CN110125408B - Method for preparing high alloy tool and die steel hollow pipe blank - Google Patents
Method for preparing high alloy tool and die steel hollow pipe blank Download PDFInfo
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- CN110125408B CN110125408B CN201910466727.1A CN201910466727A CN110125408B CN 110125408 B CN110125408 B CN 110125408B CN 201910466727 A CN201910466727 A CN 201910466727A CN 110125408 B CN110125408 B CN 110125408B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/06—Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/14—Making machine elements fittings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/115—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by spraying molten metal, i.e. spray sintering, spray casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
- B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
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Abstract
The invention provides a hollow steel ingot injection molding method of high-alloy tool and die steel, a hollow steel ingot and a preparation method of a hollow tube blank of high-alloy tool and die steel. The preparation method of the hollow steel ingot can ensure that the hollow steel ingot has uniform and fine structure and compact crystallization, greatly improves the segregation of chemical components and carbides, approaches the quality of products formed by a powder metallurgy forming method, can realize the preparation of the high-alloy tool and die steel hollow steel ingot, and can ensure that the prepared hollow steel ingot meets the requirements of the preparation of high-alloy tool and die steel hollow pipes.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a high-alloy tool and die steel hollow steel ingot injection molding method. Meanwhile, the invention also relates to a high-alloy tool and die steel hollow steel ingot prepared by the injection molding method and a preparation method of a high-alloy tool and die steel hollow tube blank by utilizing the prepared high-alloy tool and die steel hollow steel ingot.
Background
High alloy tool and die steels such as high speed steels M2, M35, M2Al, etc., high carbon chromium cold work die steels Cr12Mo1V1, high toughness and high wear resistance cold work die steels HYC3, etc., and hot work die steels such as H13E, H13, H12, etc., are widely used for manufacturing various cutting tools and various dies including large hollow broach, hob, hollow roll, shield hob, disc shear blade, etc. Because high-alloy tool and die steel contains a large amount of W, Mo, Cr, V and other alloy elements, the solidification components are not uniform during smelting, the segregation is serious, a large amount of carbides are contained, and the specification and the size of a qualified steel ingot are limited, the high-alloy tool and die steel needs to be prepared by a special metallurgical method, and a large thermal deformation amount is needed for crushing so as to improve the distribution state of the high-alloy tool and die steel to enable the high-alloy tool and die steel to have uniform structures required by tools and dies, and the tool and die steel with required performances can be obtained.
The traditional hollow tool and die manufacturing method generally adopts the process of hollowing out the core part of a solid bar stock or reaming a solid forging stock into a ring-shaped piece after punching the solid forging stock to prepare the blank, and the methods generally have the defects of time and labor waste, long process route, low yield and qualified rate, low efficiency and the like. Other conventional production methods for lower alloy steel pipes, such as a piercing technology, a three-roll continuous rolling mill steel pipe rolling technology and the like, are difficult to apply to high alloy die steel.
Because the high alloy tool and die steel has poor technological plasticity, a narrow deformation temperature range, large deformation resistance, large processing difficulty, high time consumption and cost and difficult quality guarantee. Therefore, although it is known that the quality of the hollow high-alloy tool and die steel is improved by adopting the hollow pipe, the production efficiency and the material utilization rate are also greatly improved, but for the reasons, the preparation of the hollow pipe of the high-alloy tool and die steel is always difficult. To overcome the problem, the inventor develops a hollow steel ingot made of high alloy tool and die steel to prepare a molded hollow pipe through innovative thinking, and the preparation of the hollow steel ingot with good quality to meet the preparation of the hollow pipe becomes the basis for preparing the hollow pipe made of the high alloy tool and die steel.
In the prior art, the traditional method for preparing the hollow steel ingot mostly adopts a direct casting or centrifugal casting process, and the hollow steel ingot prepared by the process can be convenient for preparing specific products by means of continuous rolling and the like in the later period. However, the hollow steel ingot prepared by the traditional method has different structures and poor uniformity, so that the prepared hollow steel ingot has low performance.
The spray forming process is a short-flow advanced forming process for atomizing and rapidly cooling molten steel for forming, and can solve the problems of alloy element segregation in the preparation process of the traditional casting process, cost increase caused by long flow of the powder metallurgy process and the like. At present, the spray forming process has been widely applied to the preparation of low melting point alloys, and a lot of research work has been carried out in the field of preparing high melting point alloy steels such as high speed steels. Based on the advantages of the injection molding process, the injection molding process is developed to prepare the high-alloy tool and die steel hollow steel ingot, so that the prepared hollow steel ingot meets the requirements of the preparation of the high-alloy tool and die steel hollow pipe, and the injection molding process has a very good meaning obviously.
