A method for improving the control of the dummy ingot head of a 2150mm continuous casting machine

Abstract

This invention discloses a method for improving the control of the dummy bar head of a 2150mm continuous casting machine. Based on a detailed analysis of the reasons why defects easily occur at the dummy bar and slab head, effective control measures were finally formulated. These measures include adjusting the distance between the dummy bar head and the top of the crystallizer and adjusting the sealing method of the dummy bar head. Ultimately, the problems of the dummy bar head pulling off and failing to open were basically eliminated. The number of times steel was leaked during the casting process was reduced from an average of 5 times throughout 2020-2022 to only 1 time in 2023, achieving good results.

Description

Technical Field

[0001] This invention relates to a method for improving the control of the sealing ingot head of a 2150mm continuous casting machine. Background Technology

[0002] Currently, the structural forms of straight-arc slab continuous casting machines are largely similar, but the ingot head forms differ significantly. Therefore, from a safety production perspective, the ingot head sealing method of thick plate continuous casting machines must differ from that used in small-section continuous casting machines. Otherwise, serious production accidents such as premature ingot detachment, inability to detach ingots, and leakage during casting may occur, which will not only greatly affect the production rhythm but also reduce the steel recovery rate, increase resource consumption and production costs, and reduce the economic benefits of enterprises. Summary of the Invention

[0003] The purpose of this invention is to provide an improved control method for the sealing of the sprue head in a 2150mm continuous casting machine, so as to effectively control wide-specification casting accidents in the continuous casting machine.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This invention provides an improved control method for the sealing ingot head of a 2150mm continuous casting machine, comprising:

[0006] (1) Avoid premature removal of the insulator.

[0007] For the fan-shaped section 4-5 where premature stripping occurs, the distance between the head of the dummy bar and the top opening after entering the crystallizer is adjusted from the original 550mm to 490-510mm. This improves the residence time of the dummy bar head in the crystallizer. The superheat of the first heat is increased by 5 degrees to increase the melting speed of the cooling material and ensure the solidification strength of the molten steel in the dovetail groove of the dummy bar head. Iron components are added to the dovetail groove to increase the tensile strength of the dummy bar and the slab head.

[0008] (2) To avoid the ingot from failing to detach

[0009] The ingot cannot be detached, meaning the ingot head is stuck to the billet, preventing the ingot rod from automatically separating from the billet and smoothly entering the recycling system after reaching the predetermined position. To address this issue, the ingot sealing process is optimized. In addition to laying a 10mm thick layer of iron pellets on the ingot head, steel blocks are added to protect the ingot head from melting. Furthermore, after laying the first layer of iron pellets on top of the ingot, a second layer of iron plate is added to facilitate better separation of the ingot head from the billet after rapid cooling of the molten steel.

[0010] (3) Avoid pouring steel leaks

[0011] Double-layered paper rope is used to seal the gap between the continuous casting machine's dummy head and the narrow-side copper plate of the crystallizer. This prevents the molten steel from directly impacting the paper rope during casting and causing it to seep down along the broken gaps. Iron slurry is also used to fill the narrow-side gap of the crystallizer to prevent molten steel from seeping in and causing a leak during casting.

[0012] Furthermore, one end of the iron component enters the dovetail groove, while the other end is placed on the upper surface of the ingot head.

[0013] Furthermore, the distance between the head of the ingot rod and the top opening after it enters the crystallizer is adjusted from the original 550mm to 490mm.

[0014] Furthermore, the distance between the head of the ingot rod and the top opening after it enters the crystallizer is adjusted from the original 550mm to 500mm.

[0015] Furthermore, the distance between the head of the ingot rod and the top opening after it enters the crystallizer is adjusted from the original 550mm to 510mm.

[0016] Furthermore, the dimensions of the steel block are 40mm × 40mm × 150mm.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0018] This invention conducts a detailed analysis of the reasons why defects easily occur at the head of the slab and the ingot, and finally formulates effective control measures, including adjusting the distance between the head of the ingot rod and the top of the crystallizer and the sealing method of the ingot head. Ultimately, the problems of the ingot head being pulled off and unable to be pulled open during the casting process are basically eliminated. The number of times the steel is leaked during the casting process has been reduced from an average of 5 times throughout 2020-2022 to only 1 time in 2023, which has achieved good results. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 A photograph of the dovetail groove;

[0021] Figure 2 Photos of iron components;

[0022] Figure 3 Photos showing the placement of the iron components;

[0023] Figure 4 Photographs of sheet metal parts;

[0024] Figure 5 A photo of paper rope;

[0025] Figure 6 A photo of iron filler used for sealing gaps. Detailed Implementation

[0026] A method for improving the control of the dummy bar head of a 2150mm continuous casting machine includes:

[0027] (1) First, confirm the role of the dummy bar in continuous casting production.

