CN102236726B - Method for predicting shrinkage porosity in molten metal solidification process and continuous shrinkage porosity prediction method - Google Patents
Method for predicting shrinkage porosity in molten metal solidification process and continuous shrinkage porosity prediction method Download PDFInfo
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Abstract
The invention discloses a method for predicting shrinkage porosity in a molten metal solidification process and a continuous shrinkage porosity prediction method. The method for predicting the shrinkage porosity in the molten metal solidification process comprises the following steps of: (1) acquiring temperature field data of molten metal; (2) selecting a predicted unit as a current unit, and acquiring pressure P, viscosity gradient Gv, equivalent cooling rate R1, feeding distance d and critical value C of the current unit in combination with the temperature field data; and (3) judging according to the acquired P, Gv, R1, d and C values based on a criterion, and if the criterion is met, judging that the current unit is a shrinkage porosity unit, wherein e is a natural napierian base. According to the method, the prediction of the shrinkage porosity in the molten metal solidification process has high accuracy. The method disclosed by the invention can be used for predicting the solidification processes of various crystals or amorphous alloy melts and has a wide application range.
Description
Technical field
The present invention relates to method and the shrinkage porosite continuous prediction method of prediction shrinkage porosite in a kind of metal liquid solidification process.
Background technology
The process of setting of foundry goods also is accompanied by the motion of heat transfer, mass transfer except the solid-liquid interface migration, many defectives of foundry goods are all closely related with process of setting.The computer simulation of casting solidification process can this change procedure of pictute, for analyzing casting flaw, prediction casting quality, optimizing casting technique positive effect is arranged.
The at present application of computing machine in the simulation casting process mainly concentrates on aspect following 4: mold filling and solidification simulation, Shrinkage Prediction, process of setting stress simulation and Numerical Simulation of Microstructure Formation during Solidification.Wherein, Shrinkage Prediction is even more important.
For generation and the degree (shrinkage porosite shape, size) thereof of predicting Shrinkage Porosity, it is necessary that the mechanism that the consideration shrinkage porosite generates is solidified parsing, but tight parsing is very difficult, in fact often adopts following several simple and easy methods to predict their generation: 1, equitemperature, etc. the solid rate curve method.(1) solidus temperature method judges that the condition that shrinkage porosite produces is: occur in g
sIn=1 the closed loop; (2) critical solid rate method judges that the condition that shrinkage porosite produces is to occur in g
s=g
ScThe closed loop in.But above method is difficult to when not existing in the closed loop judge.2, temperature gradient method judges that shrinkage porosite generation condition is g
s=1 or g
s=g
ScThe time maximum temperature G≤critical value.The method is easier, but since Critical Temperature Gradient with shape, cooldown rate and different, so precision of prediction is very low.3, solid rate gradient method.Judge that shrinkage porosite generation condition is g
s=1 or g
s=g
ScThe time maximum solid rate≤critical value.The method relatively is fit to the shrinkage porosite prediction of eutectic alloy process of setting; When the pass of solid rate and temperature is 1 pair 1 and thermograde be equal to.
The criterion of main prediction shrinkage porosite of using is at present
Wherein G is thermograde (K/cm), and R is cooldown rate (K/min), and C is critical value.But the precision of the method alloy process of setting shrinkage porosite prediction is lower.
Summary of the invention
In order to overcome the lower problem of precision of alloy process of setting shrinkage porosite prediction in the prior art, the invention provides method and the shrinkage porosite continuous prediction method of prediction shrinkage porosite in a kind of metal liquid solidification process, the precision of the method alloy liquid process of setting shrinkage porosite prediction is high, and applied range.
The method of prediction shrinkage porosite in the metal liquid solidification process disclosed by the invention comprises:
(1), obtains the temperature field data of molten metal;
(2), to choose the unit of predicting be active cell, in conjunction with described temperature field data, obtains pressure P, the viscosity gradient G of active cell
v, cooldown rate R of equal value
1And feeding distance d and critical value C;
(3), according to the P, the G that obtain
v, R
1, d and C value, according to criterion:
Judge, if satisfy above-mentioned criterion, can judge that then active cell is the shrinkage porosite unit; Wherein, at the bottom of e is natural logarithm.
The invention also discloses in addition a kind of shrinkage porosite continuous prediction method, comprising:
(a), calculate the temperature field of molten metal;
(b), determine according to the temperature field whether molten metal is about to solidify, if determine it is not to be about to solidify, then return step (a) and continue the accounting temperature field; If determine to be about to solidify, then judge according to preceding method.
