A control device and method for improving the accuracy of the zero section equipment in a slab continuous casting machine.

Abstract

This invention relates to a control device and method for improving the accuracy of the zero section of a slab continuous casting machine, belonging to the technical field of continuous casting production equipment and methods in the metallurgical industry. The technical solution of this invention is: a four-step method for tightening the connecting bolts of the inner and outer arc frames of the zero section; adding guide grooves to the vertical rollers of the zero section; using a large tolerance transition fit for the zero section roller bearings; and employing a three-step method to check the clearance of the zero section guide seat. The beneficial effects of this invention are: by adopting a new zero section guide seat structure and improving the zero section assembly process, the unstable stress on the zero section during the casting process is reduced, and the accuracy of the zero section equipment is improved, avoiding production and quality problems caused by unstable stress on the high-temperature solidified billet shell.

Description

Technical Field

[0001] This invention relates to a control device and method for improving the accuracy of the zero section of a slab continuous casting machine, belonging to the technical field of continuous casting production equipment and methods in the metallurgical industry. Background Technology

[0002] The zero section of the slab continuous casting machine is installed between the crystallizer and the sector section, located in the vertical and curved area of ​​the roll train. The zero section body is fixed on the basic frame of the sector section of the continuous casting machine, and its main function is to support and guide the slab that is initially formed in the crystallizer. The upper mounting shaft of the outer arc frame of the zero section is placed in the positioning groove on the vibration device, which plays a role in positioning the zero section vertically and horizontally; the lower mounting shaft is placed in the guide groove of the mounting base to prevent the entire zero section from rotating around the upper mounting shaft.

[0003] Furthermore, the zero section is located at the bottom of the crystallizer, where the solidified slab shell is relatively thin. When the solidified shell is not strong enough to withstand the static pressure of the molten steel, a bulge will form. If the alignment accuracy between the zero section and the crystallizer and the first sector section is poor, the unstable stress on the bulging shell will directly lead to significant fluctuations in the molten steel level in the crystallizer. Fluctuations in the crystallizer level not only affect the stability of continuous casting production but also have a significant impact on slab quality, potentially causing serious production accidents such as longitudinal cracking and slag inclusion leakage. Therefore, improving the equipment accuracy of the zero section of the slab continuous casting machine is a key focus and challenge related to continuous casting equipment maintenance, smooth production, and stable quality. Summary of the Invention

[0004] The purpose of this invention is to provide a control device and method for improving the accuracy of the zero section equipment in a slab continuous casting machine. By adopting a new zero section guide seat structure and improving the zero section assembly process, the unstable stress on the zero section during the casting process is reduced and the accuracy of the zero section equipment is improved. This avoids production and quality problems caused by unstable stress on the high-temperature solidified billet shell, and effectively solves the above-mentioned problems existing in the background art.

[0005] The technical solution of the present invention is: a control device for improving the accuracy of the zero section equipment of a slab continuous casting machine, comprising: 1. an inner and outer arc frame, a vertical roller, and a guide seat. The guide seat comprises a main vertical plate and a box structure. There are two main vertical plates, and the box structure is disposed between the two main vertical plates. Each main vertical plate is provided with a set of two lower trunnion guide blocks, which are arranged opposite to each other on the inner side of the main vertical plate. A guide groove is formed between the two lower trunnion guide blocks, and the inner and outer arc frame is installed in the guide groove. The box structure is provided with reinforcing ribs inside, and the back plate of the main vertical plate is provided with supporting ribs. The roller body of the vertical roller is provided with a guide groove.

[0006] The lower trunnion guide block is a wedge-shaped block.

[0007] The vertical roller has one or more guide grooves on its body. The guide grooves are evenly spaced on the roller body and are distributed in parallel or in a double helix structure.

[0008] The main upright plate is made of 100mm thick steel plate, the box structure is made of 50mm diameter cylindrical steel bar, and the reinforcing ribs and supporting ribs are both made of 50mm thick steel plate. The steel plates are all high-strength weather-resistant steel Q345NQR2 with a thickness tolerance of ±2mm.

