Bar stable rolling method

Abstract

The invention provides a bar stable rolling method which comprises the following steps: cooling a rolling mill inlet guide and guard plug-in during pre-finish rolling, controlling the loop quantity of loops between rolling mills, and controlling the ratio of the height of a rolling mill outlet pressing sleeve roller to the size of the section of a rolling mill outlet rolled piece; wherein during pre-finish rolling, the loop quantity of loops among 11-15 rolling mills is controlled to be 100-150 mm, and the loop quantity of loops among 15-16 rolling mills is controlled to be 150-170 mm; the ratio of the height of the outlet pressing sleeve rollers of the 11, 13, 14, 15 and 16 rolling mills to the section size of the rolling mill outlet rolled piece is controlled to be 2.1-2.5, and the ratio of the height of the outlet pressing sleeve rollers of the 12 rolling mills to the section size of the rolling mill outlet rolled piece is controlled to be 2.8-3; the width control range of the rolled pieces in each stage is as follows: the width of 11 racks is 60-63 mm, the width of 12 racks is 31-34 mm, the width of 13 racks is 58-61 mm, the width of 14 racks is 61-64 mm, the width of 15 racks is 34-37 mm, and the width of 16 racks is 22-25 mm; the rolling tonnage of 12-16 rolling mill rollers is controlled to be smaller than or equal to 7500 tons. According to the method, efficient, high-precision and low-cost production of the bar is achieved, the surface quality is improved, and remarkable economic benefits and process advancement are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a stable rolling method for bars. Background Art

[0002] Rebar is the most consumed type of steel product, accounting for about 20% of the total steel consumption. In recent years, the apparent consumption of rebar in my country has been around 250 million tons, making it the main type of steel used in construction.

[0003] The process flow of bar material: feeding, heating, rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling (module), finishing collection, storage, and the finished product specifications are R12-R22mm. The bar material equipment layout is 6 stands for rough rolling, 4 stands for intermediate rolling, 6 stands for pre-finishing rolling, and 2-6 stands for finishing rolling. The R12mm finishing rolling is 6 passes, the R14-16mm finishing rolling is 4 passes, and the R18-22mm finishing rolling is 2 passes. However, in the large-scale production process, starting from the 12-16 stands of pre-finishing rolling, it is very easy to have problems such as steel sticking to the channel line, steel piling, foreign matter pressing in and breaking.

[0004] The article “Causes and Countermeasures of Steel Pile-up in Bar Continuous Rolling Line” in “Liuzhou Iron and Steel Technology”, Issue 6, 2011, describes the causes of steel pile-up as follows: (1) incorrect setting of rolling speed and roll diameter; (2) too small tension setting after roll and hole changing; (3) electronic control reasons; (4) roll breakage; (5) large temperature fluctuation of rolled steel; (6) defects in the billet itself; (7) unreasonable material size; (8) slippage in the newly changed hole; (9) incorrect installation of guides; and (10) excessive tension in roughing and intermediate rolling, resulting in tail swinging in the downstream rolling mill.

[0005] Therefore, achieving stable rolling of bars is one of the technical difficulties that needs to be solved urgently in this field. Summary of the invention

[0006] The purpose of the present invention is to provide a stable rolling method for bars in view of the defects of the prior art, comprising:

[0007] The intermediate billet is pre-finished for 6 passes according to flat roll, box hole, pre-cut double elliptical hole, cut double round hole, elliptical hole and round hole, which correspond to 11 to 16 rolling mills respectively. During the pre-finishing rolling, the guide plug-in at the entrance of the rolling mill is cooled, the amount of loops between the rolling mills is controlled, the ratio of the height of the press roll at the exit of the rolling mill to the cross-sectional size of the rolled piece at the exit of the rolling mill is controlled, the width of the rolled piece at each stage is controlled, the difference between the two sides and the middle of the wear of the rolls of the 11 rolling mills is controlled, and the rolling tonnage of the rolls of the 12 to 16 rolling mills is controlled;

[0008] Among them, during pre-finishing rolling, the looper between 11-15 rolling mills is controlled to be 100-150mm, and the looper between 15-16 rolling mills is controlled to be 150-170mm;

[0009] The ratio of the height of the pinch rolls at the exits of the 11th, 13th, 14th, 15th, and 16th rolling mills to the cross-sectional size of the rolled piece at the exits of the rolling mills is controlled to be 2.1 - 2.5, and the ratio of the height of the pinch rolls at the exit of the 12th rolling mill to the cross-sectional size of the rolled piece at the exit of the rolling mill is controlled to be 2.8 - 3;

[0010] The width control ranges of the rolled pieces at each stage are as follows: 11th rolling mill: 60 - 63 mm, 12th rolling mill: 31 - 34 mm, 13th rolling mill: 58 - 61 mm, 14th rolling mill: 61 - 64 mm, 15th rolling mill: 34 - 37 mm, 16th rolling mill: 22 - 25 mm;

[0011] The difference between the two sides and the middle of the roll wear of the 11th rolling mill < 0.55 mm, and the controlled rolling tonnage of the rolls of the 12th - 16th rolling mills ≤ 7500 tons.

