CN100495007C - Method for forecasting defects of shrinkage cavity of ductile iron castings based on finite elements - Google Patents
Method for forecasting defects of shrinkage cavity of ductile iron castings based on finite elements Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 81
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Abstract
The invention discloses nodular iron casting shrinkage hole failure prediction method based on finite element. It adopts finite element processing simulation ProCAST to analyze nodular iron casting to gain cavity fill and temperature field analysis document, calculate unite solid phase ratio, volume, and eutectic expansion rate, search sealed and isolated areas, calculate whole volume changed value and output, and judge the shrink defects. The invention can process quantification forecast for nodular iron casting shrinkage-hole defect, and offer exact forecast reference for engineering production.
Description
Technical field
The present invention relates to the Forecasting Methodology of metal material shrinkage cavity defect, be specifically related to a kind ofly the shrinkage cavity defect of nodular iron casting be carried out forecast method based on finite element technique.
Background technology
The process of setting of spheroidal-graphite cast iron is because existing liquid state is shunk, solidification shrinkage, graphitization expansion is arranged again, so the process of setting of spheroidal-graphite cast iron is actually the dynamically result of stack of pucker ﹠ bloat, thereby the prediction of nodular iron casting shrinkage cavity defect is more complicated than only considering solidification shrinkage cast steel, aluminum casting in the process of setting.Existing Forecasting Methodology about the nodular iron casting shrinkage cavity, the pucker ﹠ bloat that is difficult in the reflection nodular iron casting process of setting dynamically superposes, and only consider graphitization expansion mostly, do not consider that the die cavity of casting mold enlarges, so can't guarantee to the shrinkage cavity precision of prediction of nodular iron casting.
(author: beam is made thrifty Li Gui and is come etc. in " Iron Mould Coated Sand nodular iron casting solidification simulation and Shrinkage Defect Prediction ", in 2001 (5) " Special Processes of Metal Castings and the non-ferrous alloys "-25-27), by setting up the mathematical model of Iron Mould Coated Sand casting solidification process simulation, adopt dynamic swelling shrinkage method (DECAM) and KG/ √ R criterion to predict the shrink defects of nodular iron casting, but not high to the precision of prediction of defective.
Patent JP19980122126 19980501 " cast article solidify analytical approach " (publication number JP11314152, date of publication on November 16th, 1999) in the patent text, adopt computing machine and carry out the analysis of solidifying of foundry goods by the analytical model that many unit constitute, solid phase amount of contraction in the time of can obtaining each non-solid phase area division and from the shrinkage cavity volume of solidification shrinkage amount, based on the analytical approach of finite difference, but the die cavity magnification factor that reckons without graphitization expansion in the nodular iron casting process of setting and cause.
" solidifying analytical approach " (publication number JP2005329465 of patent JP20050121506 20050419, date of publication on Dec 02nd, 2005) in the text, disclosed analytical approach is to calculate the amount of contraction of each unit according to the difference of adjacent cells solid rate, most of amount of contraction that it only can estimate wherein is difficult to reach the prediction of and quantification accurate to shrinkage cavity.
Summary of the invention
The object of the present invention is to provide a kind of nodular iron casting shrinkage cavity defect Forecasting Methodology based on finite element, taken into full account the influence that graphitization expansion and die cavity enlarge in the nodular iron casting process of setting, solved the problem of existing Forecasting Methodology nodular iron casting shrinkage cavity defect forecasting accuracy difference.
