a box-type tempering furnace, and then heated to 220 °C at a temperature increase rate of 80 °C / h and held for 28 h.

[0040] After tempering, the hardness of each part of the outer cylindrical surface of the concave roll 1 is detected as shown in Table 7 below. At the same time, the layer depth of the concave roll sample is detected, and the detection results are shown in Table 8: Table 7

[0041] Table 8

[0042] Result Analysis: First, the outer shape of the concave roll 1 is intact, and no cracks are found after being detected with a coloring agent. Second, the hardness detection result is HC59 - 62, meeting the required HRC58 - 62. In addition, according to the layer depth detected from the sample cutting, HRC58 can be achieved within 30 mm, the hardness gradually decreases to HRC55 at 35 mm, and continues to decrease to the matrix hardness as it goes deeper, and the layer depth also meets the requirements. It is proved that after the concave roll 1 made of 60CrMoV material undergoes the quenching method of the present invention, the concave roll 1 has achieved high hardness, a relatively deep hardened layer, and good wear resistance.

[0043] Example 6 In this example, a concave roll 1 made of 60CrMoV (an existing part in the art) is used, and its product outer dimensions are: length 640 mm, maximum diameter 550 mm, minimum diameter 460 mm, center hole diameter 220 mm, and wall thickness (effective cross-section) 165 mm. The technical requirement for quenching hardness is HRC58 - 62, and the layer depth > 30 mm. The quenching machine tool 8 used is an intermediate frequency induction machine tool, and the parameters are the same as those in Example 4.

[0044] The induction quenching method of the concave roll described in Example 3 is adopted, and the specific process is as follows: 1. Preheating of the concave roll 1: Place the concave roll 1 in a pit-type resistance furnace, close the furnace door, and heat the concave roll 1 to 350 °C at a temperature increase rate of 80 °C / h and hold for 15 h.

[0045] 2. Installation of the inductor 2 and the water spray ring 4: The installation of the inductor 2 and the water spray ring 4 is the same as that in Example 4, except that the size of the inductor 2 specially made for the concave roll is maximum diameter 680 mm and minimum diameter 580 mm, and the diameter of the selected water spray ring 4 is 720 mm.

[0046] 3. Quenching of the concave roll 1: Use the machine tool sling 3 to lift the preheated concave roll 1, and suspend it vertically on the quenching machine tool 8. The lower end of the machine tool sling 3 is a positioning pin, which can be fixed on the lower center point 6 of the quenching machine tool 8, and make the center lines of the concave roll 1, the inductor 2, and the water spray ring 4 in a straight line. Then start the intermediate frequency power supply button. First, make the intermediate frequency power very low (about 50KW), and the intermediate frequency inductor 2 starts to heat slightly. Then slowly increase the intermediate frequency power until it increases to 255KW. While the intermediate frequency starts to heat, start the rotation button of the quenching machine tool 8 to make the rotation speed of the 60CrMoV concave roll 1 between 10r / min and 12r / min. During the process of heating the concave roll 1, move the inductor 2 up and down to make the concave roll 1 heat evenly, and heat the concave roll 1 for about 45 minutes. After heating to the quenching temperature, perform cooling. Before the concave roll 1 cools, open the water valve, and the spray quenching water pressure is about 0.1Mpa. Then the water spray ring 4 quickly rises outside the concave roll 1 to make the water line completely submerge the concave roll 1, and start to cool the concave roll 1. The cooling time is about 60 minutes. The process parameters of the concave roll 1 during quenching are shown in Table 9.

[0047] Table 9

[0048] 4. Tempering and hardness testing: After the concave roll 1 is removed from the quenching machine tool 8, it is horizontally placed in a box-type tempering furnace, and then heated to 200°C at a temperature of 80°C / h and held for 40h.

[0049] After tempering, the hardness of each part of the outer cylindrical surface of the concave roll 1 is detected as shown in Table 10 below. At the same time, the case depth of the concave roll 1 is detected by cutting samples, and the detection results are shown in Table 11: Table 10

[0050] Table 11

[0051] Result analysis: First, the shape of the concave roll 1 is intact, and no cracks are found after being detected with a coloring agent; second, the hardness test shows HC58 - 61, meeting the required HRC58 - 62. In addition, according to the case depth detected by cutting samples, HRC58 can be achieved within 30mm, the hardness gradually decreases to HRC52 at 35mm, and continues to decrease to the matrix hardness as it goes deeper, and the case depth also meets the requirements. This proves that after the 60CrMoV material concave roll 1 undergoes the induction quenching method of the present invention, the concave roll 1 has achieved high hardness, a relatively deep hardened layer, and good wear resistance.