[0012] Furthermore, the cross-sectional size of the intermediate billet is controlled to be 50 - 55 mm.

[0013] Furthermore, the specific cross-sectional size of the intermediate billet before pre-finishing rolling is as follows: when the finished product size is [12, 14] mm, the cross-sectional size of the intermediate billet is controlled from 50.5 mm to 52 mm; when the finished product size is [16, 18] mm, the cross-sectional size of the intermediate billet is controlled from 52 mm to 53 mm; when the finished product size is [20, 22] mm, the cross-sectional size of the intermediate billet is controlled from 53 mm to 55 mm, and when the casting billet furnace outlet temperature is 880 - 950 °C, the cross-sectional size of the intermediate billet is controlled at the lower limit.

[0014] Furthermore, it also includes: controlling the cross-sectional size of the original billet produced by the continuous caster to be 160 - 175 mm. After the original billet produced by the continuous caster is output, it is heated. The temperature of the hot soaking section is 1030 - 1230 °C, the total heating time is 60 - 150 min, and the temperature difference of the same billet cross-section ≤ 30 °C.

[0015] Furthermore, during pre-finishing rolling, cooling is carried out by spraying cooling water on the side walls of the entrance guides of the 12th, 13th, and 14th rolling mills.

[0016] Furthermore, during pre-finishing rolling, the loop amount between the 11th - 15th rolling mills is controlled to be 100 - 120 mm, and the loop amount between the 15th - 16th rolling mills is controlled to be 165 mm.

[0017] Furthermore, the cross-sectional dimension of the rolled piece at the outlet of the 11th rolling mill is 33 - 38.6 mm, and the height of the pressure sleeve roll at the outlet of the 11th rolling mill is 81 - 83 mm; the cross-sectional dimension of the rolled piece at the outlet of the 12th rolling mill is 55.6 - 62 mm, and the height of the pressure sleeve roll at the outlet of the 12th rolling mill is 167 - 174 mm; the cross-sectional dimension of the rolled piece at the outlet of the 13th rolling mill is 32.8 - 37.4 mm, and the height of the pressure sleeve roll at the outlet of the 13th rolling mill is 78 - 82 mm; the cross-sectional dimension of the rolled piece at the outlet of the 14th rolling mill is 29 - 33 mm, and the height of the pressure sleeve roll at the outlet of the 14th rolling mill is 69 - 72 mm; the cross-sectional dimension of the rolled piece at the outlet of the 15th rolling mill is 17.4 - 22.5 mm, and the height of the pressure sleeve roll at the outlet of the 15th rolling mill is 43 - 47 mm. Further, the height of the pressure sleeve roll at the outlet of the 12th rolling mill is 170 mm.

[0018] Furthermore, the width control range of the rolled piece at each stage is as follows: for the 11th rolling mill: 61 - 62 mm, for the 12th rolling mill: 32 - 33 mm, for the 13th rolling mill: 59 - 60 mm, for the 14th rolling mill: 62 - 63 mm, for the 15th rolling mill: 35 - 36 mm, for the 16th rolling mill: 23 - 24 mm.

[0019] Furthermore, the difference between the two sides and the middle of the roll wear of the 11th rolling mill is < 0.5 mm, and the controlled rolling tonnage of the rolls of the 12th - 16th rolling mills ≤ 7000 tons.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The bar rolling method of the present invention realizes the high - efficiency, high - precision and low - cost production of bars through continuous casting billet cross - section design, guide - guard side - wall cooling, temperature - deformation coordinated control, and loop dynamic regulation, improves the surface quality, and has remarkable economic benefits and process advancement.

[0022] 2. Through the coordinated control of the billet heating system (soaking at 1030 - 1230 °C + temperature difference of the same billet ≤ 30 °C) and the pre - finishing rolling temperature - deformation, the standard deviation of the grain size is reduced. The rolling tonnage limit of the 12th - 16th rolling mills (≤ 7500 tons) improves the evenness of roll groove wear. Combined with the guide - guard cooling water, the surface scratching defects are effectively eliminated, and the product size accuracy is improved.

