CN114260440B - Method for casting bimetallic brake drum in short process - Google Patents
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Abstract
A method for casting a bimetallic brake drum in a short process belongs to the technical field of casting. The outer layer of the brake drum takes scrap automobile plate steel blocks, Q235 scrap steel, high-carbon ferrochrome and manganese nitride iron as furnace charges, and is smelted in an intermediate frequency induction furnace, continuously cast into steel plates, welded and rolled to form, and the inner layer adopts high-strength wear-resistant gray cast iron, and the two are cast into metallurgical combination through centrifugal composite casting. Realizes the efficient utilization of the waste automobile plates and has high element yield. Compared with HT250 cast iron, the cast iron for the inner layer of the bimetal brake drum has the advantages of high-temperature tensile strength, crack initiation resistance and crack expansion resistance, long service life, safe and reliable use and the like. Compared with HT250 cast iron brake drums, the service life is prolonged by more than 2.5 times, and the popularization and application have good economic and social benefits.
Description
Technical Field
The invention discloses a method for casting a brake drum, in particular relates to a method for casting a bimetal brake drum in a short process, and belongs to the technical field of casting.
Background
At present, a conventional integrally cast drum brake is widely applied to a truck, and mainly comprises a brake drum and brake shoes, and kinetic energy of the motion of the truck is converted into heat energy by utilizing friction resistance, so that the running truck is decelerated or stopped, and the running safety is ensured. When the automobile runs at a heavy load and a high speed, particularly when the automobile runs down a long slope or a steep slope, the braking force is large, and the inner wall of the brake drum is rapidly increased due to continuous repeated braking, meanwhile, the temperature difference between the inner wall and the outer wall of the brake drum is increased, and the high-temperature mechanical property of the brake drum material is also rapidly reduced. The larger the wall thickness of the brake drum, the larger the temperature difference between the inside and the outside. The temperature difference stress and the high-temperature mechanical property of the material are deteriorated, so that the inner wall of the brake drum is often developed into cracks from longitudinal microcracks, and finally the brake drum is cracked, and the service life is short. In order to improve the performance of the brake drum and prolong the service life of the brake drum, chinese patent No. 113458363A discloses a bimetal iron-iron composite brake drum and a manufacturing method thereof, wherein the outer layer of the iron-iron composite brake drum adopts high-strength ductile iron or high-strength vermicular cast iron, and the inner layer adopts wear-resistant gray cast iron; and the two are metallurgically bonded, which specifically comprises the following steps: (1) The outer layer high-strength ductile iron or high-strength vermicular cast iron of the bimetal iron-iron composite brake drum is cast by adopting shell mold casting or static pressure casting; (2) After casting the outer iron shell, centrifugally casting the composite inner wear-resistant gray cast iron, spraying a layer of fusion agent on the inner layer of the iron shell before centrifugal casting, and adopting metallurgical bonding; in order to further increase the overall strength and rigidity of the brake drum, the thickness of the high-strength ductile iron/vermicular iron layer is increased as much as possible, and the thickness of the inner wear-resistant gray cast iron layer is 3-10mm. The strength of the iron-iron composite brake drum is higher than that of a single gray cast iron brake drum, but the outer layer ductile iron or vermicular cast iron still has the defects of low plasticity and toughness and easiness in cracking in use.
Chinese invention patent CN112855808A discloses a production process of a special steel and thermal fatigue resistant nano material composite brake drum, which is characterized by comprising the following steps of: (1) machining a flange part: manufacturing a flange part above the braking surface by adopting a spinning process, and processing a welding groove on the end surface of the spun flange; (2) machining a composite braking surface blank: i, pouring an outer layer: according to the length of the cylinder, calculating the mass of molten steel required by casting the outer layer, accurately weighing, and casting the molten steel into the cylinder rotating at a high speed once, wherein the casting temperature of the molten steel is 1560-1610 ℃; pouring the intermediate friction layer to obtain a composite braking surface blank: performing oxidation protection on the inner surface of molten steel, pouring molten metal of the middle friction layer when the temperature of the molten steel is reduced to 1350-1450 ℃, and completing the compounding of the outer layer and the middle friction layer after pouring to obtain a composite braking surface blank; rough machining a composite braking surface blank, and machining a closing-in inclined plane and a welding groove on one end face of the composite braking surface blank; (3) welding and forming: welding the flange part in the step (1) and the composite braking surface blank in the step (2) to obtain a composite blank; (4) and (3) processing the composite blank in the step (3) into a finished product to prepare the composite brake drum. The Chinese patent No. 112524178A also discloses a composite brake drum, which comprises a shell matrix and an inner layer reinforcement body, wherein the inner layer reinforcement body is circumferentially arranged on the inner wall of the shell matrix, the shell matrix is made of alloy steel plates, and the inner layer reinforcement body is a vermicular graphite cast iron composite layer. The composite brake drum and the preparation method thereof change the existing brake drum structure, adopt a shell matrix and an inner layer reinforcement body for composite reinforcement, and the inner layer reinforcement body adopts a vermicular cast iron composite layer, so that the composite brake drum has special graphite structure and performance, has an expansion coefficient similar to that of a steel flange shell, and further has better fatigue resistance. The Chinese patent No. 111120546A also discloses a bimetal composite brake drum and a manufacturing method thereof, wherein the bimetal composite brake drum comprises a shell and a cast iron lining which are connected in a non-detachable way, a first wavy structure is formed on the shell, and the outer wall surface of the cast iron lining is formed with a first wavy structure The second wavy structure is matched with the shape structure; a plurality of convex ribs which are circumferentially arranged at intervals and axially extend are formed on the inner wall surface of the shell, and a plurality of grooves which are matched with the convex ribs are also formed on the outer wall surface of the cast iron lining. The manufacturing method is to realize the manufacturing of the bimetal composite brake drum by a sand casting method, a roll forming method and a die casting method respectively. The bimetal composite brake drum is firm and durable, has high safety and can effectively reduce the generation and extension of cracks. The Chinese patent No. 110814672A also discloses a preparation process of the novel bimetal composite integrated brake drum, which is characterized by comprising the following steps that firstly, the upper flange part and the lower barrel part of the welding steel ring composite brake drum are respectively processed by processing raw materials; welding the upper flange part and the lower barrel part in the first step into a whole to obtain a fine spinning blank of the outer layer steel shell of the composite brake drum; rolling the fine spinning blank of the outer layer steel shell of the composite brake drum in the second step to form the outer layer steel shell of the composite brake drum; clamping the outer layer steel shell of the composite brake drum in the third step on a centrifugal machine, and pouring a certain amount of molten iron to obtain a bimetal composite integrated brake drum blank; and fifthly, machining the bimetal composite integrated brake drum blank in the fourth step to obtain a bimetal composite integrated brake drum finished product. The Chinese patent No. 106624657A also discloses a manufacturing method of the integral steel ring of the composite brake drum, which is characterized by comprising the following steps: a. selecting the thickness of the steel plate according to the size of the thickest part of the outer steel ring of the composite brake drum; b. determining the size of a round blank, blanking the steel plate in a cutting-in-sleeve blanking mode, blanking the steel plate into a round blank with a certain diameter, calculating the corresponding diameter of the round blank according to the volume of the outer steel ring, and reserving machining allowance of 5-10 mm; the diameter of the circular blank is calculated as follows: in the above formula: d is the diameter of the round blank; v is the volume of the outer steel ring; delta is a coefficient; c. machining a positioning process hole in the center of the circular blank, wherein the diameter of the positioning process hole is equal to that of the positioning process hole 
