Method for manufacturing straightening roll for rolling angle steel

Abstract

This invention provides a method for manufacturing straightening rolls for rolled angle steel, belonging to the technical field of straightening roll manufacturing. The method includes the following steps: manufacturing a cast iron cold mold with the same outer edge shape as the cold mold, according to the weight ratio of the casting to the cold mold; applying resin sand to localized areas of the cast iron cold mold; manufacturing an upper sand core, a lower sand core, a bottom box, and an upper box, and assembling the box to form a gating system within the box; smelting; pouring molten iron into the box, maintaining the temperature inside the box after pouring, then opening the box and removing the risers and burrs; performing low-temperature stress-relief annealing on the manufactured straightening roll; cutting the upper and lower straightening rolls that are cast together, and processing to obtain the desired straightening roll. This method for manufacturing straightening rolls for rolled angle steel ensures that the axial working layer of the straightening roll cools at a uniform rate during the solidification process of the molten iron, resulting in a uniform microstructure and higher hardness, thereby improving the roll's yield and service life.

Description

Technical Field

[0001] This invention belongs to the field of straightening roller manufacturing technology, and more specifically, it relates to a method for manufacturing straightening rollers used in rolling angle steel. Background Technology

[0002] Currently, steel and metallurgical enterprises use conventional chilled ductile iron straightening rolls in the straightening process when rolling small angle steel. However, insufficient hardness often affects the quality and efficiency of straightening the angle steel. If straightening rolls with a hardness of 65-70 HSD are used, cracks will occur at the radius (R) of the lower roll, leading to roll failure. Replacing the rolls is very troublesome and also affects angle steel production. Therefore, research on straightening rolls with higher hardness is imperative. Summary of the Invention

[0003] The purpose of this invention is to provide a method for manufacturing straightening rollers used in rolling angle steel, aiming to solve the technical problem that the corners of the straightening rollers for high-hardness angle steel are prone to cracking during use, leading to the failure of the straightening rollers.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for manufacturing straightening rollers used in rolling angle steel, comprising the following steps:

[0005] According to the weight ratio of the casting to the straightening roll cold mold, a cast iron cold mold with the same shape as the outer edge of the straightening roll is made, and resin sand is applied to a part of the cast iron cold mold. The cast iron cold mold includes the upper roll cold mold and the lower roll cold mold.

[0006] The upper sand core, lower sand core, bottom box, and upper box are fabricated and arranged from bottom to top in the order of bottom box, lower sand core, lower roller cold mold, upper roller cold mold, upper sand core, and upper box. The boxes are then assembled to form a box that can be cast in series. A gating system is formed inside the box, which is then ready for melting and pouring.

[0007] The smelting process is carried out to control the Si content of the molten iron in the furnace straightening rolls within the range of 0.5-0.8%. After spheroidizing and inoculation treatment, the final composition of the straightening rolls is as follows: C content 3.2-3.5%, Si content 1.4-1.7%, Mn content 0.5-0.7%, P content ≤0.06%, S content ≤0.02%, Cr content 0.4-0.5%, Ni content 1.0-1.2%, Mo content 0.2-0.4%, and Mg content 0.04-0.06%. The spheroidizing treatment temperature at the furnace exit is 1400-1420℃, and the molten iron is inoculated twice with 0.5% ferrosilicon in the ladle. Then, 0.15% calcium barium inoculant is used for in-flow inoculation during casting to maintain the final silicon content within the range of 1.4-1.7%.

[0008] Pouring molten iron into the box to straighten the rollers, with the pouring temperature controlled within the range of 1310-1320℃, and keeping the box warm for 12 hours after pouring, then opening the box and removing the gating risers and burrs;

[0009] The manufactured straightening rolls are subjected to low-temperature stress-relief annealing, with the temperature controlled at ≤400℃, to prevent the castings from cracking.

[0010] The upper and lower straightening rolls, which are cast together, are cut and separated, and then processed separately to obtain the required straightening rolls.

[0011] In another embodiment of this application, the weight ratio of the casting to the straightening roll cold mold is 1:4.

[0012] In another embodiment of this application, resin sand is applied to both ends of the upper roller cold mold along its axial direction and to the corners near the inner wall, and the resin sand forms a ring after application.

[0013] In another embodiment of this application, a first coating area is provided at both ends of the upper roller cooling mold along its axial direction and at the corners near the inner wall. The resin sand is coated on the first coating area, and the outer end face is flush with the outer end face of the upper roller cooling mold and the inner side face is flush with the inner wall of the upper roller cooling mold.

