CN103691911B - A kind of casting method of magnesium alloy and device thereof - Google Patents
A kind of casting method of magnesium alloy and device thereof Download PDFInfo
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- CN103691911B CN103691911B CN201310692358.0A CN201310692358A CN103691911B CN 103691911 B CN103691911 B CN 103691911B CN 201310692358 A CN201310692358 A CN 201310692358A CN 103691911 B CN103691911 B CN 103691911B
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Abstract
The invention discloses a kind of casting method of magnesium alloy, the method comprises: removed the gred by magnesium alloy smelting; By gypsum mould preheating; Carry out suppressing for 1 ~ 2 minute to described lower tank with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa; Described upper tank is vacuumized, reaches regulation negative pressure value k
1, the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank, is raised to regulation negative pressure value k
2; Be that the air pressure of 10 ~ 80KPa pressurizes to described lower tank with pressure, realize pressure casting.The invention discloses a kind of casting device of magnesium alloy.Technical scheme disclosed in this invention, the foundry goods average wall thickness of production is 1.0 ~ 1.5mm, and hot strength reaches 190MPa, and percentage elongation reaches 2 ~ 3%, surface quality is high, non-oxidation, cold shut and dreg defect, and dense internal organization is functional, and technique is simple, easy to operate, cost is low.
Description
Technical field
The present invention relates to a kind of foundry engieering, particularly relate to a kind of casting method and device thereof of magnesium alloy.
Background technology
Magnesium alloy density is low, has the advantages such as high specific strength/specific stiffness, dimensionally stable, heat-conductivity conducting are good, damping vibration attenuation, electromagnetic shielding.At present, as important structural material, be widely used in the industrial circles such as Aeronautics and Astronautics, automobile, electronic communication.In national defence, owing to requiring higher to individual combat at present, as weight-reducing material, magnesium alloy also occupies a tiny space.As far back as the 1950's, the covering of the aircraft that China copies and guided missile, framework and engine crankcase adopt magnesium-rare earth alloy.After the seventies, along with developing rapidly of China's aeronautical and space technology, magnesium alloy is also progressively promoted and applies on the products such as attack plane, helicopter, guided missile, satellite.At present, China's Aeronautics and Astronautics, national defence to the active demand of loss of weight be magnesium alloy new material, the development & application of new technology provides opportunities and challenges.
Current, restriction magnesium alloy materials is Mg alloy castings casting difficulty at one of Aeronautics and Astronautics, national defence application principal element, its Key points for foundry is how to enable Complex Parts be shaped smoothly and ensure not burn in die cavity, thus improves the dimensional accuracy of foundry goods and reduce surface roughness.But Mg alloy castings manufactures primarily of die casting and sand casting, and die casting is at present the most general Mg alloy formed technique, but die casting can only less, the simple foundry goods of structure of forming dimension; Due to the existence of pore, foundry goods can not heat-treat or weld, and can not compare dark machined; Traditional sand casting can be shaped the Mg alloy castings that size is larger, complex-shaped, wall thickness is larger, is the forming technology that current large complicated Mg alloy castings extensively adopts.But because the thermal conductivity of sand mold is comparatively large, making to rely on sand casting to carry out loss of weight for the Mg alloy castings that wall thickness is less cannot realize; In addition, the dimensional accuracy of sand casting foundry goods is low, surface quality is poor, and allowance is large, adds the workload of subsequent treatment.Gypsum type melting mould founding, casting technique is simple, and replicability is good, and the foundry goods that in the profile that can be shaped, structure is extremely complicated, wall thickness is very little, if gypsum quality is good, can cast out the foundry goods that precision is high, surface quality is good.But rely on existing cast means, because the oxidation-protective effect of current gypsum mould is poor, even if adopt vacuum pouring, be also difficult to ensure that magnesium alloy liquation does not react with gypsum and even burn, hinder the popularization of plaster casting magnesium alloy.
Summary of the invention
(1) technical problem that will solve
Technical problem to be solved by this invention is: the casting method how providing a kind of magnesium alloy, to overcome magnesium alloy oxidizable incendive technical problem in casting process in prior art; And a kind of casting device of magnesium alloy is provided.
(2) technical scheme
In order to solve the problems of the technologies described above, on the one hand, the invention provides a kind of casting method of magnesium alloy, the method comprises: pour into a mould under condition of negative pressure.
