A groove tonnage lifting method based on a double-bar production line

Abstract

The present application relates to a kind of based on double bar production line's groove tonnage promotion method, specifically including the following steps, step one, redesign the groove pass of third time, in the case where the height of third time groove is maintained at 88mm unchanged, increase groove bottom width to 154mm, step two, according to the change of third time groove pass, increase the roll gap value of third time from 12mm to 18mm;Red billet size is adjusted to 147mm × 88mm elliptical size;The billet speed of third time is adjusted to 0.56m / s;Step three, increase the roll gap value of fourth time from 13mm to 14mm, red billet size is adjusted to 106mm × 105mm elliptical size;The billet speed of fourth time is adjusted to 0.76m / s;Step four, according to the cross-sectional area of third time groove pass, the R factor of the first-4 times groove of each groove is calculated, the present application can reasonably distribute the deformation of each time, reduce the impact of billet to groove;Promote groove cooling level, reduce the new groove tonnage of groove wear.

Description

Technical Field

[0001] This invention belongs to the field of bar production technology, and particularly relates to a method for increasing the tonnage of the rolling groove based on a dual bar production line. Background Technology

[0002] In the steel production industry, bar production lines are one of the key pieces of equipment for manufacturing various types of bar steel. To improve production efficiency and product quality, many companies have introduced advanced production equipment and processes from abroad. Our company's existing dual bar production line is a typical example of such advanced equipment. Built and put into operation in 2006, each line is equipped with 18 rolling mill stands, arranged in an alternating horizontal and vertical configuration, achieving twist-free, fully continuous rolling. The designed annual output is 750,000 tons (combined for both lines), with a maximum rolling speed of 18 meters per second, capable of meeting the market's large demand for high-quality bars.

[0003] However, during production, we encountered a significant technical problem: insufficient wear resistance and service life of the rolling mill grooves. Particularly during the production of bars with raw material specifications of 160×160×12000mm and 150×150×12000mm, the 1-4# rolling mills in the roughing stage use a shared pass, subjecting the rolling mill grooves to extremely high loads. Currently, the operating tonnages of the 1-4# rolling mill grooves are 20,000 tons, 20,000 tons, 18,000 tons, and 14,000 tons respectively, with the 4# rolling mill groove being particularly prone to requiring replacement due to severe wear before reaching its rated tonnage.

[0004] This frequent slot replacement has several adverse effects. First, it increases downtime and reduces production line utilization, currently hovering around 80%. Second, slot replacement increases the workload of workers, posing challenges to both production efficiency and employee health. More seriously, each slot replacement requires readjusting the tension between the mills, a process that easily produces defective products such as dimensional inconsistencies, runners, and misalignments, resulting in a low product yield of only 98.70%. Furthermore, frequent slot changes lead to frequent shifts in rolling conditions, increasing the risk of steel accumulation accidents and threatening production safety and equipment stability.

[0005] Therefore, there is an urgent need for an effective method to increase the tonnage of the rolling mill grooves, reduce the frequency of groove replacements, and improve the production line's operating rate and product qualification rate. This paper proposes a method for increasing the tonnage of rolling mill grooves on a dual-bar production line.

[0006] Through in-depth research and analysis, we discovered that by changing the groove profile of the third stand, rationally allocating the reduction amount, and optimizing the size of the red billet in each stand, the load on the groove can be effectively reduced, thereby increasing the tonnage of the groove. The implementation of this method is expected to significantly improve existing production line problems, increase production efficiency and product quality, and reduce production costs and safety risks. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for increasing the tonnage of rolling mill grooves, reducing the frequency of groove replacement, and improving production line operating rate and product qualification rate. Specifically, it relates to a method for increasing the tonnage of rolling mill grooves on a dual-bar production line.

[0008] This invention is implemented as follows: a method for increasing the tonnage of a rolling mill based on a dual-bar production line, characterized by:

[0009] Step 1: Redesign the groove pattern for the third stand. While keeping the groove height unchanged at 88mm, increase the groove bottom width to 154mm.

[0010] Step 2: Based on the changes in the roll pass shape of the 3rd stand, increase the roll gap value of the 3rd stand to 18mm; adjust the billet size to an elliptical shape of 147mm×88mm; adjust the billet exit speed of the 3rd stand to 0.56 m / s;

[0011] Step 3: Increase the roll gap value of the 4th stand from 13mm to 14mm, and adjust the billet size to an oval shape of 106mm×105mm; adjust the billet output speed of the 4th stand to 0.76 m / s;

[0012] Step 4: Calculate the R factor based on the cross-sectional area of ​​the groove pattern of the 3rd stand;

[0013]

[0014] The table above shows the roll gap, billet size, speed, and R-factor for each slot in stands 1-4.

[0015] Further preferably, the spray angle of the cooling nozzles on the cooling main pipe of all stands is adjusted so that the spray angle of the cooling nozzles gradually increases in the opposite direction of the roll rotation direction.

[0016] More preferably, each set of cooling nozzles includes two parallel nozzles with the same spray angle and a nozzle located below the two parallel nozzles.