[0014] In another embodiment of this application, resin sand is applied to both ends of the lower roller cold mold along its axial direction and to the corners near the inner wall, and the resin sand forms a ring after application.

[0015] In another embodiment of this application, a second coating area is provided at both ends of the lower roller cooling mold along its axial direction and at the corners near the inner wall. The resin sand is coated on the second coating area, and the outer end face is flush with the outer end face of the lower roller cooling mold and the inner side face is flush with the inner wall of the lower roller cooling mold.

[0016] In another embodiment of this application, the upper roller cooling pattern includes a left upper roller cooling pattern and a right upper roller cooling pattern assembled together, and the lower roller cooling pattern includes a left lower roller cooling pattern and a right lower roller cooling pattern assembled together.

[0017] In another embodiment of this application, the upper left roller cooling pattern and the upper right roller cooling pattern are connected to each other by a plurality of clamping bolts, and the lower left roller cooling pattern and the lower right roller cooling pattern are connected to each other by a plurality of clamping bolts.

[0018] In another embodiment of this application, a pouring cup is connected to the central part of the top of the box, so that molten iron from the straightening roller is poured into the box from the pouring cup.

[0019] In another embodiment of this application, three heat-insulating risers are formed at the upper end of the upper box, the bottom box has a plate-like structure, and the gating system inside the box includes a vertical gating system and a horizontal gating system, with the vertical gating system and the horizontal gating system communicating with each other.

[0020] The beneficial effects of the manufacturing method of straightening rollers for rolled angle steel provided by the present invention are as follows: Compared with the prior art, the manufacturing method of straightening rollers for rolled angle steel of the present invention includes the following steps: according to the weight ratio of the casting to the straightening roller cold mold, a cast iron cold mold with the same shape as the outer edge of the straightening roller is manufactured, and resin sand is applied to a portion of the cast iron cold mold; an upper sand core, a lower sand core, a bottom box, and an upper box are manufactured, and arranged and assembled from bottom to top in the order of bottom box, lower sand core, lower roller cold mold, upper roller cold mold, upper sand core, and upper box, forming a box body capable of continuous casting, and forming a [missing information - likely a specific component or structure] inside the box. The process involves pouring the molten iron into a gating system, followed by smelting and casting; smelting is then performed; molten iron for the straightening rolls is poured into the gating box, and the box is kept warm after pouring. The box is then opened, and the risers and burrs are removed; the manufactured straightening rolls are subjected to low-temperature stress-relief annealing; the upper and lower roll blanks of the straightening rolls, which are cast together, are cut and separated, and the required straightening rolls are obtained after processing. This invention provides a method for manufacturing straightening rolls for rolled angle steel, which makes the cooling rate of the axial working layer of the straightening roll tend to be uniform during the solidification of molten iron, resulting in a uniform structure and high hardness, thereby improving the process yield and service life of the rolls. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the box structure for a method of manufacturing straightening rollers for rolled angle steel provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the upper roller cold forming structure of a method for manufacturing straightening rollers used in rolling angle steel according to an embodiment of the present invention;

[0024] Figure 3 for Figure 2 Side view of the upper roller cold forming structure of the method for manufacturing straightening rollers used in the rolling of angle steel.

[0025] In the diagram: 1. Upper roller cold mold; 11. Upper left roller cold mold; 12. Upper right roller cold mold; 13. Connecting part; 14. Clamping bolt; 2. Lower roller cold mold; 21. Lower left roller cold mold; 22. Lower right roller cold mold; 3. Upper sand core; 4. Lower sand core; 5. Bottom box; 6. Upper box; 61. Pour cup; 62. Insulating riser; 7. Sprue; 71. Vertical sprue; 72. Horizontal sprue; 8. Resin sand; 9. First coating area; 10. Second coating area. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] Please refer to the following: Figures 1 to 3 The present invention will now describe a method for manufacturing straightening rollers for rolled angle steel. The method for manufacturing straightening rollers for rolled angle steel includes the following steps:

[0028] According to the weight ratio of the casting to the straightening roll cold mold, a cast iron cold mold with the same shape as the outer edge of the straightening roll is made, and resin sand is applied to a part of the cast iron cold mold. The cast iron cold mold includes upper roll cold mold 1 and lower roll cold mold 2.

[0029] Make the upper sand core 3, lower sand core 4, bottom box 5 and upper box 6. Set them up from bottom to top in the order of bottom box 5, lower sand core 4, lower roller cold mold 2, upper roller cold mold 1, upper sand core 3 and upper box 6 and assemble them to form a box that can be cast in series. The box has a gating channel 7, and then waits for melting and pouring.

