CN111390134B - A high-performance die-casting forming method and product based on a two-plate die-casting machine - Google Patents
A high-performance die-casting forming method and product based on a two-plate die-casting machine Download PDFInfo
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- CN111390134B CN111390134B CN202010351461.9A CN202010351461A CN111390134B CN 111390134 B CN111390134 B CN 111390134B CN 202010351461 A CN202010351461 A CN 202010351461A CN 111390134 B CN111390134 B CN 111390134B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
- B22D17/2015—Means for forcing the molten metal into the die
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
- B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
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Abstract
本发明属于金属零部件制造加工技术领域，并具体公开了一种基于两板压铸机的高性能压铸件成形方法及产品，其包括如下步骤：S1将两板压铸机的模具合模形成型腔，并锁紧模具；S2将待压铸的合金熔液以先慢速压射再快速压射的方式压射至型腔中；S3待合金熔液填满型腔后进行增压补缩，合金熔液在压力作用下冷却并凝固，然后脱模获得压铸件；S4将压铸件以先低温段二阶段保温再超短时固溶保温的方式进行固溶热处理，然后进行淬火；S5将淬火后的压铸件进行时效热处理，以此获得所需的高性能压铸件。通过本发明可制备大型高性能金属结构件，具有操作简便易行、制备成本低等优点。
The invention belongs to the technical field of metal parts manufacturing and processing, and specifically discloses a high-performance die-casting part forming method and product based on a two-plate die-casting machine, which comprises the following steps: S1. , and lock the mold; S2 injects the alloy melt to be die-casted into the cavity by first slow injection and then rapid injection; S3 is pressurized and fed after the alloy melt fills the cavity, and the alloy The melt is cooled and solidified under pressure, and then demolded to obtain die castings; S4, the die castings are solution heat treated in the form of two-stage heat preservation in the low temperature section and then ultra-short-term solution heat preservation, and then quenched; S5 will be quenched. The die-casting parts are subjected to aging heat treatment to obtain the required high-performance die-casting parts. The invention can prepare large-scale high-performance metal structural parts, and has the advantages of simple operation, low preparation cost and the like.
Description
Technical Field
The invention belongs to the technical field of manufacturing and processing of metal parts, and particularly relates to a high-performance die casting forming method and a high-performance die casting forming product based on a two-plate die casting machine.
Background
In the casting forming process of the aluminum alloy parts, the die casting is a casting method with the fastest production speed and higher quality of formed parts. Aluminum alloy die-casting is a method of rapidly filling a cavity of a metal mold with liquid aluminum alloy under high pressure and rapidly solidifying under high pressure to obtain a casting, which is also called high-pressure casting. By large aluminium alloy structural parts are generally meant highly stressed parts with a maximum dimension of more than 800 mm, or a part weight of more than 10kg, such as automotive structural parts and the like.
Most of the traditional die-casting process methods can only produce non-stressed parts such as shell parts and the like, and are rarely used for producing high-stressed structural parts such as large structural parts such as automobile auxiliary frames and the like. The main reason is that when the die is cast at high speed, molten metal fills the cavity at a high speed of tens of meters per second or more, air in the cavity cannot be exhausted in time, gas is involved in the part and exists in a supersaturated solid solution state, and subsequent heat treatment strengthening cannot be carried out. In recent years, a vacuum die-casting process is developed on the basis of a traditional die-casting machine, namely, before a mold cavity is filled with molten metal, gas in the mold cavity is pumped away by using a vacuum pumping system, so that the gas content of a casting is low, subsequent heat treatment strengthening can be performed, and automobile structural parts and the like can be produced.
The present die casting technology is based on the traditional three-plate die casting machine, and with the development of technology, a new die casting machine structure has appeared in recent years, namely a two-plate die casting machine, such as a two-plate high-speed die casting machine disclosed in patent document CN104226958A and a two-plate die casting machine disclosed in patent document CN 202079275U. The difference between the two-plate die casting machine and the three-plate die casting machine is mainly that a die closing system is adopted, a rear seat plate in the three-plate die casting machine is removed from the die closing system of the two-plate die casting machine, and only a movable die plate and a fixed die plate are contained, so that a follow-up locking mechanism is added to the tail ends of four large bars of the two-plate die casting machine to replace a toggle mechanism, and the two-plate die casting machine has a wide application prospect in die casting production. Since a two-plate die casting machine is a new technology which has recently appeared, research on a die casting process based on the two-plate die casting machine is lacked at present, and the existing die casting process is based on a three-plate die casting machine and is not suitable for the two-plate die casting machine, research is urgently needed in the field to obtain a die casting process matched with the two-plate die casting machine, so that the advantages of the two-plate die casting machine are fully exerted, and a high-stress large-scale structural member is prepared.