[0009] A control method for improving the accuracy of the zero section equipment of a slab continuous casting machine includes the following steps: (1) tightening the connecting bolts of the inner and outer arc frame of the zero section in four steps; (2) adding guide grooves to the vertical rollers of the zero section; (3) using large tolerance transition fit for the roller bearings of the zero section; (4) checking the clearance of the guide seat of the zero section in three steps.

[0010] In step (1), the four-step method requires that the four connecting bolts of the inner and outer arcs of segment zero be tightened in a certain order and with a certain torque. The specific steps are as follows:

[0011] (11) Use a bolt tensioner and tighten with 50% of the standard preload, starting from any position and proceeding diagonally.

[0012] (12) Use a bolt tensioner and tighten with 40% of the standard preload, starting from the last tightened tie rod position in the previous tightening process, and proceed in diagonal order;

[0013] (13) Use a bolt tensioner and tighten with 110% of the standard preload, starting from any position and proceeding in diagonal order;

[0014] (14) Use a bolt tensioner to pull back 10% and tighten the large tie rod with the standard preload of 100%, starting from any position and proceeding in a clockwise or counterclockwise order.

[0015] In step (2), there is more than one guide groove, which is set at fixed intervals on the roller body. The guide grooves are distributed in parallel or adopt a double helix structure.

[0016] In step (3), the zero-segment roller bearing adopts a large tolerance transition fit with a clearance range of -0.12 to -0.14 mm.

[0017] In step (4), the specific steps for checking the clearance of the zero segment guide seat in the three-step method are as follows: First, check whether the clearance of the outer arc of the guide seat meets the standard; second, check whether the shear pin of the guide seat fixing bolt is deformed; third, check whether the copper sleeve of the zero segment trunnion seat is deformed.

[0018] The beneficial effects of this invention are: by adopting a new zero-segment guide seat structure and improving the zero-segment assembly process, the unstable stress on the zero segment during the casting process is reduced and the accuracy of the zero-segment equipment is improved, thus avoiding production and quality problems caused by the unstable stress on the high-temperature solidified billet shell. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the guide seat structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the bolt tightening sequence of the present invention;

[0021] Figure 3 This is a schematic diagram of the parallel distribution of the zero-segment roller guide grooves of the present invention;

[0022] Figure 4 yes Figure 3 Enlarged structural diagram at point A;

[0023] Figure 5 This is a schematic diagram of the double-helix structure distribution of the zero-segment roller guide groove of the present invention;

[0024] Figure 6 This is a schematic diagram of the zero segment structure in the background technology of this invention;

[0025] In the diagram: 1. Lower trunnion guide block; 2. Guide groove; 3. Reinforcing rib; 4. Main upright plate; 5. Supporting rib; 6. Box structure; 7. Upper positioning groove and shaft; 8. Lower guide groove and shaft; 9. Cooling water piping and lubrication piping. Detailed Implementation

[0026] To make the purpose, technical solutions, and advantages of the invention's embodiments clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only a small part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0027] A control device for improving the accuracy of the zero section of a slab continuous casting machine includes inner and outer arc frames, vertical rollers, and guide seats. The guide seats include main vertical plates 4 and box structures 6. There are two main vertical plates 4, and the box structure 6 is disposed between the two main vertical plates 4. Each main vertical plate 4 is provided with a set of two lower trunnion guide blocks 1, which are arranged opposite each other on the inner side of the main vertical plate 4. A guide groove 2 is formed between the two lower trunnion guide blocks 1, and the inner and outer arc frames are installed in the guide groove 2. The box structure 6 is provided with reinforcing ribs 3 inside, and the back plate of the main vertical plate 4 is provided with supporting ribs 5. The rollers of the vertical section are provided with guide grooves.

[0028] The lower trunnion guide block 1 is a wedge-shaped block.

[0029] The vertical roller has one or more guide grooves on its body. The guide grooves are evenly spaced on the roller body and are distributed in parallel or in a double helix structure.

[0030] The main upright plate 4 is made of 100mm thick steel plate, the box structure 6 is a 50mm diameter cylindrical steel bar, the reinforcing rib plate 3 and the supporting rib plate 5 are both made of 50mm thick steel plate, and the steel plates are all high-strength weather-resistant steel Q345NQR2 with a thickness tolerance of ±2mm.