The technical solution adopted in the present invention is, a kind of nodular iron casting shrinkage cavity defect Forecasting Methodology based on finite element, the BFS (Breadth First Search) method of employing figure is handled the magnanimity finite element data technique in the Casting Technological Analysis process, in calculating, process of setting forms the influence that mechanism considers that dynamically graphitization expansion and die cavity enlarge from microstructure, by input temp field result and how much files of foundry goods, controlled variable and calculating parameter are set, carry out the closed area search, isolated region search and total die cavity enlarge calculating, finally draw isolated region volume change value, this method may further comprise the steps:
Step 1, employing are filled type and temperature field analysis based on the commercial processing simulation ProCAST of finite element to nodular iron casting, obtain temperature field file and how much files in the selected step-length scope of this foundry goods, and temperature field file and how much files are output as common finite element temperature file layout and how much file layouts with viewcast;
Step 2, calculate the unit solid rate of each finite element, go out unit volume by how much files according to the unit coordinate Calculation simultaneously, the eutectic expansivity when calculating eutectic transformation according to the chemical constitution of this foundry goods according to the corresponding relation of temperature and solid rate;
Step 3, employing finite element algorithm are handled initial step T=1, wherein T is a step-length, the unit solid rate of each finite element that draws according to aforementioned calculation, in conjunction with how much file datas the closed area search is carried out in above-mentioned solid phase rate field, in the unit of the solid rate that is interconnected in the foundry goods less than critical solid rate, be the closed area by this solid rate contour surface area surrounded;
Step 4, in the closed area that above-mentioned search obtains, carry out isolated region search, the all corresponding corresponding isolated region in each closed area, utilize the way of unit expansion, all belong to some isolated regions up to all isolated region unit, the boundary element that contacts with cast outer surface of searching isolated zone simultaneously calculates total die cavity expansion value according to the total surface area of boundary element;
Step 5, change the next step T=n+1 that calculates over to and circulate, wherein T is a step-length, search for the closed area and the isolated region in this step, if the isolated region that previous step is long derives from the isolated region that makes new advances, then new isolated region is numbered, calculate the volume change and the die cavity expansion value of this isolated region simultaneously, according to said method, up to finishing the search that all calculate the step;
Step 6, the total die cavity expansion value, unit volume value and the eutectic expansivity that draw according to aforementioned calculation are carried out the calculating of volume change to the isolated region that search obtains, and with isolated region volume change value output, the volume when beginning to form according to this volume change value and isolated region, the position of isolated region can be carried out quantification to the shrink defects of this foundry goods and be judged.
Characteristics of the present invention also are:
The closed area search is the BFS (Breadth First Search) method of employing figure, sets up the method for a cover search closed area, can write down size, position and the inheritance of closed area quickly and accurately, carries out according to the following steps:
(1) at first when t=0, gives the closed area numbering to all foundry goods unit :-1;
(2) during t=n, to whole unit judges, with fis〉to decide curdled appearance number be 1 for the unit of fsc, it number is 0 that curdled appearance is decided in the unit of fis＜fsc, fis is the solid rate of i unit, and fsc is the critical solid rate of alloy, fis〉unit of fsc means this element and do not have feeding capacity;
(3) begin search from the foundry goods highest point, if unit V (i, j, state k) number are 0, as the search start element, and to indicate this unit be own addressed location this unit;
(4) visit and V (i, j, k) adjacent each unit, if this unit oneself through accessed mistake, so no longer process; Otherwise, whether the solid rate of judging this unit is less than critical solid rate, if less than, then this unit is deposited in array arr[0] in, if greater than critical solid rate, illustrate to solidify then not deal with, successively the search of all adjacent cells finished, and addressed location is not recorded array arr[0] in;
(5) from array arr[0] take out successively not addressed location V (i, j, k), as initial search unit, search for according to method in the step (4), and less than the unit record of critical solid rate to arr[1], up to arr[0] in all searched the finishing in unit of record;
(6) from array arr[1] take out not addressed location V (1 successively, j, k), as initial search unit, search for according to method in the step (4), and handle arrives arr[0 less than the unit record of critical solid rate], arr[0 before using] be cleared, up to arr[0] in all searched the finishing in unit of record, jump to (5) subsequently, carry out repeatedly, finish up to search;
(7) repeat (3), give successively closed area numbering 2,3 ..., when t=n, all the closed area of unit numbering is not-1;
(8) at t
N+1Moment repeating step (1)～(4).
Isolated region search is to allow the closed area that exists in the foundry goods carry out grid in turn expand, one deck grid can only be expanded in each each closed area, regulation is own through expanding the grid of going into a certain closed area simultaneously, can not expand again into other closed areas, till all solid rates have been divided greater than critical solid rate but less than 1 grid.