On the other hand, present invention also offers a kind of casting method of magnesium alloy, the method comprises:
Step 1, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible, and described crucible is built in lower tank, with the described lower tank of seal cover board sealing;
Step 2, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds are placed on described seal cover board, and with lower tank described on cover;
Step 3, carry out suppressing for 1 ~ 2 minute to described lower tank between described seal cover board and described crucible with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa, make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer;
Step 4, by the negative-pressure vacuum pipeline being positioned at the top of described upper tank, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach regulation negative pressure value k
1, then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank from the top of described upper tank, makes the negative pressure of described upper tank be raised to regulation negative pressure value k
2;
Step 5, be that the air pressure of 10 ~ 80KPa pressurizes to described lower tank from the middle and lower part of described lower tank with pressure, make described magnesium alloy liquation be entered the die cavity being arranged in described upper tank by the stalk being built in described crucible, realize pressure casting.
Preferably, step 3 and the mist described in step 4 are the mist of 10% sulfur hexafluoride and 90% argon gas; Or 5% mist of sulfur hexafluoride and 95% argon gas.
Preferably, the regulation negative pressure value k described in step 4
1for-20 ~-50KPa, described regulation negative pressure value k
2for-10 ~-30KPa.
Preferably, step 5 also comprises adjusting process parameter, and described technological parameter comprises:
Rise liquid speed be 30 ~ 40mm/s, rise that hydraulic coupling is 5 ~ 8KPa, filling velocity is 30 ~ 60mm/s, mold filling pressure is 30 ~ 50KPa, investing time is 2 ~ 5s, crust boost pressure is 3 ~ 8KPa, crystallization time is 150 ~ 350s, crystallization boost pressure be 3 ~ 8KPa and resistance coefficient is 1.2-1.5.
Preferably, when production wall thickness is the magnesium alloy ZM10 foundry goods of 1.5mm, described magnesium alloy smelting temperature is 780 DEG C, when described gypsum mould preheat temperature is 380 DEG C, and described setting k
1for-30KPa, described setting k2 is-20KPa, described rise liquid speed be 35m/s, rise that hydraulic coupling is 6KPa, filling velocity is 40mm/s, mold filling pressure is 38KPa, investing time is 5s, crust boost pressure is 3KPa, crystallization time is 150s, crystallization boost pressure be 3KPa and resistance coefficient is 1.2.
Preferably, when production wall thickness is the magnesium alloy ZM5 foundry goods of 1.4mm, described magnesium alloy smelting temperature is 820 DEG C, and described gypsum mould preheat temperature is 400 DEG C, described setting k
1for-20KPa, described setting k2 is-10KPa, described rise liquid speed be 40m/s, rise hydraulic pressure 5KPa, filling velocity is 50mm/s, mold filling pressure is 40KPa, investing time is 3s, crust boost pressure is 5KPa, crystallization time is 250s, crystallization boost pressure be 5KPa and resistance coefficient is 1.5.
Another aspect, present invention also offers a kind of casting device of magnesium alloy, and this device comprises:
Lower tank 1, the middle and lower part of described lower tank 1 is connected with pressue device 2; The top of described lower tank 1 adopts seal diaphragm 15 to seal; The built-in melting furnace 3 of described lower tank 1 and the crucible 4 for holding magnesium alloy liquation, the built-in stalk 17 of described crucible 4, certain distance is arranged at the lower end of described stalk 17 and the bottom of described crucible 4, and described stalk 17 upper end oral area is through seal diaphragm 15; Between described crucible 4 and seal diaphragm 15, described lower tank 1 is connected with the first protective gas pipeline 7;
Upper tank 13, the top of described upper tank 13 or sidewall are connected with negative-pressure vacuum pipeline 12 and the second protective gas pipeline 16; The built-in gypsum mould 8 with die cavity 14 of described upper tank 13, described gypsum mould 8 is placed directly on described seal diaphragm 15, be provided with asbestos 10 and asbestos pressing plate 11 successively above described gypsum mould 8, described asbestos pressing plate 11 is fixedly connected with by stud 9 with described seal diaphragm 15; Described upper tank 13 is locked by retaining mechanism 5 with described seal diaphragm 15.
Preferably, described first protective gas pipeline 7 is connected with the first protective gas device and the second protective gas device respectively with the second protective gas pipeline 16; Or be connected with same protective gas device 6, controlled by control system, disconnect described second protective gas pipeline 16, connect described first protective gas pipeline 7, inject protective gas to described lower tank 1; Disconnect described first protective gas pipeline 7, connect described second protective gas pipeline 16, inject protective gas to described upper tank 13.
