Hot rolling coiler upper pinch roller and production method thereof, hot rolling coiler

Abstract

The present invention relates to the technical field of steel production equipment, and more specifically, to a hot rolling coiler upper pinch roller, a production method thereof, and a hot rolling coiler; the roller body of the hot rolling coiler upper pinch roller comprises, from the inside to the outside, an inner cylinder and a working layer, the working layer comprising a working inner layer and a working outer layer, both of which are formed by centrifugal composite casting, wherein, by weight percentage, the composition of the working outer layer comprises: C: 3.0-3.5%, Si: 0.5-1.0%, Mn: 0.5-1.0%, Cr: 1.5-2.5%, Ni: 4.0-4.5%, Mo: 0.3-1.0%, and the remainder is Fe; the composition of the working inner layer comprises: C: 3.0-3.5%, Si: 1.5-2.0%, Mn: 0.5-1.0%, and the remainder is Fe. The upper pinch roller provided by the present invention has good thermal fatigue resistance and wear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production equipment, and in particular to a pinch roller on a hot rolling coiler and a production method thereof, and a hot rolling coiler. Background Art

[0002] The pinch rolls of a hot rolling coiler are primarily used to guide and pinch the rolled steel plates. Operating at temperatures of approximately 500-700°C, they must withstand significant pressure during operation, requiring the surface of the pinch rolls to exhibit excellent thermal fatigue and wear resistance. Furthermore, due to the long cycle of roll replacement and regrinding, they must also have a long service life. Traditional upper pinch rolls are primarily constructed by welding a layer of alloy onto the roll surface, requiring multiple passes of cladding. This process can easily lead to defects such as cracks and pores, which affect the upper pinch rolls' thermal fatigue and wear resistance. Furthermore, the upper pinch rolls require preheating of the base material, coloring, and flaw detection, resulting in a long production cycle. When repairing the roll surface, high welding material quality is required, and the cladding process is complex. Furthermore, the upper pinch rolls experience significant vibration during operation, making it difficult to ensure operational stability. Furthermore, the upper pinch rolls experience significant deformation during operation, hindering product shape control. Summary of the Invention

[0003] The technical problem solved by the present invention is at least one of the following problems: the upper pinch roller in the prior art cannot guarantee good thermal fatigue resistance and wear resistance; the upper pinch roller in the prior art has a long production cycle, and when the roller surface is repaired, the quality requirements of the welding material are high, and the surfacing process is complicated; the vibration amplitude of the upper pinch roller during operation is large, and it is difficult to ensure the stability of the pinch roller during operation; the upper pinch roller is greatly deformed during operation, which is not conducive to the plate shape control of the product.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A pinch roller on a hot rolling line coiler, wherein the roller body of the pinch roller on the hot rolling line coiler includes an inner cylinder and a working layer from the inside to the outside, the working layer includes a working inner layer and a working outer layer, and the working inner layer and the working outer layer are both formed by centrifugal composite casting, wherein the working outer layer is made of high nickel-chromium-molybdenum material, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 0.5-1.0%, Mn: 0.5-1.0%, Cr: 1.5-2.5%, Ni: 4.0-4.5%, Mo: 0.3-1.0%, and the rest are Fe components; the working inner layer is made of nodular cast iron, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 1.5-2.0%, Mn: 0.5-1.0%, and the rest are Fe components.

[0006] The present invention also provides a method for producing a pinch roller on a hot rolling line coiler, which is used to produce the pinch roller on the hot rolling line coiler as described above, comprising:

[0007] Step S1, preparing an outer layer of molten iron for casting a working outer layer and an inner layer of molten iron for casting a working inner layer respectively;

[0008] Step S2, pouring the outer layer molten iron into a centrifugal mold equipped with an inner cylinder, and performing a first cooling and solidification under the action of centrifugal force to obtain a working outer layer;

[0009] Step S3: pouring the inner layer molten iron into the inner side of the working outer layer, cooling and solidifying it for the second time under the action of centrifugal force, obtaining a working inner layer between the working outer layer and the inner cylinder, and performing heat preservation treatment to obtain the pinch roller on the hot rolling line coiler.