[0031] A control method for improving the accuracy of the zero section equipment of a slab continuous casting machine includes the following steps: (1) tightening the connecting bolts of the inner and outer arc frame of the zero section in four steps; (2) adding guide grooves to the vertical rollers of the zero section; (3) using large tolerance transition fit for the roller bearings of the zero section; (4) checking the clearance of the guide seat of the zero section in three steps.

[0032] In step (1), the four-step method requires that the four connecting bolts of the inner and outer arcs of segment zero be tightened in a certain order and with a certain torque. The specific steps are as follows:

[0033] (11) Use a bolt tensioner and tighten with 50% of the standard preload, starting from any position and proceeding diagonally.

[0034] (12) Use a bolt tensioner and tighten with 40% of the standard preload, starting from the last tightened tie rod position in the previous tightening process, and proceed in diagonal order;

[0035] (13) Use a bolt tensioner and tighten with 110% of the standard preload, starting from any position and proceeding in diagonal order;

[0036] (14) Use a bolt tensioner to pull back 10% and tighten the large tie rod with the standard preload of 100%, starting from any position and proceeding in a clockwise or counterclockwise order.

[0037] In step (2), there is more than one guide groove, which is set at fixed intervals on the roller body. The guide grooves are distributed in parallel or adopt a double helix structure.

[0038] In step (3), the zero-segment roller bearing adopts a large tolerance transition fit with a clearance range of -0.12 to -0.14 mm.

[0039] In step (4), the specific steps for checking the clearance of the zero segment guide seat in the three-step method are as follows: First, check whether the clearance of the outer arc of the guide seat meets the standard; second, check whether the shear pin of the guide seat fixing bolt is deformed; third, check whether the copper sleeve of the zero segment trunnion seat is deformed.

[0040] In practical applications, the guide seat consists of a lower trunnion guide block 1, a guide groove 2, reinforcing ribs 3, a main upright plate 4, supporting ribs 5, and a housing structure 6. The main upright plate 4 is 100mm thick; the housing structure 6 has a steel plate thickness of 50mm, with two 50mm reinforcing ribs 3 inside; and 50mm supporting ribs on the back plates of the inner and outer arc guide blocks. All steel plates are made of high-strength weather-resistant steel Q345NQR2. This significantly increases the mechanical strength of the guide seat, ensuring it will never deform and effectively guaranteeing that the gap accuracy between the lower trunnion and the guide groove in the zero segment is ≤0.15mm.

[0041] During continuous casting in large-scale production, the zero section experiences significant bending reaction force from the billet, causing it to move outwards. Conversely, the weight of the bending itself, combined with the weight of the billet within the zero section, causes it to move inwards. The control of this inward / outward movement is achieved through the clearance between the lower trunnion and the guide groove, which relies on the rigidity of the guide groove. If the clearance between the lower trunnion and the guide groove is too large, the zero section will oscillate back and forth in both directions under the combined effects of bending and gravity. This oscillation directly leads to fluctuations in the molten steel level within the crystallizer and causes the billet to experience additional mechanical forces, resulting in cracks or even shell breakage and steel leakage. Therefore, precise control of the clearance between the lower trunnion and the guide groove directly impacts the molten steel level fluctuations in the crystallizer and the quality of the billet.

[0042] The improved assembly process for segment zero includes the following four parts:

[0043] 1. Four-step method for tightening the inner and outer arc connecting bolts of segment zero:

[0044] The four connecting bolts on the inner and outer arcs of segment zero must be tightened in a specific order (diagonally) and with a specific torque (reaching maximum preload in three stages):

[0045] ① Use a bolt tensioner and tighten with 50% of the standard preload, starting from any position and proceeding diagonally.

[0046] ② Use a bolt tensioner and tighten with 40% of the standard preload, starting from the last tightened tie rod position in the previous tightening process and proceeding in diagonal order;

[0047] ③ Use a bolt tensioner and tighten with 110% of the standard preload, starting from any position and proceeding diagonally.