The method comprises the steps of carrying out a first treatment on the surface of the d. The rough spinning process is carried out twice by taking a center positioning process hole as a reference, a round blank is placed on a rough spinning mold core and fixed, a rough spinning wheel is gradually pressed down along the outline of the rough spinning mold core while the rough spinning mold core and the round blank rotate at high speed, and the rough spinning process of the round blank is completed twice to form a steel ring semi-finished product with the initial shape of an outer steel ring; e. the twice finish spinning processing is carried out by taking a center positioning process hole as a reference, placing a steel ring semi-finished product with an outer steel ring initial shape on a finish spinning mold core and fixing the steel ring semi-finished product, gradually pressing down a finish spinning wheel along the outline of the finish spinning mold core while the finish spinning mold core and the steel ring semi-finished product rotate at high speed, and finishing the finish spinning processing of the steel ring semi-finished product in two times to form finish spinning blanks with different cross section shapes and different cross section wall thicknesses; f. the roll forming adopts an upper roll and a lower roll which are matched with an upper concave-convex groove and a lower concave-convex groove, a fine spinning blank is placed on the lower roll and is pressed, the upper roll is pressed down while the upper roll and the lower roll rotate at high speed, and the roll forming of the fine spinning blank is completed, so that an integral steel ring with concave-convex groove shape in the middle of a braking surface is formed. However, in the preparation process of the composite brake drum, the outer steel ring needs to consume a large amount of high-quality steel plates, so that the manufacturing cost of the composite brake drum is high.
Chinese patent No. CN106438778A discloses a composite aluminium-iron brake drum, which is characterized in that an aluminium alloy heat dissipation structure layer is composited on the outer circumferential surface of the brake drum body, a composite interface is arranged between the aluminium alloy heat dissipation structure layer and the brake drum body, and the aluminium alloy heat dissipation structure layer and the brake drum body are integrated. The brake drum body is cast iron, and the aluminum alloy heat dissipation structure layer is made of high-strength aluminum alloy materials. The advantages are that: the aluminum alloy has the characteristics of low density, high strength, good heat conductivity, obvious heat dissipation effect, light weight, high strength of the brake drum, optimized heat dissipation performance, acceleration of brake heat exchange with air during braking, heat cracking prevention, prolonged service life, cracking problem solving, and light weight requirement of the automobile. The Chinese patent No. 106736301A also discloses a molding method of the press-fit bimetal composite brake drum, which is characterized in that: the method comprises the following steps: (1) A low-carbon steel pipe with the wall thickness of 7mm is manufactured into a low-carbon steel shell with the wall thickness of 4mm, the height of 330mm and the maximum outer diameter of 483mm by a cold drawing method, and the low-carbon steel shell is used as a brake drum jacket; (2) Melting molten iron, keeping the temperature of the molten iron at 1280-1290 ℃, and casting the molten iron into a cast iron pipe by using a horizontal centrifugal casting machine; wherein the rotating speed of the horizontal centrifugal casting machine in the casting process is 600-750 r/min; (3) Machining the cast iron pipe with the inner diameter of 460mm, the thickness of 8mm and the height of 300mm to make the outer diameter of the cast iron pipe larger than the inner diameter of the low carbon steel shell, and machining a plurality of grooves on the outer wall of the cast iron pipe; (4) Fixing the low-carbon steel shell on a hydraulic press, coating epoxy resin adhesive on the outer wall of the cast iron pipe and in the groove, and pressing the cast iron pipe into the low-carbon steel shell by the hydraulic press; (5) After the cast iron pipe is completely pressed in, the cast iron pipe and the low carbon steel shell are combined into a whole to form the bimetal composite brake drum, and the brake drum is taken down and placed for 24 hours, so that the bimetal composite brake drum can be installed for use. The method for manufacturing the brake drum has the advantages of complex process, high cost and difficult popularization and application.
China is a large world of automobile production and consumption, and the automobile has more than two hundred million cars. With the updating of the automobile industry, the number of scrapped automobiles per year is continuously increased, and the number of scrapped automobiles per year exceeds 1000 ten thousand. The continuous increase of the number of the scraped cars causes huge waste of resources and aggravates environmental pollution. The Chinese patent No. 13335423A discloses a recovery treatment process for scraped car, which is characterized in that: manually and mechanically disassembling an automobile body, and disassembling a storage battery and wheels; waste oil and waste liquid of the scraped car are extracted, cleaned and recycled; detonating the air bag to recycle usable parts, nonferrous metals, nonmetal and the like of the vehicle body; five assemblies of the vehicle body are crushed into a packing block through a flatting mill or a hanging hammer; shearing and crushing the flattened car body, sorting the cut car parts, and carrying out secondary processing on the waste with larger volume; placing the processed waste into a cleaning tank, adding a cleaning agent, and soaking for 24 hours; air-drying after salvaging, and transferring and storing; the invention has the advantages of simple structure, convenience, practicability, environment friendliness and high component recovery rate, and is used for recycling the scraped car. The Chinese patent No. 110682979A also discloses a scrapped car disassembling production line, which is characterized by comprising a front and rear glass disassembling station, a car door disassembling station, an interior offline disassembling station and a chassis offline disassembling station which are longitudinally and sequentially arranged along the production line; the front and rear gear glass disassembling station is provided with a manipulator and an AGV; a mobile manipulator is arranged on a production line from a front-back glass disassembling station to the upstream of an interior offline disassembling station and used for moving the scraped car between the stations; the vehicle disassembling robot and the AGV are respectively arranged at two sides of the vehicle door disassembling station; the inner decoration offline disassembly station is connected with the chassis offline disassembly station through a ground drag chain conveying assembly line, one end of the ground drag chain conveying assembly line extends to one side of the vehicle door disassembly station and forms a closed circulating conveying route, and the inner decoration offline disassembly station is used for conveying the scraped vehicle among the vehicle door disassembly station, the inner decoration offline disassembly station and the chassis offline disassembly station; the interior trim offline disassembly station is provided with a crane, a disassembly tool and an AGV; the chassis offline disassembly station is provided with a crane, a chassis tipping device and an AGV transport trolley, and the chassis tipping device is used for tipping the scrapped automobile for 180 degrees; and a plate chain conveyor is arranged on a production line at the downstream of the chassis tipping device. The Chinese patent No. 108014899A also discloses a recovery processing method of the scraped car door, which comprises the following steps: step one: firstly, a double-shaft shredder is used for breaking an automobile door into rectangular fragments of 5-20cm multiplied by 20-60cm, and then a vertical crusher is used for breaking the primary broken product into fragments of 3-20 cm; step two: and sequentially adopting a negative pressure-cyclone separation process, a magnetic separation process, an eddy current separation process and a roller screening process to separate and recycle the light substances, the magnetic metals, the nonferrous metals, the micro-powder substances, the glass, the rubber and the plastics after the car door is broken. Chinese patent No. CN106428305a also discloses a mobile disassembly platform for scraped car, which is characterized in that: the device comprises a moving tool with a platform, wherein a lifting device for lifting an automobile and automobile components, a lifting and overturning device capable of lifting and overturning the automobile and a safe and environment-friendly pretreatment device are arranged on the platform of the moving tool; the hoisting device is arranged in the center of the platform, the two lifting turnover devices are respectively arranged at the left side and the right side of the hoisting device and are respectively positioned at the edges of the front side and the rear side of the platform, and the safe and environment-friendly pretreatment device comprises disassembling equipment, waste oil liquid extracting equipment, refrigerant recovery equipment and safety airbag detonation equipment which are distributed on the front side and the rear side of the hoisting device and on one side of the two lifting turnover devices away from the hoisting device.