[0017] More preferably, the spray angle of the uppermost set of cooling nozzles is 15°; the spray angle gradually increases in the opposite direction of the roll rotation direction by 8-15°.

[0018] The technical effects of this invention can be summarized as follows:

[0019] Optimization of the rolling groove profile: By redesigning the rolling groove profile of the third stand and widening the bottom width of the groove, the bulges (ears) generated at the roll gap when the material fluctuates are effectively reduced, the impact on the arc of the No. 4 rolling groove is reduced, and phenomena such as deep grooves and block falling are avoided, thus achieving stable rolling.

[0020] Rolling parameter adjustment: Based on the changes in the roll groove shape, the roll gap value, billet size and billet exit speed of the 3rd and 4th stands were adjusted to make the rolling process smoother and improve rolling efficiency.

[0021] R-factor calculation and application: By calculating the R-factor of each stand, data support is provided for the optimization of the rolling process, which helps to further improve the rolling effect.

[0022] Extended service life of the rolling groove: As the material loss increases, the rolling groove needs to be continuously pressed down to maintain its size. The design of increasing the roll gap can provide more pressing space and increase the tonnage of the rolling groove (the roll gap cannot be pressed down when it reaches 0 and must be replaced). By redistributing the pressing amount of each stand, the deformation of the rolling groove in each stand is made more uniform. At the same time, the cooling system is optimized, which improves the cooling effect of the rolling groove and significantly extends the service life of the rolling groove, especially the service life of the No. 4 rolling groove, which is increased by 3 times.

[0023] Improved work efficiency and pass rate: The implementation of this invention has increased the work efficiency to 91% and the pass rate to 99.97%, greatly improving production efficiency and product quality.

[0024] In summary, this invention significantly improves the service life, operating rate, and yield of the rolling groove by optimizing the groove design, adjusting rolling parameters, calculating the R-factor, and improving the cooling system, providing an effective method for increasing the tonnage of the rolling groove in a dual-bar production line. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the main cooling pipe structure for the rolls of the present invention;

[0026] Figure 2 yes Figure 1 Sectional view of AA;

[0027] Figure 3 yes Figure 1 BB section view;

[0028] Figure 4 This is a schematic diagram of the installation location of the main cooling pipe for the rolling mill.

[0029] In the diagram, 1 is the main cooling pipe for the rolls; 2 is the cooling nozzle. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] A method for increasing the tonnage of the rolling groove based on a dual-bar production line, characterized in that:

[0032] Step 1: Redesign the roll pass for the third stand. While maintaining the roll height at 88mm, increase the roll bottom width from 147mm to 154mm. The original pass design was prone to filling, and when the material fluctuated, protrusions (ears) easily formed at the roll gap. This impacted the arc of the #4 roll groove, accelerating wear and, in severe cases, causing deep grooves and chipping. The newly designed pass completely absorbed the fluctuations in the pass, maintaining an arc shape in the wide sections, facilitating biting into the #4 roll groove and achieving stable rolling.

[0033] Step 2: Based on the changes in the roll pass shape of the 3rd stand, increase the roll gap value of the 3rd stand from 12mm to 18mm; adjust the billet size from the original 140mm×88mm circular size to 147mm×88mm elliptical size; adjust the billet exit speed of the 3rd stand to 0.56 m / s;

[0034] Step 3: Increase the roll gap value of the 4th stand from 13mm to 14mm, and adjust the size of the billet from the original 105mm×105mm circular size to 106mm×105mm elliptical size; adjust the billet output speed of the 4th stand to 0.76 m / s;

[0035] Step 4: Calculate the R factor based on the cross-sectional area of ​​the groove pattern of the 3rd stand;

[0036]

[0037] The table above shows the roll gap, billet size, speed, and R-factor for each slot in stands 1-4.

[0038] Further preferably, the spray angle of the cooling nozzles 2 on the main cooling pipe 1 of all stands is adjusted so that the spray angle of the cooling nozzles gradually increases in the opposite direction of the roll rotation. Preferably, each group of cooling nozzles includes two parallel nozzles with the same spray angle and one nozzle located below the two parallel nozzles. The incremental arrangement of the main water pipe nozzles using a "double-single" alternating arrangement cools the trough, increases the contact time between the cooling water and the roll, and reduces water splashing, thus significantly improving the cooling effect.

[0039] More preferably, the spray angle of the uppermost set of cooling nozzles is 15°; the spray angle gradually increases in the opposite direction of the roll rotation direction by 8-15°.

[0040] Based on the analysis of the existing roll pass configuration and the actual use of the roll groove, the roll pass of No. 3 was redesigned, and the bottom of the groove was widened by 7mm to reduce the impact on the arc part of No. 4 roll groove; the reduction amount of each stand was redistributed to make the deformation of the roll groove more uniform in each stand; the cooling system was redesigned to increase the contact time between the cooling water and the roll, while reducing water splashing, thus greatly improving the cooling effect of the roll groove.