Disclosure of Invention
Aiming at the defects or improvement requirements in the prior art, the invention provides a high-performance die casting forming method and a product based on a two-plate die casting machine.
To achieve the above object, according to one aspect of the present invention, there is provided a high-performance die casting forming method based on a two-plate die casting machine, comprising the steps of:
s1, closing the dies of the two-plate die casting machine to form a cavity, and locking the dies;
s2, injecting the molten alloy to be die-cast into the cavity in a mode of firstly performing slow injection and then performing fast injection;
s3, pressurizing and feeding after the die cavity is filled with the molten alloy, cooling and solidifying the molten alloy under the action of pressure, and then demolding to obtain a die casting;
s4, carrying out solid solution heat treatment on the die casting in a mode of low-temperature section two-stage heat preservation and ultra-short solid solution heat preservation, and then quenching;
s5, the die casting after quenching is subjected to aging heat treatment, so that the required high-performance die casting is obtained.
More preferably, in step S2, the slow injection speed is 0.25 to 0.5m/S, preferably 0.35 m/S; the rapid injection speed is 3m/s to 5m/s, preferably 4 m/s.
More preferably, in step S2, the in-gate velocity at the time of rapid injection is 15 to 30m/S, and preferably 25 m/S.
More preferably, in step S3, the pressure-feed specific pressure for pressure-feed is 70MPa to 100MPa, and preferably 85 MPa.
Preferably, in step S4, the low-temperature-stage two-stage heat preservation is performed by heating from room temperature to 110-130 ℃ at a predetermined heating rate for 7-9 hours, and then heating to 260-280 ℃ at the same heating rate for 9-11 hours.
As a further preference, in step S4, the low-temperature stage two-stage heat preservation is further preferably performed by heating from room temperature to 120 ℃ at a preset heating rate for 8 hours, and then heating to 270 ℃ at the same heating rate for 10 hours.
More preferably, in step S4, the ultra-short-term solid solution heat preservation is preferably performed by heating to 10 to 20 ℃ below the solidus temperature of the alloy at a preset heating rate, and performing short-term heat preservation for 0.42 to 0.58 hours; the ultra-short-term solid solution heat preservation is further preferably performed by heating to 15 ℃ below the solidus temperature of the alloy at a preset heating rate, and performing short-term heat preservation for 0.5 hour.
More preferably, the aging heat treatment is to put the die casting after quenching into an aging furnace, heat the die casting from room temperature to 150 ℃ +/-10 ℃ at a preset heating speed, keep the temperature for 9-11 hours, preferably 10 hours, take the die casting out of the furnace and cool the die casting to room temperature.
More preferably, the predetermined heating rate is 30 ℃/hr to 40 ℃/hr.
According to another aspect of the invention, a high performance die cast part is provided, which is obtained by the method.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
the forming method of the invention injects the molten liquid into the cavity in a mode of first slow injection and then fast injection, can avoid the air entrainment of aluminum liquid in the injection chamber and reduce the air entrainment in the mold filling process, and can effectively remove water molecules and organic substance gas on the surface layer of the casting by firstly preserving heat in a low-temperature section and a second stage and then carrying out solution heat treatment by ultra-short solution heat preservation, simultaneously eliminate nitrogen in air involved in the die casting process and hydrogen dissolved in the alloy molten liquid, and ensure that the nitrogen and the hydrogen are diffused and discharged out in the casting.
According to the invention, the speed of the inner gate is designed to be 15-30 m/s in the rapid injection stage, and is reduced by 30-50% compared with the speed of the inner gate in the traditional die casting process of 40-60 m/s, so that the molten alloy can be filled more stably, the air entrainment is greatly reduced, the die casting is favorably subjected to heat treatment, meanwhile, the sectional area of the inner gate is larger when the speed of the inner gate is lower, the feeding is favorably realized by increasing the pressure, the feeding distance is farther, the feeding capability is stronger, the porosity is reduced, and the die casting with a denser interior is obtained.