[0052] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0053] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0054] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Induction hardening device for concave rollers, characterized in that, It includes a quenching machine tool (8). A lower center (6) is installed at the bottom of the quenching machine tool (8). A machine tool sling (3) is vertically installed on the lower center (6). A concave roll (1) is installed on the machine tool sling (3). A tray is also installed on the quenching machine tool (8). A quenching transformer is installed on the top of the tray. An inductor (2) is installed on the quenching transformer and is connected to a power connection plate (7). A water spraying ring (4) is installed at the bottom of the tray. The tray drives the inductor (2) and the water spraying ring (4) to move along the vertical direction.

2. The induction hardening device for the concave roll according to claim 1, characterized in that, The shape of the longitudinal section of the inductor (2) is similar to the outer contour shape of the longitudinal section of the concave roll (1), and the minimum dimension of the cross section of the inductor (2) is larger than the maximum dimension of the cross section of the concave roll (1); The inner diameter dimension of the water spraying ring (4) is larger than the maximum dimension of the cross section of the concave roll (1), the length dimension of the water spraying ring (4) is larger than the length dimension of the concave roll (1), and the direction of the water line (5) of the water spraying ring (4) faces the concave roll (1); The concave roll (1), the inductor (2), the machine tool sling (3) and the water spraying ring (4) are coaxially arranged.

3. Induction hardening method for a concave roll, using the induction hardening device for a concave roll as described in claim 2, characterized in that, Specifically, it is implemented according to the following steps: S1: Place the concave roll (1) in a heat treatment furnace for heating and holding, and then perform overall heating on the quenching machine tool (8); S2: Lift out the heated concave roll (1) and transfer it to the inductor (2). Start the medium-frequency power supply, set the initial power to heat the concave roll (1), and the lower center (6) rotates to drive the concave roll (1) to start rotating synchronously; S3: Observe the heating temperature of the concave roll (1), adjust the heating power of the inductor (2), move the inductor (2) up and down to heat the concave roll (1). After the concave roll (1) is heated to 880 °C, stop heating, open the water valve of the water spraying ring (4), and the tray drives the water spraying ring (4) to move upward to cool the concave roll (1); S4: Unload the cooled concave roll (1) from the quenching machine tool (8), load it into a box-type resistance furnace for tempering, and after tempering, air-cool it to room temperature.

4. The induction hardening method of the concave roll according to claim 3, wherein, In S1: The heating temperature of the concave roll (1) in the heat treatment furnace is 290 °C - 310 °C; The heating rate of the concave roll (1) in the heat treatment furnace is 80 °C / h; The holding time of the concave roll (1) in the heat treatment furnace is 8 h - 10 h; The heat treatment furnace selects a pit-type resistance furnace, and the furnace temperature uniformity of the pit-type resistance furnace is ±10 °C.

5. The induction hardening method of the concave roll according to claim 3, characterized in that, In S2: The initial power is 50 KW; the rotation speed of the concave roll (1) is 10 r / min - 12 r / min.

6. The induction hardening method of the concave roll according to claim 3, characterized in that, In S3, adjusting the heating power of the inductor (2) specifically is: according to the heating temperature of the concave roll (1), gradually increase the heating power from 50 KW to 255 KW; the heating time of the concave roll (1) in the inductor (2) is 30 min.

7. The induction hardening method of the concave roll according to claim 6, characterized in that, In S3, the water pressure of the water spraying ring (4) is 0.1 MPa, and the cooling time of the water spraying ring (4) for the concave roll (1) is 40 min.

8. The induction hardening method of the concave roll according to claim 3, characterized in that, In S4, after the concave roll (1) is unloaded from the quenching machine tool (8), it is horizontally placed in a box-type tempering furnace, heated to 210 °C at a temperature of 80 °C / h and held. The holding time depends on the effective cross section of the concave roll, and it is held for 8 - 12 min / mm; the furnace temperature uniformity of the box-type resistance furnace is ±5 °C.

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