Continuous casting mold improves online service life

Abstract: As the core component in continuous casting production, the copper mould tube is directly related to the quality and service life of the cast slab. In recent years, with the development of continuous casting towards high efficiency, the service life of the copper mould tube has become an important factor restricting continuous casting production.

Keywords: continuous casting mold; improvement; online use; lifespan

At present, as continuous casting develops towards high speed, the service life of the copper mould tube has become an important factor restricting continuous casting production. In order to extend the service life of the mold, increase the continuous casting rate, and ensure the quality of the slab, this article mainly analyzes how to improve the online service life of the continuous casting mold.

Copper mould tube function and structure

(1) The copper mould tube is equipped with a support frame, a self-connecting water connection device, and a box equipped with copper plates and support plates. There are cooling water troughs on the copper plate to obtain a uniform and high cooling effect. The copper mould tube is bolted to the vibrating table and this system ensures quick and easy replacement of the copper mould tube. (2) The wide surface and narrow surface of the copper mould tube are clamped together by a clamping device to ensure that the taper of the copper plate on the narrow surface of the copper mould tube is fixed. (3) The narrow surface is connected to the width adjustment device, and the width adjustment process is completed by a manual screw. During adjustment, the wide-side clamping cylinder is released to ensure a specific minimum gap between the wide and narrow sides, thus ensuring minimal wear on the copper plate. (4) The copper plate is cooled by a closed-circuit primary cooling system. The optimized water cooling water tank ensures the low temperature of the copper plate at high drawing speeds. (5) The foot roller is lubricated through a centralized lubrication system. (6) The cooling of the slab is achieved by an open-circuit secondary cooling system. The nozzle sprays water from the middle of the roller to the wide and narrow surfaces of the slab. (7) A thermocouple is installed on the copper plate of the copper mould tube. The copper mould tube leakage prediction system can detect the temperature field in the copper mould tube in real time through thermocouple imaging to prevent steel leakage. (8) Width adjustment mechanical device

Width adjustment mechanical device

copper mould tube width adjustment devices are divided into two categories: manual width adjustment and automatic width adjustment according to the driving mode. Automatic width adjustment can usually be divided into hydraulic and electromechanical width adjustment. Whether the width adjustment device is a manual width adjustment, an electromechanical width adjustment or a hydraulic width adjustment device, the mechanical connection part has as little air travel as possible, so that the encoder and displacement transmission hydraulic width adjustment have a simple body structure, easy installation, and high stopping accuracy. , but it requires a separate hydraulic system, and the hydraulic system is prone to failure, requiring high technical requirements for equipment maintenance; if the hydraulic pressure is unstable, hydraulic pressure alarms will be frequent, affecting workers’ emotions and production. The electromechanical width adjustment method is safe and reliable, and the width adjustment accuracy mainly relies on encoder control. The mechanical mechanism mainly uses cycloid reducer or worm gear, trapezoidal screw reduction, and self-locking mechanism to effectively prevent problems such as narrow edge drift and taper changes.

Existing problems and improvement plans

(1) Problems with foot rollers:

① The narrow-surface foot roller was originally designed as a roller with a smooth surface and no slag guide groove. During the drawing process, slag is easy to accumulate on the roller surface. ② The roller bearing seat is not designed with cooling water. In a high-temperature radiation environment, the heat from the bearing seat cannot be discharged and is transmitted to the bearing. Roller lock-up sometimes occurs.

solution:

The narrow surface foot roller is transformed into a spiral pattern roller, and the protective slag is guided out along the slag guide groove, which is not easy to accumulate and cannot form slag accumulation. An annular cooling pipeline is installed in the foot roller area, and a nozzle is installed in the hole at the bearing seat to use external cooling spray water to cool the bearing seat.