The invention also researches and designs the slow injection speed and the fast injection speed to obtain better speed, namely the slow injection speed is 0.25-0.5 m/s, preferably 0.35m/s, and the fast injection speed is 3-5 m/s, preferably 4 m/s.
The invention also researches and designs the pressurization specific pressure of the pressurization feeding, obtains better parameters, namely the pressurization specific pressure of the pressurization feeding is 70 MPa-100 MPa, preferably 85MPa, and can improve the feeding effect of the aluminum liquid under the pressurization ratio, thereby being beneficial to eliminating shrinkage cavity and shrinkage porosity in the casting.
The invention also researches and designs a low-temperature section two-stage heat preservation process, obtains better process parameters, namely heats the casting to 110-130 ℃ from room temperature at a preset heating speed for 7-9 hours, then heats the casting to 260-280 ℃ at the same heating speed for 9-11 hours, can effectively remove water molecules and organic substance gas on the surface of the casting under the process, and simultaneously removes nitrogen in air involved in the die casting process and hydrogen dissolved in alloy melt, so that the nitrogen and the hydrogen are diffused and discharged out in the casting.
The invention also researches and designs the ultrashort-time solid solution heat preservation process, obtains better process parameters, namely heats the alloy to 10-20 ℃ below the solidus temperature of the alloy at a preset heating speed, and preserves heat for 0.42-0.58 hours for a short time, can prevent bubbles and parts from deforming at high temperature under the process, effectively eliminates the defects of heat treatment, and greatly improves the mechanical property of the casting.
In addition, the invention also researches and designs an aging heat treatment process to obtain better process parameters, namely, putting the quenched die casting into an aging furnace, heating the die casting to 150 +/-10 ℃ from room temperature at a preset heating speed, preserving heat for 9-11 hours, preferably preserving heat for 10 hours, discharging the die casting from the furnace, and air cooling the die casting to room temperature.
The pressure casting prepared by the invention has better mechanical property than the pressure casting produced by the traditional three-plate die casting machine, is suitable for preparing a stressed structural member, and has better sealing property after the die is closed by utilizing the die locking characteristic of the two-plate die casting machine, so that the pressure increasing specific pressure can be improved without generating defects such as flash and the like (the pressure increasing specific pressure can be designed to be 70-100 MPa based on the invention, and is improved by 20-40 percent compared with the pressure increasing specific pressure of the traditional die casting process), the pressure casting can be subjected to heat treatment, and the mechanical property of the casting is improved by 20-50 percent compared with the mechanical property of the pressure casting produced by the traditional three-plate die casting machine after the heat treatment.
Drawings
FIG. 1 is a flow chart of a method for forming a high performance die cast part based on a two-plate die casting machine according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a solution and quench heat treatment process curve provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of an aging heat treatment process curve provided by an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The embodiment of the invention provides a high-performance die casting forming method based on a two-plate die casting machine, generally speaking, a series of preparation needs to be carried out before die casting, and the method comprises the steps of equipment check point of the two-plate die casting machine, mold preheating, spraying a layer of release agent on the surface of a die casting mold, alloy raw material inspection, smelting, conveying and the like, wherein the specific preheating temperature is determined according to actual needs, for example, 200 ℃, and the method is suitable for any die casting aluminum alloy.
As shown in fig. 1, a high-performance die casting forming method based on a two-plate die casting machine according to an embodiment of the present invention includes the following steps:
s1 mold closing
And closing the fixed template and the movable template of the die-casting mold of the two-plate die-casting machine to form a cavity, and locking the mold. Specifically, a movable die plate moves to enable a movable die on the movable die plate to be in contact with a fixed die on a fixed die plate, die assembly is carried out to form a die cavity, and the movable die and the fixed die are locked by a follow-up locking mechanism of a two-plate die casting machine so as to keep the stability of the die cavity.
S2 pouring and injection filling type
And injecting the molten alloy to be die-cast into the preheated die cavity in a mode of firstly performing slow injection and then performing fast injection. The two-plate die casting machine is the same as the three-plate die casting machine, and the injection of the molten alloy is realized by adopting an injection mechanism, the injection mechanism generally comprises a charging barrel, an injection punch matched with the charging barrel in a sliding way and an injection rod connected with the injection punch, and the injection rod drives the injection punch to act under the action of a power source to inject the molten alloy in the charging barrel into a cavity through an ingate. Specifically, aluminum alloy melt is described in detail, the aluminum alloy melt with the temperature of 680 ℃ is poured into a material barrel of an injection mechanism of a two-plate die casting machine, and then an injection rod and an injection punch are used for injecting aluminum liquid into a cavity preheated to about 200 ℃.