Again on the one hand, present invention also offers and a kind ofly adopt casting device described above to carry out the method for casting, the method comprises:
Step 1, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible 4, and described crucible 4 is built in lower tank 1, with the described lower tank 1 of seal cover board sealing;
Step 2, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds 14 are placed on described seal cover board 15, and covers described lower tank 1 with tank 13;
Step 3, carry out suppressing for 1 ~ 2 minute to described lower tank 1 by described first protective gas pipeline 7 with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa, make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer;
Step 4, by negative-pressure vacuum pipeline 12, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach-20 ~-50KPa; Then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank 13 by the second protective gas pipeline 16, make the negative pressure of described upper tank 13 be raised to-10 ~-30KPa;
Step 5, employing pressue device 2, pressurize to described lower tank 1 with the air pressure of 10 ~ 80KPa, described magnesium alloy liquation entered in described die cavity 14 by described stalk 17, realizes pressure casting.
(3) beneficial effect
Casting method and the device tool thereof of a kind of magnesium alloy provided by the present invention have the following advantages:
The present invention suppresses protection by adopting the mist of 1-10% sulfur hexafluoride and 90-99% argon gas to lower tank, the heavier sulfur hexafluoride of proportion can be made to float on above magnesium alloy liquation, generate the diaphragm of one deck compactness, both can prevent magnesium alloy liquation from continuing reaction or evaporation, by can by magnesium alloy liquation and air insulated; Vacuumize upper tank, the air in die cavity is discharged by asbestos; Under upper tank is in negative pressure state, injects protective gas, prevent that the magnesium alloy liquation in die cavity burns, the phenomenon such as misrun or cold shut, be conducive to filling type; And by pressue device, lower tank is exerted pressure, make magnesium alloy liquation from bottom to top inject die cavity along stalk, and a larger external force is provided, be conducive to filling type and solidifying, be conducive to the production of thin-wall part.Adopt technical scheme provided by the present invention, foundry goods average wall thickness is 1.0 ~ 1.5mm, and hot strength reaches 190MPa, and percentage elongation reaches 2 ~ 3%, surface quality is high, non-oxidation, cold shut and dreg defect, dense internal organization, functional, and technique is simple, easy to operate, cost is low, is easy to batch production.
Accompanying drawing explanation
Fig. 1 is the casting method schematic flow sheet of embodiment one;
Fig. 2 is the casting method schematic flow sheet of embodiment two;
Fig. 3 a is the excessive burning foundry goods schematic diagram of negative pressure;
Fig. 3 b is the scope internal shaping foundry goods schematic diagram of negative pressure in regulation negative pressure value;
Fig. 4 is the casting device schematic diagram of embodiment four.
Detailed description of the invention
Below in conjunction with Figure of description and embodiment, the specific embodiment of the present invention is described in further detail.Following examples only for illustration of the present invention, but are not used for limiting the scope of the invention.
Embodiment one
As shown in Figure 1, the present embodiment describes the casting method of the nearly pressure regulation gas shield of a kind of magnesium alloy, and the method comprises the steps:
Step 101, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible, and described crucible is built in lower tank, with the described lower tank of seal cover board sealing.
On the one hand, because magnesium alloy thin wall pieces pouring temperature is higher, magnesium alloy liquation and gypsum are easily reacted; On the other hand, this method is filled with protective gas in advance in the die cavity of gypsum mould, and can stop reacting of magnesium alloy liquation and gypsum, therefore, through test of many times, the smelting temperature of magnesium alloy is 730 DEG C ~ 820 DEG C by the present embodiment.
Step 102, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds are placed on described seal cover board, and with lower tank described on cover.
In order to prevent the temperature of gypsum mould too low, reducing the temperature of the magnesium alloy liquation in die cavity, causing the defect such as misrun, cold shut, thus first gypsum mould is carried out preheating, generally carry out preheating at 200 DEG C ~ 400 DEG C.
Step 103, carry out suppressing for 1 ~ 2 minute to described lower tank between described seal cover board and described crucible with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa; make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer.
In the mist of 1-10% sulfur hexafluoride and 90-99% argon gas; the larger sulfur hexafluoride of proportion floats on the surface of magnesium alloy liquation; react with magnesium alloy liquation; the diaphragm of the compactness of production protective action; on the one hand, magnesium alloy liquation can be stoped to continue reaction, prevent the evaporation of magnesium alloy liquation; magnesium alloy liquation and outside air can be isolated again, prevent magnesium alloy from burning.