However, recycling of car shells (also called car panels) in currently scrapped cars is commonly used as scrap steel for steel mills as steelmaking raw materials. The steel for automobile is mainly composed of plate and special steel, and has the characteristics of high strength, thin specification and corrosion resistance, because in order to lighten the dead weight of the automobile product, save materials, reduce the consumption of fuel oil, reduce the cost and improve the safety standard, the steel with high strength and thin specification must be used. In addition, in order to improve the anti-corrosion performance of the automobile product and prolong the service life of the automobile, the surface treatment technology of the inner and outer plates of the automobile must be improved, and galvanized plates or alloy galvanized plates are generally adopted. Zinc density of 7.2g/cm 3 The melting point and the boiling point are low, namely 419.5 ℃ and 906 ℃. The waste automobile shell (also called waste automobile plate) is directly used as a steelmaking raw material, zinc element is seriously volatilized, the environment is polluted, and huge waste of zinc resources is caused.
Disclosure of Invention
Aiming at the problems in the production of the bimetal composite brake drum and the use of the scrapped car shell (also called as scrapped car plate), the invention provides a method for directly smelting the scrapped car shell into molten steel, adding a proper amount of reinforcing elements into the molten steel, directly casting the molten steel into a steel plate on a sheet billet continuous casting machine, rolling a part of the steel plate into a steel cylinder on a coiling machine, and firmly welding the steel cylinder. And cutting the other part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain an outer steel shell of the bimetal brake drum, pouring inner gray cast iron on the inner surface of the outer steel shell, and casting into a whole through centrifugal composite casting to obtain the bimetal brake drum with excellent performance. The invention is characterized in that the outer layer is processed by adopting a continuous cast steel plate which is smelted by taking a scraped car shell as a main part, the inner layer is made of high-strength wear-resistant gray cast iron, and the two materials are cast into metallurgical combination through centrifugal composite casting, and the specific process steps of the method for casting the bimetallic brake drum in a short process are as follows:
(1) Firstly, coarsely crushing a scrapped automobile shell by using a waste automobile shredder, and then packaging the crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250 mm;
(2) adopting steel blocks, Q235 scrap steel, high-carbon ferrochrome and manganese nitride in the step (1) as furnace charges, wherein the mass compositions of the Q235 scrap steel, the high-carbon ferrochrome, the steel blocks and the manganese nitride in the furnace charges are respectively as follows: 20-22%,1.0-1.2%,76-78%,0.8-1.0%, the sum of the mass fractions of the four furnace charges is 100%; firstly, mixing 20-22% of Q235 scrap steel and 1.0-1.2% of high-carbon ferrochrome in a medium-frequency induction furnace, heating and melting; after the Q235 scrap steel and the high-carbon ferrochrome are completely melted, adding 0.8-1.0% of ferromanganese nitride and 76-78% of steel blocks by mass when the temperature is raised to 1580-1595 ℃; after the ferromanganese nitride and the steel block are completely melted, heating to 1615-1630 ℃, discharging to a ladle, and adding Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon with the grain size of 3-6mm into the bottom of the ladle in advance; the addition of Si-Ca-Ba alloy, ferrotitanium, aluminum magnesium alloy and rare earth ferrosilicon respectively accounts for 0.3 to 0.5 percent, 0.25 to 0.30 percent, 0.18 to 0.22 percent and 0.15 to 0.20 percent of the mass fraction of molten steel entering the ladle; after slag skimming and standing, when the temperature is reduced to 1533-1548 ℃, directly casting the molten steel on a sheet billet continuous casting machine into a steel plate with the thickness of 12-16 mm;
(3) Rolling part of the steel plate obtained in the step (2) into a steel cylinder on a coiling machine and firmly welding the steel cylinder; cutting part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain a double-metal brake drum outer layer steel shell fine-turning blank, and rolling the double-metal brake drum outer layer steel shell fine-turning blank to obtain a composite brake drum outer layer steel shell; coating borax with the thickness of 0.8-1.2mm on the joint of the outer layer steel shell and the inner layer gray cast iron on the inner surface of the outer layer steel shell, rapidly heating the inner surface of the outer layer steel shell to 610-710 ℃ by using an induction coil, and then placing the outer layer steel shell and the inner layer gray cast iron on a centrifugal machine; then pouring the inner gray cast iron; the chemical composition and mass fraction of the inner gray cast iron molten iron are controlled to be 3.71-3.96% of C,1.44-1.97% of Si,0.38-0.65% of Mn,0.37-0.46% of Cu,0.02-0.04% of Sn,0.05-0.09% of K,0.002-0.004% of B,0.003-0.006% of Ce,0.12-0.25% of Al,0.04-0.07% of Ca, 0.05% of S, 0.08% of P and the balance of Fe; the pouring temperature of molten iron is 1382-1421 ℃; the rotational speed of the centrifugal machine is 550-620rpm;
(4) immediately spraying water mist to cool the outer steel shell after the molten iron of the inner layer completely enters the casting mould, and controlling the temperature of the outer steel shell to be 220-360 ℃; and after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum.
As described above, the chemical composition of the Q235 scrap steel is 0.14-0.22% C, 0.30-0.65% Mn, less than or equal to 0.30% Si, less than or equal to 0.050% S, less than or equal to 0.045% P, and the balance Fe and unavoidable impurities.
The chemical composition and mass fraction of the high-carbon ferrochrome are 62.0-68.0% Cr, 7.0-8.5% C, 2.0-3.5% Si and the balance Fe.
The chemical composition and mass fraction of the ferromanganese nitride are 72-77% Mn,4.2-4.8% N, <1.0% C, <3.0% Si, <0.3% P, <0.02% S, and the balance Fe.