[0010] Optionally, in step S2, the pouring temperature is 1320-1340°C, and the first cooling and solidification time is 5-6 minutes.

[0011] Optionally, in step S3, the thickness of the working inner layer is 65-75 mm.

[0012] Optionally, in step S3, the pouring temperature is 1330-1350°C.

[0013] Optionally, in step S1, the method for preparing the outer layer of molten iron includes: smelting at 1500-1530°C to obtain an intermediate outer layer of molten iron, taking the intermediate outer layer of molten iron out of the furnace at 1380-1420°C, and inoculating to obtain the outer layer of molten iron; wherein the inoculant used in the inoculation treatment is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.34-0.36%.

[0014] Optionally, in step S1, the method for preparing the inner layer of molten iron includes: smelting at 1500-1530°C to obtain an intermediate inner layer of molten iron, taking the intermediate inner layer of molten iron out of the furnace at 1400-1420°C, and inoculating to obtain the inner layer of molten iron; wherein the inoculant used in the inoculation treatment is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate inner layer of molten iron is 1.1-1.3%.

[0015] Optionally, in step S2 and step S3, the centrifugal force is generated by rotating the centrifugal die, and when the diameter of the pinch roller on the hot rolling line coiler is 500-900 mm, the rotation speed of the centrifugal die is 480-600 rpm.

[0016] Optionally, in step S3, the temperature of the heat preservation treatment is 850-950° C., and the time is 40-80 hours.

[0017] The present invention also provides a hot rolling coiler, comprising the hot rolling coiler upper pinch roller as described above.

[0018] Compared with the prior art, the hot rolling line coiler upper pinch roller provided by the present invention is manufactured by centrifugal composite casting, and the carbon content in the working outer layer is 3.0-3.5%, which can ensure that the working outer layer contains a certain amount of carbides and that there is enough carbon to form free graphite. Under this carbon content, based on the heredity of the charge, the morphology of the free graphite can be improved, thereby ensuring that the working outer layer has good thermal stability and fatigue resistance, and further ensuring that the upper pinch roller has high wear resistance and thermal fatigue resistance; in addition, the chromium contained in the working outer layer is a strong carbide-forming element, which can promote the formation of (Cr, Fe )3C type carbide, under the condition of certain carbon content, forms austenite with low carbon content, and forms a small amount of martensite structure during subsequent transformation, thereby further improving the hardness and wear resistance of the working outer layer; the nickel contained in the working outer layer can enhance the strength of the working outer layer, refine the grain size of the structure, and expand the austenite phase area. Nickel can also be dissolved in the working outer layer to transform the structure of the working outer layer into bainite, and at the same time form a small amount of martensite structure, thereby improving the wear resistance of the working outer layer; the molybdenum contained in the working outer layer is a strong carbide-forming element, which can increase the hardenability. The carbide formed by molybdenum has a high hardness and can increase the wear resistance of the working outer layer. The working inner layer of the present invention is made of inoculated cast iron, wherein the carbon content is 3.0-3.5%, the silicon content is 1.5-2.0%, and the manganese content is 0.5-1.0%. Carbon and silicon are the basis for the formation of the inoculated cast iron structure. When the carbon equivalent value reaches the eutectic point, a eutectic transformation occurs. When the carbon equivalent value is constant, the silicon-carbon ratio is increased, and silicon can be dissolved in ferrite, strengthening the matrix while reducing the tendency of the molten iron to white cast. The addition of manganese can dissolve in the matrix and carbides, thereby refining pearlite and graphite, blunting the graphite flake heads, and reducing the shrinking effect of graphite on the matrix. The graphite in the inoculated cast iron structure of the working inner layer exists in a flake form. The large number of graphite flakes cut the inner layer matrix, preventing the propagation of vibration and converting vibration into heat energy for dissipation. Therefore, the material of the working inner layer has a vibration-absorbing effect, which can ensure the working stability of the upper pinch roll. The cast iron has good rigidity, which reduces the deformation of the upper pinch roll and facilitates plate shape control. In addition, the upper pinch roller in the present invention is designed with a double-layer metal centrifugal composite casting process, that is, the working layer is a centrifugal composite of a working outer layer made of a high nickel-chromium-molybdenum alloy material and a working inner layer made of a nodular cast iron material. If a single high nickel-chromium-molybdenum material is used as the working layer, due to the high alloy content, high brittleness and high internal stress of the working layer, it is very easy to crack due to the large internal stress during the insulation cooling process. Therefore, the working layer in the present invention adopts a double-layer metal centrifugal composite casting design. On the one hand, the thickness of the high nickel-chromium-molybdenum material layer is reduced, thereby reducing the internal stress and reducing the risk of cracking; on the other hand, the alloy content of the working inner layer material is low, the cost is low, and the manufacturing cost of the upper pinch roller is reduced.In addition, if the working layer of the upper pinch roller is entirely centrifugally cast using a single layer of high nickel, chromium, and molybdenum, under the influence of the alloying elements nickel, chromium, and molybdenum, a large amount of carbides and residual austenite will inevitably exist in the working layer structure. Carbides are brittle and are prone to peeling or cracking during subsequent processing. In addition, the transformation of the residual austenite increases the volume, thereby increasing the thermal stress and residual stress of the working layer. Therefore, compared to the upper pinch roller using a single layer of high nickel, chromium, and molybdenum centrifugally cast, the double-layer metal centrifugal composite casting process design of the present invention can reduce the thermal stress and residual stress of the upper pinch roller. The production method of the upper pinch roller provided by the present invention has a shorter manufacturing cycle, and the roller surface repair process of the manufactured upper pinch roller is also simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the pinch roller on the hot rolling line coiler in an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the process of producing a pinch roller on a hot rolling line coiler according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic structural diagram of a centrifugal mold in an embodiment of the present invention;