Step 104, by the negative-pressure vacuum pipeline being positioned at the top of described upper tank, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach regulation negative pressure value k
1, then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank from the top of described upper tank, makes the negative pressure of described upper tank be raised to regulation negative pressure value k
2.
Upper tank is vacuumized, air in die cavity is discharged by asbestos, tank is made to be in negative pressure state, and then inject the mist of 1-10% sulfur hexafluoride and 90-99% argon gas, this mist enters in die cavity by asbestos, react with the magnesium alloy liquation entered in die cavity and generate layer protecting film, both magnesium alloy liquation can have been stoped to continue reaction, again can by magnesium alloy liquation and gypsum mould isolation, make tank be in negative pressure state simultaneously, eliminate the condition producing counter-pressure in cavity filling process, the magnesium alloy liquation under external force drives is made to be easy to overcome own wt, other external force such as the pressure in viscous force and die cavity, be conducive to realizing anti-gravity pouring.Regulation negative pressure value k1 is generally-20 ~-50KPa, regulation negative pressure value k
2be generally-10 ~-30KPa.Value is excessive, and in stalk, air agitation is large, easily causes magnesium alloy liquation to burn in stalk, formed and be mingled with in a large number, be unfavorable for filling type, the burning foundry goods schematic diagram that the negative pressure shown in Fig. 3 a is excessive, the shaped casting figure of the negative pressure shown in Fig. 3 b within the scope of regulation negative pressure value; Too small, easily cause misrun or cold shut phenomenon.
Step 105, be that the air pressure of 10 ~ 80KPa pressurizes to described lower tank from the middle and lower part of described lower tank with pressure, make described magnesium alloy liquation be entered the die cavity being arranged in described upper tank by the stalk being built in described crucible, realize pressure casting.
Pressurize in the middle and lower part of lower tank, to avoid the sulfur hexafluoride above by magnesium alloy liquation to blow open, do not have protective effect, simultaneously, certain external force is applied to lower tank, the pressure of magnesium alloy molten surface is made to be greater than pressure in stalk, under the driving of external force, magnesium alloy liquation overcomes the gravity of self, other external force such as the pressure in viscous force and die cavity, flow along the rightabout of gravity in stalk, from bottom to top enter die cavity, thus achieve anti-gravity pouring, filling type and to solidify at foundry goods, for magnesium alloy liquation provides larger external force, to overcome thin-section casting, resistance in intricate casting, improve the feeding capacity of magnesium alloy liquation, reduce shrinkage cavity, the casting flaw such as pore and pin hole, be conducive to the formation of thin-wall part.
Also comprise adjusting process parameter in the present embodiment step 105, concrete selection principle is as follows:
1, rise liquid speed, rise liquid speed and refer to the rate of climb of melt in stalk.When the liquid speed that rises that magnesium alloy liquation enters die cavity is excessive, because casting mold cast gate bore is certain, when filling velocity one timing, easily occur spraying; Too small, the temperature drop of magnesium alloy liquation in stalk is too large, easy misrun or cold shut phenomenon.
2, rise hydraulic coupling, rise hydraulic coupling and refer to that melt completes and rise liquid process, arrive stalk mouth, pressure corresponding when connecting bottom contact.The value of this parameter is relevant with the number of magnesium alloy liquation, and magnesium alloy liquation is fewer, and this parameter value is larger.According to this value, device determines that rising liquid process terminates, and fills type and starts, fill type quality with what ensure foundry goods.
3, filling velocity refers to the rate of climb of melt in die cavity.The value of this parameter is most important to casting quality, and value is too large, can cause and fill type steadily, causes melt splash or feel suffocated; Value is too little, can cause cold shut or owe casting.Concrete size and foundry goods height, wall thickness, complexity are relevant.Generally, foundry goods average wall thickness is comparatively large, and value is less; Foundry goods average wall thickness is less, and value is larger.
4, mold filling pressure refer to melt arrive die cavity top time pressure.The value of this parameter is relevant with the height of the number of melt in melting and heat preservation stove and foundry goods.In stove, melt is fewer, and this value is larger; Foundry goods is higher, and this value is larger.
5, investing time refers to cast into cast(ing) surface solidify time required for crust from being full of.This parameter value is too large, crusts too thick, even makes foundry goods be in the mushy freezing stage, and feeding is solidified in impact, finally causes occurring shrinkage porosite, micro pine.