The rare earth ferrosilicon has the chemical composition and mass fraction of 27.0-30.0% RE, 38.0-42.0% Si, <3.0% Mn, <5.0% Ca, <3.0% Ti, and the balance of Fe and unavoidable impurities.
As described above, the chemical composition and mass fraction of the aluminum magnesium alloy are 84-86% Al and 14-16% Mg.
As described above, the chemical composition of the Si-Ca-Ba alloy is 40-45% Si, 10-12% Ca, 10-12% Ba, 0.8% C, 0.04% P, 0.06% S, and the balance Fe and unavoidable impurities.
The chemical composition and mass fraction of the ferrotitanium are as follows: 38-42% of Ti, less than or equal to 9.0% of Al, less than or equal to 3.0% of Si, less than or equal to 0.03% of S, less than or equal to 0.03% of P, less than or equal to 0.10% of C, less than or equal to 0.40% of Cu, less than or equal to 2.5% of Mn and the balance of Fe.
The invention provides a double-metal composite brake drum for steel making, which aims at solving the problems of low performance, short service life, poor use safety of the brake drum, environment pollution and the like existing in the production of the double-metal composite brake drum and the use of the scrapped automobile shell, and the scrapped automobile shell is directly used for steel making. The invention provides a method for directly smelting a scraped car shell (also called a scraped car plate) into molten steel, adding a proper amount of Cr, mn, C, N reinforcing elements into the molten steel, directly casting the molten steel into a steel plate on a sheet billet continuous casting machine, rolling a part of the steel plate into a steel cylinder on a coiling machine, and firmly welding the steel cylinder. And cutting the other part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain an outer steel shell of the bimetal brake drum, pouring inner gray cast iron on the inner surface of the outer steel shell, and casting into a whole through centrifugal composite casting to obtain the bimetal brake drum with excellent performance.
The short-process casting method of the bimetal brake drum comprises the specific process steps of firstly coarsely crushing the scraped car shells by using a waste car shredder, and then packaging the coarsely crushed car shells into steel blocks with the size of 150-250mm multiplied by 150-250mm by using a scrap steel packer. The steel for automobile is mainly composed of plate and special steel, and has the characteristics of high strength, thin specification and corrosion resistance, because in order to lighten the dead weight of the automobile product, save materials, reduce the consumption of fuel oil, reduce the cost and improve the safety standard, the steel with high strength and thin specification must be used. Because the thickness of the automobile plate is thin and is usually smaller than 3mm, if the automobile plate is directly smelted in an electric furnace, the burning loss of iron element is extremely large, and huge waste of resources is caused. Therefore, the invention proposes that the waste automobile shredder is used for coarsely crushing the waste automobile shell, then the waste steel packer is used for packing the coarsely crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250mm, and the obtained steel blocks directly enter an electric furnace to smelt molten steel, so that the iron element yield is high and the oxidation burning loss is less.
The invention comprises steel blocks, Q235 scrap steel (the chemical composition and mass fraction of the Q235 scrap steel are 0.14-0.22% of C, 0.30-0.65% of Mn, less than or equal to 0.30% of Si, less than or equal to 0.050% of S, less than or equal to 0.045% of P, the balance of Fe and unavoidable impurities), high carbon ferrochrome (the chemical composition and mass fraction of the high carbon ferrochrome are 62.0-68.0% of Cr, 7.0-8.5% of C, 2.0-3.5% of Si, and the balance of Fe) and manganese iron nitride (the chemical composition and mass fraction of the manganese iron nitride are 72-77% of Mn,4.2-4.8% of N, <1.0％C,<3.0％Si,<0.3％P,<0.02% S, the balance Fe) as furnace charge, Q2The mass compositions of the 35 scrap steel, the high-carbon ferrochrome, the steel block and the manganese iron nitride are respectively as follows: 20-22%,1.0-1.2%,76-78%,0.8-1.0%, and the sum of the mass fractions of the four furnace charges is 100%. In the invention, firstly, 20-22% of Q235 scrap steel and 1.0-1.2% of high-carbon ferrochrome are mixed, heated and melted in an intermediate frequency induction furnace, and when the temperature is raised to 1580-1595 ℃,0.8-1.0% of ferromanganese nitride and 76-78% of steel blocks are added. The smelting process is adopted because in order to improve the corrosion resistance of the automobile product and prolong the service life of the automobile, the surface treatment technology of the inner and outer plates of the automobile must be improved, and galvanized plates or alloy galvanized plates are mainly adopted at home and abroad at present. At present, most of domestic waste automobile plates contain zinc element. Zinc density of 7.2g/cm 3 The melting point and the boiling point are low, namely 419.5 ℃ and 906 ℃. The scrapped car shell (also called scrapped car plate) is directly used as a steelmaking raw material, zinc element is seriously volatilized, the environment is polluted, and huge waste of zinc resources is caused. Therefore, after the Q235 scrap steel and the high-carbon ferrochrome are melted, when the temperature is raised to 1580-1595 ℃, steel blocks processed by the outer shells of the scraped car (also called scraped car plates) are added into the furnace and combined with molten steel in the furnace, and the steel blocks are melted rapidly. Therefore, the volatilization of zinc element is avoided, the environment is well protected, and the huge waste of zinc resources is prevented. In addition, zn is easy to oxidize into ZnO, znO can be completely dissolved in ferrite of steel, has stronger solid solution strengthening effect, and can improve the strength and hardness of the steel. The residual proper amount of ZnO in the steel can also improve the atmospheric corrosion resistance of the steel. However, znO can reduce the plasticity and toughness of steel at room temperature, in order to compensate the adverse effect brought by ZnO, N element (from manganese iron nitride) and Ti element (from ferrotitanium added at the bottom of a steel ladle) are added, ti (N, C) particles are separated out at high temperature and serve as crystal cores of molten steel, grains are obviously refined, the effect of obviously improving the plasticity and toughness of steel is achieved, and the reduction caused by the plasticity and toughness of the steel at room temperature can be counteracted by ZnO.
After the ferromanganese nitride and the steel block are completely melted, the temperature is raised to 1615-1630 ℃, the ferrotitanium is discharged to a ladle, si-Ca-Ba alloy with the grain size of 3-6mm (the chemical composition and mass fraction of the Si-Ca-Ba alloy are 40-45 percent Si, 10-12 percent Ca, 10-12 percent Ba, less than 0.8 percent C, less than or equal to 0.04 percent P, less than or equal to 0.06 percent S, the balance Fe and unavoidable impurities) and ferrotitanium (the chemical composition and mass fraction of the ferrotitanium are 38-42 percent Ti, less than or equal to 9.0 percent Al, less than or equal to 3.0 percent Si, less than or equal to 0.03 percent S, less than or equal to 0.03 percent P, less than or equal to 0.10 percent C, less than or equal to 0.40 percent Cu, less than or equal to 2.5 percent Mn, the balance Fe) and rare earth ferrosilicon (the chemical composition and mass fraction of the rare earth ferrosilicon are 84-86 percent Al, 14-16 percent Mg, the chemical composition and the unavoidable impurities are 38-0.0 percent Si, less than or equal to 0.0 percent Mn, and the balance Fe; the addition amounts of Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon respectively account for 0.3-0.5%, 0.25-0.30%, 0.18-0.22% and 0.15-0.20% of the mass fraction of molten steel entering the ladle. The Si-Ca-Ba alloy 0.3-0.5%, ferrotitanium 0.25-0.30%, aluminum-magnesium alloy 0.18-0.22% and rare earth ferrosilicon 0.15-0.20% are added, so that the cast steel structure can be obviously thinned and purified, and the improvement of the performance of the continuous cast steel plate is guaranteed.