[0030] The smelting process is carried out to control the Si content of the molten iron in the furnace straightening rolls within the range of 0.5-0.8%. After spheroidizing and inoculation treatment, the final composition of the straightening rolls is as follows: C content 3.2-3.5%, Si content 1.4-1.7%, Mn content 0.5-0.7%, P content ≤0.06%, S content ≤0.02%, Cr content 0.4-0.5%, Ni content 1.0-1.2%, Mo content 0.2-0.4%, and Mg content 0.04-0.06%. The spheroidizing treatment temperature at the furnace exit is 1400-1420℃, and the molten iron is inoculated twice with 0.5% ferrosilicon in the ladle. Then, 0.15% calcium barium inoculant is used for in-flow inoculation during casting to maintain the final silicon content within the range of 1.4-1.7%.

[0031] Pouring molten iron into the box to straighten the rollers, with the pouring temperature controlled within the range of 1310-1320℃, and keeping the box warm for 12 hours after pouring, then opening the box and removing the gating risers and burrs;

[0032] The manufactured straightening rolls are subjected to low-temperature stress-relief annealing, with the temperature controlled at ≤400℃, to prevent the castings from cracking.

[0033] The upper and lower straightening roll blanks, which are cast together, are cut and separated, and then processed separately to obtain the required straightening rolls.

[0034] This invention provides a method for manufacturing straightening rollers for rolled angle steel. Compared with existing technologies, this method involves manufacturing a cast iron cold mold with the same outer edge shape as the straightening roller cold mold, based on the weight ratio of the casting to the cold mold, and partially coating the cast iron cold mold with resin sand. The method also involves manufacturing an upper sand core 3, a lower sand core 4, a bottom box 5, and an upper box 6, arranged sequentially from bottom to top in the order of bottom box 5, lower sand core 4, lower roller cold mold 2, upper roller cold mold 1, upper sand core 3, and upper box 6, and then assembling the boxes to form a box capable of continuous casting. A gating system 7 is formed inside the box, which then awaits melting and pouring. The process involves: smelting; pouring molten iron into the box for straightening rolls; maintaining the box temperature after pouring; opening the box and removing the risers and burrs; performing low-temperature stress-relief annealing on the manufactured straightening rolls; cutting and separating the upper and lower straightening roll blanks that are cast together; and processing them to obtain the required straightening rolls. This invention provides a method for manufacturing straightening rolls for rolled angle steel, which makes the cooling rate of the axial working layer of the straightening rolls tend to be uniform during the solidification of molten iron, resulting in a uniform structure and high hardness, thereby improving the process yield and service life of the rolls.

[0035] The method for manufacturing straightening rolls referred to in this invention refers to the rolls installed on straightening rolls, which are cylindrical structures used for rolling angle steel. The term "straightening roll" also refers to the method of manufacturing straightening rolls. The angle steel used for rolling angle steel refers to small angle steel. Coating with resin sand is called sand coating. After sand coating treatment, the cooling rate of the molten iron tends to be uniform, thus preventing cracking of the working layer and failure of the straightening roll, and eliminating the need to replace the straightening roll.

[0036] Because the cold casting of cast iron has a strong chilling effect on the straightening roll, the casting will generate a lot of internal stress during the solidification process. In order to prevent the straightening roll from cracking during processing and use, it is necessary to perform low-temperature stress-relieving annealing on the straightening roll, with the maximum temperature controlled below 400℃.

[0037] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 The weight ratio of the casting to the cold mold of the straightening roll is 1:4. The outer edge of the straightening roll refers to the cast iron cold mold made according to the outer edge of the existing straightening roll shape. That is, the outer edge shape of the cast iron cold mold is similar to or the same as the outer edge shape of the straightening roll, and it is made according to the above proportion.

[0038] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 The resin sand 8 is applied to both ends of the upper roller cooling mold 1 along its axial direction and near the corners of the inner wall, forming a ring shape after the resin sand 8 is applied. After the resin sand 8 is applied, it forms an integral structure with a certain thickness and width, and is firmly connected to the upper roller cooling mold 1 after application, without affecting its later use.

[0039] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 The upper roller cooling mold 1 has a first coating area 9 at both ends along its axial direction and near the inner corner of the roller. Resin sand 8 is coated on the first coating area 9, with its outer end face flush with the outer end face of the upper roller cooling mold 1 and its inner side face flush with the inner wall of the upper roller cooling mold 1. From the cross-sectional view, the first coating area 9 has an L-shaped cross-section, which is exactly the square shape formed by the coated resin sand 8, filling the first coating area 9. Its exposed end edge or side can be flush with the end edge or end face or inner wall of the upper roller cooling mold 1, so that the resin sand 8 and the upper roller cooling mold 1 combine to form an integral structure.