[0023] 3. Cooling water spray is provided on the side - wall of the guide - guard at the inlet of the 12th - 14th rolling mills to reduce the temperature of the guide - guard working surface. Combined with the stepped tension buffer formed by the loop lengths of the 11th - 15th rolling mills (90 - 120 mm) and the 15th - 16th rolling mills (150 - 170 mm), the friction coefficient between the rolled piece and the guide - guard is reduced, and the amount of iron filings adhesion is decreased.

[0024] 4. By controlling the ratio of the height of the pressure sleeve roll to the cross - section of the rolled piece, the dynamic guiding boundary conditions of the rolled piece in the loop are established. Combined with the control of the temperature gradient of the intermediate billet, the lateral offset of the rolled piece is reduced, and the steel sticking and accumulation caused by abnormal friction on the side - wall of the guide - guard are eliminated.

[0025] 5.12 - 16 stands of roll rolling tonnage limit (≤7500 tons) to reduce the standard deviation of the wear depth of the roll groove. Combining with the width control of the rolled piece in 11 - 16 stands, the gap between the guide and plug and the rolled piece is stably controlled, and the debris at the edge of the roll groove is reduced.

[0026] 6. By designing the ratio of the height of the pinch roll at the exit of the 15th stand to the cross-section of the rolled piece to be 2.1 - 2.5, the incidence of tail flicking is reduced, and foreign object entrainment caused by out-of-control of the tail is avoided. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of 6-pass pre-finishing rolling. From left to right in the figure are flat roll, box pass, pre-split double-ellipse pass, split double-round pass, ellipse pass, and round pass. Detailed Embodiment

[0028] The methods used in the following embodiments are all conventional methods in the art without special instructions.

[0029] A method for stable rolling of bars, comprising:

[0030] The intermediate billet is subjected to 6-pass pre-finishing rolling in a flat roll, box pass, pre-split double-ellipse pass, split double-round pass, ellipse pass, and round pass (as Figure 1 shown, the above 6-pass pre-finishing rolling is from left to right in sequence). During pre-finishing rolling, cool the guide and plug at the entrance of the rolling mill, control the loop amount between rolling mills, control the ratio of the height of the pinch roll at the exit of the rolling mill to the cross-sectional size of the rolled piece at the exit of the rolling mill, control the width of the rolled piece at each stage, control the difference between the two sides and the middle of the roll wear of the 11th stand rolling mill, and control the rolling tonnage of the rolls of the 12th - 16th stand rolling mills.

[0031] (1) The cross-section of the original billet obtained by continuous casting applicable to the rolling method of the present invention is 160 mm - 175 mm. This cross-section range optimizes the rolling reduction ratio, which can not only ensure sufficient deformation to eliminate internal defects of the continuous casting billet, but also avoid redundant rolling passes caused by too small a cross-section.

[0032] (2) Heat the casting billet. The temperature of the hot soaking section is 1030 - 1230 °C, the total heating time is 60 - 150 min, and the temperature difference of the same billet cross-section is ≤30 °C. The temperature control in the soaking section combined with long-time heat preservation effectively eliminates the temperature difference between the core and the surface of the billet and prevents stress cracks caused by temperature gradient during rolling. The austenitizing temperature range of 1030 - 1230 °C can improve the high-temperature plasticity of the rolled piece and reduce the rolling torque requirement.

[0033] (3) The cross-sectional dimensions of the intermediate billet before pre-finishing rolling are specifically as follows: when the finished product size is [12, 14] mm, the cross-sectional dimensions of the intermediate billet are controlled within 50.5 mm to 52 mm; when the finished product size is [16, 18] mm, the cross-sectional dimensions of the intermediate billet are controlled within 52 mm to 53 mm; when the finished product size is [20, 22] mm, the cross-sectional dimensions of the intermediate billet are controlled within 53 mm to 55 mm. The cross-sectional dimensions of the intermediate billet are inversely matched according to the finished product size to achieve a refined distribution of the pass elongation coefficient. When the casting billet tapping temperature is 880 - 950 °C, the cross-sectional dimensions of the intermediate billet are controlled at the lower limit. When the casting billet tapping temperature is relatively low (880 - 950 °C), using the lower limit cross-section can compensate for the increase in deformation resistance caused by low-temperature rolling.