The computing method of total die cavity expansion value are as follows:
The setting rate of supposing the foundry goods outer cover unit corresponding with isolated region is roughly close, it is roughly suitable that each unit enlarges role to die cavity, if total N of foundry goods outer cover unit, the volume of unit is Ve (i), and then the solid rate of outer cover unit i rises to the die cavity that causes 1.0 the process from 0.7 and enlarges expression formula and be:
It is linear to suppose that the caused die cavity of outer cover unit enlarges with its solid rate growth, and then when isolated region formed, if the solid rate of unit i is fs (i), then this unit enlarged to the die cavity that solidifies fully causing △ Vm (i) from this moment,
fs(i)≤0.7 △Vm(i)＝Vm(i) (2)
fs(i)>0.7
All outer cover units are calculated △ Vm (i), add up:
This promptly this isolated region self-forming to total die cavity expansion value of solidifying end.
The present invention has following advantage:
1, the present invention adopts in the calculating of nodular iron casting process of setting from microstructure and forms the influence that mechanism considers that dynamically graphitization expansion and die cavity enlarge, can accurately predict the size and the position of nodular iron casting shrinkage cavity defect, the prediction of quantification is provided for the shrinkage cavity defect of nodular iron casting, thereby provide support for optimizing casting Technology Design, to instruct process practice.
2, the present invention adopts finite element algorithm that the dynamic additive process of the pucker ﹠ bloat in the nodular iron casting process of setting has been carried out the isolated region search, obtained the volume change of isolated region, finite-difference algorithm commonly used can better be described complicated casting mold type wall, thereby calculates die cavity expansion value more accurately.
3, the present invention adopts the BFS (Breadth First Search) method of figure to handle magnanimity finite element data in the Casting Technological Analysis process, improves arithmetic speed and computational accuracy greatly, for Casting Technological Analysis saves time, shortens the casting Technology Design cycle.
Description of drawings
Fig. 1 is the schematic flow sheet of the inventive method;
Fig. 2 is sample casting process figure;
Fig. 3 is the closed area figure that forms in the sample process of setting;
Fig. 4 is the actual internal anatomy of sample.
Embodiment
The present invention is described in detail below in conjunction with the drawings and specific embodiments.
Forecasting Methodology of the present invention, the BFS (Breadth First Search) method of employing figure is handled the finite element data technique of the magnanimity in the Casting Technological Analysis process, in calculating, process of setting forms the influence that mechanism considers that dynamically graphitization expansion and die cavity enlarge from microstructure, by input temperature field result and how much files of foundry goods through commercial finite element software ProCAST calculating, controlled variable and calculating parameter are set, the destination file of output as calculated, can demonstrate shrinkage cavity forms in the nodular iron casting position and size, thereby reach the purpose of prediction shrinkage cavity defect.At first use interior temperature field file and how much files of selected step-length scope that ProCAST software obtains foundry goods; And then calculate the solid rate of each finite element unit according to the corresponding relation of temperature and solid rate; Go out unit volume by how much files according to the unit coordinate Calculation simultaneously; Eutectic expansivity when calculating eutectic transformation by the chemical constitution of input spheroidal-graphite cast iron; Then the initial step is handled, utilize the solid rate value to judge whether to form initial closed area, in case formation closed area, utilize the way of unit expansion to calculate initial isolated region, and the boundary element that contacted with cast outer surface of searching isolated zone, calculate total die cavity expansion value according to the total surface area of boundary element, change the next simulation step afterwards over to, circulate, search for the closed area and the isolated region in this step.If the isolated region long by previous step derives from the isolated region that makes new advances, then new isolated region is numbered, calculate the volume change and the die cavity expansion value of this isolated region simultaneously; According to said method, up to finishing the calculating that all calculate the step, obtain the number and the volume change value of final isolated region.In this process, though calculating, each step all needs to carry out the search of closed area, the search of closed area does not need each step all must carry out, when having only the closed area to derive from the closed area that makes new advances, just need carry out the search of closed area, save simulated time so greatly, improve program efficiency.After finishing the isolated region search of all being calculated the step, isolated region Search Results and statistics are exported with the form of form, the position of the volume change value of output isolated region, the volume when isolated region begins to form, isolated region comes quantification to judge whether to occur shrink defects thus.