The injection process of the invention is carried out by adopting a mode of firstly carrying out slow injection and then carrying out fast injection, the slow injection speed (injection speed of the injection plunger) is 0.25-0.5 m/s, preferably 0.35m/s, and the fast injection speed (injection speed of the injection plunger) is 3-5 m/s, preferably 4 m/s. Specifically, the injection punch performs slow injection, and when the space of the charging barrel is filled with the molten alloy, the injection punch performs fast injection molding. When the mold is injected quickly, the speed of an inner gate is designed to be 15-30 m/s, preferably 25m/s, and the injection specific pressure is 60MPa until the whole cavity is filled with the molten alloy. Specifically, the inner gate is a place where the pouring system is connected with the casting and a place where aluminum liquid enters a casting cavity, and the sectional area of the inner gate can be increased during mold design and manufacturing so as to ensure that the inner gate speed is 15-30 m/s when the injection speed of the punch is 3-5 m/s.
S3 pressurization, cooling solidification, demoulding and cleaning
After the whole cavity is filled with the alloy melt, the specific pressure is increased, the melt is forced to perform feeding (namely pressurization feeding) on the casting, the alloy melt is cooled and solidified under the action of pressure, and the pressurization specific pressure is 70-100 MPa, preferably 85 MPa; and then demolding to obtain a die casting, specifically releasing a locking mechanism of the two-plate die casting machine, moving a movable die plate backwards to separate a movable die from a fixed die, taking out the die casting, and cleaning a pouring system, an overflow groove, a slag collecting ladle and the like.
S4 solid solution and quenching
Carrying out solution heat treatment on the die casting in a mode of firstly carrying out low-temperature section two-stage heat preservation and then carrying out ultra-short solution heat preservation, and then quenching. Specifically, the die casting is placed into a solid solution heat treatment furnace for solid solution treatment, and the heating process adopts a low-temperature section two-stage heat preservation mode and an ultra-short time solid solution heat preservation mode for heating and temperature rise. As shown in fig. 2, first, heating from room temperature to 110-130 ℃ at a predetermined heating rate, for example, 40 ℃/hr, and holding the temperature for 7-9 hours, preferably heating to 120 ℃ and holding the temperature for 8 hours; then, heating to 260-280 ℃ at a preset heating speed of 40 ℃/hour for example, and carrying out second-stage heat preservation for 9-11 hours, preferably heating to 270 ℃ and preserving heat for 10 hours; finally, heating to the alloy solution temperature T at a predetermined heating rate, such as 40 ℃/hrsxKeeping the temperature for 0.42 to 0.58 hours in a short time, preferably 0.5 hour, TsxThe temperature is 10 to 20 ℃ below the alloy solidus line, preferably 15 ℃ below the alloy solidus line. And (4) rapidly discharging the product out of the furnace after the heat preservation is finished, and quenching the product in water to rapidly cool the product to room temperature.
S5 aging heat treatment
And carrying out aging heat treatment on the quenched die casting to obtain the required high-performance die casting. As shown in FIG. 3, the die casting after quenching is placed in an aging furnace, heated from room temperature to 150 ℃. + -. 10 ℃ at a predetermined heating rate of, for example, 30 ℃/hr, kept at the temperature for 9 to 11 hours, preferably 10 hours, taken out of the furnace and air-cooled to room temperature to obtain a desired die casting.