[0034] (4) During the pre-finishing rolling process, the loop amount of the loop is generally 90 - 120 mm. In the present patent technology, during the pre-finishing rolling, six passes of rolling are carried out. The loop amount between the 11th to 15th stands is controlled according to the conventional 100 - 120 mm, and the loop amount between the 15th and 16th stands is controlled at 150 - 170 mm. Further, the loop amount between the 15th and 16th stands is controlled at 165 mm, which has the best effect and achieves the purpose of pre-finishing rolling without tension. The loop amount of the loop between the 11th and 15th stands is conventionally set to 100 - 120 mm to buffer the fluctuation of the metal mass flow per second, while increasing the loop amount between the 15th and 16th stands to 150 - 170 mm can effectively cope with the sudden change in the metal flow rate in the high-speed area before finishing rolling.

[0035] (5) Six passes of finish rolling are carried out in the pre-finish rolling. The outgoing profile of the 11th stand is 33 - 38.6 mm, and the height of the pinch roll is 81 - 83 mm; the outgoing profile of the 12th stand is 55.6 - 62 mm, and the height of the pinch roll is 167 - 174 mm; the outgoing profile of the 13th stand is 32.8 - 37.4 mm, and the height of the pinch roll is 78 - 82 mm; the outgoing profile of the 14th stand is 29 - 33 mm, and the height of the pinch roll is 69 - 72 mm; the outgoing profile of the 15th stand is 17.4 - 22.5 mm, and the height of the pinch roll is 43 - 47 mm. Further, the height of the pinch roll at the exit of the loop of the 12th stand is controlled at 170 mm. The ratio of the height of the pinch roll to the cross-sectional size of the rolled piece restricts the swinging amplitude of the rolled piece in the loop through geometric constraints. For example, when the height of the pinch roll is too low, the rolled piece is prone to friction with the side wall of the loop, resulting in local temperature rise and chip adhesion; while when the height is too high, the deviation of the rolled piece cannot be effectively suppressed. The ratio of the height of the pinch roll to the cross-sectional size of the rolled piece ensures the stable guiding of the rolled piece in the loop. The height of the pinch roll at the exit of the 12th stand is fixed at 170 mm. By presetting the height and profile ratio, the influence of the action delay of the loop-forming roll on the head tension of the rolled piece is reduced. This design can avoid the steel piling caused by the dynamic speed drop at the head. The outgoing profile of the 15th stand is 17.4 - 22.5 mm corresponding to the height of the pinch roll of 43 - 47 mm. By reducing the tail tension of the rolled piece in the loop and combining with the mechanical limit of the pinch roll, the tail whipping is suppressed. This design effectively solves the contradiction of "drawing steel - piling steel" in the traditional loop control and provides an innovative solution for the continuous and stable rolling of high-speed bar steel.

[0036] (6) The control range of the width of the rolled piece in each stage is as follows: 11th stand: 61 - 62 mm, 12th stand: 32 - 33 mm, 13th stand: 59 - 60 mm, 14th stand: 62 - 63 mm, 15th stand: 35 - 36 mm, 16th stand: 23 - 24 mm. Further, the width of the rolled piece of the 12th stand is controlled at 32.5.

[0037] (7) The rolling tonnage controlled by the rolls of the 12th - 16th stands of the rolling mill ≤ 7000 tons.

[0038] The reason for adding side wall cooling water to the entrance guides of the 12th, 13th, and 14th stands of the rolling mill in the present invention is that the guide cooling water reduces the heat generated by the friction when the intermediate billet contacts the guide inserts during the rolling process, and eliminates the problem of steel sticking and plugging the channel line caused by the adhesion of the iron chips of the rolled piece to the side wall of the guide due to dry friction. The 12# - 14# rolling mills are in the split rolling stage. The rolled piece has a large deformation and intense metal flow in this area. The frictional heat between the rolled piece and the side wall of the guide is significantly higher than that of other stands. And the thickness of the rolled piece in this area is relatively thin. The frictional resistance of the side wall of the guide directly affects the balance of the second flow rate of the rolled piece. The side wall cooling water can reduce the friction coefficient and reduce the risk of steel piling or drawing steel caused by tension fluctuation.

[0039] The reason why the present invention controls the shape size of the intermediate billet obtained after medium rolling is as follows. When the cross-sectional size of the intermediate billet is too large, during the pre-finishing rolling, due to the large material shape, it will rub against the side walls of the sliding guides and the inner walls of the rolling guide inserts between the 11th and 16th stands. The scale scraped off by the rolled piece at high temperature will adhere to the side walls of the sliding guides and the inner walls of the rolling guide inserts. Long-term production will cause slag accumulation and steel piling up. When the cross-sectional size of the intermediate billet is too small, during the pre-finishing rolling, the edge rolling of the 12th stand is not good, and uneven splitting and steel piling up are likely to occur during the pre-splitting and splitting rolling of the 13th and 14th stands.

