A bloom crystallizer and a bloom production method suitable for high-drawing speed production

Abstract

The present application relates to the technical field of steel smelting, and in particular to a square billet crystallizer suitable for high-pulling speed production and a square billet production method. The crystallizer is composed of an upper crystallizer with a copper tube length of 800-850 mm and a lower crystallizer with a copper tube length of 600-750 mm. The cross-sectional size of the lower copper tube of the upper crystallizer and the upper copper tube of the lower crystallizer are completely the same. The lower crystallizer is made into a gas-permeable shape from 1 / 2 thickness to the hot surface of the copper tube. The holes of the gas-permeable copper tube are oil delivery pipelines. After improving the lubricating effect of the lower cavity inside the crystallizer body, the billet pulling resistance is reduced, and the problem that the billet pulling resistance increases sharply with the increase of the length of the crystallizer is solved. Therefore, the total length of the crystallizer can be lengthened to 1400-1600 mm, the growth time of the billet shell in the crystallizer is improved, the thickness of the billet shell out of the crystallizer is improved, the high-pulling speed continuous casting machine is suitable, and the highest pulling speed of 7.5 m / min can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a square billet crystallizer suitable for high-pulling speed production and a square billet production method. BACKGROUND

[0002] The square billet is a steel billet with a square cross section produced by a continuous casting machine and used for machining profiles, and the cross section of the square billet is generally less than 200mm*200mm. In the square billet production process, the high-pulling speed process can not only improve the continuous casting hourly output and reduce the flow number of the casting machine, but also improve the surface temperature of the red billet after the fixed-size cutting, and the improvement of the surface temperature of the continuous casting red billet provides a strong guarantee for the realization of the subsequent hot sending, hot charging and direct sending and direct rolling, so the high-pulling speed process is the core of the low-cost continuous casting process.

[0003] However, the improvement of the pulling speed will lead to the shortening of the growth time of the billet shell in the crystallizer, the reduction of the thickness of the billet shell out of the crystallizer, and the reduction of the strength of the billet shell out of the crystallizer. At present, the highest pulling speed of the domestic 160mm*160mm square billet is about 4.5-5.5m / min. For example, the high-pulling speed square billet crystallizer provided in the Chinese patent document CN 216324983 U (application number 202122897538.5) can realize a pulling speed of 5.5m / min at most, but if the pulling speed is further improved, it may lead to the quality defects of the billet such as leakage and bulging. Lengthening the crystallizer can offset the problem of the thinning of the billet shell out of the crystallizer caused by the improvement of the pulling speed, but it will also bring the problems of the increase of the pulling resistance and the increase of the wear of the crystallizer. The reason is that: “the protective slag of the crystallizer melts and flows into the space between the crystallizer and the solidified billet shell to act as a lubricant, but due to the low temperature of the wall of the crystallizer, the liquid protective slag will quickly solidify, and the liquid slag film can only cover the upper part of the crystallizer, and the space between the lower part of the crystallizer and the billet is mainly filled with solid protective slag, which leads to the large friction resistance between the lower part of the crystallizer and the billet, and the continuous lengthening of the crystallizer will rapidly increase the friction resistance, and when the friction resistance exceeds the strength of the billet shell, the billet will be pulled off, leading to the leakage accident”.

[0004] The prior art mainly reduces the pulling resistance and improves the lubrication effect of the crystallizer by optimizing the taper of the crystallizer, reducing the melting point and viscosity of the protective slag, and improving the melting speed of the protective slag, but these technologies can only make the length of the crystallizer reach about 1000mm.

[0005] The lengthening of the crystallizer can increase the residence time of the billet in the crystallizer, thereby increasing the thickness of the billet shell out of the crystallizer, but it will also lead to the increase of the pulling resistance. Therefore, how to improve the lubrication effect of the crystallizer while greatly increasing the length of the crystallizer is a problem to be solved at present.