The filling speed and the pressurizing pressure have important influence on the porosity and the density of the die-casting part, and the injection process of the invention is carried out by adopting a mode of firstly carrying out slow injection and then carrying out fast injection, so that the air entrainment of the aluminum liquid in the injection chamber can be avoided, and the air entrainment in the filling process can be reduced. Under the condition that the injection speed is kept to be 3-5 m/s and the injection specific pressure is kept to be 60MPa, which are the same as those of the traditional die-casting process, the speed of the inner gate is designed to be 15-30 m/s, and is reduced by 30-50% compared with the speed of 40-60 m/s of the inner gate in the traditional die-casting process. Specifically, the speed of the inner gate can be reduced by increasing the sectional area of the inner gate by 30% to 50% while keeping the normal punch speed at about 4m/s, and the speed of the inner gate can be reduced by 30% to 50%. The design of the inner gate speed of 15-30 m/s has the advantages that firstly, the injection speed of the inner gate is reduced, the molten alloy is filled more stably, the entrainment is greatly reduced, and the heat treatment of the die casting is facilitated; and secondly, the increase of the sectional area of the inner sprue is beneficial to realizing feeding by increasing pressure, and the feeding distance is longer, so that the die casting process can adopt higher pressurization specific pressure, the pressurization specific pressure is improved by 20-40% compared with the pressurization specific pressure of the traditional die casting process, the feeding capability is stronger, the porosity is reduced, and a die casting with a denser interior is obtained.
The solution heat treatment process has a significant effect on the gas emission of the die casting and the generation of blister heat treatment defects. The invention adopts a low-temperature section two-stage heat preservation mode to heat and raise the temperature in the heating process of the solid solution heat treatment process, and has obvious difference from the traditional method for linearly heating the solid solution heat treatment to the solid solution temperature. Heating to 110-130 ℃ in the first stage, preserving heat for a long time, effectively removing water molecules on the surface layer of the casting, partially removing nitrogen in air involved in the die-casting process and hydrogen dissolved in the alloy melt, and allowing the nitrogen and the hydrogen to diffuse and discharge outwards in the casting. Heating to 260-280 ℃ in the second stage, preserving heat for a long time, and effectively removing organic substance gas on the surface layer of the casting, wherein the organic substance gas mainly comprises decomposition products of injection ram oil, a mold release agent and the like and enters the surface layer of the casting, and meanwhile, nitrogen in air involved in the die casting process and hydrogen dissolved in the alloy melt can be continuously removed in the stage. The invention has another important characteristic that the ultra-short time solid solution heat preservation is carried out for only 0.42 to 0.58 hours, which is greatly reduced compared with the traditional solid solution heat preservation time (about 4 hours), thereby further preventing the generation of bubbles and the high-temperature deformation of parts at high temperature. By the solution heat treatment process (low-temperature section two-stage heat preservation and ultra-short time solution heat preservation), the heat treatment defect can be effectively eliminated, and the mechanical property of the casting is greatly improved.
The invention can prepare high-performance aluminum alloy die-cast structural parts, and the density of the prepared die-cast parts is 2.7g/cm3The tensile strength is 295MPa or more, the yield strength is 215MPa or more, and the elongation is 3.5% or more.
The following are specific examples of the present invention:
example 1
This embodiment die cast an aluminum alloy automotive structural member of the ADC12 designation. Before die casting, a series of preparation is carried out, including equipment inspection of a two-plate die casting machine, mold preheating (preheating temperature is 200 ℃), spraying of a layer of release agent on the surface of a die casting mold, aluminum alloy smelting, aluminum liquid conveying and the like.
A die casting cycle and heat treatment process specifically includes the steps of:
closing and locking: contacting a movable mould and a fixed mould, closing the mould to form a cavity, and locking the mould by using a follow-up locking mechanism of a two-plate die casting machine;
pouring and injecting: pouring 680 ℃ aluminum alloy melt into a charging barrel of a die casting machine, and injecting molten aluminum into a die cavity preheated to 200 ℃ by using a punch, wherein the injection process is specifically that low-speed injection is performed firstly, and the low-speed injection speed is 0.25 m/s; when the space between the injection punch head and the charging barrel is full of materials, performing rapid injection molding, wherein the speed of the injection punch head is 4m/s, the speed of an inner pouring gate is 25m/s, and the injection specific pressure is 60MPa until the whole cavity is filled with aluminum liquid;
pressurizing, cooling and solidifying: pressurizing and feeding are carried out, the pressurizing specific pressure is 85MPa, and the cooling and solidification of the aluminum alloy part are finished under the action of pressure;
demolding and cleaning: the locking mechanism of the two-plate die casting machine is released, and the movable die is separated from the fixed die; taking out the die casting, and cleaning a pouring system, an overflow groove, a slag collecting ladle and the like;
solid solution and quenching: putting the die casting into a solid solution heat treatment furnace, heating and raising the temperature in a low-temperature stage two-stage heat preservation mode in the heating process, heating from room temperature to 120 ℃ at a speed of 40 ℃/h for first-stage heat preservation, and preserving the heat for 8 h; then heating to 270 ℃ at the speed of 40 ℃/hour for second-stage heat preservation, and preserving heat for 10 hours; finally heating to 15 ℃ below the solidus line of the aluminum alloy at 40 ℃/hour, and keeping the temperature for 0.5 hour in a short time; rapidly discharging the furnace after the heat preservation is finished, quenching the furnace into water, and rapidly cooling the furnace to room temperature;
aging heat treatment: and (3) putting the quenched die casting into an aging furnace, heating to 150 +/-10 ℃ from room temperature at a speed of 40 ℃/h, preserving heat for 10 h, discharging from the furnace, and air cooling to room temperature.