As shown in Figure 1, this method may further comprise the steps:
Step 1, employing are filled type and analysis of temperature field based on the commercial processing simulation software Pro CAST of finite element to nodular iron casting, obtain temperature field file and how much files, and temperature field file and how much files being output as common finite element temperature file layouts such as patran or ideas and how much file layouts with the visualization model viewcast of ProCAST software, this file layout is the machine readable text presents;
Step 2, calculate the unit solid rate of each finite element, go out unit volume by how much files according to the unit coordinate Calculation simultaneously, the eutectic expansivity when calculating eutectic transformation according to the chemical constitution of this foundry goods according to the corresponding relation of temperature and solid rate;
The eutectic expansivity can be calculated with reference to spheroidal-graphite cast iron eutectic freezing curve by the chemical constitution of input spheroidal-graphite cast iron.
Step 3, employing finite element algorithm are handled initial step T=1, wherein T is a step-length, the unit solid rate of each finite element that draws according to aforementioned calculation, in conjunction with how much file datas the closed area search is carried out in above-mentioned solid phase rate field, adopt the BFS (Breadth First Search) method of figure, can find out the solid rate that is interconnected in the foundry goods unit automatically less than critical solid rate, solid rate (critical solid rate) when regulation feeding molten iron stops to flow is 0.7, is the closed area by this solid rate contour surface area surrounded;
The BFS (Breadth First Search) method of employing figure of the present invention is carried out the closed area search, set up the method for a cover search closed area, can write down the size and the position of closed area quickly and accurately, and inheritance, carried out the search of single closed area at this, improved search speed greatly, and can arrive qualified all unit searches, the situation of searching can not occur leaking, concrete searching method carries out according to the following steps:
(1) at first when t=0, gives the closed area numbering to all foundry goods unit :-1;
(2) during t=n, to whole unit judges, with fis〉to decide curdled appearance number be 1 for the unit of fsc, it number is 0 that curdled appearance is decided in the unit of fis＜fsc, fis is the solid rate of i unit, and fsc is the critical solid rate of alloy, fis〉unit of fsc means this element and do not have feeding capacity;
(3) begin search from foundry goods highest point (being generally dead head), if unit V (i, j, state k) number are 0, as the search start element, and to indicate this unit be own addressed location this unit;
(4) visit and V (i, j, k) adjacent each unit, if this unit oneself through accessed mistake, so no longer process; Otherwise, whether the solid rate of judging this unit is less than critical solid rate, if less than, then this unit is deposited in array arr[0] in, if greater than critical solid rate, illustrate to solidify then not deal with, successively the search of all adjacent cells finished, and addressed location is not recorded array arr[0] in;
(5) from array arr[0] take out successively not addressed location V (i, j, k), as initial search unit, search for according to method in the step (4), and less than the unit record of critical solid rate to arr[1], up to arr[0] in all searched the finishing in unit of record;
(6) from array arr[1] take out not addressed location V (1 successively, j, k), as initial search unit, search for according to method in the step (4), and handle arrives arr[0 less than the unit record of critical solid rate], arr[0 before using] be cleared, up to arr[0] in all searched the finishing in unit of record, jump to (5) subsequently, carry out repeatedly, finish up to search;
(7) repeat (3), give successively closed area numbering 2,3 ..., when t=n, all the closed area of unit numbering is not-1;
(8) at t
N+1Moment repeating step (1)～(4).