[0006] Rapeseed oil and mineral oil were widely used in the early development of continuous casting to lubricate the crystallizer, but they were gradually replaced by crystallizer protective slag due to the large molten steel level fluctuation in the crystallizer, poor molten steel oxidation prevention effect and other reasons, but their lubricating effect on the billet is good, and the lubricating effect is verified by large-scale production. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art, provide a billet crystallizer suitable for high-drawing speed production and a billet production method, the crystallizer is composed of an upper crystallizer with a copper pipe length of 800-850 mm and a lower crystallizer with a copper pipe length of 600-750 mm, the lower opening of the upper crystallizer and the upper opening of the lower crystallizer are tightly connected, the upper crystallizer is a conventional billet crystallizer manufactured by the prior art, and the lower crystallizer is different from the prior art: the copper pipe of the lower crystallizer is made into a copper pipe with a hot surface that is breathable and a cold surface that is not breathable by a 3D printing method, lubricating oil is injected between the billet and the hot surface of the crystallizer through the holes of the breathable copper pipe, and the taper of the lower crystallizer is 0.47-0.65%.

[0008] To achieve the above technical effects, the present application adopts the following technical solutions:

[0009] A billet crystallizer suitable for high-drawing speed production has the following structure:

[0010] (1) The crystallizer is composed of an upper crystallizer with a copper pipe length of 800-850 mm and a lower crystallizer with a copper pipe length of 600-750 mm.

[0011] The length of the copper pipe of the upper crystallizer is 800-850 mm, the length of the copper pipe of the lower crystallizer is 600-750 mm, the cross-sectional size of the lower opening of the copper pipe of the upper crystallizer is the same as that of the upper opening of the copper pipe of the lower crystallizer, and the lower opening of the upper crystallizer and the upper opening of the lower crystallizer are tightly connected by welding.

[0012] The upper crystallizer and the lower crystallizer share a set of crystallizer vibration systems to keep the synchronization of the crystallizer vibration, and the crystallizer vibration system adopts the prior art.

[0013] The upper crystallizer and the lower crystallizer each have a set of cooling water systems to distinguish the cooling intensity, during billet drawing production, the water amount of the cooling copper pipe of the upper crystallizer is 2300L / min~2700L / min, the water amount of the cooling copper pipe of the lower crystallizer is 2000L / min~2400L / min, and other cooling processes adopt the prior art.

[0014] (2) The copper pipe of the lower crystallizer is a breathable copper pipe with a hot surface that is breathable and a cold surface that is not breathable, which is made by a 3D printing method.

[0015] The 3D printing method is used to make the lower crystallizer copper pipe 1 / 2 thickness to the hot surface into a breathable state, and the hole of the breathable copper pipe is an oil conveying pipeline. The specific structure of the oil conveying pipeline is that the 3D printing method is used to print an oil conveying main pipeline at the 1 / 2 thickness of the lower crystallizer copper pipe and the external lubricant storage device, and print an oil conveying secondary main pipeline and an oil conveying branch pipeline between the 1 / 2 thickness of the lower crystallizer copper pipe and the hot surface. The opposite outer side of the oil conveying main pipeline is in communication with the external lubricant storage device, the opposite inner side of the oil conveying main pipeline is connected to the oil conveying branch pipeline through the oil conveying secondary main pipeline arranged in the lower crystallizer, and the oil conveying branch pipeline intersects with the hot surface of the copper pipe to form an oil conveying hole.

[0016] The oil conveying secondary main pipeline is connected with the oil conveying main pipeline and the oil conveying branch pipeline. The oil conveying main pipeline is a fine hole with a diameter of 2000-4000 μm, the oil conveying secondary main pipeline is a fine hole with a diameter of 500-1000 μm, the oil conveying branch pipeline is a fine hole with a diameter of 100-200 μm, and the number density of the oil conveying hole at the hot surface of the copper pipe is 0.5-2 / cm. 2 The diameter size of the oil conveying hole at the hot surface of the copper pipe is the same as the diameter of the oil conveying branch pipeline.