Example 2
This embodiment is die cast an aluminum alloy automotive structural member of YL112 brand. Before die casting, a series of preparation is carried out, including equipment inspection of a two-plate die casting machine, mold preheating (preheating temperature is 200 ℃), spraying of a layer of release agent on the surface of a die casting mold, aluminum alloy smelting, aluminum liquid conveying and the like.
A die casting cycle and heat treatment process specifically includes the steps of:
closing and locking: contacting a movable die with a fixed die, closing the die to form a cavity, and locking the die by using a follow-up locking mechanism of a two-plate die casting machine;
pouring and injecting: pouring 680 ℃ aluminum alloy melt into a charging barrel of a die casting machine, and injecting aluminum liquid into a die cavity preheated to 200 ℃ by using an injection punch, wherein the injection process is specifically that low-speed injection is carried out firstly, and the low-speed injection speed is 0.5 m/s; when the space between the injection punch head and the charging barrel is full of materials, performing rapid injection molding, wherein the speed of the injection punch head is 3m/s, the speed of an inner pouring gate is 15m/s, and the injection specific pressure is 60MPa until the whole cavity is filled with aluminum liquid;
pressurizing, cooling and solidifying: pressurizing and feeding are carried out, the pressurizing specific pressure is 100MPa, and the cooling and solidification of the aluminum alloy part are finished under the action of pressure;
demolding and cleaning: the locking mechanism of the two-plate die casting machine is released, the movable die is separated from the fixed die, the die casting is taken out, and a pouring system, an overflow groove, a slag collecting ladle and the like are cleaned;
solid solution and quenching: putting the die casting into a solid solution heat treatment furnace, heating and raising the temperature in a low-temperature stage two-stage heat preservation mode in the heating process, heating from room temperature to 110 ℃ at a speed of 30 ℃/h for first-stage heat preservation, and preserving the heat for 9 h; then heating to 260 ℃ at the speed of 30 ℃/hour for second-stage heat preservation, and preserving heat for 11 hours; finally heating to 10 ℃ below the solidus line of the aluminum alloy at the rate of 30 ℃/hour, and keeping the temperature for 0.42 hour in a short time; rapidly discharging the furnace after the heat preservation is finished, quenching the furnace into water, and rapidly cooling the furnace to room temperature;
aging heat treatment: and (3) putting the quenched die casting into an aging furnace, heating to 150 +/-10 ℃ from room temperature at a speed of 40 ℃/hour, preserving heat for 9 hours, discharging from the furnace, and air cooling to room temperature.
Example 3
This embodiment die cast an aluminum alloy automotive structural member of the ADC6 designation. Before die casting, a series of preparation is carried out, including equipment inspection of a two-plate die casting machine, mold preheating (preheating temperature is 200 ℃), spraying of a layer of release agent on the surface of a die casting mold, aluminum alloy smelting, aluminum liquid conveying and the like.