[0048] ④ Use a bolt tensioner to pull back 10% and tighten the large tie rod with 100% standard preload, starting from any position and proceeding in a clockwise or counterclockwise sequence;

[0049] By using the above four-step method to tighten the inner and outer arc tie rod bolts of segment zero, the problem of changes occurring shortly after the roll gap of segment zero is put on the line is significantly improved.

[0050] The initial problem was that operators consistently tightened the large tie rod nuts clockwise or counterclockwise in one go. Research revealed that if the bolt tie rods were tightened to the standard preload in one go, while the other tie rods remained loose, the relatively large force caused the inner arc frame of section zero to tilt towards the first tightened tie rod. When preloading clockwise or counterclockwise, the preload of the second tie rod fixed this tilt. However, when tightening the opposite tie rods, the angle between the tie rod and the inner arc tie rod hole resulted in a component of the tightening force in the horizontal direction of the inner arc, preventing complete tightening. This led to inconsistent actual tightening of the four tie rods, causing deviations in the roll gap data for the four directions. Furthermore, some tie rods were not fully tightened, which could cause a rapid increase in roll gap data after loading the billet during production, necessitating a shutdown and section replacement.

[0051] Furthermore, after being tightened, the screw is in a state of elastic deformation. Especially under high temperature and vibration loads, prolonged continuous pressure will cause creep. Once the screw undergoes plastic deformation, its strength will decrease significantly or it may even fail. The final 10% adjustment allows some of the elastic deformation to recover, while also eliminating pre-tightening stress. Afterward, the screw's deformation under continuous pressure remains within the elastic deformation range, greatly reducing the probability of plastic strain and failure. This allows the screw to maintain continuous high-strength pressure, an effect that cannot be achieved by tightening it to 100%.

[0052] 2. Add guide grooves to the vertical rollers in section zero:

[0053] At fixed intervals, guide grooves are designed on the body of the flat roll (or smooth roll) (the internal installation structure of the roll body remains unchanged). The guide grooves are distributed in parallel or adopt a double helix structure. The advantages are that the guide grooves on the roll body reduce the chance of slag and water accumulation between the roller's arc surface and the billet, reduce the possibility of protective slag being squeezed into the billet shell surface and the billet being soaked in water, disperse and remove accumulated water and slag, prevent slag pits on the billet surface, and reduce the unevenness of billet cooling, thereby improving the continuous casting process and billet quality. At the same time, this structure increases the heat dissipation area, and thermal stress and deformation can be released through the grooves, reducing deformation and cracks in the rolls and bearings, and extending the service life of the rolls and bearings.

[0054] By using the addition of a guide groove, the abnormal damage rate of the zero section roller is greatly reduced, and the mold protective slag can also be smoothly removed after the billet comes out of the mold.

[0055] 3. The zero-section roller bearing adopts a large tolerance transition fit:

[0056] To reduce mechanical clearance during continuous casting machine manufacturing, the zero-section roller bearings all use small tolerance interference fits. However, in actual production, excessively small fit clearances can affect assembly and restrict movement during hot and cold deformation. These factors can affect the normal operation of the bearings and even cause jamming. Inappropriate bearing fit dimensions are a major reason why bearings cannot operate normally.

[0057] Considering the actual working conditions of high temperature and alternating load for the zero-segment roller bearing, a large tolerance transition fit is adopted, with a clearance range of -0.12 to 0.14 mm. This appropriately increases the clearance between the bearing and other parts, increasing the flexibility of roller rotation and reducing the likelihood of jamming during thermal expansion. After completing the roller assembly, the outer edge of the roller sleeve is ground using specialized equipment to ensure its dimensional accuracy and coaxiality requirements. When measuring the roller gap value after assembly, a special tool is used to eliminate accumulated clearances in each component, ensuring the accuracy and uniformity of the roller gap value.

[0058] 4. Use a three-step method to check the clearance of the zero segment guide seat:

[0059] The first step is to check whether the clearance of the outer arc of the guide seat meets the standard.

[0060] The second step is to check whether the shear pin of the guide seat fixing bolt is deformed.

[0061] The third step is to check whether the copper bushing of the zero segment trunnion seat is deformed.