6, the pressure increment that the boost pressure that crusts refers to provide to make foundry goods crust under pressure, is namely full of on the basis of die cavity at melt, then increases certain pressure.While can ensureing that melt crusts under stress, improve feeding capacity.This parameter value is too large, there will be scab phenomenon, casting mold even can be made to deform.
7, after crystallization time refers to that foundry goods completes shells solidify, finally the required time is solidified completely.This parameter value is too little, and foundry goods can not solidify completely, too early pressure release, cast structure can be caused not fine and close, do not reach feeding object; Value is too large, stalk can be made to freeze, affect operating efficiency.The concrete value of this parameter is relevant with casting weight, wall thickness etc.
8, crystallization boost pressure refers to that unit is KPa in order to make foundry goods crystallization and the larger supercharging value provided under larger pressure.Why providing this supercharging value, is to make foundry goods reach better feeding in process of setting, makes to organize finer and close.According to the rated operating pressure of used frock and equipment, give larger value as far as possible.
9, resistance coefficient value is mainly in order to consider the complexity of die cavity.Fill type height for identical, die cavity is more complicated, and the pressure of needs is larger, so foundry goods is more complicated, this parameter value is larger.
Through test of many times, according to the rated operating pressure of the height of magnesium alloy liquation amount, foundry goods average wall thickness, foundry goods, casting weight and the frock used and equipment, the liquid speed that rises in the present embodiment can be 30 ~ 40mm/s, rise hydraulic coupling and can be 5 ~ 8KPa, filling velocity can be 30 ~ 60mm/s, mold filling pressure can be 30 ~ 50KPa, investing time can be 2 ~ 5s, crust boost pressure can be 3 ~ 8KPa, crystallization time can be 150 ~ 350s, crystallization boost pressure can be 3 ~ 8KPa, and resistance coefficient can be 1.2-1.5.
Adopt the technical scheme of the present embodiment, foundry goods average wall thickness is 1.0 ~ 1.5mm, and hot strength reaches 190MPa, and percentage elongation reaches 2 ~ 3%, surface quality is high, non-oxidation, cold shut, dreg defect, dense internal organization, functional, and technique is simple, easy to operate, cost is low, is easy to batch production.
Embodiment two
With ZM10 magnesium alloy, gypsum mould batching (mass fraction) be below: the silica flour of 15% ~ 20%, the talcum powder of 6% ~ 8%, the αsemiwatergypsum of 60% ~ 85%, the MgS0 of 18% ~ 25%
4, water and other materials, mixed gases matching is 10% sulfur hexafluoride and 90% argon gas is raw material; casting device structure chart shown in composition graphs 4; specifically introduce the present embodiment, as shown in Figure 2, the concrete steps of the casting method of a kind of magnesium alloy nearly pressure regulation gas shield that the present embodiment is recorded are as follows:
Step 201, carries out melting by ZM10 magnesium alloy at 780 DEG C, slags tap, and the magnesium alloy liquation after slagging-off is put into crucible, with the lower tank of seal diaphragm sealing.
Step 202, carries out preheating at 380 DEG C to gypsum mould, mould assembling by upper and lower for upper cover tank.
Step 203, carries out suppressing for 1 minute to lower tank with the air pressure that the mist of 10% sulfur hexafluoride and 90% argon gas, pressure are 5KPa.
Step 204, vacuumizes upper tank, makes the negative pressure of tank reach-30KPa, then the mist of described 10% sulfur hexafluoride and 90% argon gas is injected upper tank, makes the negative pressure of tank be raised to-20Kpa.
Step 205, adjusting process parameter is that the air pressure of 50KPa carries out pressure pouring to lower tank with pressure.
Wherein, rising liquid speed is 35m/s, and rising hydraulic coupling is 6KPa, and filling velocity is 40mm/s, and mold filling pressure is 38KPa, and investing time is 5s, and crust boost pressure is 3KPa, and crystallization time is 150s, and crystallization boost pressure is 3KPa, and resistance coefficient is 1.2.Pressurizeed to lower tank 1 by pressue device 2, its applied pressure is 50KPa, to realize pressure casting.
The technical scheme adopting the present embodiment to record produces a mould four gypsum mould thin-section castings, foundry goods average wall thickness 1.5mm, and surface smoothness is 3.6.