[0017] The lubricating oil is uniformly injected between the steel billet and the hot surface of the lower crystallizer through the hole of the breathable copper pipe, the injection speed of the lubricating oil is 50-300 L / min, the pressure of the oil in the oil conveying pipeline is 2-6 atmospheres to prevent the oil conveying pipeline from being blocked, and the lubricating oil is rapeseed oil or mineral oil suitable for crystallizer lubrication sold on the market.

[0018] The lubricating oil flows out from the hot surface of the lower crystallizer copper pipe after passing through the oil conveying main pipeline, the oil conveying secondary main pipeline and the oil conveying branch pipeline in sequence.

[0019] The 3D printing method is used to make the lower crystallizer copper pipe 1 / 2 thickness to the cold surface into a dense and non-breathable state.

[0020] The upper part of the upper crystallizer is provided with a protective slag adding device, and the protective slag adding device is an existing device.

[0021] The taper of the hot surface of the upper crystallizer copper pipe is 0.4-2.5% / m, and the taper of the hot surface of the lower crystallizer copper pipe is 0.47-0.65% / m. The hot surfaces of the upper crystallizer and the lower crystallizer copper pipe are all in a self-top-to-bottom shrinkage state.

[0022] Further preferably, in the upper crystallizer,

[0023] The upper surface of the upper crystallizer to the segment 100 mm below the upper surface of the upper crystallizer is a straight pipe segment;

[0024] The segment 100 mm-200 mm below the upper surface of the upper crystallizer has a taper of (2-2.5)% / m;

[0025] The segment 200 mm-400 mm below the upper surface of the upper crystallizer has a taper of (1-1.25)% / m;

[0026] The taper of the section 400mm below the top surface of the upper crystallizer to 600mm below the top surface of the upper crystallizer is (0.6-0.7) % / m;

[0027] The taper of the section 600mm below the top surface of the upper crystallizer to the bottom surface of the upper crystallizer is (0.4-0.5) % / m.

[0028] Further preferably, in the lower crystallizer,

[0029] The taper of the section from the top surface of the lower crystallizer to 200mm below the top surface of the lower crystallizer is (0.6-0.65) % / m;

[0030] The taper of the section 200mm below the top surface of the lower crystallizer to 400mm below the top surface of the lower crystallizer is (0.55-0.6) % / m;

[0031] The taper of the section 400mm below the top surface of the lower crystallizer to 600mm below the top surface of the lower crystallizer is (0.5-0.55) % / m;

[0032] The taper of the section 600mm below the top surface of the lower crystallizer to the bottom surface of the lower crystallizer is (0.47-0.5) % / m.

[0033] More preferably, the adjacent taper sections are connected by a round corner.

[0034] The application also provides a billet production method using the above-mentioned billet crystallizer, molten steel and protective slag are injected from the upper end of the crystallizer body, and the molten steel is discharged after sequentially passing through the upper crystallizer and the lower crystallizer.

[0035] The upper part of the upper crystallizer is provided with a protective slag adding device, and the protective slag adding device is an existing device.

[0036] The water flow rate of the water cooling device at the upper crystallizer is (2300-2700) L / min, the water flow rate of the water cooling device at the lower crystallizer is (2000-2400) L / min, the injection speed of the lubricant in the lubricating pipeline is (50-300) L / min, and the pressure in the lubricating pipeline is maintained at 2 atm (standard atmospheric pressure)-6 atm,

[0037] The drawing speed of the billet crystallizer is (4-7.5) m / min.

[0038] Preferably, the lubricant is selected from rapeseed oil or mineral oil, and the mineral oil is a commercially available mineral oil for crystallizer lubrication, such as spindle oil (low viscosity spindle bearing oil), and specifically, Fujian Chunrun Technology Co., Ltd. produces No. 32 spindle oil.