[0022] Figure 4 Schematic diagram of the hot rolling line coiler pinch roller in the centrifugal mold after preparation in an embodiment of the present invention;

[0023] Figure 5 This is one of the metallographic organization diagrams of the working outer layer prepared in Example 1 (magnified 100 times);

[0024] Figure 6 The second metallographic structure diagram of the working outer layer prepared in Example 1 (magnified 50 times);

[0025] Figure 7 This is one of the metallographic organization diagrams of the working outer layer prepared in Example 2 (magnified 100 times);

[0026] Figure 8 This is the second metallographic structure diagram of the working outer layer prepared in Example 2 (magnified 50 times).

[0027] Description of reference numerals:

[0028] 1. Inner tube, 2. Working layer, 201. Working inner layer, 202. Working outer layer. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] It should be noted that, unless otherwise specified, the features of the embodiments of the present invention may be combined with each other. The terms "comprising," "including," "containing," and "having" are non-restrictive and may include other steps and other components that do not affect the results. The above terms encompass the terms "consisting of" and "consisting essentially of." Unless otherwise specified, materials, equipment, and reagents were commercially available.

[0031] like Figure 1 As shown, an embodiment of the present invention provides a pinch roller on a hot rolling line coiler, wherein the roller body of the pinch roller on the hot rolling line coiler includes an inner cylinder 1 and a working layer 2 from the inside to the outside, wherein the working layer 2 includes a working inner layer 201 and a working outer layer 202, wherein both the working inner layer 201 and the working outer layer 202 are formed by centrifugal composite casting, wherein the working outer layer 202 is made of high nickel-chromium-molybdenum material, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 0.5-1.0%, Mn: 0.5-1.0%, Cr: 1.5-2.5%, Ni: 4.0-4.5%, Mo: 0.3-1.0%, and the rest are Fe components; the working inner layer 201 is made of nodular cast iron, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 1.5-2.0%, Mn: 0.5-1.0%, and the rest are Fe components.