Step 4, carry out isolated region search in the closed area that above-mentioned search obtains, the boundary element that contacts with cast outer surface of searching isolated zone simultaneously calculates total die cavity expansion value according to the total surface area of boundary element;
Isolated region is meant when the closed area has just formed, the closed area together with solid rate around this closed area greater than critical solid rate but less than 1 area of space.The method of nodular iron casting isolated region search, for solid rate greater than critical solid rate but rationally to divide less than 1 area of space be the comparison difficulty.Because spheroidal-graphite cast iron is mushy freezing, generally speaking, when the closed area forms, solid rate is greater than critical solid rate but exist scope big less than 1 area of space, the solid rate gradient is little in the zone, everywhere solid rate difference is not obvious between closed area and the closed area, has also caused very big difficulty for the reasonable division of isolated region.Can carry out the division of isolated region by nearby principle for this reason: promptly for some solid rates greater than critical solid rate but less than for 1 the unit, it is nearest from the space length of which closed area, which zone is its volume change just having the greatest impact to, so, it just should be divided and return this zone.But want to estimate exactly each solid rate greater than critical solid rate but nearest from which closed area less than 1 unit, must obtain the bee-line of this unit to each closed area, doing like this needs a large amount of evaluation works.For fear of big calculated amount, the present invention adopts following method to carry out the search of isolated region:
Allowing the closed area that exists in the foundry goods carry out grid in turn expands, one deck grid can only be expanded in each each closed area, regulation is own through expanding the grid of going into a certain closed area simultaneously, can not expand again into other closed areas, till all solid rates have been divided greater than critical solid rate but less than 1 grid.This method can not cause the big error of calculation under the little situation of foundry goods mesh generation size, can satisfy the precision of actual engine request.
The computing method of total die cavity expansion value are as follows:
The die cavity expansion value Vm that produces is because the foundry goods shell expands: △ t * casting surface area, wherein △ t is for making the outwards mobile distance of cast(ing) surface because the foundry goods shell expands, this value can be measured by experiment, the part that takes place after the sealing of feeding passage among the Vm is designated as △ Vm, and △ Vm will directly enter the net volume change calculations of isolated region.
The computing method of △ Vm are as follows:
Outside wedge angle and chill, approaching substantially with the setting rate of the corresponding foundry goods of isolated region outer cover unit partly, suppose that the setting rate of the foundry goods outer cover unit corresponding with isolated region is roughly close, it is roughly suitable that each unit enlarges role to die cavity.If the total N of foundry goods outer cover unit, the volume of unit is Ve (i), then the solid rate of outer cover unit i rises to the die cavity that causes 1.0 the process from the solid rate of outer cover unit i from 0.7 and enlarges and can closely try to be expressed as:
It is linear to suppose that the caused die cavity of outer cover unit enlarges with its solid rate growth, and then when isolated region formed, if the solid rate of unit i is fs (i), then this unit enlarged to the die cavity that solidifies fully causing △ Vm (i) from this moment,
fs(i)≤0.7 △Vm(i)＝Vm(i) (2)
fs(i)>0.7
All outer cover units are calculated △ Vm (i), and then add up:
This promptly this isolated region self-forming to the die cavity expansion value of solidifying end.
Enlarge in order to calculate die cavity more accurately, the foundry goods shell expands total die cavity expansion value of producing can just form by first closed area of foundry goods the time, and the contained foundry goods case surface of this isolated region is long-pending * and △ t calculates.
For by initial isolated region through once or repeatedly deriving from the isolated region of coming, its self-forming enlarges to the die cavity that solidifies end also can be calculated according to the method described above.Deriving from each outer cover unit of isolated region, must be the outer cover unit of upper level isolated region, and it is constant that its solid rate rises to from 0.7 that the die cavity that causes 1 the process enlarges, just this moment outer cover unit the solid rate value increase to some extent.Therefore through type (3) and (4) are calculated and are derived from the isolated region self-forming to solidifying the caused die cavity expansion in each unit of its shell when finishing, and are this derivation district self-forming after adding up to total die cavity expansion value of solidifying end.
Step 5, then change the next step T=n+1 that calculates over to and circulate, search for the closed area and the isolated region in this step, if the isolated region long by previous step derives from the isolated region that makes new advances, then new isolated region is numbered, calculate the volume change and the die cavity expansion value of this isolated region simultaneously; According to said method, up to finishing the search that all calculate the step.
