Special-shaped flat steel hole pattern design and rolling process

Abstract

The invention relates to a special-shaped flat steel pass design and rolling technology, and relates to the technical field of pass rolling. A square billet continuous casting billet is used for heating the square billet to a high-temperature state; the heated steel billets step by step on a steel tapping roller way, the steel tapping roller way conveys the steel billets, oxide scales on the surfaces of the steel billets are removed through a high-pressure water descaling box, the steel billets enter a rough rolling area to be rolled, the number of rough rolling units is six, and box rolling, square rolling, oval rolling, round rolling, oval rolling and round hole rolling are sequentially used; head and tail defects of the blank are removed, the blank enters an intermediate rolling unit to be rolled, the intermediate rolling unit is provided with six machines, and oval rolling, round rolling, flat rolling, vertical roll rolling, flat rolling and flat hole pattern rolling are sequentially used; the defects of head bending and the like are removed, the steel plate enters a finishing mill group to be rolled, the finishing mill group is provided with five machines, and flat, vertical roll, flat, vertical hole and flat roll hole patterns are sequentially used for rolling. And performing multi-length shearing according to a set length. And cooling on a cooling bed after multi-length. The special-shaped flat steel can be formed at a time through hot rolling, energy is saved, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to a hole profile design and a rolling process for a special-shaped flat steel, and belongs to the technical field of hole profile rolling. Background Art

[0002] At present, the transmission chain industry uses hot-rolled coils to form special-shaped flat steel, which is mainly used to process conveyor chain plates for transmission devices. The hot-rolling process of coils is cumbersome, time-consuming, labor-intensive, and energy-intensive, which is not conducive to low-carbon production. Under the current low-carbon and environmental protection concept, steel mills are actively researching low-carbon processes to ensure the quality of finished products while reducing energy consumption and low-carbon emissions. At the same time, it improves process efficiency and shortens the process cycle. Summary of the invention

[0003] In order to solve the above problems, the present invention discloses a hole design and rolling process for special-shaped flat steel, and the specific technical scheme is as follows: A special-shaped flat steel pass design and rolling process includes the following steps: Step S1: Select a steel billet and heat it to a high temperature state of 1060-1090°C; Step S2: The heated billet steps onto the steel-out roller table, which transports the square continuous casting billet through a high-pressure water descaling box to remove the iron oxide scale on the surface of the square continuous casting billet, and then enters the rough rolling area for rolling. The rough rolling mill group has a total of 6 stands, which use the stand rolling with the hole types of box type, square type, oval type, round type, oval type, and round hole type in turn; Step S3: After being rolled by the rough rolling mill, the 1# flying shear performs head and tail trimming to remove the head and tail defects of the billet, and then enters the intermediate rolling mill for rolling. The intermediate rolling mill has a total of 6 stands, which are rolled in turn using stands with elliptical, round, flat roll, vertical roll, flat roll, and flat roll hole shapes; Step S4: After rolling by the intermediate rolling mill, the 2# flying shear performs head trimming to remove the head bending defect, and then enters the finishing rolling mill for rolling. The finishing rolling mill has a total of 5 stands, which are rolled in the following order: flat roll type, vertical roll type, flat roll type, vertical roll type, and flat roll type; Step S5: After being rolled by the finishing mill, the 3# flying shear performs multiple-length shearing according to the set length; Step S6: After the multiple-length cutting, the steel is placed on a cooling bed for cooling. To ensure that no bending occurs during the cooling process, one of the first multiple-length steel pieces is cut to a fixed length. The cooling bed movement rhythm is three steps in motion and two steps in idleness. Step S7: After the cooling bed is cooled to 280-320° C., the cold shear is used to cut the pieces to the required length; Step S8: Cut to length and pack for storage.

[0004] Furthermore, the steel billet is a square continuous casting billet of 150 mm×150 mm.

[0005] Furthermore, the steel billet is a 40Cr continuous casting billet, and the chemical composition and mass percentage of the 40Cr continuous casting billet are: C0.37-0.44%, Si0.17-0.37%, Mn0.5-0.8%, Cr0.8-1.1%, Ni≤0.3%, S≤0.03%, P≤0.03%, and the rest are iron and other inevitable elements.