[0028] The main task of continuous casting is to pour qualified molten steel into a billet of a certain shape. Molten steel is poured from the tundish into the crystallizer, where it is cooled by heat transfer through the copper plates and cooling water, forming a billet shell of a certain safe thickness that matches the shape of the crystallizer. This allows for continuous production. However, in case of abnormal situations such as equipment maintenance, equipment failure, insufficient molten steel supply, or production accidents, the machine needs to be shut down. Production is restarted only after the problem hindering continuous production is resolved. Because molten steel needs to be poured from the tundish into the crystallizer and cooled to form a billet shell of a certain thickness before entering the fan-shaped section, a device to support the molten steel needs to be placed inside the crystallizer (900mm in length) during restarting production. After the molten steel solidifies into a billet shell of a certain thickness, the leveling machine is then started to pull it out, achieving the purpose of continuous casting.

[0029] The function of the dummy bar is to block the bottom of the crystallizer and support the initial molten steel poured into the crystallizer. After the molten steel solidifies into a safe billet shell of a certain thickness, it enters the fan-shaped section with the traction force of the dummy bar by the straightening system until the straightening system of the continuous casting machine has enough force to act on the billet.

[0030] The ingot-drawing mechanism consists of two parts: the ingot-drawing rod and the ingot-drawing head, which are rigidly connected together. The ingot-drawing head, which acts to seal the molten steel, has a dovetail groove structure on its end face. The main function of the dovetail groove is that after the molten steel solidifies at this location, the solidified billet head and the dovetail groove form an interlocking shape, so that the ingot-drawing chain, driven by the straightening system, can drive the billet through the connection between the ingot-drawing head and the billet. The dovetail groove... Figure 1 As shown.

[0031] Therefore, the dummy bar plays a crucial role in the continuous casting process.

[0032] If the dummy ingot head is not adequately prepared before casting, production accidents such as premature dummy ingot removal, inability to remove the dummy ingot, and leakage of steel during casting may occur. The causes and consequences of these three types of accidents will be analyzed and improved below.

[0033] (2) Avoid premature removal of the ingot.

[0034] Premature detachment of the dummy bar occurs when the dummy bar head separates from the billet prematurely. This results in insufficient force from the continuous casting machine's straightening system to pull the billet within the fan-shaped section, causing the billet to become stuck in the fan-shaped section during the initial pouring stage. Once the pouring stops, production is forced to halt, and the stuck billet must be removed by overhead crane in reverse using emergency procedures. There are many reasons for premature detachment, such as low initial molten steel temperature, insufficient initial molten steel flow, or excessive cooling material at the dummy bar head used for rapid cooling of the initial molten steel. However, the underlying principle is the same: insufficient molten steel entering the dovetail groove of the dummy bar head, or insufficient strength of the billet solidified around the dovetail groove, causes the billet at this point to break due to the strong traction force exerted by the dummy bar on subsequent billets.

[0035] Based on on-site analysis of numerous incidents of premature ingot removal, the premature removal typically occurs in the 4th-5th segment of the fan-shaped section. At this point, the ratio of the frictional resistance experienced by the billet to the pulling force exerted on the billet by the straightening system is at its maximum. Simultaneously, the pulling force exerted by the straightening system on the ingot rod exceeds the tensile strength of the arc-shaped billet head at the dovetail groove of the ingot head, leading to fracture and resulting in premature ingot removal and billet stagnation. Looking at the fractured arc-shaped billet head, the interior was filled with a large amount of cooling material—iron particles. This indicates that excessive iron particles were laid before casting, the molten steel temperature was too low, or the initial casting volume was too small, resulting in incomplete melting of the iron particles. After solidification, the unmelted iron particles inside the arc-shaped billet head reduced the tensile strength of the billet at that point, leading to the accident. To address this, this invention adjusts the distance between the head and the top of the dummy bar after entering the crystallizer from 550mm to 500mm, improving the residence time of the dummy bar head in the crystallizer. It also increases the superheat of the first casting by 5 degrees Celsius, increasing the melting rate of the cooling material and ensuring the solidification strength of the molten steel in the dovetail groove of the dummy bar head. An iron component is added inside the dovetail groove to increase the tensile strength of the dummy bar and the billet head (one end enters the dovetail groove, and the other end is placed on the upper surface of the dummy bar head). The iron component is as follows: Figure 2 As shown, the iron components are placed in the following positions. Figure 3 As shown.