Step 6, the total die cavity expansion value, unit volume value and the eutectic expansivity that draw according to aforementioned calculation are carried out the calculating of volume change to the isolated region that search obtains, and the position of exporting isolated region volume change value, the volume when isolated region begins to form, isolated region, come quantification to judge whether to occur shrink defects thus.
The volume change that the present invention is directed in the nodular iron casting process of setting is calculated, to complex-shaped foundry goods, the initial closed area that produces is often along with becoming a plurality of closed areas dividing of process of setting in the process of setting, and promptly a closed area derives several closed areas.Equally, isolated region also exists derived relation.The present invention is changed to according to judging shrink defects with the final no longer net volume of the isolated region of division.
In order to improve ductile iron solidification process simulation precision, reach quantification and accurately predict the purpose of nodular iron casting shrinkage cavity defect, the present invention has deduced the News Search process that ductile iron solidification is shunk from the solidification and crystallization aspect, by to handling through the temperature field of commercial computed in software data, solved and analyzed a difficult problem of judging defective in the processing simulation, for engineering is provided by the actual definite basis for forecasting that provides.
Below provide and use the example that the inventive method is verified sample.
Figure 2 shows that the sample casting process figure that verifies, for these samples, all having confining liquid phase region as shown in Figure 3 in process of setting, use the calculating of method of the present invention to the volume change of these isolated regions, is-0.83 * 10 for the volume change of this isolated region of sample a
-6m
3, be-0.26 * 10 for the volume change of this isolated region of sample b
-6m
3, sample a, b all shrinkage cavity defect can occur as can be known, and defect size be a greater than b, and be 0.12 * 10 for its volume change of sample C
-6m
3, shrinkage cavity defect can not appear then, and this result with actual casting sample is consistent, as shown in Figure 4, has reflected the shrinkage cavity situation of this sample preferably.
Claims (4)
1. nodular iron casting shrinkage cavity defect Forecasting Methodology based on finite element, the BFS (Breadth First Search) method of employing figure is handled the magnanimity finite element data technique in the Casting Technological Analysis process, in calculating, process of setting forms the influence that mechanism considers that dynamically graphitization expansion and die cavity enlarge from microstructure, by input temp field result and how much files of foundry goods, controlled variable and calculating parameter are set, carry out closed area search, isolated region search and total die cavity and enlarge calculating, finally draw isolated region volume change value, it is characterized in that this method may further comprise the steps:
Step 1, employing are filled type and temperature field analysis based on the commercial processing simulation ProCAST of finite element to nodular iron casting, obtain temperature field file and how much files in the selected step-length scope of this foundry goods, and temperature field file and how much files are output as common finite element temperature file layout and how much file layouts with viewcast;
Step 2, calculate the unit solid rate of each finite element, go out unit volume by how much files according to the unit coordinate Calculation simultaneously, the eutectic expansivity when calculating eutectic transformation according to the chemical constitution of this foundry goods according to the corresponding relation of temperature and solid rate;
Step 3, employing finite element algorithm are handled initial step T=1, wherein T is a step-length, the unit solid rate of each finite element that draws according to aforementioned calculation, carry out the closed area search in conjunction with the solid rate field that the geometry file data constitutes the unit solid rate by above-mentioned each finite element, in the unit of the solid rate that is interconnected in the foundry goods less than critical solid rate, be the closed area by this solid rate contour surface area surrounded that is interconnected;
Step 4, in the closed area that above-mentioned search obtains, carry out isolated region search, the all corresponding corresponding isolated region in each closed area, utilize the way of unit expansion, all belong to some isolated regions up to all isolated region unit, the boundary element that contacts with cast outer surface of searching isolated zone simultaneously calculates total die cavity expansion value according to the total surface area of boundary element;
Step 5, change the next step T=n+1 that calculates over to and circulate, wherein T is a step-length, search for the closed area and the isolated region in this step, if the isolated region that previous step is long derives from the isolated region that makes new advances, then new isolated region is numbered, calculate the volume change and the die cavity expansion value of this isolated region simultaneously, according to said method, up to finishing the search that all calculate the step;
Step 6, the total die cavity expansion value, unit volume value and the eutectic expansivity that draw according to aforementioned calculation are carried out the calculating of volume change to the isolated region that search obtains, and with isolated region volume change value output, the volume when beginning to form according to this volume change value and isolated region, the position of isolated region can be carried out quantification to the shrink defects of this foundry goods and be judged.