Disclosure of Invention
In view of the above, the present invention aims to provide a spray forming method for a high alloy tool and die steel hollow steel ingot, so as to prepare the high alloy tool and die steel hollow steel ingot.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a high alloy tool and die steel hollow steel ingot injection molding method comprises the following steps:
a1, rolling a steel plate into a core cylinder meeting the requirements of inner diameter and height, welding and sealing the top end of the core cylinder by the steel plate, and welding a flange plate at the bottom end of the core cylinder;
a2, fixing the cartridge on a rotatable collecting tray in the jet chamber by one end welded with a flange plate, and enabling the axis of the cartridge to be coaxial with the rotation axis of the collecting tray;
a3, heating and preserving the refined high-alloy tool and die steel molten steel, then spraying the molten steel to the rotating collecting tray and the rotating core barrel so that the collecting tray and the core barrel can receive atomized semi-molten steel drops for deposition, and continuously moving the collecting tray downwards during spraying so as to gradually deposit and form a sprayed steel ingot, and stopping spraying and moving the sprayed steel ingot out of a spraying chamber when the sprayed steel ingot reaches the required height;
and a4, air-cooling the sprayed steel ingot, then putting into a furnace for annealing, and after annealing, discharging from the furnace for air-cooling to obtain the high-alloy tool and die steel hollow steel ingot.
Further, the thickness of the steel plate is 3-5 mm.
Furthermore, the steel plate welded and sealed at the top end of the core cylinder is in a spherical crown shape.
Furthermore, the steel plate is a low-carbon steel plate, and the core barrel, the closed top end and the outer surface of the flange plate are subjected to rust removal treatment.
Further, the solid-liquid ratio of the atomized semi-molten steel drops received by the collecting tray and the core cylinder is 7: 3.
Further, the required height of the sprayed steel ingot is 90-110mm higher than the top end of the welding and closing core barrel.
Further, the annealing in the step a4 includes using low temperature softening annealing, or high temperature spheroidizing annealing.
Compared with the prior art, the invention has the following advantages:
the injection molding method of the high-alloy tool and die steel hollow steel ingot adopts the injection steel-making process to mold the hollow steel ingot, ensures that the inner hole is ensured by the prepared core barrel, can ensure that the hollow steel ingot has uniform and fine structure, fine and compact crystals, greatly improves chemical composition segregation and carbide segregation, and can approach the quality of a powder metallurgy molding product, thereby realizing the preparation of the high-alloy tool and die steel hollow steel ingot, and utilizing the advantages of the injection molding process to ensure that the prepared hollow steel ingot meets the requirements of the preparation of high-alloy tool and die steel hollow pipes.
The invention also relates to a high-alloy tool and die steel hollow steel ingot prepared by the high-alloy tool and die steel hollow steel ingot injection molding method.
In addition, the invention also relates to a preparation method of the high-alloy tool and die steel hollow pipe blank, which comprises the following steps:
b1, filling rheological materials meeting the hot forging deformation requirement in the hollow steel ingot of the high-alloy tool and die steel, tamping the rheological materials, and then closing one end of an opening of the hollow steel ingot, wherein the hot forging deformation requirement comprises that the rheological materials have a melting point higher than the forging heating temperature, do not react with steel materials during heating, do not change the volume of the rheological materials during hot forging deformation, and can uniformly flow along with the deformation of the steel ingot;
b2, putting the hollow steel ingot filled with the rheological material into a furnace for heating;
b3, discharging the heated hollow steel ingot out of the furnace, performing radial forging on a finish forging machine to obtain a high alloy tool and die steel billet with the diameter meeting the requirement, putting the high alloy tool and die steel billet into the furnace for annealing, and cooling and straightening after annealing;
b4, determining the positions of inner holes at two ends of the high alloy tool and die steel billet, cutting off the end part of the steel billet at the positions, and removing the filled rheological material to obtain the high alloy tool and die steel hollow pipe billet.
Further, the rheological material in step b1 is alundum, and the deformation ratio of the hollow ingot should not be less than 3 when the finish forging machine in step b3 is radially forged.