[0006] Furthermore, the heating method of the steel billet is as follows: after the steel billet enters the furnace, the furnace pressure is maintained at a slight positive pressure of 10 to 40 Pa, and the furnace time is controlled to be shortened as much as possible; The steel billet is evenly heated in the first and second heating stages, wherein the heating time of the steel billet in the first heating stage is no more than 54 minutes, and the heating time in the second heating stage is no more than 40 minutes. The soaking stage is quickly heated to ensure that the heating time is no less than 45 minutes. The total heating time of the steel billet in the furnace is 110-180 minutes; The heating temperature of the upper layer of the first heating stage is 820-890°C, the heating temperature of the lower layer of the first heating stage is 800-870°C; the heating temperature of the second heating stage is 1030-1080°C; the heating temperature of the equalizing stage is 1070-1110°C.

[0007] Furthermore, the furnace pressure is maintained at a slight positive pressure of 25 to 30 Pa.

[0008] Furthermore, there are a total of 17 racks in steps S2 to S4, and the clamping directions of two adjacent racks are perpendicular to each other.

[0009] Furthermore, the height and width of the rolled product after rolling on each frame in step S2 are as follows: box-type frame: height 165.0 mm, width 108.0 mm, square frame: height 119.0 mm, width 119.0 mm, elliptical frame: height 138.0 mm, width 81.5 mm, round frame: height 99.0 mm, width 99.0 mm, elliptical frame: height 113.0 mm, width 60.9 mm, round hole frame: height 75.0 mm, width 75.0 mm.

[0010] Furthermore, the height and width of the rolled product after rolling on each stand in step S3 are as follows: elliptical stand: height 83.8 mm, width 42.2 mm, round stand: height 54.0 mm, width 54.0 mm, flat roll stand: height 70.0 mm, width 30.0 mm, vertical roll stand: height 60.0 mm, width 33.0 mm, flat roll stand: height 65.2 mm, width 20.0 mm, flat roll stand: height 67.2 mm, width 15.0 mm.

[0011] Furthermore, in step S4, the height and width of the rolled product after rolling on each stand are as follows: flat roll stand: height 68.8 mm, width 11.0 mm, Vertical roller type frame: height 56.0mm, width 12.9mm, Flat roller type frame: height 57.0mm, width 9.0mm, Vertical roller type frame: height 55.5mm, width 9.2mm, groove bottom size 9.5mm, arc transition R1mm on the left, side wall slope 7°, outer round angle R8mm; arc transition R5mm on the right, side wall slope 7°, outer round angle R8mm, groove size 14mm, height 55.5mm, symmetrical upper and lower parts, roller gap 20.5mm; Flat roller type frame: height 55.7mm, width 7.9mm, upper roller with groove bottom 30.5mm, inner fillet R22mm, transition arc radius R3mm, outer fillet R1mm, notch 57.5mm, hole height 6.3mm, no convexity, lower roller is flat roller, and the roller gap between the upper and lower rollers is 1.6mm.

[0012] Furthermore, the specifications of the special-shaped flat steel are width × thickness of 55mm × 7.8mm, the allowable error of width is ±0.5mm, and the allowable error of thickness is ±0.2mm; the cross-sectional shape of the special-shaped flat steel is a symmetrical structure, the top and bottom surfaces are both horizontal, the horizontal width of the top surface is 30.5mm, and both sides extend toward the bottom surface with an arc of radius 22mm on the same side, and the extended end continues to bend toward the bottom with a transition arc with a radius of 3mm, and the end of the transition arc bends outward with an arc with a radius of 1mm, and a horizontal section is arranged outward at the bent end, the horizontal section is parallel to the bottom, the thickness of the parallel section is 1.6mm, and the thickness of the horizontal section and the top surface is 6.3mm.