(2) Lubrication issues:

① The lubrication of the copper mould tube foot roller adopts centralized lubrication. The copper mould tube foot roller, bending section and vibration share a dry oil pump. Among them, the copper mould tube foot roller and vibration share a dry oil pipeline, and the supply of dry oil is insufficient. The copper mould tube foot roller cannot be effectively lubricated, and locking of the foot roller occurs from time to time. ② The dry oil pipeline of the foot roller bearing seat is designed to be too long and the layout is messy. Due to the limitations of the working space and observation angle, it is easy to scratch the lubrication pipeline during the lifting of the copper mould tube, causing leakage and causing poor lubrication of the bearing seat.

solution:

An oil pump was added to the lubrication station to separate the copper mould tube, bending section, and vibration lubrication system. A dry oil pump independently supplied oil to the copper mould tube to ensure sufficient oil. The length of the oil pipe was shortened (from 1250mm to 900mm), the layout was standardized, and the pipe clamps were used to avoid places prone to scratches, which greatly reduced the chance of scratches during the lifting of the copper mould tube.

(3)Copper mould tube cone running problem:

The taper of the copper mould tube is an important parameter of the copper mould tube. Different steel types and different sections correspond to different tapers. Suitable and stable taper. If the taper is too large, it will increase the casting resistance, increase the wear of the copper plate, and reduce the service life of the copper plate. If the taper is too small, it may cause the billet to bulge during the casting process, thereby causing cracks. The narrow surface taper setting ensures the taper by adjusting the upper and lower worm gear reducers of the copper mould tube and locking the position. During the production process, affected by the pressure of the hot billet, coupled with the aging of the taper adjustment device, frequent taper runs occurred in the early stage, often causing production delays and billet quality accidents.

solution:

a.Off-line maintenance and replacement of the aging adjustment device to improve the accuracy of the adjustment device. Use the “pull up and push down” adjustment method to ensure that the upper transmission device of the copper mould tube is tightened and the lower transmission device is tightened.

b. Make welding jackscrews at the positions of the upper and lower opening back plates on the narrow surface. After the taper adjustment is completed, use the jacking screws to tighten the upper and lower opening back plates to avoid loosening due to force during the steel pouring process, thereby ensuring the stability of the taper.

(4) The problem of water leaking from corner seams:

The annular seal between the copper plate and the back plate of the copper mould tube is made of silicone, which has poor high-temperature resistance. After the copper mould tube is put online for a period of time, the sealing ring will deform due to heat, causing water leakage at the corner seams, causing production to slow down.

solution:

Change the ring seal material and replace the original silicone seal with a fluorine rubber seal. For copper plates that have been repaired many times, due to the relatively large amount of wear, it is necessary to add a sealant step when assembling the annular sealing ring between water tanks.

(5) The problem of false alarms in steel breakout prediction:

The mold breakout prediction system frequently reports false alarms, causing continuous casting production to slow down and greatly affecting the quality of the slab and production rhythm.

① The contents of the copper mould tube turnover card are not comprehensive, and key data such as key maintenance points and offline detection of thermocouples are missing, making it impossible to guarantee the quality of off-line maintenance. ② For off-line maintenance of the copper mould tube, only use a multimeter to measure the resistance of the thermocouple wire. The quality of the thermocouple is determined by the resistance value, and the actual temperature change effect and thermocouple stability cannot be detected. ③ The narrow-surface thermocouple signal line is not protected and is often burned during the production process due to slag fishing operations and other reasons, affecting the normal use of the steel breakage prediction system. ④ The connection between the narrow surface of the copper mould tube and the back plate is not protected. During the slag removal process, the protective slag can easily burn the thermocouple signal wire through the gap.

solution:

Revise the contents of the copper mould tube turnover card, add key points, thermocouple offline testing and other contents to effectively realize the full tracking of the copper mould tube and improve the accuracy and quality of off-line maintenance.

Use the steel plate to make a special detection tool corresponding to the copper plate thermocouple installation position, accurately locate the thermocouple installation position, use the cutting handle to position and bake, and use the steel leakage prediction intelligent detection system to achieve comprehensive offline detection of the thermocouple.

Install an anti-scalding tube on the narrow thermocouple signal cable, and install a protective plate on the narrow panel wiring location to avoid scalding the cable during the slag removal process.

Install a protective baffle on the narrow back plate, and apply sealant to the gap between the copper plate and the back plate to prevent protective slag from entering along the gap between the copper plate and the back plate and scalding the thermocouple signal wire.

Conclusion

All in all, the steady improvement of slab quality is an important way to improve the online service life of continuous casting molds. This ensures the personal safety of on-site production personnel and lays a good foundation for enterprises to adjust product structure and improve market competitiveness

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