2. according to the described Forecasting Methodology of claim 1, it is characterized in that the search of described closed area is the BFS (Breadth First Search) method of employing figure, set up the method for a cover search closed area, can write down size, position and the inheritance of closed area quickly and accurately, carry out according to the following steps:
(1) at first at t
n, give the closed area numbering to all foundry goods unit :-1 at=0 o'clock;
(2) t
nDuring=n, to whole unit judges, with fis〉to decide curdled appearance number be 1 for the unit of fsc, it number is 0 that curdled appearance is decided in the unit of fis＜fsc, fis is the solid rate of i unit, and fsc is the critical solid rate of alloy, fis〉unit of fsc means this element and do not have feeding capacity;
(3) begin search from the foundry goods highest point, if unit V (i, j, state k) number are 0, and this unit as the search start element, and is indicated this unit and is addressed location;
(4) (k) adjacent each unit is if the accessed mistake in this unit so no longer processes for i, j with V in visit; Otherwise, whether the solid rate of judging this unit is less than critical solid rate, if less than, then this unit is deposited in array arr[0] in, if greater than critical solid rate, illustrate to solidify then not deal with, successively the search of all adjacent cells finished, and addressed location is not recorded array arr[0] in;
(5) from array arr[0] take out successively not addressed location V (i, j, k), as initial search unit, search for according to method in the step (4), and less than the unit record of critical solid rate to arr[1], up to arr[0] in all searched the finishing in unit of record;
(6) from array arr[1] take out not addressed location V (i successively, j, k), as initial search unit, search for according to method in the step (4), and handle arrives arr[0 less than the unit record of critical solid rate], arr[0 before using] be cleared, up to arr[1] in all searched the finishing in unit of record, jump to (5) subsequently, carry out repeatedly, finish up to search;
(7) repeat (3), give successively closed area numbering 2,3 ..., when t=n, all the closed area of unit numbering is not-1;
(8) at t
N+1Moment repeating step (1)～(4).
3. according to the described Forecasting Methodology of claim 1, it is characterized in that, the search of described isolated region is to allow the closed area that exists in the foundry goods carry out grid in turn expand, one deck grid can only be expanded in each each closed area, regulation has expanded the grid into a certain closed area simultaneously, can not expand again into other closed areas, till all solid rates have been divided greater than critical solid rate but less than 1 grid.
4. according to the described Forecasting Methodology of claim 1, it is characterized in that the computing method of described total die cavity expansion value are as follows:
The setting rate of supposing the foundry goods outer cover unit corresponding with isolated region is roughly close, it is roughly suitable that each unit enlarges role to die cavity, if total N of foundry goods outer cover unit, the volume of unit is Ve (i), and then the solid rate of outer cover unit i rises to the die cavity that causes 1.0 the process from 0.7 and enlarges expression formula and be:
Wherein: V
mFor the die cavity expansion value of foundry goods shell expansion generation, generally by test determination; V
m(i) rise to the die cavity expansion value that causes 1.0 the process for the solid rate of foundry goods outer cover unit i from 0.7.
It is linear to suppose that the caused die cavity of outer cover unit enlarges with its solid rate growth, then when isolated region forms, if the solid rate of unit i is f
s(i), then this unit will cause Δ V from this moment to solidifying fully
m(i) die cavity enlarges,
f
s(i)≤0.7 ΔV
m(i)＝V
m(i) (2)
f
s(i)>0.7
All outer cover units are calculated Δ V
m(i), add up:
This promptly this isolated region self-forming to total die cavity expansion value of solidifying end.
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