By said method, high to the precision of shrinkage porosite prediction in the metal liquid solidification process.And the method can be predicted applied range to the process of setting of various crystal or non-crystaline amorphous metal liquation.
Embodiment
In order to make technical matters solved by the invention, technical scheme and beneficial effect clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, is not intended to limit the present invention.
The method of prediction shrinkage porosite in the metal liquid solidification process disclosed by the invention comprises:
(1), obtains the temperature field data of molten metal;
(2), to choose the unit of predicting be active cell, in conjunction with described temperature field data, obtains pressure P, the viscosity gradient G of active cell
v, cooldown rate R of equal value
1And feeding distance d and critical value C;
(3), according to the P, the G that obtain
v, R
1, d and C value, according to criterion:
Judge, if satisfy above-mentioned criterion, can judge that then active cell is the shrinkage porosite unit; Wherein, at the bottom of e is natural logarithm.Be e in the present invention value be 2.71828.
According to said method disclosed by the invention, compare with existing shrinkage porosity criterion, the inventor finds, has introduced the pressure P of another molten metal as the criterion influence factor, can improve Accuracy of Judgement.Simultaneously, the present inventor has proposed with viscosity gradient G according to the analysis-by-synthesis of the various factors in the metal liquid solidification process
vAs a large influence factor of criterion, and creationary in conjunction with feeding distance d, increase new parameter e
dThereby, formed above-mentioned criterion
Inventor's discovery, in metal liquid solidification process, the feeding distance of metal also has considerable influence to its process of setting.As the particular community of metal, the feeding distance of metal is larger, more easily obtains feeding when producing shrinkage defect in the metal liquid solidification process.For existing criterion, do not consider feeding distance, can be equivalent to that feeding distance is 0 in the criterion disclosed by the invention, the feeding distance that is equivalent to give tacit consent to metal this moment is 0, is not inconsistent with actual conditions.In the present invention, by increasing new parameter e
dConsider feeding distance, the feeding distance of metal is larger, and the predicted value that calculates by above-mentioned criterion is also larger, meets feeding distance larger, more easily obtains the practical situation of feeding.Greatly improved precision of prediction.Introducing pressure P and G
vAnd in conjunction with e
dAfter criterion revised, the precision of prediction that shrinkage porosite in the metal liquid solidification process is produced had improved greatly.And, than traditional solid rate gradient criterion, the present invention is by adopting in this area not used viscosity gradient criterion, can realize the shrinkage porosite prediction to the process of setting of the metal that comprises the various forms such as crystal, amorphous, and cooldown rate of equal value is not subjected to the impact of metallic crystal form, the scope of the application of expansion; The precision of prediction has also obtained further raising.Adopt method disclosed by the invention to after the shrinkage porosite situation is judged in the metal liquid solidification process, be conducive to the technician smelting technology of metal is adjusted.
In above-mentioned criterion, the unit of pressure P is Pa, viscosity gradient G
vUnit be kg/ (m
2.s), cooldown rate R of equal value
1Unit be K/min, the unit of feeding distance d is mm.
In the present invention, the temperature field data can obtain by existing the whole bag of tricks among the step a, as calculating by the thermal conduction study fundamental equation.
Casting solidification process is actually the unstable heat exchanging process between " casting and mold-environment ".All phenomenons in conducting heat in casting solidification process, have been consisted essentially of: hot conduction, thermal convection, heat radiation.After liquid metal injects casting mold, the heat of liquid metal internal arrives the surface of foundry goods by the heat conduction, then pass to casting mold by heat radiation and heat, arrive again the outside surface of casting mold by the heat conduction, be dispersed in the environment by heat radiation and convection current at last.Meanwhile the temperature of liquid metal constantly descends in the casting mold die cavity, and non-uniform temperature.This unevenness has caused the thermal convection of the liquid metal in the casting mold die cavity.
The below describes heat conduction, thermal convection and heat radiation respectively.
1, heat conduction heat exchange
The heat conduction is called for short heat conduction, and it belongs to transmission of heat by contact, is continuous medium in the situation that there is not the relative displacement of material among part, the heat transmission that the thermal vibration of the microscopic particles such as dependence molecule, atom and free electron is carried out.In closely knit opaque solid, can only rely on the heat-conducting mode transferring heat.