[0032] In the embodiment of the present invention, the functions of the elements in the working outer layer 202 are as follows:

[0033] C: The carbon content in the working outer layer is 3.0-3.5%, which can ensure that the working outer layer contains a certain amount of carbides and that there is enough carbon to form free graphite. At this carbon content, based on the heredity of the charge, the morphology of free graphite can be improved, thereby ensuring that the working outer layer has good thermal stability and fatigue resistance, and thus ensuring that the upper pinch roller has high wear resistance and thermal fatigue resistance.

[0034] Si: Regulates hardness. Silicon in molten iron can be deoxidized. Inoculated ferrosilicon can reduce the tendency of molten iron to be supercooled, providing conditions for graphite precipitation, thereby obtaining a good graphite morphology. Secondly, silicon can shorten the incubation period, reduce the stability of austenite, and accelerate the transformation process.

[0035] Cr: Chromium is a strong carbide-forming element, which can promote the formation of (Cr, Fe)3C type carbides in the working outer layer. Under the condition of a certain carbon content, it forms austenite with a low carbon content, and forms a small amount of martensite structure during subsequent transformation, thereby further improving the hardness and wear resistance of the working outer layer.

[0036] Mn: The role of manganese is to assist in silicon deoxidation. Manganese can also remove sulfur from molten iron. In addition, manganese can improve the stability of austenite.

[0037] Ni: Nickel can increase the strength of the working outer layer, refine the grain size, and expand the austenite phase. Nickel can also be dissolved in the working outer layer to transform the structure of the working outer layer into bainite, while forming a small amount of martensite structure, thereby improving the wear resistance of the working outer layer.

[0038] Mo: Molybdenum is a strong carbide-forming element that can increase hardenability. The carbide formed by molybdenum has a high hardness and can increase the wear resistance of the working outer layer.

[0039] Compared with the prior art, the hot rolling line coiler upper pinch roller provided by the present invention is manufactured by centrifugal composite casting, and the carbon content in the working outer layer is 3.0-3.5%, which can ensure that the working outer layer contains a certain amount of carbides and that there is enough carbon to form free graphite. Under this carbon content, based on the heredity of the charge, the morphology of the free graphite can be improved, thereby ensuring that the working outer layer has good thermal stability and fatigue resistance, and further ensuring that the upper pinch roller has high wear resistance and thermal fatigue resistance; in addition, the chromium contained in the working outer layer is a strong carbide-forming element, which can promote the formation of (Cr, Fe )3C type carbide, under the condition of certain carbon content, forms austenite with low carbon content, and forms a small amount of martensite structure during subsequent transformation, thereby further improving the hardness and wear resistance of the working outer layer; the nickel contained in the working outer layer can enhance the strength of the working outer layer, refine the grain size of the structure, and expand the austenite phase area. Nickel can also be dissolved in the working outer layer to transform the structure of the working outer layer into bainite, and at the same time form a small amount of martensite structure, thereby improving the wear resistance of the working outer layer; the molybdenum contained in the working outer layer is a strong carbide-forming element, which can increase the hardenability. The carbide formed by molybdenum has a high hardness and can increase the wear resistance of the working outer layer. The working inner layer of the present invention is made of inoculated cast iron, wherein the carbon content is 3.0-3.5%, the silicon content is 1.5-2.0%, and the manganese content is 0.5-1.0%. Carbon and silicon are the basis for the formation of the inoculated cast iron structure. When the carbon equivalent value reaches the eutectic point, a eutectic transformation occurs. When the carbon equivalent value is constant, the silicon-carbon ratio is increased, and silicon can be dissolved in ferrite, strengthening the matrix while reducing the tendency of the molten iron to white cast. The addition of manganese can dissolve in the matrix and carbides, thereby refining pearlite and graphite, blunting the graphite flake heads, and reducing the shrinking effect of graphite on the matrix. The graphite in the inoculated cast iron structure of the working inner layer exists in a flake form. The large number of graphite flakes cut the working inner layer matrix, preventing the propagation of vibration and converting vibration into heat energy for dissipation. Therefore, the material of the working inner layer has a vibration-absorbing effect, which can ensure the working stability of the upper pinch roll. The cast iron has good rigidity, which reduces the deformation of the upper pinch roll and facilitates plate shape control. In addition, the upper pinch roller in the present invention is designed with a double-layer metal centrifugal composite casting process, that is, the working layer is a centrifugal composite of a high-nickel-chromium-molybdenum alloy working outer layer and a nodular cast iron working inner layer. If a single high-nickel-chromium-molybdenum material is used as the working layer, due to the high alloy content, high brittleness and high internal stress of the working layer, it is very easy to crack due to the large internal stress during the insulation cooling process. Therefore, the working layer in the present invention adopts a double-layer metal centrifugal composite casting design. On the one hand, the thickness of the high-nickel-chromium-molybdenum material layer is reduced, thereby reducing the internal stress and reducing the risk of cracking; on the other hand, the alloy content of the working inner layer material is low, the cost is low, and the manufacturing cost of the upper pinch roller is reduced.Furthermore, if the working layer of the upper pinch roll is entirely centrifugally cast from a single layer of high-nickel, chromium, and molybdenum, the influence of the alloying elements nickel, chromium, and molybdenum will inevitably lead to the presence of a large amount of carbides in the working layer. Carbides are metastable phases that, under certain conditions, can transform into a stable system of austenite plus graphite. This transformation reduces shrinkage, thereby increasing thermal and residual stresses in the working layer. Therefore, compared to upper pinch rolls centrifugally cast from a single layer of high-nickel, chromium, and molybdenum, the dual-layer metal centrifugal composite casting process design of the present invention can reduce thermal and residual stresses in the upper pinch roll.