After slag skimming and standing, the temperature of the molten steel is reduced to 1533-1548 ℃, and the molten steel is directly cast into a steel plate with the thickness of 12-16mm on a sheet billet continuous casting machine, so that the method has the advantages of high production efficiency, high molten steel yield and the like. The invention rolls the obtained partial steel plate into a steel cylinder on a coiling machine and welds the steel cylinder firmly. In addition, part of the steel plate is cut into a flange, the flange and the steel cylinder are welded into a whole to obtain a double-metal brake drum outer layer steel shell finish-spinning blank, and the composite brake drum outer layer steel shell finish-spinning blank is rolled to form the composite brake drum outer layer steel shell. The borax with the thickness of 0.8-1.2mm is coated on the joint of the inner surface of the outer steel shell and the inner gray cast iron, and the inner surface of the outer steel shell is rapidly heated to 610-710 ℃ by an induction coil, so that the joint effect of the outer steel shell and the inner gray cast iron can be obviously improved, and the strength of the joint layer is improved. Placing the steel shell on a centrifuge, and then pouring inner gray cast iron; the chemical composition and mass fraction of the inner gray cast iron molten iron are controlled to be 3.71-3.96% of C,1.44-1.97% of Si,0.38-0.65% of Mn,0.37-0.46% of Cu,0.02-0.04% of Sn,0.05-0.09% of K,0.002-0.004% of B,0.003-0.006% of Ce,0.12-0.25% of Al,0.04-0.07% of Ca, 0.05% of S, 0.08% of P and the balance of Fe; the pouring temperature of molten iron is 1382-1421 ℃; the rotational speed of the centrifugal machine is 550-620rpm. The gray cast iron of the invention has high carbon content, large graphite quantity and good heat conductivity. However, an increase in the amount of graphite significantly reduces the strength of cast iron. In order to eliminate the adverse effect of the increase of graphite on strength, 0.02-0.04% of Sn,0.05-0.09% of K,0.002-0.004% of B,0.003-0.006% of Ce and 0.04-0.07% of Ca are added in the invention, so that the refinement and purification of cast iron tissues are realized, and the strength of cast iron is improved. In addition, 0.12-0.25% Al and 0.37-0.46% Cu are added, so that the strength of cast iron can be further improved. In particular, the addition of 0.002-0.004% of B can improve the wear resistance of cast iron. According to the invention, when the molten iron of the inner layer completely enters the casting mould, the spray water immediately sprays to cool the outer layer steel shell, and the temperature of the outer layer steel shell is controlled at 220-360 ℃. The outer steel shell is ensured not to reduce the strength due to solidification and heat dissipation of the inner molten iron. And after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum.
Compared with the prior art, the invention has the following characteristics:
1) The invention realizes the high-efficiency utilization of the scraped car shell (also called the scraped car plate), the iron element yield is up to more than 98 percent, and the defect of serious environmental pollution caused by the gasification of zinc element in the steel making of the common scraped car plate is overcome.
2) The invention has the advantages of short flow and high efficiency in producing the bimetal brake drum, realizes that the continuous cast steel plate directly replaces the rolled steel plate to produce the outer steel shell of the bimetal brake drum, and has short production period and low production cost.
3) The short-process cast bimetallic brake drum provided by the invention has the advantages that the tensile strength of the outer layer exceeds 880MPa, the elongation exceeds 26%, and the fracture toughness exceeds 85MPa m 1/2 The hardness of the inner layer reaches 240-260HBS, and the tensile strength exceeds 480MPa.
4) Compared with HT250 cast iron, the cast iron of the inner layer of the short-process cast bimetallic brake drum has high-temperature tensile strength and high crack initiation and expansion resistance, prevents the brake drum from losing efficacy due to deformation, and has the advantages of long service life, safe and reliable use and the like; compared with HT250 cast iron brake drums, the service life is prolonged by more than 2.5 times, and the popularization and application have good economic and social benefits.
Drawings
FIG. 1 is a schematic view of an outer steel shell of a bimetallic composite brake drum
FIG. 2 is a schematic diagram of a finished bimetallic composite brake drum
1-outer layer steel shell, 2-inner layer high-strength gray cast iron.
Detailed Description
The present invention will be further described in detail with reference to the following examples, but the present invention is not limited to the following examples.