[0039] The beneficial effects of the application are as follows:

[0040] 1. The present application provides a billet crystallizer and billet production method, in which, on the basis of retaining the lubrication of the crystallizer protective slag, additional lubricating oil is added to lubricate the cast billet, the liquid crystallizer protective slag lubricates the upper crystallizer, and the lubricating oil in the lower crystallizer carbonizes after contacting the cast billet, and the residual carbon and carbide can provide good lubrication, which can solve the problem that the liquid protective slag cannot flow to the lower part of the crystallizer, the lubrication effect of the lower part of the crystallizer is poor, and the overall lubrication effect of the crystallizer can be improved. After improving the lubrication effect of the lower cavity of the crystallizer body, the drawing resistance can be reduced, and the problem that the drawing resistance increases sharply with the increase of the length of the crystallizer can be solved, so that the total length of the crystallizer can be lengthened to 1400-1600mm, the growth time of the cast billet shell in the crystallizer can be improved, and the thickness of the shell can be improved. The high-speed continuous casting machine can realize the highest drawing speed of 7.5m / min.

[0041] 2. By improving the lubrication effect of the lower part of the crystallizer, the frictional resistance between the lower part of the crystallizer and the cast billet shell is reduced (in the traditional crystallizer, a gap is intentionally left between the lower part of the crystallizer and the cast billet shell to reduce the drawing resistance), so the taper of the lower crystallizer can be appropriately increased to improve the adhesion of the lower crystallizer to the surface of the cast billet, the taper of the lower crystallizer in the prior art (0-0.45) % / m (Research on Key Technologies of High Speed Continuous Casting of Small Square Billets of Carbon Steel, Chen Yang, Doctoral Dissertation) is improved to (0.47-0.65) % / m in the present application, the air gap between the cast billet shell and the crystallizer wall is reduced or eliminated, the cooling effect of the crystallizer on the shell is improved, and the thickness of the shell is improved. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a structural schematic diagram of the square billet crystallizer provided in example 1;

[0043] Figure 2 is a schematic diagram of the lubrication mode between the square billet crystallizer and the cast billet shell in example 2;

[0044] In the figure, 1 is the upper crystallizer, 2 is the lower crystallizer, 21 is the main oil supply line, 22 is the secondary oil supply line, 23 is the oil supply branch, 3 is the liquid crystallizer protective slag, 4 is the solid crystallizer protective slag, 5 is the liquid surface crystallizer protective slag, 6 is the lubricant carbide, 7 is the air gap, and 8 is the cast billet. DETAILED DESCRIPTION

[0045] The present application will be further described below in conjunction with examples and drawings.

[0046] Example 1

[0047] The billet casting mould of a certain threaded steel plant is 160mm*160mm square billet, the upper limit of casting billet speed using traditional crystallizer protective slag lubrication is 4.5m / min, the temperature of the steel billet transported to the rolling material plant is about 800-850℃, most of the casting billets need to be heated by electromagnetic induction coil before direct rolling, in order to further improve the temperature of the steel billet transported to the rolling material plant, the casting billet speed needs to be improved, therefore, the square billet crystallizer suitable for high speed production is used in the plant.

[0048] As shown in the accompanying drawings of the present application, Figure 1 The crystallizer is composed of the upper crystallizer 1 with copper pipe length of 800mm and the lower crystallizer 2 with copper pipe length of 700mm, the cross-sectional size of the lower copper pipe of the upper crystallizer 1 and the cross-sectional size of the upper copper pipe of the lower crystallizer 2 are completely the same, the lower opening of the upper crystallizer 1 and the upper opening of the lower crystallizer 2 are tightly connected by welding.

[0049] The upper crystallizer 1 and the lower crystallizer 2 share a set of crystallizer vibration system to keep the synchronization of the crystallizer vibration, the crystallizer vibration system uses the prior art.

[0050] The upper crystallizer 1 and the lower crystallizer 2 have a set of cooling water system respectively to distinguish the cooling intensity, when the billet is produced, the water quantity of the cooling copper pipe of the upper crystallizer is 2300L / min~2700L / min, the water quantity of the cooling copper pipe of the lower crystallizer is 2000L / min~2400L / min, other cooling processes use the prior art.

[0051] The copper pipe of the lower crystallizer 2 is the air-permeable copper pipe with hot surface air-permeable and cold surface air-impermeable made by 3D printing method.