[0040] The reason why the present invention controls the loop roller of the pre-finishing mill is as follows. When the loop amount is too small, drawing rolling is likely to occur during the rolling process, which is not conducive to the accurate control of the material shape. When the loop amount is too large, large fluctuations in the loop amount are likely to occur during the rolling process, affecting the rolling stability. Through on-site process adjustment practice, the loop amount between the 15th and 16th stands needs to be controlled unconventionally to achieve continuous and stable rolling.

[0041] The reason why the present invention controls the loop compressing roller of the pre-finishing mill is as follows. When the loop compressing roller of the pre-finishing mill is too low, it is easy to cause the rolled piece to be blocked and steel to pile up during the rolling process, and large fluctuations in the loop amount are likely to occur. When the loop compressing roller of the pre-finishing mill is too high, it is easy to cause insufficient restriction ability of the loop compressing roller on the rolled piece, losing the function of loop compressing. In this process plan, the loop compressing roller at the outlet of the 12th stand cannot be controlled according to the conventional height. For example, if the ratio of the height of the loop compressing roller to the material shape matching rolling is controlled according to the conventional 2.1 - 2.5, it is easy to cause slag accumulation and steel piling up due to abnormal groping of the lower edge of the guide insert at the inlet of the 13th stand. Therefore, the loop compressing roller at the outlet of the 12th stand needs to be controlled according to the unconventional height to achieve stable production of the 13th stand.

[0042] The reason why the present invention controls the wear of the rolls in the pre-finishing mill is as follows. When the difference between the two sides and the middle of the roll wear of the 11th mill is ≥ 0.5 mm, the middle of the rolled material shape is 1.0 mm thicker than the two sides. During the pre-splitting process of the 13th stand, uneven splitting is likely to occur. When uneven splitting occurs, slag accumulation and steel piling up are likely to occur in the channels with a larger material shape after splitting. Therefore, to ensure the accuracy of pre-splitting, the uniformity of the roll wear of the 11th mill must be the primary control point. For the rolls of the 12th - 16th mills, by controlling the rolling tonnage, specifically, the rolling tonnage is controlled at ≤ 7000 tons, the control of the roll groove wear is achieved. Here, the rolling tonnage refers to the single-use amount of the roll.

[0043] The reason for controlling the width of the rolled piece in the present invention is that stable production can be achieved by the conventional shape control of stands 11, 13, 14, 15, and 16. However, when the width of the rolled piece at stand 12 is less than 32 mm, the edge trimming effect of the box pass is poor, and the gap between the width of the rolled piece and the inner wall of the plug of the entrance guide at stand 13 is small, which is likely to cause mutual friction between the rolled piece and the inner wall of the guide. The scale scraped off by the rolled piece at high temperature adheres to the inner wall of the guide, and slag accumulation and steel piling will occur during long-term production. When the width of the rolled piece at stand 12 is greater than 33 mm, the edge trimming amount of the box pass is too large, which is likely to cause the width of the rolled piece to be too small. When the rolled piece enters the entrance guide at stand 13, due to the small width of the rolled piece, the clamping and centering effect of the vertical roll guide wheels of the entrance guide at stand 13 on the rolled piece becomes poor, and uneven pre-splitting is likely to occur. Slag accumulation and steel piling are likely to occur in the channels with a relatively large shape after splitting. Therefore, the width of the rolled piece at stand 12 should be strictly restricted.

[0044] The present invention will be further described below through examples and comparative examples.

[0045] Example 1

[0046] The finished steel grade is HRB400E, the finished specification is 12 mm, and 14,800 tons are rolled.

[0047] (1) The cross-section of the original billet obtained by continuous casting is 170 - 172 mm.

[0048] (2) The billet tapping temperature: 930°C - 1050°C, and the billet residence time in the furnace is 75 - 120 minutes.

[0049] (3) The cross-section size of the intermediate billet obtained by medium rolling is controlled to be (51.2 - 51.7) mm * (51.3 - 51.8) mm.

[0050] (4) The loop roll control of pre-finishing rolling is carried out, and six passes of finishing rolling are performed. The loop amount between each rolling mill from 11 to 15 is controlled according to the conventional 100 - 120 mm, and in addition, the loop amount between stands 15 - 16 is controlled at 155 mm.