Embodiment three
The casting method of the nearly pressure regulation gas shield of a kind of magnesium alloy that the present embodiment is recorded, substantially identical with the technical scheme that above preferred embodiment is recorded, difference be raw material and technological parameter different:
One, raw material is different, and magnesium alloy is ZM5, mixed gases matching is 5% sulfur hexafluoride+95% argon gas;
Two, magnesium alloy ZM5 melt temperature is 820 DEG C, and the preheat temperature of gypsum mould is 400 DEG C;
Three, upper tank is vacuumized, make the negative pressure of tank reach-20KPa, then described mist is injected upper tank, make the negative pressure of tank be raised to-10Kpa;
Four, carry out suppressing for 2 minutes to lower tank with the air pressure that the mist of 5% sulfur hexafluoride and 95% argon gas, pressure are 3Kpa
Five, be that the air pressure of 55KPa carries out pressure pouring to lower tank with pressure, rising liquid speed is 40m/s, rising hydraulic coupling is 5Kpa, filling velocity is 50mm/s, and mold filling pressure is 40Kpa, and investing time is 3s, crust boost pressure is 5Kpa, crystallization time is 250s, and crystallization boost pressure is 5Kpa, and resistance coefficient is 1.5.
The technical scheme adopting the present embodiment to record produces mould gypsum mould thin-section casting, foundry goods average wall thickness 1.4mm, and surface smoothness is 3.6.
Embodiment four
As shown in Figure 4, the casting device of a kind of magnesium alloy that the present embodiment is recorded, as shown in Figure 4, this device comprises: lower tank 1, and the middle and lower part of lower tank 1 is connected with pressue device 2; The top of lower tank 1 adopts seal diaphragm 15 to seal; The built-in melting furnace 3 of lower tank 1 and the crucible 4 for holding magnesium alloy liquation, the built-in stalk 17 of crucible 4, certain distance is arranged at the lower end of stalk 17 and the bottom of described crucible 4, and stalk 17 upper end oral area is through seal diaphragm 15; Between crucible 4 and seal diaphragm 15, lower tank 1 is connected with the first protective gas pipeline 7.
Upper tank 13, the top of upper tank 13 or sidewall are connected with negative-pressure vacuum pipeline 12 and the second protective gas pipeline 16; The built-in gypsum mould 8 with die cavity 14 of upper tank 13, gypsum mould 8 is placed directly on seal diaphragm 15, and be provided with asbestos 10 and asbestos pressing plate 11 successively above gypsum mould 8, asbestos pressing plate 11 is fixedly connected with by stud 9 with seal diaphragm 15; Upper tank 13 is locked by retaining mechanism 5 with seal diaphragm 15.
The first protective gas pipeline 7 of the present embodiment can be connected with the first protective gas device and the second protective gas device respectively with the second protective gas pipeline 16, also can be connected with same protective gas device 6, be controlled by control system.Disconnect the second protective gas pipeline 16, connect the first protective gas pipeline 7, downward tank 1 injects protective gas; Disconnect the first protective gas pipeline 7, connect the second protective gas pipeline 16, upwards tank 13 injects protective gas.
Embodiment five
The present embodiment describes and a kind ofly adopts device described above casting to carry out the method for casting, and the method comprises.
Step 501, step 1, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible 4, and described crucible 4 is built in lower tank 1, with the described lower tank 1 of seal cover board sealing.
Step 502, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds 14 are placed on described seal cover board 15, and covers described lower tank 1 with tank 13.
Step 503, carry out suppressing for 1 ~ 2 minute to described lower tank 1 by described first protective gas pipeline 7 with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa; make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer.
Step 504, by negative-pressure vacuum pipeline 12, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach-20 ~-50KPa; Then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank 13 by the second protective gas pipeline 16, make the negative pressure of described upper tank 13 be raised to-10 ~-30KPa.
Step 505, employing pressue device 2, pressurize to described lower tank 1 with the air pressure of 10 ~ 80KPa, described magnesium alloy liquation entered in described die cavity 14 by described stalk 17, realizes pressure casting.