[0052] The lubricating grease is uniformly injected between the steel billet and the hot surface of the crystallizer through the holes of the air-permeable copper pipe, the injection speed of the lubricating grease is 50-300L / minute, in order to prevent the blockage of the oil pipeline, the oil pressure in the oil pipe is 2-6atm, the lubricating grease is rapeseed oil.

[0053] The 3D printing method is used to make the lower crystallizer copper pipe 1 / 2 thickness to the hot surface into a breathable state, and the hole of the breathable copper pipe is an oil conveying pipeline. The specific structure of the oil conveying pipeline is that the 3D printing method is used to print an oil conveying main road 21 at the 1 / 2 thickness of the lower crystallizer copper pipe and the external lubricant storage device, and print an oil conveying secondary trunk road 22 and an oil conveying branch road 23 between the 1 / 2 thickness of the lower crystallizer copper pipe and the hot surface of the copper pipe. The opposite outer side of the oil conveying main road 21 is communicated with the external lubricant storage device, the opposite inner side of the oil conveying main road 21 is connected to the oil conveying branch road 23 through the oil conveying secondary trunk road 22 arranged in the lower crystallizer, the oil conveying branch road 23 and the hot surface of the copper pipe intersect to form an oil conveying hole, the oil conveying secondary trunk road 22 is connected with the oil conveying main road 21 and the oil conveying branch road 23, and the lubricating oil flows out from the hot surface of the lower crystallizer copper pipe 2 in turn through the oil conveying main road 21, the oil conveying secondary trunk road 22 and the oil conveying branch road 23.

[0054] The oil conveying main road 21 is a fine hole with a diameter of 3000 μm, the oil conveying secondary trunk road 22 is a fine hole with a diameter of 800 μm, the oil conveying branch road 23 is a fine hole with a diameter of 150 μm, and the number density of the oil injection fine holes at the hot surface of the copper pipe is 1 / cm 2 The diameter of the oil conveying hole at the hot surface of the copper pipe is the same as the diameter of the oil conveying branch road.

[0055] The taper of the hot surface of the upper crystallizer 1 copper pipe is (0.4-2.5) % / m, and the taper of the hot surface of the lower crystallizer 2 copper pipe is (0.47-0.65) % / m. Both the upper crystallizer 1 and the lower crystallizer 2 are self-contracted from top to bottom.

[0056] Specifically, in the upper crystallizer 1,

[0057] The upper surface of the upper crystallizer to the 100 mm segment below the upper surface of the upper crystallizer is a straight pipe segment;

[0058] The 100 mm-200 mm segment below the upper surface of the upper crystallizer, the taper is (2-2.5) % / m;

[0059] The 200 mm-400 mm segment below the upper surface of the upper crystallizer, the taper is (1-1.25) % / m;

[0060] The 400 mm-600 mm segment below the upper surface of the upper crystallizer, the taper is (0.6-0.7) % / m;

[0061] The 600 mm segment below the upper surface of the upper crystallizer to the bottom surface of the upper crystallizer, the taper is (0.4-0.5) % / m.

[0062] In the lower crystallizer 2,

[0063] The 200 mm segment below the upper surface of the lower crystallizer to the lower surface of the lower crystallizer, the taper is (0.6-0.65) % / m;

[0064] The taper of the section 200mm-400mm below the top surface of the lower crystallizer is (0.55-0.6) % / m;

[0065] The taper of the section 400mm-600mm below the top surface of the lower crystallizer is (0.5-0.55) % / m;

[0066] The taper of the section 600mm below the top surface of the lower crystallizer to the bottom surface of the lower crystallizer is (0.47-0.5) % / m.

[0067] The adjacent taper sections are connected by a round corner.

[0068] Example 2

[0069] A billet production method using the above-mentioned billet crystallizer, in this example, the size of the billet is 160mmx160mm, the molten steel and the protective slag are injected from the upper end of the crystallizer body, the molten steel sequentially passes through the upper crystallizer 1 and the lower crystallizer 2 and is discharged,

[0070] The water flow rate of the water cooling device of the upper crystallizer is 2500L / min, the water flow rate of the water cooling device of the lower crystallizer is 2200L / min, the injection speed of the lubricant in the lubricating pipeline is 150L / min, and the pressure in the lubricating pipeline is maintained at 5atm,

[0071] The drawing speed of the billet crystallizer is 7.5m / min.