[0062] By following this three-step progressive inspection method, step by step, we can discover the real hidden problems, quickly identify and eliminate abnormalities, and prevent the gap of the zero section guide seat from exceeding the standard after the continuous casting machine starts pouring.

[0063] Case Study: A domestic steel mill produces over 10 million tons of high-quality continuously cast slabs annually. Before implementing this invention, the replacement cycle for the zero section of the continuous casting machine was 1-2 months. Furthermore, due to the excessive precision of the zero section equipment, fluctuations in the liquid level in the crystallizer during production caused frequent transverse cracks at the outer arc corners of the slabs, severely impacting production flow and product quality. After adopting this invention, the replacement cycle for the zero section of the continuous casting machine at this steel mill was reduced to 4-6 months, effectively ensuring smooth production and product quality, while significantly reducing equipment maintenance and costs.

[0064] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A control method for improving the accuracy of the zero-segment equipment of a slab continuous casting machine, characterized in that, The steps include: (1) Tightening the tie rod bolts of the inner and outer arc frame of the zero section using a four-step method; (2) Adding guide grooves to the vertical rollers of the zero section; (3) Using a large tolerance transition fit for the bearings of the zero section rollers; (4) Using a three-step method to check the clearance of the zero section guide seat. In step (1), the four-step method requires that the four tie rod bolts of the inner and outer arcs of segment zero be tightened in a certain order and with a certain torque. The specific steps are as follows: (11) Use a bolt tensioner and tighten with 50% of the standard preload, starting from any position and proceeding diagonally. (12) Use a bolt tensioner and tighten with 40% of the standard preload, starting from the last tightened tie rod bolt in the previous tightening process, and proceed in diagonal order; (13) Use a bolt tensioner and tighten with 110% of the standard preload, starting from any position and proceeding in diagonal order; (14) Use a bolt tensioner to pull back 10% and tighten the tie rod bolt with the standard preload of 100%, starting from any position and proceeding in a clockwise or counterclockwise order; In step (4), the specific steps for checking the clearance of the zero segment guide seat in the three-step method are as follows: First, check whether the clearance of the outer arc of the guide seat meets the standard; second, check whether the shear pin of the guide seat fixing bolt is deformed; third, check whether the copper sleeve of the zero segment trunnion seat is deformed. The control device used in the control method includes an inner and outer arc frame, a vertical roller and a guide seat. The guide seat includes a main plate (4) and a box structure (6). There are two main plates (4). The box structure (6) is set between the two main plates (4). Each main plate (4) is provided with a set of lower trunnion guide blocks (1). Each set of lower trunnion guide blocks (1) has two blocks, which are arranged opposite to each other on the inner side of the main plate (4). A guide groove (2) is formed between the two lower trunnion guide blocks (1). The inner and outer arc frame is installed in the guide groove (2). The box structure (6) is provided with a reinforcing rib plate (3). The back plate of the main plate (4) is provided with a supporting rib plate (5). The roller body of the vertical roller is provided with a guide groove. The lower trunnion guide block (1) is a wedge-shaped block. The vertical roller has one or more guide grooves on its body. The guide grooves are evenly spaced on the roller body and are distributed in parallel or in a double helix structure.

2. The control method for improving the accuracy of the zero-segment equipment of a slab continuous casting machine according to claim 1, characterized in that: The main upright plate (4) is made of 100mm thick steel plate, the box structure (6) is a 50mm diameter cylindrical steel bar, the reinforcing rib plate (3) and the supporting rib plate (5) are both made of 50mm thick steel plate, and the steel plates are all high-strength weather-resistant steel Q345NQR2 with a thickness tolerance of ±2mm.

3. The control method for improving the accuracy of the zero-segment equipment of a slab continuous casting machine according to claim 1, characterized in that: In step (2), there is more than one guide groove, which is set at fixed intervals on the roller body. The guide grooves are distributed in parallel or adopt a double helix structure.

4. The control method for improving the accuracy of the zero-segment equipment of a slab continuous casting machine according to claim 1, characterized in that: In step (3), the zero-segment roller bearing adopts a large tolerance transition fit with a clearance range of -0.12 to -0.14 mm.

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