Inject the sulfur hexafluoride of the protective gas of lower tank, react with magnesium alloy liquation, generate the diaphragm with the compactness preventing magnesium alloy liquation from burning away or to evaporate, under on making, tank is in negative pressure state, the protective gas injected enters in gypsum mould by asbestos and asbestos pressing plate, thus the air in die cavity is discharged, both can realize magnesium alloy liquation and gypsum mould isolation, contribute to realizing vacuum-assist pouring, magnesium alloy liquation in lower tank, under pressue device externally applied forces, avoid the sulfur hexafluoride blowing magnesium alloy molten surface open on the one hand, on the other hand, make magnesium alloy liquation under the driving of external force, overcome self gravitation, the external force such as the pressure in viscous force and die cavity, from bottom to top die cavity is injected along stalk, carry out pressure casting.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the technology of the present invention principle; can also make some improvement and modification, these improve and modification also should be considered as protection scope of the present invention.
Claims (9)
1. a casting method for magnesium alloy, is characterized in that, the method comprises the steps:
Step 1, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible, and described crucible is built in lower tank, with the described lower tank of seal cover board sealing;
Step 2, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds are placed on described seal cover board, and with lower tank described on cover;
Step 3, carry out suppressing for 1 ~ 2 minute to described lower tank between described seal cover board and described crucible with 1-10% sulfur hexafluoride and the mist of 90-99% argon gas, the air pressure of 1 ~ 5Kpa, make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer;
Step 4, by the negative-pressure vacuum pipeline being positioned at the top of described upper tank, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach regulation negative pressure value k
1, then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank from the top of described upper tank, makes the negative pressure of described upper tank be raised to regulation negative pressure value k
2;
Step 5, be that the air pressure of 10 ~ 80KPa pressurizes to described lower tank from the middle and lower part of described lower tank with pressure, make described magnesium alloy liquation be entered the die cavity being arranged in described upper tank by the stalk being built in described crucible, realize pressure casting.
2. casting method according to claim 1, is characterized in that, step 3 and the mist described in step 4 are the mist of 10% sulfur hexafluoride and 90% argon gas; Or 5% mist of sulfur hexafluoride and 95% argon gas.
3. casting method according to claim 1 and 2, is characterized in that, the regulation negative pressure value k described in step 4
1for-20 ~-50KPa, described regulation negative pressure value k
2for-10 ~-30KPa.
4. casting method according to claim 1 and 2, is characterized in that, step 5 also comprises adjusting process parameter, and described technological parameter comprises:
Rise liquid speed be 30 ~ 40mm/s, rise that hydraulic coupling is 5 ~ 8KPa, filling velocity is 30 ~ 60mm/s, mold filling pressure is 30 ~ 50KPa, investing time is 2 ~ 5s, crust boost pressure is 3 ~ 8KPa, crystallization time is 150 ~ 350s, crystallization boost pressure be 3 ~ 8KPa and resistance coefficient is 1.2-1.5.
5. casting method according to claim 4, is characterized in that, when production wall thickness is the magnesium alloy ZM10 foundry goods of 1.5mm, described magnesium alloy smelting temperature is 780 DEG C, when described gypsum mould preheat temperature is 380 DEG C, and described regulation negative pressure value k
1for-30KPa, described regulation negative pressure value k
2for-20KPa, described rise liquid speed be 35m/s, rise that hydraulic coupling is 6KPa, filling velocity is 40mm/s, mold filling pressure is 38KPa, investing time is 5s, crust boost pressure is 3KPa, crystallization time is 150s, crystallization boost pressure be 3KPa and resistance coefficient is 1.2.
6. casting method according to claim 4, is characterized in that, when production wall thickness is the magnesium alloy ZM5 foundry goods of 1.4mm, described magnesium alloy smelting temperature is 820 DEG C, and described gypsum mould preheat temperature is 400 DEG C, described regulation negative pressure value k
1for-20KPa, described regulation negative pressure value k2 is-10KPa, described rise liquid speed be 40m/s, rise hydraulic coupling 5KPa, filling velocity is 50mm/s, mold filling pressure is 40KPa, investing time is 3s, crust boost pressure is 5KPa, crystallization time is 250s, crystallization boost pressure be 5KPa and resistance coefficient is 1.5.
