CN101963608A - Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method - Google Patents
Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method Download PDFInfo
- Publication number
- CN101963608A CN101963608A CN200910109137XA CN200910109137A CN101963608A CN 101963608 A CN101963608 A CN 101963608A CN 200910109137X A CN200910109137X A CN 200910109137XA CN 200910109137 A CN200910109137 A CN 200910109137A CN 101963608 A CN101963608 A CN 101963608A
- Authority
- CN
- China
- Prior art keywords
- active cell
- temperature field
- molten metal
- shrinkage porosite
- unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
The invention discloses a method for predicting shrinkage porosity in the metal liquid solidification process and a shrinkage porosity continuous prediction method. The method for predicting shrinkage porosity in the metal liquid solidification process comprises the following steps of: (1) acquiring the temperature field data of a metal liquid; (2) selecting a unit to be predicted as a current unit, and acquiring the pressure P, the viscosity gradient Gv, the cooling rate R and the critical value C of the current unit by combining the temperature field data; and (3) judging on the basis of the criterion P*Gv/R(-2)<=C according to the acquired P, Gv, R and C values, and if the criterion is satisfied, judging the current unit to be a shrinkage porosity unit. The method has high precision for predicting shrinkage porosity in the metal liquid solidification process. Moreover, the method can be used for predicting the solidification processes of various crystal or amorphous alloy molten liquids and has 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 molten metal process of setting, method and the shrinkage porosite continuous prediction method of prediction shrinkage porosite in especially a kind of non-crystaline amorphous metal liquid process of setting.
[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 application of computing machine in the simulation casting process at present mainly concentrates on aspect following 4: fill type solidification simulation, Shrinkage Prediction, process of setting stress simulation and the simulation of process of setting microstructure.Wherein, Shrinkage Prediction is even more important.
For generation and the degree (shrinkage cavity form, size) thereof of predicting the foundry goods shrinkage porosite, considered that mechanism that shrinkage porosite generates solidifies that to resolve be necessary, but tight parsing is difficulty very, 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.This method is easier, but since the 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.This 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 a critical value.But this method is lower to alloy graining process shrinkage porosite accuracy of predicting.
[summary of the invention]
In order to overcome in the prior art to the lower problem of alloy graining process shrinkage porosite accuracy of predicting, the invention provides method and the shrinkage porosite continuous prediction method of prediction shrinkage porosite in a kind of molten metal process of setting, this method is to alloy liquid process of setting shrinkage porosite accuracy of predicting height, and applied range.
The method of prediction shrinkage porosite comprises in the molten metal process of setting disclosed by the invention:
(I), obtain the temperature field data of molten metal;
(II), 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 and critical value C;
(III), according to the P, the G that obtain
v, R and C value, according to criterion:
Judge,, can judge that then active cell is the shrinkage porosite unit if satisfy above-mentioned criterion.
Shrinkage porosite continuous prediction method disclosed by the invention comprises:
(1), calculates the temperature field of molten metal;
(2), 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 (1) 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 molten metal process of setting.
By said method, to shrinkage porosite accuracy of predicting height in the molten metal process of setting.And this method can be predicted applied range to the process of setting of various crystal or non-crystaline amorphous metal liquation.
[description of drawings]
Fig. 1 is the process flow diagram of prediction shrinkage porosite method in the molten metal process of setting disclosed by the invention.
[embodiment]
In order to make technical matters to be solved by this invention, technical scheme and beneficial effect clearer, below the present invention is further elaborated.
The method of prediction shrinkage porosite in the molten metal process of setting disclosed by the invention comprises:
(I), obtain the temperature field data of molten metal;
(II), 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 and critical value C;
(III), according to the P, the G that obtain
v, R and C value, according to criterion:
Judge,, can judge that then active cell is the shrinkage porosite unit if satisfy above-mentioned criterion.
According to said method disclosed by the invention, compare with existing shrinkage porosity criterion, the inventor finds that the pressure P of having introduced another molten metal can improve the accuracy of judging as the criterion influence factor.Simultaneously, the present inventor has proposed with viscosity gradient G according to the analysis-by-synthesis of the various factors in the molten metal process of setting
vAs a big influence factor of criterion, thereby formed above-mentioned criterion
The inventor finds, after introducing pressure P, can improve the degree of accuracy of judging.And than traditional solid rate gradient criterion, the present invention is by adopting the not used viscosity gradient criterion in this area, can realize shrinkage porosite prediction, the scope of the application of expansion to the process of setting of the metal that comprises various forms such as crystal, amorphous; Accuracy of predicting has also obtained further raising.Adopt method disclosed by the invention to after the shrinkage porosite situation is judged in the molten metal process of setting, help 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), the unit of cooldown rate R is K/min.
In the present invention, the temperature field data can obtain by existing the whole bag of tricks in the step (I), 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: heat conduction, thermal convection, heat radiation.