[0051] (5) The loop press roll control of pre-finishing rolling is carried out. Six passes of finishing rolling are performed in pre-finishing rolling. The shape at the exit of stand 11 is 33 mm, and the height of the loop press roll is 81 mm; the shape at the exit of stand 12 is 55.6 mm, and the height of the loop press roll is 167 mm; the shape at the exit of stand 13 is 32.8 mm, and the height of the loop press roll is 78 mm; the shape at the exit of stand 14 is 29 mm, and the height of the loop press roll is 69 mm; the shape at the exit of stand 15 is 17.4 mm, and the height of the loop press roll is 43 mm.

[0052] (6) The width of the rolled piece at each stage is as follows: stand 11: 61.5 mm, stand 12: 32.2 mm, stand 13: 59 mm, stand 14: 62.8 mm, stand 15: 35.6 mm, stand 16: 23 mm.

[0053] (7) Control the difference between the two sides and the middle of the roll wear of the 11th rolling mill to be 0.4 mm. The controlled rolling tonnage of the rolls of the 12th to 16th rolling mills is as follows: 12th: 6580 tons, 13th: 6420 tons, 14th: 6350 tons, 15th: 6210 tons, 16th: 5980 tons.

[0054] Effect: During the production of R12 specification this time, no slag accumulation and steel piling accidents occurred in the pre-finishing rolling process during continuous rolling.

[0055] Example 2

[0056] The finished steel grade is HRB400E, the finished specification is 16 mm, and the rolling tonnage is 16841 tons.

[0057] (1) The cross-section of the original billet obtained by continuous casting is 165 - 170 mm.

[0058] (2) The billet furnace outlet temperature: 930 °C - 1000 °C, and the billet residence time in the furnace is 70 - 110 minutes.

[0059] (3) Control the cross-section size of the intermediate billet obtained by medium rolling to be (51.8 - 52.2) mm * (51.7 - 52.3) mm.

[0060] (4) Control the loop roll of the pre-finishing rolling. Perform six passes of finishing rolling. The loop amount between the 11th to 15th rolling mills is controlled at 100 - 140 mm according to the conventional method. In addition, the loop amount between the 15th and 16th rolling mills is controlled at 165 mm.

[0061] (5) Control the loop pressing roll of the pre-finishing rolling. Perform six passes of finishing rolling in the pre-finishing rolling. The outlet stock shape of the 11th rolling mill is 33 mm, and the height of the loop pressing roll is 82 mm; the outlet stock shape of the 12th rolling mill is 55.6 mm, and the height of the loop pressing roll is 170 mm; the outlet stock shape of the 13th rolling mill is 32.8 mm, and the height of the loop pressing roll is 79 mm; the outlet stock shape of the 14th rolling mill is 29 mm, and the height of the loop pressing roll is 70 mm; the outlet stock shape of the 15th rolling mill is 17.4 mm, and the height of the loop pressing roll is 43 mm.

[0062] (6) The width of the rolled pieces at each stage is as follows: 11th: 61.1 mm, 12th: 32.5 mm, 13th: 59.4 mm, 14th: 62.7 mm, 15th: 35.6 mm, 16th: 23.3 mm.

[0063] (7) Control the difference between the two sides and the middle of the roll wear of the 11th rolling mill to be 0.4 mm. The controlled rolling tonnage of the rolls of the 12th to 16th rolling mills is as follows: 12th: 6850 tons, 13th: 6720 tons, 14th: 6630 tons, 15th: 6480 tons, 16th: 6320 tons.

[0064] Effect: During the production of R16 specifications this time, no slag accumulation and steel piling accidents occurred in the pre-finishing rolling process during continuous rolling.

[0065] Example 3

[0066] The finished steel grade is HRB400E, the finished specification is 22mm, and 14,300 tons are rolled.

[0067] (1) The cross-section of the original billet obtained by continuous casting is 165 - 170mm.

[0068] (2) The billet tapping temperature: 980°C - 1050°C, and the billet residence time in the furnace is 65 - 100 minutes.

[0069] (3) The cross-sectional dimensions of the intermediate billet obtained by medium rolling are controlled to be (52.8 - 53.2)mm * (52.7 - 53.3)mm.

[0070] (4) Control the loop roller in pre-finishing rolling, conduct six passes of finishing rolling, and control the loop amount between the 11th - 15th rolling mills at the conventional 105 - 150mm, and in addition, control the loop amount between the 15th - 16th stands at 175mm.