According to the preparation method of the high alloy tool and die steel hollow tube blank adopting the high alloy tool and die steel hollow steel ingot, the filling rheological material and the finish forging cogging process are combined, so that a new preparation process of the high alloy tool and die steel hollow tube blank can be formed, the forging preparation of the high alloy tool and die steel hollow tube blank is as convenient as the conventional solid steel ingot forging preparation, the manufacturing process flow of the high alloy tool and die steel hollow tube blank can be shortened, the quality is improved, the material utilization rate is improved, and the production efficiency is improved.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. Meanwhile, as not specifically described, the machining and forming method and the machining equipment adopted in the embodiment are performed according to the process specification of the corresponding steel grade by referring to the conventional machining and forming process in the existing high-alloy tool and die machining.
Example one
The embodiment relates to a spray forming method of a high-alloy tool and die steel hollow steel ingot, which integrally prepares a cylindrical high-alloy tool and die steel hollow steel ingot with a hollow interior through a spray forming process, and the prepared hollow steel ingot is specifically used for preparing a high-alloy tool and die steel hollow pipe blank so as to form a novel preparation method of the high-alloy tool and die steel hollow pipe blank.
The injection molding method of the high alloy tool and die steel hollow steel ingot of the embodiment specifically comprises the following steps: firstly, rolling a steel plate into a core cylinder meeting the requirements of inner diameter and height, welding and sealing the top end of the core cylinder by the steel plate, welding a flange plate at the bottom end of the core cylinder, fixing the core cylinder on a rotatable collecting tray in an injection chamber by one end with the flange plate welded, and enabling the axis of the core cylinder to be coaxial with the rotation axis of the collecting tray; heating and insulating the refined high-alloy tool and die steel molten steel, then spraying the molten steel to a rotating collecting tray and a rotating core barrel so that the collecting tray and the core barrel are subjected to deposition of atomized semi-molten steel drops, and continuously moving the collecting tray downwards during spraying so as to gradually deposit and form a sprayed steel ingot, and stopping spraying and moving the sprayed steel ingot out of a spraying chamber when the sprayed steel ingot reaches a required height; and finally, air-cooling the sprayed steel ingot, then putting the steel ingot into a furnace for annealing, and taking the steel ingot out of the furnace for air-cooling after annealing to obtain the high-alloy tool and die steel hollow steel ingot.
The thickness of the steel plate used for rolling into the core cylinder and sealing the top end of the core cylinder in the forming method is between 3mm and 5mm, and can be 3mm, 3.5mm, 3.75mm, 4mm, 4.25mm, 4.5mm or 5mm, for example. Meanwhile, the steel plate is generally made of a low carbon steel plate, such as A3 steel. Furthermore, the inner diameter and height of the rolled core barrel may be set according to design requirements, and as a preferred arrangement, the steel plate at the top end of the core barrel should be set to a spherical crown shape welded at the end of the core barrel to achieve closure of the top end of the core barrel by the spherical end. And after the top end of the core barrel is welded and sealed, the core barrel, the sealed top end of the core barrel and the outer surface of the flange plate are preferably subjected to rust removal treatment, and then close combination with a steel ingot deposited subsequently is ensured through rust removal.
In this embodiment, the core barrel is generally formed by rolling the core barrel by a rolling machine and then welding the core barrel by a welding machine, and the spherical crown-shaped top end closed steel plate is obtained by punching the core barrel on a press machine. The flange welded at the bottom end of the core barrel can be directly made of finished parts, or can be manufactured on site by punching a steel plate. The flange plate can be made of the same material as the core cylinder and the steel plate sealed at the top end of the core cylinder, the hole diameter of the flange plate is equal to that of the core cylinder, and the thickness of the flange plate can be set to be consistent with that of the core cylinder and the top end sealing steel plate in the shape of a spherical crown.
The injection chamber of the injection molding machine is internally provided with a collecting tray for bearing the core barrel, the center of the collecting tray is provided with a central rod vertical to the collecting tray, the collecting tray is sleeved outside the central rod and is supported by a molding machine body for installing the central rod, and under the drive of a rotating motor in the molding machine, the collecting tray can rotate around the axis of the central rod, namely, the rotating center of the collecting tray coincides with the axis of the central rod, and meanwhile, the collecting tray can also move up and down along the axial direction of the central rod under the drive of a slideway arranged on the molding machine and an internal moving motor.