1, heat conduction heat exchange
Heat conduction is called for short heat conduction, and it belongs to transmission of heat by contact, be continuous medium under the situation that does not have each several part relative displacement between the material, the heat transferred that relies on the thermal vibration of microscopic particles such as molecule, atom and free electron to carry out.In closely knit opaque solid, can only rely on heat-conducting mode to transmit heat.
For determining of multidimensional temperature field, must analyze the micro unit in the heat conductor based on energy conservation and Fourier's law, draw the three-dimensional heat conducting differential equation of expression heat conduction phenomenon basic law:
In the formula:
The density of ρ-object, Kg/m
3
λ-coefficient of heat conductivity, W/mK;
C-specific heat, J/m
3
The T-temperature, K;
The t-time, s;
The coordinate of x, y, z-arbitrfary point.
2, thermal convection heat exchange
Convection current is meant between the fluid each several part relative displacement takes place, the caused heat transferred 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, adopts the formula that newton proposed, that is:
Q＝αA(T
f-T
w)
In the formula:
Heat under α-unit temperature difference on unit area, W/m
2K;
The A-heat interchanging area, m
2
T
f-environment temperature, K;
T
wThe temperature of-wall, K.
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 that object is 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 promptly 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 of surrounding environment heat radiation heat exchange:
In the formula:
The area of dissipation of A-object, m
2
T
1The temperature of-object, K;
T
2The temperature of-environment, K.
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, as according to as described in the temperature field data, adopt the flow field simulation method to calculate, obtain the pressure P of active cell.Also can directly utilize the mode of calculating hydrostatic pressure to calculate the static pressure of molten metal.After calculation of pressure finishes, remain to follow-up shrinkage porosity criterion and use.
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;
The difference of viscosity number of getting active cell and certain adjacent cells obtains a quotient divided by the distance of active cell and this adjacent cells, repeats this step, gets the viscosity gradient that is of quotient maximum then.
In the present invention, the acquisition methods of cooldown rate R is: get active cell in the temperature of current time and the difference of previous moment temperature, divided by time step, obtain the cooldown rate of active cell with this difference.Above-mentioned time step is the mistiming of current time and previous moment.
And solidifying 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 as criterion critical value C.At certain alloy material,, carry out actual die casting based on conditions such as given model and extrusion processes.By being carried out subdivision, foundry goods observes the position of inner shrinkage porosite, size and shape etc.Then, constantly this critical value is adjusted, carried out sunykatuib analysis.Contrast by situation shrinkage porosite in situations such as position, size and the shape of shrinkage porosite in the analog result and the actual die casting, consistent up to analog result with shrinkage porosite situation in the actual die casting.This critical value is the shrinkage porosity criterion critical value of this alloy material.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.
In the present invention, also disclose a kind of shrinkage porosite continuous prediction method, having comprised:
(1), calculates the temperature field of molten metal;
(2), 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 (1) 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 molten metal process of setting.
In said method, the temperature field of having calculated molten metal in step (1) then in step (I), 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 (1) can obtain by the thermal conduction study Equation for Calculating.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, be example with the non-crystaline amorphous metal, its process of setting is carried out shrinkage porosite predict continuously.Concrete grammar is: after Metal Melting finishes, constantly, determine according to the temperature field whether molten metal is about to solidify by the temperature field of thermal conduction study Equation for Calculating molten metal, if not, then return step (1) and continue the accounting temperature field; If determine to be about to solidify, choosing the unit of predicting is active cell, according to the said temperature field data, adopts the flow field simulation method to calculate, and obtains 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;
The difference of viscosity number of getting active cell and certain adjacent cells obtains a quotient divided by the distance of active cell and this adjacent cells, repeats this step, and that gets the quotient maximum then is viscosity gradient G
v
Then, get active cell, divided by time step, obtain the cooldown rate R of active cell with this difference in the temperature of current time and the difference of previous moment temperature.
At last, according to the P, the G that obtain
v, R, and in conjunction with known critical value C, according to criterion:
Judge,, can judge that then active cell is the shrinkage porosite unit if satisfy above-mentioned criterion.
Adopt the method for prediction shrinkage porosite in the molten metal process of setting disclosed by the invention, can realize the accurately predicting of shrinkage porosite situation in the molten metal process of setting.And the applied range of this method can be predicted shrinkage porosite situation in the molten metal process of setting of each metalloid material such as eutectic or amorphous.
Claims (8)
1. the method for prediction shrinkage porosite in the molten metal process of setting comprises:
(I), obtain the temperature field data of molten metal;
(II), 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 and critical value C;
(III), according to the P, the G that obtain
v, R and C value, according to criterion:
Judge,, can judge that then active cell is the shrinkage porosite unit if satisfy above-mentioned criterion.
2. method according to claim 1, wherein, the temperature field data obtain by the thermal conduction study Equation for Calculating in the described step (I).
3. method according to claim 1, wherein, the acquisition methods of described pressure P is: according to described temperature field data, adopt the flow field simulation method to calculate, obtain the pressure P of active cell.