[0071] (5) Control the loop compressing roller in pre-finishing rolling. Conduct six passes of finishing rolling in pre-finishing rolling. The profile at the exit of the 11th stand is 38.6mm, and the height of the loop compressing roller is 83mm; the profile at the exit of the 12th stand is 62mm, and the height of the loop compressing roller is 174mm; the profile at the exit of the 13th stand is 37.4mm, and the height of the loop compressing roller is 82mm; the profile at the exit of the 14th stand is 33mm, and the height of the loop compressing roller is 72mm; the profile at the exit of the 15th stand is 22.5mm, and the height of the loop compressing roller is 47mm.

[0072] (6) The width of the rolled piece at each stage is as follows: 11th stand: 61mm, 12th stand: 32.3mm, 13th stand: 59.9mm, 14th stand: 62.4mm, 15th stand: 35.2mm, 16th stand: 23.1mm.

[0073] (7) Control the difference between the two sides and the middle of the roll wear of the 11th rolling mill to be 0.4mm. The rolling tonnage controlled by the rolls of the 12th - 16th rolling mills is as follows: 12th stand: 6980 tons, 13th stand: 6870 tons, 14th stand: 6750 tons, 15th stand: 6620 tons, 16th stand: 6490 tons.

[0074] Effect: During the production of R22 specifications this time, no steel piling accidents occurred in the pre-finishing rolling process during continuous rolling.

[0075] Example 4

[0076] The finished steel grade is HRB500E, the finished specification is 18mm, and 14,300 tons are rolled.

[0077] (1) The cross-section of the original billet obtained by continuous casting is 165 - 170 mm.

[0078] (2) The tapping temperature of the steel billet: 1100 °C - 1150 °C, and the residence time of the steel billet in the furnace is 90 - 140 minutes.

[0079] (3) The size of the intermediate billet obtained by medium rolling is controlled to be (52.8 - 53.0) mm * (52.7 - 53.2) mm.

[0080] (4) The control of the loop roller in pre-finishing rolling, six passes of finishing rolling are carried out, the loop amount between the 11th - 15th rolling mills is controlled according to the conventional 105 - 150 mm, and in addition, the loop amount between the 15th - 16th stands is controlled according to 175 mm.

[0081] (5) The control of the loop collapsing roller in pre-finishing rolling, six passes of finishing rolling are carried out in pre-finishing rolling. The profile at the exit of the 11th stand is 34 mm, and the height of the loop collapsing roller is 82 mm; the profile at the exit of the 12th stand is 55.6 mm, and the height of the loop collapsing roller is 167 mm; the profile at the exit of the 13th stand is 32.8 mm, and the height of the loop collapsing roller is 78 mm; the profile at the exit of the 14th stand is 29 mm, and the height of the loop collapsing roller is 69 mm; the profile at the exit of the 15th stand is 17.4 mm, and the height of the loop collapsing roller is 43 mm.

[0082] (6) The width of the rolled pieces at each stage is as follows: 11th stand: 61.5 mm, 12th stand: 32.1 mm, 13th stand: 59.6 mm, 14th stand: 62.5 mm, 15th stand: 35.7 mm, 16th stand: 23.2 mm.

[0083] (7) The difference between the two sides and the middle of the roll wear of the 11th rolling mill is controlled to be 0.4 mm. The controlled rolling tonnage of the rolls of the 12th - 16th rolling mills is as follows: 12th stand: 6740 tons, 13th stand: 6590 tons, 14th stand: 6430 tons, 15th stand: 6280 tons, 16th stand: 6120 tons.

[0084] Effect: During the production of the R18 specification this time, no steel piling accident occurred in pre-finishing rolling during continuous rolling.

[0085] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A method for stable rolling of bar stock, in which the intermediate billet is subjected to 6 passes of pre-finishing rolling according to flat roll, box pass, pre-split double-ellipse pass, split double-round pass, ellipse pass, and round pass, corresponding to 11 to 16 rolling mills respectively, characterized in that, Including: During pre-finishing rolling, cooling the entrance guide plug of the rolling mill, controlling the loop amount between rolling mills, controlling the ratio of the height of the pinch roll at the rolling mill exit to the cross-sectional size of the rolled piece at the rolling mill exit, controlling the width of the rolled piece at each stage, controlling the difference between the wear on both sides and in the middle of the rolls of the 11 rolling mills, and controlling the rolling tonnage of the rolls of the 12th to 16th rolling mills; Among them, during pre-finishing rolling, the loop amount between the 11th to 15th rolling mills is controlled to be 100 - 150 mm, and the loop amount between the 15th to 16th rolling mills is controlled to be 150 - 180 mm; The ratio of the height of the pinch roll at the exits of the 11th, 13th, 14th, 15th, and 16th rolling mills to the cross-sectional size of the rolled piece at the rolling mill exit is controlled to be 2.1 - 2.5, and the ratio of the height of the pinch roll at the exit of the 12th rolling mill to the cross-sectional size of the rolled piece at the rolling mill exit is controlled to be 2.8 - 3; The control ranges of the width of the rolled piece at each stage are as follows: for the 11th rolling mill: 60 - 63 mm, for the 12th rolling mill: 31 - 34 mm, for the 13th rolling mill: 58 - 61 mm, for the 14th rolling mill: 61 - 64 mm, for the 15th rolling mill: 34 - 37 mm, for the 16th rolling mill: 22 - 25 mm; The difference between the wear on both sides and in the middle of the rolls of the 11th rolling mill < 0.55 mm, and the controlled rolling tonnage of the rolls of the 12th to 16th rolling mills ≤ 7500 tons.