For determining of multidimensional temperature field, must analyze the micro unit in the heat conductor take energy conservation and Fourier's law as the basis, draw the three-dimensional heat conducting differential equation of expression Heat Conduction Phenomenon basic law:
In the formula:
Q
3-thermally conductive heat amount changing value, unit is: J;
The density of ρ-object, unit is: Kg/m
3
λ-coefficient of heat conductivity, unit is: W/mK;
C-specific heat, unit is: J/m
3
The T-temperature, unit is: K;
The t-time, unit is: s;
The coordinate figure of x, y, z-arbitrfary point.
Choose active cell, namely obtain x, y, the z value of active cell, then according to concrete metal species, can inquire its density p, coefficient of heat conductivity λ and specific heat c.According to the temperature field data in a upper moment, obtain the temperature data T of a upper moment active cell again, can calculate thermally conductive heat amount changing value by above-mentioned equation.
Wherein, because the temperature of initial time is prior setting, namely sets and begin modeling and simulation of solidification after molten metal reaches certain temperature, this temperature is the temperature of initial time, so be known for the temperature field data of initial time.According to these known initial time temperature field data, can calculate from initial time to next thermally conductive heat amount changing value constantly.
2, thermal convection heat exchange
Convection current refers between the fluid each several part relative displacement occur, the caused heat transfer mode of the mutual blending of cold flow object.Convection current only can occur in the fluid, and must be accompanied by heat conduction.
Convection heat transfer is formal what calculate, the formula that adopts newton to propose, that is:
Q
1＝αA(T
f-T
w)
In the formula:
Q
1-thermal convection thermal change value, unit is: J;
The poor lower heat exchange amount on unit area of α-unit temperature, unit is: W/m
2K;
The A-heat interchanging area, unit is: m
2
T
fEnvironment temperature in the-thermal convection heat transfer process, unit is: K;
T
wThe temperature of-wall, unit is: K.
In the above-mentioned equation, α can look into by the related tool book and get for certain specific metal material.
T
fActual temperature according to environment in the thermal convection process is set.
T
wThe temperature field data of passing through are directly obtained.
A is different for particular model, and as all different with cube for right cylinder, but the surface area of the model of the active cell that all can select by calculating obtains.
Can calculate thermal convection thermal change value Q by above-mentioned equation
1
3, heat radiation heat exchange
Directly can not transmit radiation energy between the two articles of contact, at this moment need not to exist any medium between the object yet.Usually the process of object being sent radiant rays and propagation thereof calls radiation, and object calls heat radiation to the interior process that can be converted into external emitted radiation line and propagation thereof of itself, and namely the object phenomenon of sending radiation energy because of the reason of heat is called heat radiation.Be called the heat radiation heat exchange by sending and accept the heat exchange that radiation energy carries out between the object.
Casting mold is to the heat exchange amount of surrounding environment heat radiation heat exchange:
In the formula:
Q
2-heat radiation thermal change value, unit is: J;
The blackness of ε-grey body, 0-1;
σ
b-Si Difen-Boltzmann constant is 5.67 * 10
-8(W/m
2K
4);
A
1The area of dissipation of-object, unit is: m
2
T
1The temperature of object in the-heat radiation process, unit is: K;
T
2The temperature of environment in the-heat radiation process, unit is: K.
In the above-mentioned equation, ε can look into by the related tool book and get for certain specific metal material.
T
1Be the temperature of active cell.
T
2The Temperature Setting of environment obtains in the heat radiation process.
A
1Different for particular model, as all different with cube for right cylinder, but the surface area of the model of the active cell that all can select by calculating obtains.
Can calculate heat radiation thermal change value Q by above-mentioned equation
2
Method by thermal conduction study equation accounting temperature field data comprises:
(11), choose arbitrary unit, based on upper one constantly temperature field data, draw on this unit constantly a temperature data; Then calculate this unit was carved into current time from upper a period of time total amount of heat changing value by heat conduction, thermal convection, heat radiation, by this total amount of heat changing value, adopt the temperature variation equation to calculate this unit was carved into current time from upper a period of time temperature change value; Again based on upper one constantly temperature data and be carved into the temperature change value of current time from upper a period of time, obtain the temperature data of this unit current time;
Described temperature variation equation is:
Wherein: Q is the total amount of heat changing value, is aforementioned Q
1, Q
2, Q
3Sum, unit is J, and C is the specific heat of metal, and unit is kJ/kg ℃, and ρ is the density of metal, unit is kg/m
3, V is the volume of active cell, unit is m
3
(12), repeating step (11), to calculating by the temperature variation equation all unit of molten metal, obtain the temperature field data of molten metal.