4. 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;
The difference of viscosity number of getting active cell and certain adjacent cells obtains a quotient divided by the distance of active cell and this adjacent cells, repeats this step, gets the viscosity gradient that is of quotient maximum then.
5. method according to claim 1, wherein, the acquisition methods of the cooldown rate R of described active cell is: get active cell in the temperature of current time and the difference of previous moment temperature, divided by time step, obtain the cooldown rate of active cell with this difference.
6. method according to claim 1, wherein, the acquisition methods of described critical value C is: combine with simulation by actual die casting, and revise and obtain.
7. shrinkage porosite continuous prediction method comprises:
(1), calculates the temperature field of molten metal;
(2), 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 (1) and continue the accounting temperature field; If determine to be about to solidify, then judge according to the method for prediction shrinkage porosite in any described molten metal process of setting among the claim 1-6.
8. shrinkage porosite continuous prediction method according to claim 7, wherein, the temperature field described in the step (1) obtains by the thermal conduction study Equation for Calculating.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910109137XA CN101963608A (en) | 2009-07-25 | 2009-07-25 | Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910109137XA CN101963608A (en) | 2009-07-25 | 2009-07-25 | Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101963608A true CN101963608A (en) | 2011-02-02 |
Family
ID=43516572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200910109137XA Pending CN101963608A (en) | 2009-07-25 | 2009-07-25 | Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101963608A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105081288A (en) * | 2015-08-17 | 2015-11-25 | 共慧冶金设备科技(苏州)有限公司 | Experiment simulation device and method for studying solidification process of metal melt under temperature field and flow field coupled condition |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100458801C (en) * | 2006-12-22 | 2009-02-04 | 山东大学 | Method for prediction of shrinkage porosity in casting solidification simulation |
-
2009
- 2009-07-25 CN CN200910109137XA patent/CN101963608A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100458801C (en) * | 2006-12-22 | 2009-02-04 | 山东大学 | Method for prediction of shrinkage porosity in casting solidification simulation |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105081288A (en) * | 2015-08-17 | 2015-11-25 | 共慧冶金设备科技(苏州)有限公司 | Experiment simulation device and method for studying solidification process of metal melt under temperature field and flow field coupled condition |
| CN105081288B (en) * | 2015-08-17 | 2018-11-27 | 共慧冶金设备科技(苏州)有限公司 | It is a kind of for studying the experimental simulation device and method of metal bath process of setting under temperature field-flow field coupling condition |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Carlson et al. | Prediction of shrinkage pore volume fraction using a dimensionless Niyama criterion | |
| Shepel et al. | Numerical simulation of filling and solidification of permanent mold castings | |
| Lewis et al. | Finite element simulation of metal casting | |
| CN101984348B (en) | Determination method of copperplate heat flux based on mass balance and heat balance continuous casting mould | |
| Mahmoodkhani et al. | Numerical modelling of the material flow during extrusion of aluminium alloys and transverse weld formation | |
| Zappulla et al. | Multiphysics modeling of continuous casting of stainless steel | |
| Alexandrou et al. | Mathematical and computational modeling of die filling in semisolid metal processing | |
| Bounds et al. | A computational model for defect prediction in shape castings based on the interaction of free surface flow, heat transfer, and solidification phenomena | |
| CN104899412A (en) | Aluminum alloy casting mechanical performance prediction method | |
| Duan et al. | Experimental measurements for numerical simulation of macrosegregation in a 36-ton steel ingot | |
| CN108446505B (en) | Method for calculating solidification heat transfer of casting blank in funnel crystallizer | |
| Yan et al. | Numerical simulation of AZ91D alloy automobile plug in pressure die casting process | |
| CN102294466B (en) | Method for predicting shrinkage in metal liquid solidification process | |
| Zhang et al. | Influence of thermomechanical shrinkage on macrosegregation during solidification of a large-sized high-strength steel ingot | |
| Hétu et al. | Numerical modeling of casting processes | |
| JP4914429B2 (en) | Solidification analysis method and solidification analysis program for molten alloy | |
| Wang et al. | Prediction on lubrication and friction of mold flux based on inverse problem in a continuous slab casting process | |
| CN106944607A (en) | A kind of inoculant alloy grain structure Numerical Predicting Method | |
| Anglada et al. | Prediction and validation of shape distortions in the simulation of high pressure die casting | |
| CN102236726B (en) | Method for predicting shrinkage porosity in molten metal solidification process and continuous shrinkage porosity prediction method | |
| CN101963608A (en) | Method for predicting shrinkage porosity in metal liquid solidification process and shrinkage porosity continuous prediction method | |
| Monde et al. | Shrinkage induced flow during directional solidification of pure substance in a bottom cooled cavity: A study on flow reversal phenomena | |
| Egole et al. | Micro-macro model for the transient heat and fluid transport in solidification structure evolution during static casting processes | |
| Qin et al. | Improvement of three-dimensional bulge deformation model for continuous casting slab | |
| Yongyou et al. | Determination of interfacial heat transfer coefficient and its application in high pressure die casting process |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C12 | Rejection of a patent application after its publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20110202 |