[0072] In this example, the lubricant is selected to be rapeseed oil.

[0073] As shown in Figure 2 Fig. 1, the liquid crystallizer protective slag 3 formed after the liquid surface crystallizer protective slag 5 on the crystallizer molten steel liquid surface in the upper crystallizer 1 melts, after the liquid crystallizer protective slag 3 flows into the space between the cast billet 8 and the crystallizer, the part close to the crystallizer body contacts the inner wall of the crystallizer body and rapidly solidifies to form a layer of solid crystallizer protective slag 4, and a part of the liquid crystallizer protective slag 3 remains between the solid crystallizer protective slag 4 and the cast billet 8, which has a lubricating effect on the cast billet 8, but the temperature of the upper crystallizer 1 gradually decreases from top to bottom, and the remaining liquid crystallizer protective slag 3 also gradually decreases, when the liquid crystallizer protective slag 3 completely solidifies at the lower part of the upper crystallizer 1, the lubricating effect between the cast billet 8 and the crystallizer wall becomes poor, and an air gap 7 appears, and the heat conduction effect between the cast billet 8 and the crystallizer wall also becomes poor.

[0074] At this time, the lubricating grease enters the lower crystallizer 2 along the main oil delivery path 21, the secondary oil delivery path 22 and the tertiary oil delivery path 23, and the lubricating grease in the lower crystallizer 2 carbonizes under the high-temperature baking of the cast slab 8. The residual lubricant carbide 6 between the crystallizer wall of the lower crystallizer 2 and the solid mold flux has a good lubricating effect, which can solve the problem that the liquid mold flux cannot flow to the lower part of the crystallizer and the lower part of the crystallizer has poor lubricating effect, and can improve the overall lubricating effect of the crystallizer.

[0075] After improving the lubricating effect of the lower crystallizer 2, the drawing resistance can be reduced, so the taper of the lower crystallizer can be appropriately increased, and the adhesion between the inner surface of the lower crystallizer 2 and the surface of the cast slab 8 can be improved (in the traditional crystallizer, a gap is intentionally left between the lower part of the crystallizer and the cast slab shell to reduce the drawing resistance), Figure 2 In the above, the air gap 7 exists between the solid mold flux 4 of the upper crystallizer 1 and the cast slab 8. After the taper of the copper tube hot surface of the lower crystallizer 2 is increased to 0.47-0.65% / m, the air gap 7 between the cast slab 8 and the solid mold flux 4 in the lower crystallizer 2 is eliminated, the thermal resistance between the crystallizer and the shell is reduced, and thus the thickness of the shell out of the crystallizer can be improved.

[0076] By Figure 2 As can be seen, since the lubricating grease is additionally added to the lower crystallizer 2 of the crystallizer to lubricate the cast slab 8, the problem that the drawing resistance increases sharply with the increase of the length of the crystallizer is alleviated, so the total length of the crystallizer can be increased to 1500mm, the growth time of the cast slab shell in the crystallizer can be improved, the thickness of the shell out of the crystallizer can be improved, and the crystallizer is suitable for high-speed continuous casting machines.

[0077] Experimental Example 1

[0078] The device provided in Example 1 and the billet production method of Example 2 and the billet crystallizer device and method used by Fujian Sanming Steel provided in page 159 of "Key Technology Research on High Speed Continuous Casting of Small Square Billets of Plain Carbon Steel", Doctoral Dissertation of Chen Yang were used respectively to produce 160mmx160mm square billets, and the crystallizer length, the drawing speed and the cast slab characteristic parameters were summarized as follows:

[0079] Table 1 Comparison of parameters

[0080]