Wherein, thermally conductive heat amount changing value, thermal convection thermal change value, heat radiation thermal change value can be calculated by preceding method.Thermally conductive heat amount changing value, thermal convection thermal change value, heat radiation thermal change value sum are the total amount of heat changing value.
Those skilled in the art can obtain the said temperature field data by the calculating of above equation.
The pressure P of active cell can obtain by existing the whole bag of tricks, such as the molten metal static pressure that can directly adopt active cell as pressure P.After calculation of pressure finishes, remain to follow-up shrinkage porosity criterion and use.
Wherein, described molten metal static pressure can be calculated in the following way:
P＝h×ρ×g
In the formula:
The molten metal static pressure that the P-active cell is subject to, unit: Pa;
The h-active cell is apart from the distance at the top, molten bath at place, unit: m;
The density of ρ-molten metal, unit: kg/m
3
G-acceleration of gravity, unit: m/s
2
In the said method, the molten bath may be defined as in the metal liquid solidification process, the zone that molten metal can be interconnected.Namely a molten bath can comprise a plurality of unit.The division in molten bath can adopt existing many molten baths partitioning technology to carry out.
In method disclosed by the invention, viscosity gradient G
vAcquisition methods be:
Choose 26 adjacent cells adjacent with active cell, described 26 adjacent cells are 6 unit adjacent with the active cell face, 12 unit and with active cell summit adjacent 8 unit adjacent with the active cell rib, the distance of active cell and each adjacent cells is the distance between active cell central point and the adjacent cells central point;
Obtain the viscosity number of active cell and 26 adjacent cells;
Get the difference of viscosity number of active cell and one of them adjacent cells divided by the distance of active cell and this adjacent cells, obtain a quotient, repeat this step, then getting maximum quotient is viscosity gradient.
In the said method, the method of obtaining the viscosity number of active cell and 26 adjacent cells is: in conjunction with the temperature field data, obtain respectively the temperature data of active cell and 26 adjacent cells, according to the temperature data of active cell and 26 adjacent cells, obtain respectively the viscosity number of active cell and 26 adjacent cells.
For every kind of fixing molten metal that forms, when other conditions were constant, its viscosity under fixing temperature was fixed, and namely viscosity has fixing curve with respect to temperature.So, obtain the temperature data of active cell and 26 adjacent cells after, can directly read respectively the viscosity of active cell and 26 adjacent cells.As can according to the temperature data of active cell and 26 adjacent cells, in conjunction with the temperature-viscograph of this metal material, directly reading the viscosity number of active cell and 26 adjacent cells.Temperature-the viscograph of above-mentioned metal material is for recording by prior art.
In the present invention, cooldown rate R of equal value
1Acquisition methods be: the latent heat that active cell is discharged in a time step is converted into the equivalence reduction value of active cell temperature in this time step, get the actual reduction value sum of this equivalence reduction value and this unit actual temperature, then divided by described time step, obtain the cooldown rate R of equal value of active cell
1Above-mentioned time step is the mistiming of current time and previous moment.
Solidify the key criterion that whether produces shrinkage porosite as weighing molten metal, critical value C is most important.For different alloys, critical value C is also different.Usually, this critical value C is known.Simultaneously, this critical value C also can obtain voluntarily.The acquisition methods of critical value C can be the whole bag of tricks of the prior art, mainly obtains with the method that simulation combines by actual die casting such as criterion critical value C.For certain alloy material, based on conditions such as given model and extrusion processes, carry out actual die casting.Observe position of inner shrinkage porosite etc. by foundry goods being carried out subdivision.Then, constantly this critical value is adjusted, set the predicted critical value, adopt basic criterion
Carry out sunykatuib analysis and obtain to comprise and the analog result of shrinkage porosite position the position of analog result with foundry goods inside shrinkage porosite contrasted, if the position of shrinkage porosite is not identical in analog result and the actual foundry goods, then adjust the predicted critical value, simulate again; If analog result is identical with the position of shrinkage porosite in the actual foundry goods, then this predicted critical value is critical value C.For verifying the correctness of this critical value, can analyze according to different models and extrusion process.In the prior art, critical value C can directly obtain by the correlation technique dictionary enquiry.In the present invention, the acquisition methods of critical value C is: combine with simulation by actual die casting, and revise and obtain.