A die casting cycle and heat treatment process specifically includes the steps of:
closing and locking: contacting a movable mould and a fixed mould, closing the mould to form a cavity, and locking the mould by using a follow-up locking mechanism of a two-plate die casting machine;
pouring and injecting: pouring 680 ℃ aluminum alloy melt into a charging barrel of a die casting machine, and injecting aluminum liquid into a die cavity preheated to 200 ℃ by using an injection punch, wherein the injection process is specifically low-speed injection, and the low-speed injection speed is 0.35 m/s; when the space between the injection punch head and the charging barrel is full of materials, performing rapid injection molding, wherein the speed of the injection punch head is 5m/s, the speed of an inner pouring gate is 30m/s, and the injection specific pressure is 60MPa until the whole cavity is filled with aluminum liquid;
pressurizing, cooling and solidifying: pressurizing and feeding are carried out, the pressurizing specific pressure is 70MPa, and the cooling and solidification of the aluminum alloy part are finished under the action of pressure;
demolding and cleaning: the locking mechanism of the two-plate die casting machine is released, the movable die is separated from the fixed die, the die casting is taken out, and a pouring system, an overflow groove, a slag collecting ladle and the like are cleaned;
solid solution and quenching: putting the die casting into a solid solution heat treatment furnace, heating and raising the temperature in a low-temperature stage two-stage heat preservation mode in the heating process, heating from room temperature to 130 ℃ at a speed of 40 ℃/h for first-stage heat preservation, and preserving the heat for 7 h; then heating to 280 ℃ at the speed of 40 ℃/hour for second-stage heat preservation, and preserving the heat for 9 hours; finally heating to 20 ℃ below the solidus line of the aluminum alloy at 40 ℃/hour, and keeping the temperature for 0.58 hour in a short time; rapidly discharging the furnace after the heat preservation is finished, quenching the furnace into water, and rapidly cooling the furnace to room temperature;
aging heat treatment: and (3) putting the quenched die casting into an aging furnace, heating the die casting to 150 +/-10 ℃ at the room temperature at the speed of 30 ℃/hour, preserving the temperature for 11 hours, discharging the die casting out of the furnace, and air-cooling the die casting to the room temperature.
The ADC12 aluminum alloy die-casting sample obtained in the embodiment 1-3 is used for room temperature mechanical property test, a material universal tester is used for testing tensile strength, yield strength and elongation, and an Archimedes principle is used for testing part density. Comparative example ADC12 aluminum alloy was die cast using a conventional three-plate die casting machine die casting process, and the same heat treatment process was used as in the present invention.
The test results are shown in Table 1, and it can be seen from Table 1 that the density of the casting produced by the present invention is 2.7g/cm3The tensile strength is 295MPa or more, the yield strength is 215MPa or more, and the elongation is 3.5% or more. Through the same heat treatment, the density of the casting is improved by 5.4-6.2% compared with that of the casting 1 in the comparative example of the traditional process, high-density die casting is realized, the mechanical property is improved by 20-40% compared with that of the die casting produced by the traditional process (tensile strength and yield strength), and the toughness (elongation) is improved by 100-160%. Compared with the casting adopting the conventional heat treatment process or not in the traditional die casting process, the die casting prepared by the invention has more improved mechanical properties.
TABLE 1 results of Performance test of examples 1 to 3 and comparative example 1
| Item | Part density/(g/cm)3) | Tensile strength/MPa | Yield strength/MPa | Elongation/percent |
| Comparative example 1 | 2.58 | 241 | 162 | 1.9 |
| Example 1 | 2.73 | 296 | 216 | 5.0 |
| Example 2 | 2.74 | 306 | 220 | 4.6 |
| Example 3 | 2.72 | 298 | 221 | 3.8 |
The present die casting process is based on a conventional three-plate die casting machine, and the die casting process of the present invention is based on a two-plate die casting machine developed in recent years. The two-plate die casting machine is locked by combining machinery and hydraulic pressure, so that the two-plate die casting machine has the advantages of convenience and rapidness in die thickness adjustment, uniform distribution of die locking force, automatic compensation of die thickness variation and non-parallelism, small occupied area, energy conservation and the like.