The core barrel is fixed on the collecting tray, namely one end of the core barrel, which is welded with the flange plate, is buckled on the collecting tray, wherein the central rod is inserted into the core barrel, and the position of the core barrel is adjusted to ensure that the axis of the core barrel is coaxial with the rotation axis of the collecting tray, so that the verticality between the axis of the core barrel and the collecting tray is ensured, and when the core barrel rotates along with the collecting tray, the rotation deviation of the core barrel can be within an allowable range, and the symmetry and the wall thickness consistency of the subsequently formed hollow steel ingot are ensured. After the position of the core barrel is adjusted, the flange plate and the collecting tray can be fixedly connected through a bolt pair or other fastening connecting pieces, and the core barrel is fixed on the collecting tray.
After the core barrel is fixed, the refined molten steel of the high-alloy tool and die steel is poured into a ladle furnace for heating and heat preservation, after the temperature of the molten steel and the injection parameters are adjusted, the molten steel flows out through a leakage hole of a tundish, high-pressure nitrogen atomizes the molten steel through an injection disc of an injection molding machine, and can be injected to a collecting tray and the core barrel which are driven to rotate by a rotating motor at a set angle and speed, so that the collecting tray and the core barrel can carry out deposition on atomized semi-molten steel drops. Meanwhile, the collection tray drives the core barrel to move downwards continuously under the driving of the moving motor in the injection process, and the injection steel ingot taking the inner barrel as the core can be formed through gradual deposition.
It should be noted that the above-mentioned injection parameters generally include the temperature of molten steel, the rotation speed of the collecting tray, the initial height difference and distance between the collecting tray and the injection tray, and the downward moving speed of the collecting tray. The above spraying parameters are all related to the components and characteristics of the sprayed steel, and during specific implementation, according to the requirements of a general alloy steel spraying forming process, corresponding settings can be carried out according to different components of the steel, and the setting meets the requirement that the solid-to-liquid ratio of atomized semi-molten steel drops received by the collecting tray and the core cylinder is 7: 3, the product is obtained. The injection rate during injection is selected within the adjustable rate range of the injection machine, and on the basis of meeting the solid-liquid ratio, the injection rate can be generally made to be larger as much as possible, so that the density after deposition is favorably improved.
By limiting the solid-liquid ratio of the received atomized semi-molten steel drops, the embodiment can ensure that the sprayed steel ingot formed by the solidified steel drops is compact and has no cavity, and can not form serious segregation due to excessive liquid, thereby finally becoming a high-quality sprayed hollow steel ingot. Of course, in addition to the above preferred solid-to-liquid ratio, the solid-to-liquid ratio of the received shot steel droplets may be other values depending on the steel type, but it is assumed that the density of the deposit is increased.
The required height of the sprayed steel ingot when the spraying is stopped in the embodiment is 90mm-110mm higher than the top end of the welding closed end of the core barrel, namely the top end of the height of the sprayed steel ingot is higher than the top end of the spherical closed end of the core barrel. The arrangement can ensure that the sprayed hollow steel ingot has enough strength, thereby being capable of well meeting the requirements of filling rheological materials and radially forging to prepare the hollow pipe blank in the subsequent embodiment II. The height may be, for example, 90mm, 95mm, 100mm, 102mm, 105mm or 110 mm. In addition, the annealing in this embodiment may be a low temperature softening annealing method, or a high temperature spheroidizing annealing method. The main purpose of annealing is to transform the solidification structure from austenite to pearlite so as to obtain a near-equilibrium structure, reduce hardness, eliminate stress, prevent cracking of the sprayed hollow steel ingot during storage, and facilitate processing operations such as inspection, coping, sawing and the like.
It should be noted that, after annealing and air cooling, the embodiment can further perform flaw detection, inspection and coping on the molded injection hollow steel ingot, and the above operations can be performed by adopting the conventional technical means, and after the above operations, the high alloy tool and die steel hollow steel ingot is stored for standby. For the difference between the material for preparing the core barrel and the material of the tool and die steel subjected to spray deposition, and the finally prepared hollow steel ingot contains the core barrel, it needs to be noted that the existence of the core barrel in the prepared steel ingot does not influence the subsequent use of the steel ingot, and the core barrel part serving as the machining allowance can be completely removed finally in the subsequent machining.
The injection molding method of the embodiment adopts an injection molding process, ensures the inner hole of the molded hollow steel ingot by the inner cylinder, can utilize the process characteristics of injection molding, enables the prepared hollow steel ingot to have uniform and fine structure, fine and dense crystals, greatly improves the segregation of chemical components and eutectic carbide, can approach the quality of products molded by powder metallurgy, and can ensure the quality of the prepared hollow steel ingot.