[0040] like Figure 2 As shown, an embodiment of the present invention further provides a method for producing a pinch roller on a hot rolling coiler, which is used to produce the pinch roller on the hot rolling coiler as described above, comprising:

[0041] Step S1, preparing an outer layer molten iron for casting the working outer layer 202 and an inner layer molten iron for casting the working inner layer 201 respectively;

[0042] Step S2: pouring the outer layer molten iron into a centrifugal mold equipped with the inner cylinder 1, and performing a first cooling and solidification under the action of centrifugal force to obtain a working outer layer 202;

[0043] Traditional upper pinch rollers primarily require a single alloy layer to be built up on the roller surface, requiring multiple passes and processes such as preheating the base metal and coloring and flaw detection, resulting in a long production cycle. Roller surface repair also places high demands on the quality of the welding material and requires a complex build-up welding process. The production method for upper pinch rollers provided by the embodiments of the present invention shortens the manufacturing cycle and simplifies the roller surface repair process.

[0044] It should be noted that the centrifugal mold adopts a conventional structure, and its structure is as follows Figure 3 As shown in the figure, the hot rolling line coiler pinch roller is prepared in the centrifugal mold, as shown in the figure. Figure 4 shown.

[0045] In some embodiments of the present invention, in step S2, the pouring temperature is 1320-1340°C, the first cooling and solidification time is 5-6 minutes, and the thickness of the working outer layer is 15-25 mm. In step S3, the pouring temperature is 1330-1350°C and the pouring time is 11-16 minutes, ensuring a thickness of the working inner layer of 65-75 mm. In embodiments of the present invention, the working layer of the upper pinch roller comprises a composite outer layer of high-nickel-chromium-molybdenum material and an inner layer of nodular cast iron. The pouring timing and temperature of the inner layer are crucial to the bonding strength and fusion layer thickness of the two layers. Based on the square root law of metal solidification theory combined with practical experience, the pouring timing of the inner layer of the upper pinch roller is determined to ensure a sufficient liquid phase or solidified zone on the inner surface of the outer layer to ensure bonding strength between the outer and inner layers while preventing the outer layer from being washed away and thinned, resulting in insufficient outer layer thickness. Furthermore, the thickness of the bonding layer must be controlled to prevent metallic elements in the outer layer from penetrating into the inner layer. Therefore, in the embodiment of the present invention, the cooling and solidification time of the working outer layer is set to 5-6 minutes.