The die casting has the advantages that the porosity is reduced, the interior of the die casting is more compact, the condition of heat treatment can be achieved, the speed is 30-50% lower than that of a traditional inner pouring gate, the molten alloy is more stably filled, and the air entrainment is greatly reduced; meanwhile, compared with the traditional die casting process, the pressurization specific pressure is improved by 20-40%, the feeding capacity is stronger, the porosity is reduced, the interior is denser, and therefore the die casting can be subjected to heat treatment to further improve the strength. The pressure casting has higher mechanical property than the pressure casting produced by the traditional three-plate die casting machine, is suitable for stressed structural parts, has better sealing property after the die is closed by utilizing the die locking characteristic of the two-plate die casting machine, thereby improving the pressurization specific pressure without generating the defects of flash and the like, can carry out heat treatment on the pressure casting, and improves the mechanical property of the casting by 20 to 50 percent compared with the pressure casting produced by the traditional three-plate die casting machine after the heat treatment. The invention utilizes the two-plate die casting machine, adopts the die casting process for production, saves energy, has lower cost, has small motor power of the two-plate die casting machine, has energy-saving effect, and saves 17 to 27 percent of energy compared with the traditional three-plate die casting machine. In addition, by adopting the process of the invention, parts such as automobile structural parts and the like which can be subjected to heat treatment can be produced under the non-vacuum die-casting condition, the investment cost and the use cost of vacuum die-casting equipment are saved, and the production cost of the aluminum alloy structural part is relatively lower. The invention can solve the problems of easy shrinkage porosity and shrinkage cavity, low density, incapability of heat treatment strengthening and the like of large aluminum alloy die-cast structural parts, thereby improving the density and mechanical property of castings, and being suitable for the preparation of large high-performance aluminum alloy die-cast structural parts, such as automobile auxiliary frames and other large structural parts.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (12)
1. A high-performance die casting forming method based on a two-plate die casting machine is characterized by comprising the following steps:
s1, closing the dies of the two-plate die casting machine to form a cavity, and locking the dies;
s2, injecting the molten alloy to be die-cast into the cavity in a mode of firstly performing slow injection and then performing fast injection, and ensuring that the speed of the inner gate is 15-30 m/S during fast injection by increasing the sectional area of the inner gate;
s3, pressurizing and feeding after the die cavity is filled with the molten alloy, cooling and solidifying the molten alloy under the action of pressure, and then demolding to obtain a die casting;
s4, heating the die casting from room temperature to 110-130 ℃ at a preset heating speed, preserving heat for 7-9 hours, then heating to 260-280 ℃ at the same heating speed, preserving heat for 9-11 hours to realize low-temperature section two-stage heat preservation, then heating to 10-20 ℃ below the solidus temperature of the alloy at the preset heating speed, carrying out ultra-short time solid solution heat preservation for 0.42-0.58 hours, and finally quenching;
s5, the die casting after quenching is subjected to aging heat treatment, so that the required high-performance die casting is obtained.
2. The high-performance die casting forming method based on the two-plate die casting machine according to claim 1, wherein in step S2, the slow injection speed is 0.25m/S to 0.5 m/S; the rapid injection speed is 3-5 m/s.
3. The high-performance die casting forming method based on the two-plate die casting machine according to claim 2, wherein in step S2, the slow shot speed is 0.35 m/S; the fast shot velocity was 4 m/s.
4. The high-performance die casting forming method based on the two-plate die casting machine according to claim 1, wherein in step S2, the in-gate speed at the time of rapid injection is 25 m/S.
5. The method for forming a high-performance die cast product based on a two-plate die casting machine according to claim 1, wherein in step S3, the specific pressurization pressure for the pressurization feeding is 70MPa to 100 MPa.
6. The method for forming a high-performance die cast product based on a two-plate die casting machine according to claim 5, wherein in step S3, the specific pressurization pressure of the pressurization feeding is 85 MPa.
7. The method of forming a high-performance die cast article based on a two-plate die casting machine according to claim 1, wherein the low-temperature stage two-stage heat-retaining is performed by heating from room temperature to 120 ℃ at a predetermined heating rate for 8 hours, and then heating to 270 ℃ at the same heating rate for 10 hours in step S4.
8. The method for forming a high-performance die cast product based on a two-plate die casting machine according to claim 1, wherein the ultra-short-term solid solution heat preservation is performed by heating to 15 ℃ below the solidus temperature of the alloy at a predetermined heating rate and holding for 0.5 hour for a short time in step S4.
9. The method for forming a high-performance die casting based on a two-plate die casting machine according to claim 1, wherein the aging heat treatment comprises placing the quenched die casting into an aging furnace, heating the die casting from room temperature to 150 ℃ ± 10 ℃ at a preset heating rate, keeping the temperature for 9-11 hours, discharging and air cooling to room temperature.
10. The method of forming a high performance die cast part based on a two plate die casting machine according to claim 9, wherein the aging heat treatment holding time is 10 hours.
11. The method of forming a high performance die cast part based on a two-plate die casting machine according to claim 1, wherein the predetermined heating rate is 30 ℃/hr to 40 ℃/hr.
12. A high performance die cast article prepared by the method of any one of claims 1 to 11, said high performance die cast article having a density of 2.7g/cm3The tensile strength is 295MPa or more, the yield strength is 215MPa or more, and the elongation is 3.5% or more.
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