[0013] The beneficial effects of the present invention are: The present invention converts the continuous casting square billet into special-shaped flat steel by hot rolling once, and does not need to go through the production process of converting the coil into the special-shaped flat steel, which greatly reduces the production process, reduces material loss, reduces production cost, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the process flow of the present invention, Figure 2 This is a schematic diagram of the front hole shape of the 55×7.8 special-shaped flat steel product of the present invention. Figure 3 This is a schematic diagram of the hole type of the 55×7.8 special-shaped flat steel product of the present invention, that is, a schematic diagram of the cross-section of the 55×7.8 special-shaped flat steel product, Figure 4 This is the actual picture of the finished product of 55×7.8 special-shaped flat steel of the present invention. Figure 5 This is a width measurement diagram of the actual 55×7.8 special-shaped flat steel product of the present invention. Figure 6 This is a thickness measurement diagram of the actual 55×7.8 special-shaped flat steel finished product of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0016] Combined with Figure 1 It can be seen that the specific process of the design and rolling process of this special-shaped flat steel is as follows: S1: Use the steel billet (150mm square billet continuous casting billet) to heat it to a high temperature state to facilitate subsequent rolling; S2: The heated billet steps onto the steel-out roller table, which transports the billet through a high-pressure water descaling box to remove the oxidized iron scale on the surface of the billet, and then enters the rough rolling area for rolling. The rough rolling unit has a total of 6 machines, which use box + square + ellipse + round + ellipse + round hole types in turn; S3: After being rolled by the rough rolling mill, the 1# flying shear performs head and tail trimming to remove the head and tail defects of the billet, and then enters the intermediate rolling mill for rolling. The intermediate rolling mill has a total of 6 machines, which use elliptical + round + flat + vertical hole + flat + flat hole type rolling in turn; S4: After rolling by the intermediate rolling mill, the 2# flying shear is used for head trimming to remove defects such as head bending, and then the billet enters the finishing mill for rolling. The finishing mill has a total of 5 stands, which are rolled using the flat + vertical hole + flat + vertical hole + flat hole hole type in sequence. The billet enters the finishing mill, which consists of 13#, 14#, 15# cantilever mills with a diameter of 450 and 16#, 17# cantilever mills with a diameter of 370, all of which are open-type hole types. Among them, four vertical loopers are respectively set between 13#-14#, 14#-15#, 15#-16#, and 16#-17# mills to ensure the continuity and stability of the rolling process. Accurate size and shape can be obtained through rolling by the finishing mill.

[0017] S5: After rolling by the finishing mill, the 3# flying shear performs multiple-length shearing according to the set length.

[0018] S6: After dividing into multiple sizes, place on cooling bed for cooling.

[0019] S7: After the cooling bed is cooled, use cold shears to cut to size and cut to size according to the specified length.

[0020] S8: Cut to length and pack into warehouse.

[0021] The 150mm square billet continuous casting ingot was selected from the 40Cr continuous casting ingot produced by the dephosphorization furnace continuous casting workshop of Huaigang. The chemical composition was controlled according to the technical requirements. The specific content of each element is shown in Table 1 below.

[0022] Table 1 Chemical composition of 40Cr continuous casting billet

[0023] Heating process The heating temperature and the time in the furnace of the present invention are strictly controlled according to Table 2. After the steel enters the furnace, the furnace pressure is maintained at a slight positive pressure of 10-40Pa, generally controlled at 25-30Pa, and the time in the furnace is controlled to be shortened as much as possible. The steel billet should be evenly heated in the first and second heating stages, wherein the heating time of the billet in the first heating stage is not more than 54 minutes, and the heating time in the second heating stage is not more than 40 minutes. The soaking stage is quickly heated to ensure that the heating time is not less than 45 minutes.

[0024] Table 2 Heating process

[0025] Rolling schedule and pass type The rolling process of 55×7.8 special-shaped flat steel 40Cr steel is shown in Table 3. There are 17 rolling mills in total, of which the first two are box-square hole type, 3-8 are elliptical-round hole type, and 8 is 54 round. From 9th frame onwards, the hole type of flat roll plus vertical rolling is used. The hole type of finished product and before finished product is shown in the figure Figure 2 shown.

[0026] Table 3 55×7.8 Special Shaped Flat Steel Rolling Schedule

[0027] Table 3 55×7.8 Special Shaped Flat Steel Rolling Process

[0028] In Table 3: the width of the rolled piece corresponds to the left-right dimension of the pass shape, the height of the rolled piece corresponds to the up-down dimension of the pass shape, H indicates that the rolling mill is placed horizontally, and V indicates that the rolling mill is placed vertically. The values ​​marked with ellipses are the base circle diameters of the corresponding elliptical pass shapes, in mm, and the values ​​marked with circles are the diameters of the circular holes, in mm.