The method for injection molding of a hollow steel ingot according to the present embodiment will be further described below by way of specific preparation examples.
In this preparation example, specifically, the hollow steel ingot is injection-molded by using M2(W6Mo5Cr4V2) steel, and the hollow steel ingot to be prepared by the injection-molding of the tool and die steel has an inner diameter of 200mm, an outer diameter of 500mm and a height of 1500 mm. The specific process steps are as follows.
The core barrel is first prepared. A3 low carbon steel plate with the thickness of 5mm is adopted, rolled into a cylinder with the inner diameter of phi 200mm by a plate rolling machine, welded into a cylinder shape by a welding seam machine, and then both ends are cut flat to obtain a core cylinder, wherein the height (namely the axial length) of the core cylinder is 1400 mm. Then, a spherical cap having a diameter of 200mm and a height of 50mm was punched out of a 5mm thick a3 mild steel plate in a press machine, and the spherical cap was welded to the top end of the core barrel to close the top end of the core barrel. Then, a flange plate with the inner aperture of phi 200mm and the outer aperture of phi 500mm is punched out by using an A3 steel plate with the thickness of 5mm, and the flange plate is welded to the bottom end of the core barrel, and the perpendicularity between the flange plate and the core barrel needs to be ensured. And finally, performing sand blasting and rust removing treatment on the outer surface of the core cylinder with the closed top end and the outer surface of the flange.
Then, the core barrel with the top end closed and the bottom end fixedly connected with the flange plate is placed into an injection chamber of the injection machine, the core barrel is sleeved on a center rod of the injection machine through one end connected with the flange plate and is placed on a rotatable collecting tray, the position of the core barrel is adjusted, the axis of the core barrel is coaxial with the axis of the collecting tray, and the core barrel and the collecting tray are fixed together through the flange plate after the core barrel is adjusted.
Then, smelting by adopting a 3-ton intermediate frequency furnace, according to the conventional smelting process of high alloy tool and die steel, proportioning, deoxidizing, adjusting components, refining and adjusting IF and LF to obtain qualified M2 molten steel, then tapping into a ladle heating furnace, and carrying out electroslag heating and heat preservation to ensure that the molten steel reaches the temperature required by molten steel injection.
Then, adjusting injection parameters, flowing out molten steel through a tundish eye, enabling high-pressure nitrogen to pass through an injection disc to form an atomization cone on the molten steel, enabling molten droplets to fly to a rotating collection tray and a core barrel to be captured and deposited by the collection tray, enabling the initial height of the collection tray to be 500mm away from the injection disc, enabling the horizontal distance between the collection tray and the core barrel to be 600mm, enabling the collection tray and the core barrel to bear atomized semi-molten steel droplet deposition, enabling the collection tray to move downwards continuously, keeping the height of an injection collection surface to be 500mm away from the injection disc at any time, and gradually depositing to form a hollow injection steel ingot. And stopping spraying when the deposition height of the sprayed steel ingot reaches 1550mm, namely the thickness of the sprayed steel ingot exceeds 100mm of the top end of the spherical crown, and removing the sprayed steel ingot out of the spraying bin after solidification.
In the injection process, specifically, graphite electrodes can be adopted in a smelting steel ladle of an injection forming machine to electrify and heat molten steel through covering protective slag, argon is introduced into air holes in the bottom of the steel ladle to be stirred, the superheat degree of the molten steel reaches 100-150 ℃, then a molten steel flow guide pipe is opened, the molten steel flows into a tundish preheated to about 1000 ℃ through the flow guide pipe in the bottom of the steel ladle, the size of an inlet of the flow guide pipe is controlled to enable the flow rate of the molten steel to be 80-150 kg/min, the tundish is continuously supplemented with heat in the injection process, the superheat degree of the molten steel is kept at 100-150 ℃, the molten steel enters an injection deposition chamber through an opening eye leakage of the tundish, a gas injection valve is opened, nitrogen is adopted as a gas medium to carry out atomization deposition, the purity of the nitrogen is over 99.999%, and the pressure of a gas nozzle is 1.0-1.5 MPa.