[0046] In some embodiments of the present invention, in step S1, the method for preparing the outer layer of molten iron includes: smelting at 1500-1530°C to obtain an intermediate outer layer of molten iron, taking the intermediate outer layer of molten iron out of the furnace at 1380-1420°C, and inoculating to obtain the outer layer of molten iron; wherein the inoculant used in the inoculation treatment is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.34-0.36%.

[0047] In some embodiments of the present invention, in step S1, the method for preparing the inner layer of molten iron includes: smelting at 1500-1530°C to obtain an intermediate inner layer of molten iron, tapping the intermediate inner layer of molten iron at 1400-1420°C, and inoculating the inner layer of molten iron; wherein the inoculating agent used in the inoculation is 75SiFe, and the mass ratio of the inoculant to the mass of the intermediate inner layer of molten iron is 1.1-1.3%. Compared to the working inner layer of ductile iron, inoculated cast iron only requires the addition of 75SiFe as an inoculant during production. However, during production, ductile iron has a final silicon content that is approximately 0.7 higher than that of inoculated cast iron; secondly, its chemical composition has high requirements for phosphorus and sulfur content, requiring dephosphorization and sulfur treatment of the molten iron; and thirdly, the production of ductile iron requires the use of long-lasting inoculants, spheroidizers, etc. for inoculation and spheroidization, which is complex and has high material costs. Therefore, inoculated cast iron is used for the working inner layer. Cast iron inoculation treatment can promote graphitization, increase the number of eutectic clusters, control the graphite morphology, and thus improve the strength properties of cast iron.

[0048] In some embodiments of the present invention, in step S2 and step S3, the centrifugal force is generated by rotating the centrifugal die, and when the diameter of the pinch roller on the hot rolling line coiler is 500-900 mm, the rotation speed of the centrifugal die is 480-600 rpm.

[0049] In some embodiments of the present invention, in step S3, the temperature of the heat preservation treatment is 850-950° C. and the time is 40-80 hours.

[0050] The present invention also provides a hot rolling coiler, comprising the hot rolling coiler upper pinch roller as described above.

[0051] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0052] Example 1

[0053] The working outer layer is composed of 3.0% C, 0.5% Si, 0.7% Mn, 1.5% Cr, 4.0% Ni, 0.4% Mo, and the remainder is Fe. The working inner layer is composed of 3.0% C, 1.5% Si, 0.5% Mn, and the remainder is Fe. High-quality Benxi Q10 pig iron, nickel plate, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, and scrap steel are used as ingredients.

[0054] 1.1. Melting at 1520°C to obtain an intermediate outer layer of molten iron, the intermediate outer layer of molten iron is tapped at 1400°C and inoculated to obtain an outer layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.35%.

[0055] 1.2. An intermediate inner layer of molten iron is obtained by smelting at 1510°C, the intermediate inner layer of molten iron is tapped at 1405°C, and inoculated to obtain the inner layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate inner layer of molten iron is 1.2%.

[0056] 1.3. Pour the outer layer of molten iron into a centrifugal mold equipped with an inner cylinder, and cool and solidify it while the centrifugal mold rotates to obtain a working outer layer; wherein the pouring temperature is 1340°C, the first cooling and solidification time is 5 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0057] 1.4. The inner layer of molten iron is poured onto the inner side of the working outer layer, and cooled and solidified while the centrifugal mold rotates, thereby obtaining a working inner layer between the working outer layer and the inner tube. The pouring temperature is 1340° C., the pouring time is 16 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0058] 1.5. Keep the temperature at 900℃ for 72h to obtain the pinch roller on the hot rolling line coiler.

[0059] Example 2

[0060] The working outer layer is composed of 3.3% C, 0.7% Si, 0.7% Mn, 1.7% Cr, 4.2% Ni, 0.4% Mo, and the remainder is Fe. The working inner layer is composed of 3.3% C, 1.5% Si, 0.7% Mn, and the remainder is Fe. High-quality Benxi Q10 pig iron, nickel plate, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, and scrap steel are used as ingredients.