7. a casting device for magnesium alloy, is characterized in that, this device comprises:
Lower tank (1), the middle and lower part of described lower tank (1) is connected with pressue device (2); The top of described lower tank (1) adopts seal diaphragm (15) sealing; The built-in melting furnace of described lower tank (1) (3) and the crucible (4) for holding magnesium alloy liquation, described crucible (4) built-in stalk (17), certain distance is arranged at the lower end of described stalk (17) and the bottom of described crucible (4), and described stalk (17) upper end oral area is through seal diaphragm (15); Between described crucible (4) and seal diaphragm (15), described lower tank (1) is connected with the first protective gas pipeline (7);
Upper tank (13), the top of described upper tank (13) or sidewall are connected with negative-pressure vacuum pipeline (12) and the second protective gas pipeline (16); The built-in gypsum mould with die cavity (14) of described upper tank (13) (8), described gypsum mould (8) is placed directly on described seal diaphragm (15), be provided with asbestos (10) and asbestos pressing plate (11) successively above described gypsum mould (8), described asbestos pressing plate (11) is fixedly connected with by stud (9) with described seal diaphragm (15); Described upper tank (13) and described seal diaphragm (15) are locked by retaining mechanism (5).
8. casting device according to claim 7, is characterized in that, described first protective gas pipeline (7) is connected with the first protective gas device and the second protective gas device respectively with the second protective gas pipeline (16); Or be connected with same protective gas device (6), controlled by control system, disconnect described second protective gas pipeline (16), connect described first protective gas pipeline (7), inject protective gas to described lower tank (1); Disconnect described first protective gas pipeline (7), connect described second protective gas pipeline (16), inject protective gas to described upper tank (13).
9. adopt the device described in any one of claim 7 ~ 8 to carry out a method of casting, it is characterized in that, the method comprises:
Step 1, the magnesium alloy liquation being 730 DEG C ~ 820 DEG C by rear for melting slagging-off, temperature put into crucible (4), and described crucible (4) is built in lower tank (1), with the described lower tank (1) of seal cover board sealing;
Step 2, by after preheating, temperature is that 200 DEG C ~ 400 DEG C gypsum moulds (14) are placed on described seal cover board (15), and covers described lower tank (1) with tank (13);
Step 3, carry out suppressing for 1 ~ 2 minute to described lower tank (1) by described first protective gas pipeline (7) with the air pressure of the mist of 1-10% sulfur hexafluoride and 90-99% argon gas, 1 ~ 5Kpa, make described sulfur hexafluoride float over above described magnesium alloy liquation, form protective layer;
Step 4, by negative-pressure vacuum pipeline 12, described upper tank to be vacuumized, make the negative pressure value of described upper tank reach-20 ~-50KPa; Then the mist of 1-10% sulfur hexafluoride and 90-99% argon gas is injected described upper tank (13) by the second protective gas pipeline (16), make the negative pressure of described upper tank (13) be raised to-10 ~-30KPa;
Step 5, employing pressue device (2), with the air pressure of 10 ~ 80KPa, described lower tank (1) is pressurizeed, (17 enter in described die cavity (14), realize pressure casting by described stalk to make described magnesium alloy liquation.
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| CN105921720B (en) * | 2016-05-20 | 2017-10-20 | 河南理工大学 | A kind of magnesium alloy thin wall pieces preparation method |
| CN105834409B (en) * | 2016-05-20 | 2017-09-19 | 河南理工大学 | A kind of magnesium alloy thin wall pieces integration system is for former |
| CN106153815B (en) * | 2016-07-01 | 2017-07-04 | 河南理工大学 | A kind of magnesium alloy gypsum mould gas shield flame retardant effect experimental facilities and experimental technique |
| CN111230044A (en) * | 2020-03-02 | 2020-06-05 | 青田保俐铸造有限公司 | Magnesium alloy investment casting equipment and method for carrying out investment casting by adopting same |
| CN114273638A (en) * | 2020-09-28 | 2022-04-05 | 中国科学院金属研究所 | Low-pressure precision casting method of magnesium alloy thin-wall shell part |
| CN112317723B (en) * | 2020-11-02 | 2022-02-15 | 东南大学 | Metal casting method and equipment based on photocuring printing and casting mold differential pressure pouring |
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| BG22157A1 (en) * | 1975-10-27 | 1977-05-20 | ||
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| FR2705044B1 (en) * | 1993-05-10 | 1995-08-04 | Merrien Pierre | LOW PRESSURE PILOT CASTING PROCESS OF A VACUUM MOLD FOR ALUMINUM OR MAGNESIUM ALLOYS AND DEVICE FOR ITS IMPLEMENTATION. |
| US6945310B2 (en) * | 2003-05-19 | 2005-09-20 | Takata Corporation | Method and apparatus for manufacturing metallic parts by die casting |
| CN101219471B (en) * | 2008-01-22 | 2011-01-19 | 西北工业大学 | Device and method for producing integrated magnesium base composite material |
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