In addition, on other spraying process parameters, the temperature of the molten steel is 1530 ℃, the rotating speed of the collecting tray is 60r/min, the downward moving speed of the collecting tray is 75mm/min, and the spraying speed of the spraying machine is 100 kg/min. The design of the parameters ensures that when the molten steel fog drops reach the collecting tray and the core barrel, the solid-liquid ratio of the molten steel fog drops in a semi-molten state is 7: 3.
and (4) after the sprayed steel ingot is moved out of the spraying chamber, air cooling is carried out to 600 ℃, and then the sprayed steel ingot is loaded into a well type annealing furnace for softening annealing. The annealing condition is specifically that the temperature is kept for 6 hours at 860 ℃, and then the annealing material is slowly cooled to 550 ℃ at the cooling speed of less than or equal to 15 ℃/h. And finally, discharging and air cooling to obtain the high-alloy tool and die steel hollow steel ingot.
The prepared hollow steel ingot is further subjected to flaw detection, inspection and grinding generally, and then is stored for later use.
In addition, the embodiment also relates to a high-alloy tool and die steel hollow steel ingot formed by the injection forming method, a specific preparation example of the formed hollow steel ingot can still refer to the preparation examples in the previous text, and the hollow steel ingot formed by the embodiment has uniform and fine structure, and the bore diameter and the cross section consistency of the inner bore can be well guaranteed, so that the hollow steel ingot is a high-quality hollow steel ingot.
The specific application of the shaped hollow ingot of this example will be explained in the following example two.
Example two
The embodiment relates to a preparation method of a high-alloy tool and die steel hollow pipe blank, which specifically comprises the steps of filling rheological materials meeting the hot forging deformation requirement in a hollow steel ingot prepared in the embodiment I, tamping the rheological materials, and then sealing one end of an opening of the hollow steel ingot. And then, heating the hollow steel ingot filled with the rheological material in a furnace, discharging the hollow steel ingot from the furnace after heating, performing radial forging on a finish forging machine to obtain a high alloy tool and die steel billet with the diameter meeting the requirement, then, feeding the high alloy tool and die steel billet into the furnace for annealing, and cooling and straightening after annealing. And then, determining the positions of inner holes at two ends of the straightened high-alloy tool and die steel billet, cutting off the end part of the steel billet at the positions, and removing the filled rheological material to obtain the high-alloy tool and die steel hollow pipe billet.
Wherein the hot forging deformation requirements mentioned in the above preparation method include that the rheological material has a melting point higher than the forging heating temperature, does not react with the steel material when heated, and hot forgingThe volume of the rheological material does not change when the material is deformed, and the rheological material can uniformly flow along with the deformation of the steel ingot. The uniform rheology is that when the steel ingot filled with the rheological material is radially forged, the rheological material can correspondingly flow along with the lengthening and thinning of the steel ingot due to the change of the length-diameter ratio of the steel ingot caused by forging, so that the whole rheological material is lengthened and thinned, the configuration of the steel ingot after forging change is always kept consistent, and the rheological material is ensured to be in a stable filling and filling state in the steel ingot. In practice, the rheological material can be, for example, alumina (Al)2O3) The particle size of alundum powder is 60-120 μm. Of course, other materials besides alundum may be used for the above-described rheological material that meets the hot forging deformation requirements.
By filling the rheological material meeting the hot forging deformation requirement, the inner wall of the hollow steel ingot can be supported in the subsequent radial forging so as to ensure the shape of the inner hole. And the rheological material meets the requirement of hot forging deformation, and can be easily cleaned from an inner hole after being processed.
In the above preparation method of this embodiment, the hollow steel ingot filled with the rheological material is heated according to the cogging heating specification of the corresponding steel grade of the high-alloy tool and die steel. And the subsequent annealing of the high alloy tool and die steel billet can be carried out according to the annealing process system of the corresponding steel grade. In addition, the heated hollow steel ingot is radially forged on a finish forging machine, the stress on the periphery of the steel ingot is uniform, and the whole rheological material is lengthened along with the unchanged volume and becomes thinner in proportion to the steel ingot under the condition that the steel ingot is drawn out, so that the uniform wall thickness and the inner hole roundness of the steel ingot can be kept through the support of the rheological material during forging.
In this embodiment, the deformation ratio of the ingot of the hollow center steel should be not less than 3, for example, it may be 3, 3.2, 3.5 or 4, 4.5, 5, etc. when the finish forging is performed on the finish forging machine. The high alloy tool and die steel can be quenched completely by air quenching to generate martensite transformation, and the structure stress cracking is easily caused, so that annealing is needed in time after the steel ingot is slowly cooled after the steel ingot is forged on a precision forging machine. After annealing, the steel ingot is straightened, and the steel ingot prepared by the embodiment can keep the shape of the pipe blank without being flattened by the same way as the existing solid steel material during straightening by depending on the supporting effect of the rheological material filled in the steel ingot.