[0061] 2.1. Melting at 1520°C to obtain an intermediate outer layer of molten iron, the intermediate outer layer of molten iron is discharged from the furnace at 1410°C and inoculated to obtain an outer layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.35%.

[0062] 2.2. An intermediate inner layer of molten iron is obtained by smelting at 1510°C, the intermediate inner layer of molten iron is tapped at 1405°C, and inoculated to obtain the inner layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate inner layer of molten iron is 1.2%.

[0063] 2.3. Pour the outer layer of molten iron into a centrifugal mold equipped with an inner cylinder, and cool and solidify it while the centrifugal mold rotates to obtain a working outer layer; wherein the pouring temperature is 1335°C, the first cooling and solidification time is 5 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0064] 2.4. The inner layer of molten iron is poured onto the inner side of the working outer layer, and cooled and solidified while the centrifugal mold rotates, thereby obtaining a working inner layer between the working outer layer and the inner tube. The pouring temperature is 1340° C., the pouring time is 13 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0065] 2.5. Keep the temperature at 900℃ for 72h to obtain the pinch roller on the hot rolling line coiler.

[0066] Example 3

[0067] The working outer layer is composed of 3.3% C, 0.7% Si, 0.7% Mn, 1.8% Cr, 4.35% Ni, 0.35% Mo, and the remainder is Fe. The working inner layer is composed of 3.2% C, 1.6% Si, 0.7% Mn, and the remainder is Fe. High-quality Benxi Q10 pig iron, nickel plate, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, and scrap steel are used as ingredients.

[0068] 3.1. Melting at 1520°C to obtain an intermediate outer layer of molten iron, the intermediate outer layer of molten iron is discharged from the furnace at 1410°C and inoculated to obtain an outer layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.35%.

[0069] 3.2. Smelting at 1510°C to obtain an intermediate inner layer of molten iron, the intermediate inner layer of molten iron is tapped at 1405°C and inoculated to obtain the inner layer of molten iron; wherein the inoculant used in the inoculation is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate inner layer of molten iron is 1.2%.

[0070] 3.3. Pour the outer layer of molten iron into a centrifugal mold equipped with an inner cylinder, and cool and solidify it while the centrifugal mold rotates to obtain a working outer layer; wherein the pouring temperature is 1335°C, the first cooling and solidification time is 5 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0071] 3.4. The inner layer of molten iron is poured onto the inner side of the working outer layer, and cooled and solidified while the centrifugal mold rotates, thereby obtaining a working inner layer between the working outer layer and the inner tube. The pouring temperature is 1330° C., the pouring time is 11 minutes, and the centrifugal mold rotates at a speed of 540 rpm.

[0072] 3.5. Keep the temperature at 900℃ for 72h to obtain the pinch roller on the hot rolling line coiler.

[0073] Experimental example

[0074] The tensile strength and hardness of the working outer layer and the working inner layer in Examples 1-3 were tested, and the results are shown in Tables 1 and 2. The wear resistance of the metal can be measured based on the hardness of the material. It can be seen from Table 1 that the tensile strength of the high nickel-chromium-molybdenum alloy used as the working outer layer is 421-472 MPa, and the hardness is 69-76 HSD. The hardness of the finished upper pinch rollers welded with different welding wires in the prior art is generally below 64 HSD. It can be seen that the wear resistance of the high nickel-chromium-molybdenum alloy used as the working outer layer of the upper pinch roller in Examples 1-3 of the present invention is better than that of the welded roller, and the roller body of the centrifugal composite pinch roller contains 1%-2% free graphite, which cuts the matrix and prevents the expansion of cracks. Graphite has excellent thermal conductivity, and the peeling of free graphite during operation can play a certain lubricating effect. Therefore, the high nickel-chromium-molybdenum centrifugal composite upper pinch roller has good heat fatigue resistance. As can be seen from Table 2, the tensile strength of the working inner layer prepared in Examples 1-3 is 261-278 MPa, and the hardness is 193-207 HB.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] The metallographic structure of the working outer layer prepared in Example 1 was analyzed. Figure 5 and Figure 6 The metallographic structure of the working outer layer prepared in Example 2 was analyzed. Figure 7 and Figure 8 ,Depend on Figure 5-8 It can be seen that the microstructures of the working outer layers prepared in Example 1 and Example 2 consist of graphite, bainite, martensite, austenite and carbide, and graphite exists in the working outer layer in a free form.