[0081] As shown in Table 1, compared with the traditional crystallizer, after the total length of the square billet crystallizer is increased from 900 mm to 1500 mm (increased by 70%), the tension of the straightening mill is only increased by about 0.5 KN (increased by about 10%), the reason is that the square billet crystallizer provided by the application is composed of an upper crystallizer and a lower crystallizer, the length of the upper crystallizer is less than that of the traditional crystallizer, which can reduce the length of the position in the crystallizer that cannot be covered by the liquid protective slag, which is equivalent to reducing the friction between the crystallizer and the cast billet, and the lower crystallizer is lubricated by grease, the oil injection holes are uniformly distributed on the copper plate wall, and the carbon and carbide left after the high-temperature carbonization of the lubricating grease can provide good lubrication effect, so the lubrication effect between the crystallizer body and the cast billet is good, while the lower part of the traditional crystallizer cannot be covered by the hot-state protective slag, and the lubrication effect between the lower part of the traditional crystallizer and the cast billet is poor. The crystallizer provided by the application can solve the problem that the liquid protective slag cannot flow to the lower part of the crystallizer, and the lubrication effect of the lower part of the crystallizer is poor, and can improve the overall lubrication effect of the crystallizer.

[0082] At the same time, after the maximum drawing speed is increased from 4.5 m / min to 7.5 m / min, the billet shell thickness at the maximum drawing speed is increased by 2 mm, the reason is that the total length of the square billet crystallizer is about 600 mm longer than that of the traditional crystallizer, so after the drawing speed is increased, the residence cooling time of the cast billet in the crystallizer is not shortened, and the taper of the lower crystallizer in the crystallizer is 0.47-0.65% / m, increasing the taper is beneficial to reduce the air gap between the cast billet and the crystallizer wall, reduce the thermal resistance between the cast billet and the crystallizer wall, improve the heat transfer effect between the cast billet and the crystallizer wall, and increase the cast billet shell thickness.

[0083] Compared with the traditional crystallizer, after the square billet crystallizer provided by the application is used, the temperature of the cut-to-size cast billet and the single-flow hourly output of the cast billet are greatly increased, the reason is that the great increase of the drawing speed of the continuous casting machine is beneficial to improve the production efficiency of the enterprise and reduce the subsequent rolling line cast billet heating cost.

[0084] At the same time, the service life of the crystallizer is increased from 13,000 tons to 19,000 tons, the reason is that the square billet production method provided by the application improves the lubrication effect between the crystallizer wall and the cast billet, the wear of the crystallizer copper plate is reduced, and the service life of the crystallizer is improved.

[0085] In summary, compared with the traditional crystallizer, after the square billet crystallizer and the square billet production method provided by the application are used, the quality of the cast billet and the wear of the crystallizer are not deteriorated, while the continuous casting hourly output and the surface temperature of the red billet after cutting-to-size are greatly increased, which can bring good economic benefits to the enterprise.