In this embodiment, as a preferred embodiment, the positions of the inner holes at both ends of the steel billet can be determined by ultrasonic flaw detection, where the positions of the inner holes are both ends of the inner hole with the same inner diameter in the steel billet. In addition, when the positions of both ends of the inner hole are determined by ultrasonic flaw detection, it is needless to say that the type and size of the flaw can be determined by simultaneously detecting the flaw on the billet, and the detected flaw positions can be removed together when both ends of the billet are removed. After the inner hole positions at the two ends are determined, the two ends of the steel blank can be removed through a band saw so that the filled rheological material can be exposed at the two ends of the steel blank, and then the prepared tube blank can be obtained by cleaning the rheological material.
Compared with the existing preparation method of the high-alloy tool and die steel pipe, the preparation method of the embodiment has the following advantages:
the utilization rate of the material is greatly improved. For example, in the prior art, a forged solid bar is adopted to prepare an undercut broach blank (a longer tube), and a lathe is adopted to machine and undercut an inner hole, so that the utilization rate of steel is low. The hollow ingot can be directly forged, and the hollow ingot with a proper aperture can be designed according to calculation, forged into a more proper tube blank and then processed into an empty broach blank, so that the material utilization rate is greatly improved, and the inner wall quality is much better than that of a directly empty bar.
The process links for preparing the ring product can be reduced. Taking the preparation of the shield hobbing cutter ring as an example, the existing process is that after blanking a solid bar, the solid bar is forged into a cake shape, then the cake shape is punched, reamed, forged or rolled into the hobbing cutter ring in sequence, and then the hobbing cutter ring is machined and formed. If the preparation method is adopted to prepare the hollow pipe blank, the process flow is that after the hollow pipe blank is precisely blanked, the hollow pipe blank is reamed, swaged or rolled into a hobbing cutter ring, and then is machined and formed. Compared with the prior art, the invention omits the working procedures of cake forging, punching and reheating, and simultaneously reduces the waste of punching materials, the defects of the inner wall caused by the quality problem of punching and the like.
The metallurgical quality of the tube blank can be improved, the metallurgical defect distribution is improved, and the quality and the yield of finished tubes and annular cutters made of the tube blank are improved.
The hollow steel ingot formed by injection molding in the embodiment of the invention has a much smaller solidification size (about 1/4 of the diameter of the solid ingot) and a much better solidification condition than the solid ingot with the same diameter, and the metallurgical loose defect is in the middle of the tube wall and slight, and meanwhile, the closed defect can be welded in the subsequent tube blank forging process, so that the solid ingot is prevented from forming the metallurgical defect in a large range at the center or the opening defect which can be formed at the inner wall of a finished pipe fitting or the inner hole of a ring part after punching or hollowing.
The method for producing the hollow shell of the present embodiment is further described below by using specific production examples.
In this preparation example, the hollow steel ingot prepared in example one was used, and the tool and die steel tube blank prepared in this example was specifically used for manufacturing a cold band edge trimmer disc blade. At this time, the tube blank required to be prepared in this example had an outer diameter of 240mm and an inner diameter of 105mm, and the process steps thereof were as follows.
Firstly, filling baked aluminum oxide powder into an inner hole of a hollow steel ingot, tamping while filling, covering an opening end of the steel ingot with an iron plate after filling, and welding and sealing. And then, heating the hollow steel ingot filled with the aluminum oxide powder in an SX55 annular furnace at 1150 ℃, preserving heat for 5 hours, forging the hollow steel ingot out of the furnace into a steel ingot with the outer diameter of 250mm on an SX55 precision forging machine, after the precision forging, air-cooling the hollow steel ingot to about 400 ℃, then putting the hollow steel ingot into an electric annealing furnace for annealing at 880 ℃, preserving heat for 4 hours to 740 ℃, then slowly cooling the hollow steel ingot to 650 ℃ at the temperature of less than or equal to 10 ℃/hour, then furnace-cooling the hollow steel ingot to 550 ℃, and air-cooling the hollow steel ingot out of the furnace.