[0080] After actual use, the upper pinch roller produced by the present invention has an average steel passing capacity of 530,000 tons, which is about twice that of the upper pinch roller made by surfacing welding in the prior art. It can be seen that the upper pinch roller produced by the present invention has a longer working life.

[0081] In addition, it should be noted that, although the present invention is disclosed as above, the scope of protection of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for producing a pinch roller on a hot rolling line coiler, characterized in that: The roller body of the pinch roller on the hot rolling line coiler comprises an inner cylinder (1) and a working layer (2) from the inside to the outside, the working layer (2) comprises a working inner layer (201) and a working outer layer (202), the working inner layer (201) and the working outer layer (202) are both formed by centrifugal composite casting, wherein the working outer layer (202) is made of a high nickel-chromium-molybdenum material, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 0.5-1.0%, Mn: 0.5-1.0%, Cr: 1.5-2.5%, Ni: 4.0-4.5%, Mo: 0.3-1.0%, and the rest is Fe; the working inner layer (201) is made of a nodular cast iron material, and its components, by weight percentage, include: C: 3.0-3.5%, Si: 1.5-2.0%, Mn: 0.5-1.0%, and the rest is Fe; The production method comprises: Step S1, preparing an outer layer of molten iron for casting a working outer layer (202) and an inner layer of molten iron for casting a working inner layer (201); Step S2, pouring the outer layer molten iron into a centrifugal mold equipped with an inner cylinder (1), and performing a first cooling and solidification under the action of centrifugal force to obtain the working outer layer (202); Step S3, pouring the inner layer molten iron into the inner side of the working outer layer (202), performing a second cooling and solidification under the action of centrifugal force, obtaining the working inner layer (201) between the working outer layer (202) and the inner cylinder (1), performing heat preservation treatment, and obtaining the pinch roller on the hot rolling line coiler; The preparation method of the inner layer molten iron includes: smelting at 1500-1530°C to obtain an intermediate inner layer molten iron, taking the intermediate inner layer molten iron out of the furnace at 1400-1420°C, and inoculating to obtain the inner layer molten iron; wherein the inoculant used in the inoculation treatment is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate inner layer molten iron is 1.1-1.3%.

2. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, characterized in that: In step S2, the pouring temperature is 1320-1340° C., and the first cooling and solidification time is 5-6 minutes.

3. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, wherein: In step S3, the thickness of the working inner layer (201) is 65-75 mm.

4. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, wherein: In step S3, the pouring temperature is 1330-1350°C.

5. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, wherein: In step S1, the method for preparing the outer layer of molten iron includes: smelting at 1500-1530°C to obtain an intermediate outer layer of molten iron, tapping the intermediate outer layer of molten iron at 1380-1420°C, and inoculating to obtain the outer layer of molten iron; wherein the inoculant used in the inoculation treatment is 75SiFe, and the ratio of the mass of the inoculant to the mass of the intermediate outer layer of molten iron is 0.34-0.36%.

6. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, wherein: In the step S2 and the step S3, the centrifugal force is generated by rotating the centrifugal die. When the diameter of the pinch roller on the hot rolling line coiler is 500-900 mm, the rotation speed of the centrifugal die is 480-600 rpm.

7. The method for producing a pinch roller on a hot rolling line coiler according to claim 1, wherein: In step S3, the temperature of the heat preservation treatment is 850-950° C. and the time is 40-80 hours.

8. A hot rolling coiler, characterized in that: It comprises a pinch roller on a hot rolling line coiler; the pinch roller on the hot rolling line coiler is manufactured by the production method of the pinch roller on a hot rolling line coiler according to any one of claims 1 to 7.

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