2. The bar stable rolling method according to claim 1, characterized in that: The cross-sectional size of the intermediate billet is controlled to be 50 - 55 mm.

3. The bar stable rolling method according to claim 2, characterized in that, The specific cross-sectional size of the intermediate billet before pre-finishing rolling is: When the finished product size is [12, 14] mm, the cross-sectional size of the intermediate billet is controlled from 50.5 mm to 52 mm; when the finished product size is [16, 18] mm, the cross-sectional size of the intermediate billet is controlled from 52 mm to 53 mm; when the finished product size is [20, 22] mm, the cross-sectional size of the intermediate billet is controlled from 53 mm to 55 mm, and when the casting billet tapping temperature is 880 - 950 °C, the cross-sectional size of the intermediate billet is controlled according to the lower limit.

4. The bar stable rolling method according to claim 2, characterized in that, It also includes: Controlling the cross-sectional size of the original billet produced by the continuous casting machine to be 160 - 175 mm. After the original billet produced by the continuous casting machine is produced, it is heated. The temperature of the hot soaking section is 1030 - 1230 °C, the total heating time is 60 - 150 min, and the temperature difference of the same billet cross-section ≤ 30 °C.

5. The bar stable rolling method according to claim 1, characterized in that: During pre-finishing rolling, cooling is carried out by spraying cooling water on the side walls of the entrance guides of the 12th, 13th, and 14th rolling mills.

6. The bar stable rolling method according to claim 1, characterized in that: During pre-finishing rolling, the loop amount between the 11th to 15th rolling mills is controlled to be 100 - 120 mm, and the loop amount between the 15th to 16th rolling mills is controlled to be 165 mm.

7. The bar stable rolling method according to claim 1, characterized in that: The cross-sectional dimension of the rolled piece at the outlet of the 11th rolling mill is 33 - 38.6 mm, and the height of the sleeve pressing roll at the outlet of the 11th rolling mill is 81 - 83 mm; the cross-sectional dimension of the rolled piece at the outlet of the 12th rolling mill is 55.6 - 62 mm, and the height of the sleeve pressing roll at the outlet of the 12th rolling mill is 167 - 174 mm; the cross-sectional dimension of the rolled piece at the outlet of the 13th rolling mill is 32.8 - 37.4 mm, and the height of the sleeve pressing roll at the outlet of the 13th rolling mill is 78 - 82 mm; the cross-sectional dimension of the rolled piece at the outlet of the 14th rolling mill is 29 - 33 mm, and the height of the sleeve pressing roll at the outlet of the 14th rolling mill is 69 - 72 mm; the cross-sectional dimension of the rolled piece at the outlet of the 15th rolling mill is 17.4 - 22.5 mm, and the height of the sleeve pressing roll at the outlet of the 15th rolling mill is 43 - 47 mm.

8. The bar stable rolling method according to claim 7, characterized in that: The height of the sleeve pressing roll at the outlet of the 12th rolling mill is 170 mm.

9. The bar stable rolling method according to claim 1, characterized in that: The width control ranges of the rolled pieces in each stage are as follows: 11th stand: 61 - 62 mm, 12th stand: 32 - 33 mm, 13th stand: 59 - 60 mm, 14th stand: 62 - 63 mm, 15th stand: 35 - 36 mm, 16th stand: 23 - 24 mm.

10. The bar stable rolling method according to claim 1, characterized in that: The difference between the two sides and the middle of the roll wear of the 11th rolling mill < 0.5 mm, and the controlled rolling tonnage of the rolls of the 12th - 16th rolling mills ≤ 7000 tons.

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