Example 1:
a method for casting a bimetal brake drum in a short process is characterized in that the outer layer is processed by adopting a continuous cast steel plate which is mainly smelted by a scraped car shell, the inner layer is made of high-strength wear-resistant gray cast iron, and the two materials are cast into metallurgical combination by centrifugal composite casting, and the specific process steps are as follows:
(1) firstly, coarsely crushing a scrapped automobile shell by using a waste automobile shredder, and then packaging the coarsely crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250mm by using a scrap steel packer;
(2) adopting steel blocks, Q235 scrap steel (the chemical composition and the mass fraction of the Q235 scrap steel are 0.17 percent C,0.54 percent Mn,0.23 percent Si,0.041 percent S,0.039 percent P and the balance of Fe and unavoidable impurities), high-carbon ferrochrome (the chemical composition and the mass fraction of the high-carbon ferrochrome are 62.70 percent Cr,8.26 percent C,2.39 percent Si and the balance of Fe) and manganese nitride (the chemical composition and the mass fraction of the manganese nitride are 76.05 percent Mn,4.27 percent N,0.36 percent C,1.52 percent Si,0.15 percent P,0.013 percent S and the balance of Fe) in the step (1), and firstly mixing, heating and melting the Q235 scrap steel and the high-carbon ferrochrome in an intermediate frequency induction furnace; after the Q235 scrap steel and the high-carbon ferrochrome are completely melted, adding ferromanganese nitride and steel blocks when the temperature is raised to 1587 ℃; the mass compositions of the Q235 scrap steel, the high-carbon ferrochrome, the steel block and the manganese iron nitride are respectively as follows: 21%,1.1%,77%,0.9%; after the ferromanganese nitride and the steel block are completely melted, heating to 1624 ℃, discharging to a ladle, and adding Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon with the particle size of 3-6mm into the bottom of the ladle in advance; si-Ca-Ba alloy (the chemical composition and mass fraction of the Si-Ca-Ba alloy are 42.81% Si, 11.36% Ca, 10.95% Ba, 0.51% C, 0.028% P, 0.047% S, the balance Fe and unavoidable impurities), ferrotitanium (the chemical composition and mass fraction of the ferrotitanium are 38.05% Ti,6.56% Al,2.13% Si,0.026% S,0.029% P,0.074% C,0.08% Cu,2.16% Mn, the balance Fe), aluminum magnesium alloy (the chemical composition and mass fraction of the aluminum magnesium alloy are 85% Al, 15% Mg), and rare earth ferrosilicon (the chemical composition mass fraction of the rare earth ferrosilicon is 29.53% RE,41.28% Si,2.15% Mn,3.82% Ca,1.94% Ti, the balance Fe and unavoidable impurities) are added into the steel ladle in the amounts of 0.4%, 0.20% and 0.30% by mass fraction of the molten steel, respectively; after slag skimming and standing, when the temperature is reduced to 1537 ℃, directly casting the molten steel on a sheet billet continuous casting machine into a steel plate with the thickness of 15 mm;
(3) Rolling part of the steel plate obtained in the step (2) into a steel cylinder on a coiling machine and firmly welding the steel cylinder; cutting part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain a double-metal brake drum outer layer steel shell fine-spinning blank, and rolling the double-metal brake drum outer layer steel shell fine-spinning blank to form a double-metal brake drum outer layer steel shell 1; and borax with the thickness of 0.8-1.2mm is coated on the joint of the inner surface of the outer steel shell 1 and the inner gray cast iron 2; the inner surface of the outer steel shell is rapidly heated to 610-710 ℃ by an induction coil and then placed on a centrifuge; then pouring the inner gray cast iron 2; the chemical composition of the inner gray cast iron molten iron and the mass fraction thereof are controlled to be 3.79 percent of C,1.74 percent of Si,0.50 percent of Mn,0.42 percent of Cu,0.03 percent of Sn,0.08 percent of K,0.003 percent of B,0.005 percent of Ce,0.18 percent of Al,0.06 percent of Ca,0.028 percent of S,0.051 percent of P and the balance of Fe; the pouring temperature of molten iron is 1397 ℃; the rotational speed of the centrifuge is 600rpm;
(4) immediately spraying water mist to cool the outer steel shell 1 after the molten iron of the inner layer completely enters the casting mould, and controlling the temperature of the outer steel shell 1 at 280-340 ℃; and after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum, wherein the mechanical properties are shown in Table 1.
Table 1 mechanical properties of short-process cast bimetallic brake drums
Example 2:
a method for casting a bimetal brake drum in a short process is characterized in that the outer layer is processed by adopting a continuous cast steel plate which is mainly smelted by a scraped car shell, the inner layer is made of high-strength wear-resistant gray cast iron, and the two materials are cast into metallurgical combination by centrifugal composite casting, and the specific process steps are as follows:
(1) firstly, coarsely crushing a scrapped automobile shell by using a waste automobile shredder, and then packaging the coarsely crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250mm by using a scrap steel packer;
(2) adopting steel blocks, Q235 scrap steel (the chemical composition and the mass fraction of the Q235 scrap steel are 0.14 percent C,0.65 percent Mn,0.21 percent Si,0.031 percent S,0.043 percent P and the balance of Fe and unavoidable impurities), high-carbon ferrochrome (the chemical composition and the mass fraction of the high-carbon ferrochrome are 62.77 percent Cr,7.94 percent C,2.63 percent Si and the balance of Fe) and manganese nitride (the chemical composition and the mass fraction of the manganese nitride are 72.51 percent Mn,4.47 percent N,0.39 percent C,1.45 percent Si,0.18 percent P,0.016 percent S and the balance of Fe) in the step (1), and mixing, heating and melting the Q235 scrap steel and the high-carbon ferrochrome in an intermediate frequency induction furnace; after the Q235 scrap steel and the high-carbon ferrochrome are completely melted, adding ferromanganese nitride and steel blocks when the temperature is raised to 1580 ℃; the mass compositions of the Q235 scrap steel, the high-carbon ferrochrome, the steel block and the manganese iron nitride are respectively as follows: 20%,1.0%,78%,1.0%; after the ferromanganese nitride and the steel block are completely melted, heating to 1615 ℃, discharging to a ladle, and adding Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon with the particle size of 3-6mm into the bottom of the ladle in advance; si-Ca-Ba alloy (the chemical composition and mass fraction of the Si-Ca-Ba alloy are 43.26% Si, 10.15% Ca, 11.62% Ba, 0.30% C, 0.035% P, 0.047% S, the balance Fe and unavoidable impurities), ferrotitanium (the chemical composition and mass fraction of the ferrotitanium are 39.54% Ti,3.86% Al,1.03% Si,0.022% S,0.027% P,0.064% C,0.13% Cu,1.08% Mn, the balance Fe), aluminum magnesium alloy (the chemical composition and mass fraction of the aluminum magnesium alloy are 84% Al, 16% Mg), and rare earth ferrosilicon (the chemical composition mass fraction of the rare earth ferrosilicon is 27.51% RE,41.47% Si,1.55% Mn,2.09% Ca,1.38% Ti, the balance Fe and unavoidable impurities) are added into the steel ladle to respectively account for 0.3%, 0.30% and 0.20% of the mass fraction of the molten steel; after slag skimming and standing, when the temperature is reduced to 1533 ℃, directly casting the molten steel on a sheet billet continuous casting machine into a steel plate with the thickness of 12 mm;
(3) Rolling part of the steel plate obtained in the step (2) into a steel cylinder on a coiling machine and firmly welding the steel cylinder; cutting part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain a double-metal brake drum outer layer steel shell fine-spinning blank, and rolling the composite brake drum outer layer steel shell fine-spinning blank to form a composite brake drum outer layer steel shell 1; and borax with the thickness of 0.8-1.2mm is coated on the joint of the inner surface of the outer steel shell and the inner gray cast iron 2; the inner surface of the outer steel shell 1 is rapidly heated to 610-710 ℃ by an induction coil and then is placed on a centrifuge; then pouring the inner gray cast iron 2; the chemical composition of the inner gray cast iron molten iron is controlled to be 3.71 percent of C,1.97 percent of Si,0.38 percent of Mn,0.46 percent of Cu,0.02 percent of Sn,0.09 percent of K,0.002 percent of B,0.006 percent of Ce,0.12 percent of Al,0.07 percent of Ca,0.027 percent of S,0.053 percent of P and the balance of Fe; the pouring temperature of molten iron is 1382 ℃; the rotational speed of the centrifuge is 550rpm;
(4) immediately spraying water mist to cool the outer steel shell 1 after the molten iron of the inner layer completely enters the casting mould, and controlling the temperature of the outer steel shell 1 at 220-280 ℃; and after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum, wherein the mechanical properties are shown in Table 2.