[0036] (3) To prevent the ignition coil from failing to detach.

[0037] The ingot cannot detach, meaning the ingot head is stuck to the billet, preventing the ingot rod from automatically separating from the billet and smoothly entering the recycling system after reaching the predetermined position. To address this, this invention optimizes the ingot sealing process. In addition to a 10mm thick layer of iron granules at the ingot head, a 40mm×40mm×150mm steel block is added to protect the ingot head from melting. Furthermore, after the first layer of iron granules, a second layer of iron plate is added on top of the ingot to facilitate better separation of the ingot head from the billet after rapid cooling of the molten steel. The iron plate components are as follows: Figure 4 As shown.

[0038] (4) Avoid pouring steel leaks

[0039] Common causes of molten steel leakage during initial casting include: poor sealing of the dummy ingot head, causing molten steel to leak through the gap between the dummy ingot head and the copper plate after casting begins; molten steel burning through the sealing material; insufficient cooling material on the dummy ingot head, resulting in insufficient cooling and weak billet shell strength; and a billet shell that is too thin to support the static pressure of the molten steel. Based on recent accident cases, most leakage occurs on the narrow side of the crystallizer. This invention uses an additional double layer of paper rope to seal the gap between the dummy ingot head and the narrow-side copper plate of the crystallizer. This prevents molten steel from directly impacting the paper rope during initial casting, which could cause it to seep through the gaps in the damaged paper rope. The narrow-side gap of the crystallizer is also filled with sludge to prevent molten steel from seeping in and causing leakage during initial casting. The paper rope is used as a sealant. Figure 5 As shown, iron mud Figure 6 As shown.

[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving the control of the sealing ingot head of a 2150mm continuous casting machine, characterized in that, include: (1) Avoid premature removal of the spindle For the fan-shaped section 4-5 where premature stripping occurs, the distance between the head of the dummy bar and the top opening after entering the crystallizer is adjusted from the original 550mm to 490-510mm. This improves the residence time of the dummy bar head in the crystallizer. The superheat of the first heat is increased by 5 degrees to increase the melting speed of the cooling material and ensure the solidification strength of the molten steel in the dovetail groove of the dummy bar head. Iron components are added to the dovetail groove to increase the tensile strength of the dummy bar and the slab head. (2) To avoid the ingot from failing to detach The ingot cannot be detached, meaning the ingot head is stuck to the billet, preventing the ingot rod from automatically separating from the billet and smoothly entering the recycling system after reaching the predetermined position. To address this issue, the ingot sealing process is optimized. In addition to laying a 10mm thick layer of iron pellets on the ingot head, steel blocks are added to protect the ingot head from melting. Furthermore, after laying the first layer of iron pellets on top of the ingot, a second layer of iron plate is added to facilitate better separation of the ingot head from the billet after rapid cooling of the molten steel. (3) Avoid pouring steel leaks Double-layered paper rope is used to seal the gap between the continuous casting machine's dummy head and the narrow-side copper plate of the crystallizer. This prevents the molten steel from directly impacting the paper rope during casting and causing it to seep down along the broken gaps. Iron slurry is also used to fill the narrow-side gap of the crystallizer to prevent molten steel from seeping in and causing a leak during casting.

2. The method for improving the control of the sealing ingot head of a 2150mm continuous casting machine according to claim 1, characterized in that, One end of the iron component enters the dovetail groove, and the other end is placed on the upper surface of the ingot head.

3. The method for improving the control of the sealing ingot head of a 2150mm continuous casting machine according to claim 1, characterized in that, After the siphon rod enters the crystallizer, the distance between the head and the top opening is adjusted from the original 550mm to 490mm.

4. The method for improving the control of the sealing ingot head of a 2150mm continuous casting machine according to claim 1, characterized in that, After the siphon rod enters the crystallizer, the distance between the head and the top opening is adjusted from the original 550mm to 500mm.

5. The method for improving the control of the sealing ingot head of a 2150mm continuous casting machine according to claim 1, characterized in that, After the siphon rod enters the crystallizer, the distance between the head and the top opening is adjusted from the original 550mm to 510mm.

6. The method for improving the control of the sealing ingot head of a 2150mm continuous casting machine according to claim 1, characterized in that, The steel block measures 40mm × 40mm × 150mm.

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