[0029] Size and groove consumption analysis Without changing the original equipment foundation, only the tooling parts are newly developed. In 2024, Huaigang successfully completed the production of 55×7.8 special-shaped flat steel. The measured dimensions can be controlled within the range of width ±0.5mm and thickness ±0.2mm. Figure 2As shown, the hole profile of the finished 55×7.8 special-shaped flat steel (17# frame) upper roller has a groove bottom of 30.5mm, inner fillet R22mm, transition arc radius R3mm, outer fillet R1mm, notch 57.5mm, hole height 6.3mm, no convexity, the lower roller is a flat roller, and the gap between the upper and lower rollers is 1.6mm. The hole profile of the front of the finished product (16# frame) has a groove bottom size of 9.5mm, a circular arc transition of R1mm on the left, a side wall slope of 7°, and an outer fillet R8mm; the circular arc transition of R5mm on the right, a side wall slope of 7°, an outer fillet R8mm, a notch size of 14mm, a height of 55.5mm, symmetry between the upper and lower parts, and a roll gap of 20.5mm. Figure 2 and 3 It can be seen that the hole profiles of the finished product and the front of the finished product are both special-shaped. The conventional flat steel finished product frame has no hole profile, and the upper and lower rollers are symmetrically arranged as flat rollers. The frame hole profile of the front of the finished product (i.e. the second to last frame, the 16th frame) is symmetrical up and down. The design method of left-right symmetry is different. The advantage is that the right part of the hole profile of the front of the finished product (the large arc transition part on site after the frame is installed is the end of the roller head, i.e. the upper half of the rolled piece) has a large arc radius transition, which can ensure that the rolled piece can basically come out of the approximate shape after being rolled by the 16# frame, avoiding the problem of ear defects on the side of the finished product after rolling due to the left-right symmetry (small arc transition). At the same time, the side wall slope is designed to be 7°, and the roller turning only needs to turn 5-7mm, which improves the utilization rate of the roller and reduces cost consumption; the upper roller of the finished product has an open hole, and the lower roller is a flat roller, which can make it easier to produce special-shaped flat steel.

[0030] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0031] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A special-shaped flat steel pass design and rolling process, characterized in that: The following steps are involved: Step S1: Select a steel billet and heat it to a high temperature state of 1060-1090°C; Step S2: The heated billet steps onto the steel-out roller table, which transports the square continuous casting billet through a high-pressure water descaling box to remove the iron oxide scale on the surface of the square continuous casting billet, and then enters the rough rolling area for rolling. The rough rolling mill group has a total of 6 stands, which use the stand rolling with the hole types of box type, square type, oval type, round type, oval type, and round hole type in turn; Step S3: After being rolled by the rough rolling mill, the 1# flying shear performs head and tail trimming to remove the head and tail defects of the billet, and then enters the intermediate rolling mill for rolling. The intermediate rolling mill has a total of 6 stands, which are rolled in turn using stands with elliptical, round, flat roll, vertical roll, flat roll, and flat roll hole shapes; Step S4: After rolling by the intermediate rolling mill, the 2# flying shear performs head trimming to remove the head bending defect, and then enters the finishing rolling mill for rolling. The finishing rolling mill has a total of 5 stands, which are rolled in the following order: flat roll type, vertical roll type, flat roll type, vertical roll type, and flat roll type; Step S5: After being rolled by the finishing mill, the 3# flying shear performs multiple-length shearing according to the set length; Step S6: After the multiple-length cutting, the steel is placed on a cooling bed for cooling. To ensure that no bending occurs during the cooling process, one of the first multiple-length steel pieces is cut to a fixed length. The cooling bed movement rhythm is three steps in motion and two steps in idleness. Step S7: After the cooling bed is cooled to 280-320° C., the cold shear is used to cut the pieces to the required length; Step S8: Cut to length and pack for storage.

2. The hole design and rolling process of the special-shaped flat steel according to claim 1 is characterized in that: The steel billet is a square continuous casting billet of 150 mm×150 mm.

3. The hole design and rolling process of the special-shaped flat steel according to claim 1 is characterized in that: The steel billet is a 40Cr continuous casting billet, and the chemical composition and mass percentage of the 40Cr continuous casting billet are: C0.37-0.44%, Si0.17-0.37%, Mn0.5-0.8%, Cr0.8-1.1%, Ni≤0.3%, S≤0.03%, P≤0.03%, and the rest are iron and other inevitable.