Table 2 mechanical properties of short-process cast bimetallic brake drums
Example 3:
a method for casting a bimetal brake drum in a short process is characterized in that the outer layer is processed by adopting a continuous cast steel plate which is mainly smelted by a scraped car shell, the inner layer is made of high-strength wear-resistant gray cast iron, and the two materials are cast into metallurgical combination by centrifugal composite casting, and the specific process steps are as follows:
(1) firstly, coarsely crushing a scrapped automobile shell by using a waste automobile shredder, and then packaging the coarsely crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250mm by using a scrap steel packer;
(2) the steel block, Q235 scrap steel (the chemical composition and the mass fraction of the Q235 scrap steel are 0.22 percent C,0.30 percent Mn,0.18 percent Si,0.038 percent S,0.044 percent P and the balance of Fe and unavoidable impurities), high-carbon ferrochrome (the chemical composition and the mass fraction of the high-carbon ferrochrome are 65.67 percent Cr,8.38 percent C,2.94 percent Si and the balance of Fe) and manganese nitride (the chemical composition and the mass fraction of the manganese nitride are 76.04 percent Mn,4.74 percent N,0.59 percent C,1.64 percent Si,0.22 percent P,0.019 percent S and the balance of Fe) in the step (1) are adopted as furnace materials, and the Q235 scrap steel and the high-carbon ferrochrome are mixed, heated and melted in an intermediate frequency induction furnace; after the Q235 scrap steel and the high-carbon ferrochrome are completely melted, adding ferromanganese nitride and steel blocks when the temperature is raised to 1595 ℃; the mass compositions of the Q235 scrap steel, the high-carbon ferrochrome, the steel block and the manganese iron nitride are respectively as follows: 22%,1.2%,76%,0.8%; after the ferromanganese nitride and the steel block are completely melted, heating to 1630 ℃, discharging to a ladle, and adding Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon with the particle size of 3-6mm into the bottom of the ladle in advance; si-Ca-Ba alloy (the chemical composition and mass fraction of the Si-Ca-Ba alloy are 44.62 percent Si, 11.61 percent Ca, 10.28 percent Ba, 0.43 percent C, 0.029 percent P,0.051 percent S, the balance Fe and unavoidable impurities), ferrotitanium (the chemical composition and mass fraction of the ferrotitanium are 38.19 percent Ti,3.62 percent Al,2.09 percent Si,0.026 percent S,0.021 percent P,0.051 percent C,0.18 percent Cu, less than or equal to 0.95 percent Mn, the balance Fe), aluminum magnesium alloy (the chemical composition and mass fraction of the aluminum magnesium alloy are 86 percent Al, 14 percent Mg), and rare earth ferrosilicon (the chemical composition mass fraction of the rare earth ferrosilicon is 29.48 percent RE,38.07 percent Si,1.51 percent Mn,2.68 percent Ca,1.57 percent Ti, the balance Fe and unavoidable impurities) are added into steel ladle in the amounts of 0.5 percent, 0.15 percent and 0.15 percent by mass of molten steel, respectively; after slag skimming and standing of molten steel, when the temperature is reduced to 1548 ℃, directly casting the molten steel on a sheet billet continuous casting machine into a steel plate with the thickness of 16 mm;
(3) Rolling part of the steel plate obtained in the step (2) into a steel cylinder on a coiling machine and firmly welding the steel cylinder; cutting part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain a double-metal brake drum outer layer steel shell fine-spinning blank, and rolling the double-metal brake drum outer layer steel shell fine-spinning blank to form a double-metal brake drum outer layer steel shell 1; and borax with the thickness of 0.8-1.2mm is coated on the joint of the inner surface of the outer steel shell 1 and the inner gray cast iron 2; the inner surface of the outer steel shell is rapidly heated to 610-710 ℃ by an induction coil and then placed on a centrifuge; then pouring the inner gray cast iron 2; the chemical composition of the inner gray cast iron molten iron is controlled to be 3.96 percent of C,1.44 percent of Si,0.65 percent of Mn,0.37 percent of Cu,0.04 percent of Sn,0.05 percent of K,0.004 percent of B,0.003 percent of Ce,0.25 percent of Al,0.04 percent of Ca,0.029 percent of S,0.059 percent of P and the balance of Fe; the pouring temperature of molten iron is 1421 ℃; centrifuge speed 620rpm;
(4) immediately spraying water mist to cool the outer steel shell 1 after the molten iron of the inner layer completely enters the casting mould, and controlling the temperature of the outer steel shell 1 at 300-360 ℃; and after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum, wherein the mechanical properties are shown in Table 3.
Table 3 mechanical properties of short-process cast bimetallic brake drums
The invention realizes the high-efficiency utilization of the scraped car shell (also called the scraped car plate), the iron element yield is up to more than 98 percent, and the defect of serious environmental pollution caused by the gasification of zinc element in the steel making of the common scraped car plate is overcome. . The invention has the advantages of short flow and high efficiency in producing the bimetal brake drum, realizes that the continuous cast steel plate directly replaces the rolled steel plate to produce the outer steel shell of the bimetal brake drum, and has short production period and low production cost. The invention relates to a short-flow castingWhen the bimetal brake drum is manufactured, the tensile strength of the outer layer exceeds 880MPa, the elongation exceeds 26 percent and the fracture toughness exceeds 85MPa m 1/2 The hardness of the inner layer reaches 240-260HBS, and the tensile strength exceeds 480MPa. Compared with HT250 cast iron, the cast iron of the inner layer of the short-process cast bimetallic brake drum has the advantages of high-temperature tensile strength, high crack initiation and expansion resistance, long service life, safe and reliable use and the like, and prevents the brake drum from being invalid due to deformation; compared with HT250 cast iron brake drums, the service life is prolonged by more than 2.5 times, and the popularization and application have good economic and social benefits. The bimetal brake drum has excellent wear resistance, thermal fatigue resistance and corrosion resistance, the service life of the brake drum is prolonged, the driving safety of the brake drum is improved, the driving mileage of the brake drum exceeds 10 ten thousand kilometers, and the popularization of the technology of the invention has obvious economic and social benefits.