[0040] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 The resin sand 8 is applied to both ends of the lower roller cooling mold 2 along its axial direction and near the corners of the inner wall, forming a ring after the resin sand 8 is applied. The resin sand 8 on the lower roller cooling mold 2 has the same structure as the resin sand 8 on the upper roller cooling mold 1, except that its width and thickness are greater than those of the resin sand 8 on the upper roller cooling mold 1.

[0041] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 A second coating area 10 is provided at both ends of the lower roller cooling mold 2 along its axial direction and near the inner corner of the mold. Resin sand 8 is coated on the second coating area 10, with its outer end face flush with the outer end face of the lower roller cooling mold 2 and its inner end face flush with the inner wall of the lower roller cooling mold 2. The structure of the second coating area 10 is the same as that of the first coating area 9, except that its width and thickness are greater than those of the first coating area 9. This ensures that the thickness and width of the resin sand 8 coating can match the thickness and width of either the first coating area 9 or the second coating area 10.

[0042] To facilitate the assembly and subsequent use of the upper roll cold profile 1 and lower roll cold profile 2, as a specific embodiment of the manufacturing method of straightening rolls for rolling angle steel provided by the present invention, please refer to [link to relevant documentation]. Figures 1 to 3The upper roller cooling mold 1 comprises an upper left roller cooling mold 11 and an upper right roller cooling mold 12 assembled together, and the lower roller cooling mold 2 comprises a lower left roller cooling mold 21 and a lower right roller cooling mold 22 assembled together. From the front view, both the upper left roller cooling mold 11 and the upper right roller cooling mold 12 are approximately semi-circular structures, with connecting parts 13 at the top and bottom. When the two connecting parts 13 are connected, the upper left roller cooling mold 11 and the upper right roller cooling mold 12 can be joined together to form a single unit.

[0043] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 The upper left and upper right cold rollers 11 and 12 are connected to each other by multiple connecting bolts 14, and the lower left and lower right cold rollers 21 and 22 are connected to each other by multiple connecting bolts 14. From the front view, both the lower left and lower right cold rollers 21 and 22 are approximately semi-circular structures, with connecting parts 13 at the top and bottom. When the two connecting parts 13 are connected, the lower left and lower right cold rollers 21 and 22 can be joined together to form a single unit.

[0044] The aforementioned connecting part 13 is a lug-like shape with a connecting hole. It is used together with the engaging bolt 14 and engaging nut. After passing through the connecting hole, it is locked, which can make the two connecting parts 13 abut against each other to form a whole.

[0045] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 A pouring cup 61 is connected to the center of the top of the box, allowing molten iron for the straightening rollers to be poured into the box from the pouring cup 61. In practice, molten iron is poured into the gating channel 7 inside the box through the pouring cup 61, causing the molten iron to form a casting inside the box, ultimately forming the straightening rollers.

[0046] As a specific embodiment of the method for manufacturing straightening rollers for rolled angle steel provided by the present invention, please refer to [the relevant documentation]. Figures 1 to 3 This design creates three heat-insulating risers 62 at the top of the upper box 6, giving the bottom box 5 a plate-like structure. The gating system 7 within the box includes a vertical gating 71 and a horizontal gating 72, which are interconnected. Molten iron flows within the vertical gating 71 and horizontal gating 72 inside the box, solidifying to form a casting (straightening roller).

[0047] The present invention mainly involves applying sand locally at the end corners or appropriate positions near the inner wall of the straightening rolls at both ends. This reduces the cooling rate of the molten iron in the straightening rolls after casting at the preset position of the cold mold, making the cooling rate of the axial working layer of the straightening rolls more uniform, and making the internal structure of the working layer uniform and the hardness reaching a high level of 55-60 HSD.

[0048] The upper straightening roll cold mold (upper roll cold mold 1) and the lower straightening roll cold mold (lower roll cold mold 2) are stacked together for cascade casting, reducing the gating system and riser from 2 sets to 1 set, thereby improving the process yield of the straightening roll.