According to the present invention, after obtaining critical value C, the acquisition methods of described feeding distance d is: for fixing metal material, based on fixing model and extrusion process condition, carry out actual die casting, obtain foundry goods; Foundry goods is carried out the position that subdivision is determined the inner shrinkage porosite of foundry goods;
Then, according to the critical value C that obtains, set the prediction feeding distance, adopt criterion
Carry out sunykatuib analysis, obtain to comprise the analog result of shrinkage porosite position, the position of analog result with the inner shrinkage porosite of foundry goods contrasted, if the position of shrinkage porosite is not identical in analog result and the actual foundry goods, then feeding distance is predicted in adjustment, simulates again; If analog result is identical with the position of shrinkage porosite in the actual foundry goods, then this prediction feeding distance is feeding distance d.
Obtain above-mentioned P, G
v, R
1, after d and the C value, according to criterion:
Judge, if satisfy above-mentioned criterion, can judge that then active cell is the shrinkage porosite unit.
For the ease of using in practice, in the present invention, a kind of shrinkage porosite continuous prediction method is also disclosed, comprising:
(a), calculate the temperature field of molten metal;
(b), determine according to the temperature field whether molten metal is about to solidify, if determine it is not to be about to solidify, then return step (a) and continue the accounting temperature field; If determine to be about to solidify, then judge according to the method for prediction shrinkage porosite in the above-mentioned metal liquid solidification process.
In said method, the temperature field of having calculated molten metal in step (a) then in step (b), can directly adopt this temperature field as required temperature field data.
In the said method, determine according to the temperature field whether molten metal is about to be solidified as method well known in the art.Molten metal is solidified as phase transition process, and those skilled in the art can judge whether to be about to solidify according to the temperature field data of the molten metal that obtains.
Equally, the temperature field described in the step (a) can calculate by the thermal conduction study equation.Among the present invention, the acquisition of various data and calculating all can be finished by computer installation of the prior art.
According to the present invention, take non-crystaline amorphous metal as example, its process of setting is carried out shrinkage porosite predict continuously.Concrete grammar is: after Metal Melting finishes, constantly calculates the temperature field of molten metal by the thermal conduction study equation, determines according to the temperature field whether molten metal is about to solidify, if not, then return step (a) and continue the accounting temperature field; If determine to be about to solidify, choosing the unit of predicting is active cell, selects the molten metal static pressure of active cell as the pressure P of active cell.
Choose 26 adjacent cells adjacent with active cell, described 26 adjacent cells are 6 unit adjacent with the active cell face, 12 unit and with active cell summit adjacent 8 unit adjacent with the active cell rib, the distance of active cell and each adjacent cells is the distance between active cell central point and the adjacent cells central point;
Obtain the viscosity number of active cell and 26 adjacent cells;
Get the difference of viscosity number of active cell and certain adjacent cells divided by the distance of active cell and this adjacent cells, obtain a quotient, repeat this step, then getting maximum quotient is viscosity gradient G
v
Then, the latent heat that active cell is discharged in a time step is converted into the equivalence reduction value of active cell temperature in this time step, get the actual reduction value sum of this equivalence reduction value and this unit actual temperature, then divided by described time step, obtain the cooldown rate R1 of equal value of active cell.
At last, according to the P, the G that obtain
v, R
1, d, and in conjunction with known critical value C, according to criterion:
Judge, if satisfy above-mentioned criterion, can judge that then active cell is the shrinkage porosite unit.
Adopt the method for prediction shrinkage porosite in the metal liquid solidification process disclosed by the invention, can realize the accurately predicting of shrinkage porosite situation in the metal liquid solidification process.And the applied range of the method can be predicted shrinkage porosite situation in the metal liquid solidification process of each metalloid material such as eutectic or amorphous
The above only is preferred embodiment of the present invention, not in order to limiting the present invention, all any modifications of doing within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (9)
1. the method for prediction shrinkage porosite in the metal liquid solidification process comprises:
(1), obtains the temperature field data of molten metal;
(2), to choose the unit of predicting be active cell, in conjunction with described temperature field data, obtains pressure P, the viscosity gradient G of active cell
v, cooldown rate R of equal value
1And feeding distance d and critical value C;
(3), according to the P, the G that obtain
v, R
1, d and C value, according to criterion:
Judge, if satisfy above-mentioned criterion, can judge that then active cell is the shrinkage porosite unit; Wherein, at the bottom of e is natural logarithm;
Wherein, the acquisition methods of described feeding distance d is: for fixing metal material, based on fixing model and extrusion process condition, carry out actual die casting, obtain foundry goods; Foundry goods is carried out the position that subdivision is determined the inner shrinkage porosite of foundry goods; Then, according to the critical value C that obtains, set prediction feeding distance d ', adopt criterion
Carry out sunykatuib analysis, obtain to comprise the analog result of shrinkage porosite position, the position of analog result with the inner shrinkage porosite of foundry goods contrasted, if the position of shrinkage porosite is not identical in analog result and the actual foundry goods, then feeding distance is predicted in adjustment, simulates again; If analog result is identical with the position of shrinkage porosite in the actual foundry goods, then this prediction feeding distance is feeding distance d.