4. The hole design and rolling process of the special-shaped flat steel according to claim 1 is characterized in that: The specific heating method of the steel billet is as follows: after the steel billet enters the furnace, the furnace pressure is maintained at a slight positive pressure of 10 to 40 Pa, and the time in the furnace is controlled to be shortened as much as possible; The steel billet is evenly heated in the first and second heating stages, wherein the heating time of the steel billet in the first heating stage is no more than 54 minutes, and the heating time in the second heating stage is no more than 40 minutes. The soaking stage is quickly heated to ensure that the heating time is no less than 45 minutes. The total heating time of the steel billet in the furnace is 110-180 minutes; The heating temperature of the upper layer of the first heating stage is 820-890°C, the heating temperature of the lower layer of the first heating stage is 800-870°C; the heating temperature of the second heating stage is 1030-1080°C; the heating temperature of the equalizing stage is 1070-1110°C.

5. The hole design and rolling process of the special-shaped flat steel according to claim 4 is characterized in that: The furnace pressure is maintained at a slight positive pressure of 25 to 30 Pa.

6. The hole design and rolling process of the special-shaped flat steel according to claim 1 is characterized in that: There are a total of 17 racks in steps S2 to S4, and the clamping directions of two adjacent racks are perpendicular to each other.

7. The hole design and rolling process of the special-shaped flat steel according to claim 6 is characterized in that: The height and width of the rolled product after rolling on each stand in the step S2 are as follows: box-type stand: height is 165.0 mm, width is 108.0 mm, square stand: height is 119.0 mm, width is 119.0 mm, elliptical stand: height is 138.0 mm, width is 81.5 mm, round stand: height is 99.0 mm, width is 99.0 mm, elliptical stand: height is 113.0 mm, width is 60.9 mm, round hole stand: height is 75.0 mm, width is 75.0 mm.

8. The hole design and rolling process of the special-shaped flat steel according to claim 6 is characterized in that: In the step S3, the height and width of the rolled product after rolling on each stand are as follows: elliptical stand: height 83.8 mm, width 42.2 mm, round stand: height 54.0 mm, width 54.0 mm, flat roller stand: height 70.0 mm, width 30.0 mm, vertical roller stand: height 60.0 mm, width 33.0 mm, flat roller stand: height 65.2 mm, width 20.0 mm, flat roller stand: height 67.2 mm, width 15.0 mm.

9. The hole design and rolling process of the special-shaped flat steel according to claim 6 is characterized in that: The height and width of the rolled product after rolling on each stand in step S4 are as follows: Flat roll stand: height 68.8 mm, width 11.0 mm, Vertical roller type frame: height 56.0mm, width 12.9mm, Flat roller type frame: height 57.0mm, width 9.0mm, Vertical roller type frame: height 55.5mm, width 9.2mm, groove bottom size 9.5mm, arc transition R1mm on the left, side wall slope 7°, outer round angle R8mm; arc transition R5mm on the right, side wall slope 7°, outer round angle R8mm, groove size 14mm, height 55.5mm, symmetrical upper and lower parts, roller gap 20.5mm; Flat roller type frame: height 55.7mm, width 7.9mm, upper roller with groove bottom 30.5mm, inner fillet R22mm, transition arc radius R3mm, outer fillet R1mm, notch 57.5mm, hole height 6.3mm, no convexity, lower roller is flat roller, and the roller gap between the upper and lower rollers is 1.6mm.

10. The hole design and rolling process of special-shaped flat steel according to claim 1, characterized in that: The specifications of the special-shaped flat steel are width × thickness of 55mm × 7.8mm, the allowable error of width is ±0.5mm, and the allowable error of thickness is ±0.2mm. The cross-sectional shape of the special-shaped flat steel is a symmetrical structure. The top and bottom surfaces are both horizontal. The horizontal width of the top surface is 30.5mm, and both sides extend toward the bottom surface with an arc with a radius of 22mm on the same side. The extended end continues to bend toward the bottom with a transition arc with a radius of 3mm, and the end of the transition arc bends outward with an arc with a radius of 1mm. A horizontal section is arranged outward at the bent end, and the horizontal section is parallel to the bottom. The thickness of the parallel section is 1.6mm, and the thickness of the horizontal section and the top surface is 6.3mm.

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