And then, performing point straightening on the annealed steel ingot on a hydraulic straightening machine, performing ultrasonic flaw detection after the bending degree meets the requirement, determining the end positions of two ends of an inner hole, cutting off the head of the steel ingot by using a band saw to expose the inner hole, then cleaning the aluminum oxide powder in the steel ingot, and detecting that the aperture of the inner hole is about phi 98 mm. Because the powdery aluminum oxide is heated and then forged to be more compact, the space volume occupied by the whole aluminum oxide is reduced, and the reduction ratio of the inner diameter to the outer diameter of the tube blank is slightly larger.
And finally, machining the outer circle and the inner circle of the tube blank by using a lengthened lathe according to the requirement to obtain a finished tube blank with the outer circle phi of 240mm and the inner diameter phi of 105 mm. And through determination, in the preparation process, the yield of the black skin from the hollow steel ingot to the tube blank is about 82%, and the prepared tube blank has the eutectic carbonization grade of 3 grade, so that the tube blank is a true high-quality high-alloy steel tube for the tool and die.
The hollow pipe blank prepared by the preparation method of the high-alloy tool and die steel hollow pipe blank is suitable for manufacturing thick-wall hollow pipe materials, can be further used for manufacturing annular tool and die cutters, can save the process and materials for hollowing out solid materials compared with the prior art, can improve the production efficiency, and has good practicability.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. A preparation method of a high-alloy tool and die steel hollow pipe blank is characterized by comprising the following steps:
a1, rolling a steel plate into a core cylinder meeting the requirements of inner diameter and height, welding and sealing the top end of the core cylinder by the steel plate, and welding a flange plate at the bottom end of the core cylinder;
a2, fixing the cartridge on a rotatable collecting tray in the jet chamber by one end welded with a flange plate, and enabling the axis of the cartridge to be coaxial with the rotation axis of the collecting tray;
a3, heating and preserving the refined high-alloy tool and die steel molten steel, then spraying the molten steel to the rotating collecting tray and the rotating core barrel so that the collecting tray and the core barrel can receive atomized semi-molten steel drops for deposition, and continuously moving the collecting tray downwards during spraying so as to gradually deposit and form a sprayed steel ingot, and stopping spraying and moving the sprayed steel ingot out of a spraying chamber when the sprayed steel ingot reaches the required height;
a4, cooling the sprayed steel ingot by air, then putting into a furnace for annealing, and after annealing, discharging from the furnace for air cooling to obtain a high-alloy tool and die steel hollow steel ingot;
b1, filling rheological materials meeting the hot forging deformation requirement in the hollow steel ingot of the high-alloy tool and die steel, tamping the rheological materials, and then closing one end of an opening of the hollow steel ingot, wherein the hot forging deformation requirement comprises that the rheological materials have a melting point higher than the forging heating temperature, do not react with steel materials during heating, do not change the volume of the rheological materials during hot forging deformation, and can uniformly flow along with the deformation of the steel ingot;
b2, putting the hollow steel ingot filled with the rheological material into a furnace for heating;
b3, discharging the heated hollow steel ingot out of the furnace, performing radial forging on a finish forging machine to obtain a high alloy tool and die steel billet with the diameter meeting the requirement, putting the high alloy tool and die steel billet into the furnace for annealing, and cooling and straightening after annealing;
b4, determining the positions of inner holes at two ends of the high alloy tool and die steel billet, cutting off the end part of the steel billet at the positions, and removing the filled rheological material to obtain the high alloy tool and die steel hollow pipe billet.
2. The method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the thickness of the steel plate is 3-5 mm.
3. The method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the steel plate welded and sealed at the top end of the core cylinder is in a spherical crown shape.
4. The method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the steel plate is a low-carbon steel plate, and the core barrel, the closed top end and the outer surface of the flange plate are subjected to rust removal treatment.
5. The method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the solid-liquid ratio of the atomized semi-molten steel drops received by the collecting tray and the core cylinder is 7: 3.
6. the method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the required height of the sprayed steel ingot is 90-110mm higher than the top end of the core barrel welded and closed.
7. The method for producing a high alloy tool and die steel hollow shell according to any one of claims 1 to 6, characterized in that: the annealing in step a4 includes using low temperature softening annealing, or high temperature spheroidizing annealing.
8. The method for preparing the high alloy tool and die steel hollow shell according to claim 1, characterized in that: the rheological material in step b1 is alumina, and the deformation ratio of the hollow ingot is not less than 3 when the finish forging is carried out on the finish forging machine in step b 3.
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