Claims (4)
1. A method for casting a bimetallic brake drum in a short process is characterized in that the outer layer of the brake drum is processed by adopting a continuous cast steel plate which is mainly smelted by a scraped car shell, the inner layer of the brake drum is made of high-strength wear-resistant gray cast iron, and the two materials are metallurgically combined by centrifugal composite casting, and the method comprises the following steps:
(1) firstly, coarsely crushing a scrapped automobile shell by using a waste automobile shredder, and then packaging the coarsely crushed automobile shell into steel blocks with the size of 150-250mm multiplied by 150-250mm by using a scrap steel packer;
(2) adopting steel blocks, Q235 scrap steel, high-carbon ferrochrome and manganese nitride in the step (1) as furnace charges, wherein the mass compositions of the Q235 scrap steel, the high-carbon ferrochrome, the steel blocks and the manganese nitride in the furnace charges are respectively as follows: 20-22%,1.0-1.2%,76-78%,0.8-1.0%, the sum of the mass fractions of the four furnace charges is 100%; firstly, mixing 20-22% of Q235 scrap steel and 1.0-1.2% of high-carbon ferrochrome in a medium-frequency induction furnace, heating and melting; after the Q235 scrap steel and the high-carbon ferrochrome are completely melted, adding 0.8-1.0% of ferromanganese nitride and 76-78% of steel blocks by mass when the temperature is raised to 1580-1595 ℃; after the ferromanganese nitride and the steel block are completely melted, heating to 1615-1630 ℃, discharging to a ladle, and adding Si-Ca-Ba alloy, ferrotitanium, aluminum-magnesium alloy and rare earth ferrosilicon with the grain size of 3-6mm into the bottom of the ladle in advance; the addition of Si-Ca-Ba alloy, ferrotitanium, aluminum magnesium alloy and rare earth ferrosilicon respectively accounts for 0.3 to 0.5 percent, 0.25 to 0.30 percent, 0.18 to 0.22 percent and 0.15 to 0.20 percent of the mass fraction of molten steel entering the ladle; after slag skimming and standing, when the temperature is reduced to 1533-1548 ℃, directly casting the molten steel on a sheet billet continuous casting machine into a steel plate with the thickness of 12-16 mm;
(3) Rolling part of the steel plate obtained in the step (2) into a steel cylinder on a coiling machine and firmly welding the steel cylinder; cutting part of the steel plate into a flange, welding the flange and the steel cylinder into a whole to obtain a double-metal brake drum outer layer steel shell fine-turning blank, and rolling the double-metal brake drum outer layer steel shell fine-turning blank to obtain a composite brake drum outer layer steel shell; coating borax with the thickness of 0.8-1.2mm on the joint of the outer layer steel shell and the inner layer gray cast iron on the inner surface of the outer layer steel shell, rapidly heating the inner surface of the outer layer steel shell to 610-710 ℃ by using an induction coil, and then placing the outer layer steel shell and the inner layer gray cast iron on a centrifugal machine; then pouring the inner gray cast iron; the chemical composition and mass fraction of the inner gray cast iron molten iron are controlled to be 3.71-3.96% of C,1.44-1.97% of Si,0.38-0.65% of Mn,0.37-0.46% of Cu,0.02-0.04% of Sn,0.05-0.09% of K,0.002-0.004% of B,0.003-0.006% of Ce,0.12-0.25% of Al,0.04-0.07% of Ca, 0.05% of S, 0.08% of P and the balance of Fe; the pouring temperature of molten iron is 1382-1421 ℃; the rotational speed of the centrifugal machine is 550-620rpm;
(4) immediately spraying water mist to cool the outer steel shell after the molten iron of the inner layer completely enters the casting mould, and controlling the temperature of the outer steel shell to be 220-360 ℃; and after the molten iron in the inner layer is completely solidified, stopping spraying water mist, naturally cooling to room temperature, and finally finishing to the specified size and precision to obtain the short-process casting bimetallic brake drum.
2. A method of casting a bimetallic brake drum in a short pass according to claim 1 wherein the Q235 scrap steel has a chemical composition and mass fraction of 0.14 to 0.22% c,0.30 to 0.65% mn, 0.30% si, 0.050% s, 0.045% p, the balance Fe and unavoidable impurities;
the chemical composition and mass fraction of the high-carbon ferrochrome are 62.0-68.0% Cr, 7.0-8.5% C, 2.0-3.5% Si and the balance Fe;
the chemical composition and mass fraction of the ferromanganese nitride are 72-77% Mn,4.2-4.8% N, <1.0% C, <3.0% Si, <0.3% P, <0.02% S, and the balance Fe.
3. A method of casting a bimetallic brake drum in a short pass according to claim 1 wherein the rare earth ferrosilicon has a chemical composition and mass fraction of 27.0 to 30.0% re,38.0 to 42.0% si, <3.0% mn, <5.0% ca, <3.0% ti, the balance Fe and unavoidable impurities;
the aluminum magnesium alloy comprises 84-86% of Al and 14-16% of Mg by mass percent;
the chemical composition and mass fraction of the Si-Ca-Ba alloy are 40-45% of Si, 10-12% of Ca, 10-12% of Ba, less than or equal to 0.8% of C, less than or equal to 0.04% of P, less than or equal to 0.06% of S, and the balance of Fe and unavoidable impurities;
the ferrotitanium comprises the following chemical components in percentage by mass: 38-42% of Ti, less than or equal to 9.0% of Al, less than or equal to 3.0% of Si, less than or equal to 0.03% of S, less than or equal to 0.03% of P, less than or equal to 0.10% of C, less than or equal to 0.40% of Cu, less than or equal to 2.5% of Mn and the balance of Fe.
4. A bimetallic brake drum prepared according to the method of any one of claims 1-3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN103993221A (en) * | 2014-05-26 | 2014-08-20 | 四川省富邦钒钛制动鼓有限公司 | Vanadium titanium cast iron brake drum and preparation method thereof |
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| FR2538277B1 (en) * | 1982-12-23 | 1985-09-13 | Kuhn Sa | METHOD FOR MOLDING A CROWN BRAKE ROTOR AND CROWN BRAKE ROTOR OBTAINED BY THIS METHOD |
| US6148498A (en) * | 1999-07-30 | 2000-11-21 | Hayes Lemmerz International, Inc. | Method of making a brake drum ring |
| CN102000950A (en) * | 2010-11-02 | 2011-04-06 | 嘉兴四通车轮股份有限公司 | Manufacturing method of high-strength light bi-metal brake drum and high-strength light bi-metal brake drum thereof |
| CN102601337B (en) * | 2012-03-09 | 2013-12-11 | 河南科技大学 | Shaping method of bimetallic composite-material brake drum |
| CN206290622U (en) * | 2016-12-08 | 2017-06-30 | 驻马店恒久机械制造有限公司 | A kind of Novel brake drum |
| CN107824765A (en) * | 2017-10-19 | 2018-03-23 | 驻马店恒久机械制造有限公司 | A kind of impeller flange form steel pricker closes brake drum and preparation method thereof |
| CN111828510A (en) * | 2019-04-18 | 2020-10-27 | 河南理工大学 | Reusable brake drum and manufacturing method thereof |
| CN110814672A (en) * | 2019-11-14 | 2020-02-21 | 山西汤荣机械制造股份有限公司 | Preparation process of novel bimetal composite integrated brake drum |
| CN111120546A (en) * | 2020-01-18 | 2020-05-08 | 山东浩信昌盛汽车零部件智能制造有限公司 | Bimetal composite brake drum and manufacturing method thereof |
| CN112524178A (en) * | 2020-12-18 | 2021-03-19 | 驻马店市新创业管桩附件有限公司 | Composite brake drum and preparation method thereof |
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