Claims

1. A bloom crystallizer suitable for high-pull rate production, characterized in that, The structure is as follows: The crystallizer is composed of an upper crystallizer with a copper pipe length of 800-850 mm and a lower crystallizer with a copper pipe length of 600-750 mm, The cross-sectional size of the lower copper pipe of the upper crystallizer and the cross-sectional size of the upper copper pipe of the lower crystallizer are completely the same, and the lower opening of the upper crystallizer and the upper opening of the lower crystallizer are tightly connected by welding, The upper crystallizer and the lower crystallizer share a set of crystallizer vibration systems, The upper crystallizer and the lower crystallizer each have a set of cooling water systems, and when the billet is drawn, the water flow of the cooling copper pipe of the upper crystallizer is 2300 L / min~2700 L / min, and the water flow of the cooling copper pipe of the lower crystallizer is 2000 L / min~2400 L / min; The copper pipe of the lower crystallizer is a 3D-printed air-permeable copper pipe with a hot surface that is air-permeable and a cold surface that is air-impermeable, The 3D printing method is used to make the lower crystallizer copper pipe 1 / 2 thickness to the hot surface into an air-permeable state, and the hole of the air-permeable copper pipe is an oil delivery pipeline, and the specific structure of the oil delivery pipeline is that the 3D printing method is used to print an oil delivery main trunk at the 1 / 2 thickness of the external lubricant storage device and the lower crystallizer copper pipe, and print an oil delivery secondary trunk and an oil delivery branch between the 1 / 2 thickness of the lower crystallizer copper pipe and the hot surface, the outer side of the oil delivery main trunk is communicated with the external lubricant storage device, the inner side of the oil delivery main trunk is connected to the oil delivery branch through the oil delivery secondary trunk arranged inside the lower crystallizer, and the oil delivery branch intersects with the hot surface of the copper pipe to form an oil delivery hole, The oil delivery sub-main road is connected with the oil delivery main road and the oil delivery branch, the oil delivery main road is a fine hole with a diameter of 2000-4000 μm, the oil delivery branch main road is a fine hole with a diameter of 500-1000 μm, the oil delivery branch is a fine hole with a diameter of 100-200 μm, and the number density of the oil delivery holes at the hot surface of the copper pipe is 0.5-2 per cm 2 The diameter size of the oil delivery hole at the hot surface of the copper pipe is the same as that of the oil delivery branch. The lubricating oil is uniformly injected between the steel billet and the hot surface of the lower crystallizer through the oil delivery pipeline, the injection speed of the lubricating oil is 50-300 L / min, the pressure of the oil in the oil delivery pipeline is 2-6 atmospheres, and the lubricating oil is rapeseed oil or mineral oil, The lubricating oil flows out from the hot surface of the lower crystallizer copper pipe after passing through the oil delivery main trunk, the oil delivery secondary trunk and the oil delivery branch in turn, The upper part of the upper crystallizer is provided with a protective slag adding device, The taper of the hot surface of the upper crystallizer copper pipe is 0.4-2.5% / m, and the taper of the hot surface of the lower crystallizer copper pipe is 0.47-0.65% / m, and the hot surfaces of the upper crystallizer and the lower crystallizer copper pipe are all in a self-top-to-bottom shrinkage shape; The drawing speed of the square billet crystallizer is 4-7.5 m / min.

2. A bloom crystalliser as claimed in claim 1, wherein In the upper crystallizer, The section from the top surface of the upper crystallizer to the section 100 mm below the top surface of the upper crystallizer is a straight pipe section; The section 100 mm-200 mm below the top surface of the upper crystallizer has a taper of 2-2.5% / m; The section 200 mm-400 mm below the top surface of the upper crystallizer has a taper of 1-1.25% / m; The section 400 mm-600 mm below the top surface of the upper crystallizer has a taper of 0.6-0.7% / m; The section from the section 600 mm below the top surface of the upper crystallizer to the bottom surface of the upper crystallizer has a taper of 0.4-0.5% / m.

3. The bloom crystallizer of claim 1 wherein, In the lower crystallizer, The section from the top surface of the lower crystallizer to the section 200 mm below the top surface of the lower crystallizer has a taper of 0.6-0.65% / m; The section 200 mm-400 mm below the top surface of the lower crystallizer has a taper of 0.55-0.6% / m; The section 400 mm-600 mm below the top surface of the lower crystallizer has a taper of 0.5-0.55% / m; The taper of the section from 600mm below the top surface of the lower crystallizer to the bottom surface of the lower crystallizer is 0.47-0.5% / m.

4. A bloom crystalliser as claimed in either of claims 2 or 3, wherein, The adjacent taper sections are connected by a round corner.

5. A billet production method characterized by, The billet crystallizer is used to inject molten steel and protective slag from the upper end of the crystallizer, and the molten steel sequentially passes through the upper crystallizer and the lower crystallizer and is discharged, The upper crystallizer is provided with a protective slag adding device, The water flow of the cooling copper pipe of the upper crystallizer is 2300-2700L / min, the water flow of the cooling copper pipe of the lower crystallizer is 2000-2400L / min, the injection speed of the lubricant in the lubricating pipe is 50-300L / min, and the pressure in the lubricating pipe is kept at 2-6 atmospheres, The drawing speed of the billet crystallizer is 4-7.5m / min.

6. The square production method according to claim 5, characterized by, The lubricant is selected from rapeseed oil or mineral oil.

Images