[0041] To further optimize the cooling effect, a cooling and dust removal device for a bar and wire rod rolling production line, as described in the applicant's earlier application CN202020423796.2, is installed on the exit guide box to deeply cool the working rolls. This cooling and dust removal device is installed on the exit guide box, directly facing the gap between the exit guide and the rolling groove. It includes a base frame welded from hollow square tubing, comprising a main water inlet pipe, an upper spray pipe, a lower spray pipe, and a bypass branch pipe. One end of the main water inlet pipe is connected to a water inlet connector. Two upper spray nozzles are symmetrically installed on the upper spray pipe. The lower spray pipe is connected to the main water inlet pipe via the bypass branch pipe, and two lower spray nozzles are installed on the lower spray pipe. Both the two upper and two lower spray nozzles are inclined towards the gap between the exit guide box and the rolling groove.

[0042] Example 1

[0043] Production specifications: Ø50 round steel

[0044] Steel grade: 20, Q235B

[0045] Rolling mills used: Stands 1 through 12

[0046] Table 1 Rolling Procedure for Ø50 Round Steel

[0047]

[0048] Continuous production: 45,000 tons

[0049] This rolling process uses 160mm steel produced by the company's steelmaking plant. 2The 11400mm square billet, conforming to standard YB / T 2011-2014, was heated in a furnace to the initial rolling temperature of 1030-1050℃. After passing through the first 6 stands of the roughing mill, it entered the 7th-12th stands after passing through the #1 swing shear head, finally producing the finished product. It was then naturally cooled on a 120-meter cooling bed, cut to 9 meters, and then bundled and packaged for collection. During production, the tension was stable at each stand. The produced round steel products passed the tests, with a pass rate of 99.97% and a yield rate of 98.63%. The final steel throughput of each rolling slot is shown in Table 2 below.

[0050]

[0051] As can be seen from Table 2, the actual tonnage used for each sortie has increased significantly compared to the rated tonnage. In particular, the tonnage used for the 4th sortie in the rolling mill has increased from 14,000 tons to 40,100 tons, which is more than three times the original tonnage.

[0052] To ensure the surface quality of finished round steel products, it is stipulated that the rolling groove of each finished product stand shall not exceed the rated tonnage.

[0053] Example 2

[0054] Production specifications: Ø60 round steel

[0055] Steel grades: 20, 45

[0056] Rolling mills used: first to tenth stands

[0057] Table 3: Rolling Procedure for Ø60 Round Steel

[0058]

[0059] Continuous production: 41,000 tons

[0060] This rolling process uses 160mm steel produced by the company's steelmaking plant. 2 The 11400mm square billet, conforming to standard YB / T 2011-2014, was heated in a furnace to the initial rolling temperature of 1030-1050℃. After passing through the first 6 stands of the roughing mill, it entered the 7th-12th stands after passing through the #1 swing shear head, producing the final finished product. It was then naturally cooled on a 120-meter cooling bed, cut to 9 meters, and then bundled and collected. The tension was stable at each stand during production, and the produced round steel products passed the tests, with a pass rate of 99.98% and a yield rate of 98.85%. The final steel throughput of each rolling slot is shown in Table 4 below.

[0061]

[0062] As can be seen from Table 4, the actual tonnage used for each sortie has increased significantly compared to the rated tonnage. In particular, the tonnage used for the 4th sortie in the rolling mill has increased from 14,000 tons to 41,000 tons, which is more than three times the original tonnage.

[0063] To ensure the surface quality of finished round steel products, it is stipulated that the rolling groove of each finished product stand shall not exceed the rated tonnage.

[0064] In summary, this invention provides a novel rolling mill tonnage system that can rationally allocate deformation amounts for each stand, reduce the impact of billets on the rolling mill groove, improve the cooling level of the rolling mill groove, and reduce rolling mill groove wear.

[0065] 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 increasing the rolling groove tonnage of a double-bar production line, characterized by: The method comprises the following steps: Step one, redesign the groove profile of the third pass, increase the groove bottom width to 154mm while maintaining the groove height of the third pass at 88mm, Step two, increase the third pass roll gap to 18mm according to the change of the third pass groove profile; adjust the red billet size to 147mm x 88mm oval size; adjust the third pass exit speed to 0.56m / s; Step three, increase the fourth pass roll gap from 13mm to 14mm, adjust the red billet size to 106mm x 105mm oval size; adjust the fourth pass exit speed to 0.76m / s; Step four, calculate the R factor according to the cross-sectional area of the third pass groove profile, The above table is the roll gap, red billet size, speed and R factor table corresponding to each pass.

2. The method for increasing the rolling groove tonnage of a double-bar production line according to claim 1, characterized in that: Adjust the spray angle of the cooling nozzles on the cooling main pipe of all passes, so that the spray angle of the cooling nozzles gradually increases along the reverse direction of the rolling direction.

3. The method according to claim 2, wherein the method is characterized in that: Each group of cooling nozzles includes two parallel nozzles with the same spray angle and one nozzle located below the two parallel nozzles.

4. The method according to claim 2, wherein the method is characterized by: The spray angle of the uppermost group of cooling nozzles is 15°; the spray angle gradually increases by 8-15° along the reverse direction of the rolling direction.

Images