[0049] The outer edge of the straightening roll along its axial section has lines of varying shapes, with different distances from the straight line forming the inner hole, resulting in significant differences in wall thickness. After casting, the cooling rate of different parts of the straightening roll varies under the action of the cold molds (including upper roll cold mold 1 and lower roll cold mold 2), leading to inconsistent microstructure and hardness of the working layer. To achieve a more uniform microstructure and hardness in the working layer, we apply sand coating to the cold molds corresponding to the faster-cooling outer edges of the casting. This reduces the cooling intensity of the cold molds on the molten iron in these areas, making the axial cooling rate of the straightening roll's working layer more uniform, thus obtaining a working layer with similar hardness and improving the service life of the straightening roll.

[0050] By partially applying sand to the cold mold to reduce the cooling intensity of the cold mold on the molten iron, the cooling rate of the axial working layer of the straightening roll tends to be uniform during the solidification process of the molten iron, thereby obtaining a working layer with similar hardness, and stably obtaining a working layer with a hardness of 55-60HSD, which directly improves the service life of the straightening roll.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing straightening rollers for rolling angle steel, characterized in that, Includes the following steps: According to the weight ratio of the casting to the straightening roll cold mold, a cast iron cold mold with the same shape as the outer edge of the straightening roll is made, and resin sand is applied to a part of the cast iron cold mold. The cast iron cold mold includes the upper roll cold mold and the lower roll cold mold. The upper sand core, lower sand core, bottom box, and upper box are fabricated and arranged from bottom to top in the order of bottom box, lower sand core, lower roller cold mold, upper roller cold mold, upper sand core, and upper box. The boxes are then assembled to form a box that can be cast in series. A gating system is formed inside the box, which is then ready for melting and pouring. The smelting process is carried out to control the Si content of the molten iron in the furnace straightening rolls within the range of 0.5-0.8%. After spheroidizing and inoculation treatment, the final composition of the straightening rolls is as follows: C content 3.2-3.5%, Si content 1.4-1.7%, Mn content 0.5-0.7%, P content ≤0.06%, S content ≤0.02%, Cr content 0.4-0.5%, Ni content 1.0-1.2%, Mo content 0.2-0.4%, and Mg content 0.04-0.06%. The spheroidizing treatment temperature at the furnace exit is 1400-1420℃, and the molten iron is inoculated twice with 0.5% ferrosilicon in the ladle. Then, 0.15% calcium barium inoculant is used for in-flow inoculation during casting to maintain the final silicon content within the range of 1.4-1.7%. Pouring molten iron into the box to straighten the rollers, with the pouring temperature controlled within the range of 1310-1320℃, and keeping the box warm for 12 hours after pouring, then opening the box and removing the gating risers and burrs; The manufactured straightening rolls are subjected to low-temperature stress-relief annealing, with the temperature controlled at ≤400℃, to prevent the castings from cracking. The upper and lower straightening rolls, which are cast together, are cut and separated, and then processed separately to obtain the required straightening roll pieces. Resin sand is applied to both ends of the upper roller cooling mold along its axial direction and at the corners near the inner wall, forming a ring after the resin sand is applied; resin sand is also applied to both ends of the lower roller cooling mold along its axial direction and at the corners near the inner wall, forming a ring after the resin sand is applied.

2. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, The weight ratio of the casting to the straightening roll cold mold is 1:

4.

3. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, The upper roller cooling mold has a first coating area at both ends along its axial direction and near the corner of the inner wall. The resin sand is coated in the first coating area, with the outer end face flush with the outer end face of the upper roller cooling mold and the inner side face flush with the inner wall of the upper roller cooling mold.

4. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, The lower roller cooling mold has a second coating area at both ends along its axial direction and near the corner of the inner wall. The resin sand is coated in the second coating area, with the outer end face flush with the outer end face of the lower roller cooling mold and the inner side face flush with the inner wall of the lower roller cooling mold.

5. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, The upper roller cooling pattern comprises a left upper roller cooling pattern and a right upper roller cooling pattern assembled together, and the lower roller cooling pattern comprises a left lower roller cooling pattern and a right lower roller cooling pattern assembled together.

6. The method for manufacturing straightening rollers for rolled angle steel as described in claim 5, characterized in that, The upper left and upper right cold rollers are connected to each other by multiple clamping bolts, and the lower left and lower right cold rollers are connected to each other by multiple clamping bolts.

7. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, A pouring cup is connected to the center of the top of the box, allowing molten iron from the straightening rollers to be poured into the box from the pouring cup.

8. The method for manufacturing straightening rollers for rolled angle steel as described in claim 1, characterized in that, The upper box has three heat-insulating risers at its top, the bottom box has a plate-like structure, and the gating system inside the box includes a vertical gating system and a horizontal gating system, with the vertical gating system and the horizontal gating system connected to each other.

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