2. method according to claim 1, wherein, the temperature field data communication device is crossed the thermal conduction study equation and is calculated in the step (1).
3. method according to claim 2, wherein, described method by thermal conduction study equation accounting temperature field data comprises:
(11), choose arbitrary unit, based on upper one constantly temperature field data, draw on this unit constantly a temperature data; Then calculate this unit was carved into current time from upper a period of time total amount of heat changing value by heat conduction, thermal convection, heat radiation, by this total amount of heat changing value, adopt the temperature variation equation to calculate this unit was carved into current time from upper a period of time temperature change value; Again based on upper one constantly temperature data and be carved into the temperature change value of current time from upper a period of time, obtain the temperature data of this unit current time;
Described temperature variation equation is:
Wherein: Q is the total amount of heat changing value, and unit is J, and C is the specific heat of metal, and unit is kJ/kg ℃, and ρ is the density of metal, and unit is kg/m
3, V is the volume of active cell, unit is m
3
(12), repeating step (11), to calculating by the temperature variation equation all unit of molten metal, obtain the temperature field data of molten metal.
4. method according to claim 1, wherein, described pressure is the molten metal static pressure of active cell.
5. method according to claim 1, wherein, described viscosity gradient G
vAcquisition methods be:
Choose 26 adjacent cells adjacent with active cell, described 26 adjacent cells are 6 unit adjacent with the active cell face, 12 unit and with active cell summit adjacent 8 unit adjacent with the active cell rib, the distance of active cell and each adjacent cells is the distance between active cell central point and the adjacent cells central point;
Obtain the viscosity number of active cell and 26 adjacent cells;
Get the difference of viscosity number of active cell and one of them adjacent cells divided by the distance of active cell and this adjacent cells, obtain a quotient, repeat this step, then getting maximum quotient is viscosity gradient G
v
6. method according to claim 5, wherein, the method of obtaining the viscosity number of active cell and 26 adjacent cells is: in conjunction with the temperature field data, obtain respectively the temperature data of active cell and 26 adjacent cells, according to the temperature data of active cell and 26 adjacent cells, obtain respectively the viscosity number of active cell and 26 adjacent cells.
7. method according to claim 1, wherein, the cooldown rate R of equal value of described active cell
1Acquisition methods be: the latent heat that active cell is discharged in a time step is converted into the equivalence reduction value of active cell temperature in this time step, get the actual reduction value sum of this equivalence reduction value and this unit actual temperature, then divided by described time step, obtain the cooldown rate R of equal value of active cell
1
8. method according to claim 1, wherein, the acquisition methods of described critical value C is:
For fixing metal material, based on fixing model and extrusion process condition, carry out actual die casting, obtain foundry goods; Foundry goods is carried out the position that subdivision is determined the inner shrinkage porosite of foundry goods;
Then, set predicted critical value C ', adopt basic criterion
Carry out sunykatuib analysis, obtain to comprise the analog result of shrinkage porosite position, the position of analog result with foundry goods inside shrinkage porosite contrasted, if the position of shrinkage porosite is not identical in analog result and the actual foundry goods, then adjust the predicted critical value, simulate again; If analog result is identical with the position of shrinkage porosite in the actual foundry goods, then this predicted critical value is critical value C.
9. shrinkage porosite continuous prediction method comprises:
(a), calculate the temperature field of molten metal;
(b), determine according to the temperature field whether molten metal is about to solidify, if determine it is not to be about to solidify, then return step (a) and continue the accounting temperature field; If determine to be about to solidify, then according to claim 1-8 in the described method of any one judge.
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