CN103424318B

CN103424318B - A kind of determination method of metal sheet forming limit curve

Info

Publication number: CN103424318B
Application number: CN201210164718.5A
Authority: CN
Inventors: 苏钰; 程光; 牛景弘; 王伟; 王一伟; 王娟
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2012-05-23
Filing date: 2012-05-23
Publication date: 2017-10-10
Anticipated expiration: 2032-05-23
Also published as: CN103424318A

Abstract

The present invention relates to a kind of determination method of metal sheet forming limit curve, stamping simulation is carried out to being tested sheet metal by Stamping CAE simulation-analysis software DYNAFORM softwares, so that it is determined that the FLD0 values in forming limit diagram, by Keeler formula, the shaping limit curve of tested sheet metal is calculated and obtained.Compared with the conventional method, the determination method more simple possible of metal sheet forming limit curve of the present invention, and cost is relatively low, error is smaller.

Description

A kind of determination method of metal sheet forming limit curve

Technical field

Sheet metal Plastic Forming performance index --- the determination method of shaping limit curve is characterized the present invention relates to one kind.

Background technology

The basic mechanical performance index of sheet metal can only make qualitative, comprehensive half to sheet material forming performance and comment Valency.For the shaping of complicated shape part, each local reality of blank can not be described and weigh comprehensively with basic mechanical performance index Border deformation.Shaping limit curve (Forming Limit Curves-- are abbreviated as FLC) is be conceived to complex parts every One deformation is local, and it is local buckling limiting strain principal strain ε of the plate under differently strained path₁With secondary strain stress₂Constitute Strip-form curve.FLD (Forming Limit Diagram- are abbreviated as FLD, identical with FLC physical meaning) is comprehensively, intuitively The forming property for reflecting plate under strain conditions, be a kind of quantitative description to sheet metal formability, it is qualitative With the effective means of quantitative study plate partial plastic forming performance.

The test method for obtaining metal sheet forming curve (FLC) now is according to national standard：GB/T 15825.8- 1995《Sheet metal formability is tested with test method-forming limit diagram (FLD)》To be tested.Its method substantially step For：

1st, grid is printed on sheet metal using electrochemical process, and cuts various sizes of sheet coupon and accordingly tested Carried out in equipment stamping；

2nd, warp mesh circle is measured in the critical grid garden near stamping rear selection necking down area on tool microscope Major axis and minor axis dimension, so as to obtain principal strain ε₁, secondary strain stress₂Value, then by (ε₁, ε₂) coordinate points are plotted to ε₁For horizontal stroke Coordinate, ε₂For in the coordinate system of ordinate, you can obtain the forming limit diagram of sheet metal.

The difficulty that this method test FLD faces often mainly has：

1st, because the grid being printed on sheet metal can not produce prestrain, it is necessary to by electrochemical corrosion in metallic plate Grid is printed on material, and corresponding grid printed apparatus price is relatively expensive；

2nd, the dimensions of metal blank sample needed for during test obtains FLC is up to nine kinds, every kind of at least to prepare 3-5 pieces, material requested is more (3-5 groups)；

3rd, after metallic plate punching deformation, because sheet metal comes in contact with punch-die, extruded in forming process, change The electrochemical corrosion grid at the larger position of shape amount is usually worn, and causes the grid after abrasion to be difficult to it is clear that measuring, calculating ε₁、ε₂ Produce certain difficulty, relative increase draws the error and difficulty of FLC curves.

The content of the invention

A kind of metal sheet forming limit curve is provided it is an object of the invention to overcome the defect of prior art really Determine method, this method more simple possible.

The object of the present invention is achieved like this：

A kind of determination method of metal sheet forming limit curve of the present invention, comprises the following steps：

S1：The experiment of different drawing heights is carried out to the slab for being tested sheet metal on forcing press, slab drawing is measured Just there is the rupture drawing height h2 ruptured in limit drawing modulus h1 and drawing during success；

S2：The stress-strain diagram of tested sheet metal is obtained by tension test；

S3：The newly-built tested sheet metal in the material depot of Stamping CAE simulation-analysis software DYNAFORM softwares Material depot, imports the material database, first in DYNAFORM by the stress-strain diagram of the obtained tested sheet metals of step S2 An initial FLD0 value is set in the newly-built material depot of software, actual forcing press punching press is simulated for DYNAFORM softwares Shaping；

S4：Forcing press punch test convex mould, cavity plate, slab, blank holder mathematical model are imported in DYNAFORM softwares, Related process parameters in forcing press punch test set the corresponding process parameters in DYNAFORM simulation softwards, set pole Drawing height h1 and rupture drawing height h2 are limited, stamping simulation is carried out respectively；

S5：If analog result is consistent with actual punching press situation, the initial FLD0 values set in step S3 are defined as FLD0 values in forming limit diagram, by Keeler formula, calculate and obtain the shaping limit curve of tested sheet metal；

If analog result is not met with actual punching press situation, comparative simulation result and actual punching press result are corresponding to increase Big or reduction FLD0 values, are combined into until the FLD0 values set in DYNAFORM softwares make analog result be consistent with actual punching press result Only, so far FLD0 is determined, then by Keeler formula, calculates and obtain the shaping limit curve of tested sheet metal.

Compared with the conventional method, the determination method more simple possible of metal sheet forming limit curve of the present invention, and Cost is relatively low, and error is smaller.

Brief description of the drawings

The cylindrical element of forcing press punching press drawing when Fig. 1 is slab diameter 87mm stretching height 21mm (drawing does not rupture)；

(drawing produces broken the cylindrical element of forcing press punching press drawing when Fig. 2 is slab diameter 88mm, stretching height 20mm Split)；

Fig. 3 is introduced into the stress-strain diagram of experiment dual phase steel in DYNAFORM softwares；

Fig. 4 is the shaping limit curve that experiment dual phase steel uses initial FLD0 values；

Fig. 5 is the forming process simulation image that FLD0 is 0.24；

Fig. 6 is the forming process simulation image that FLD0 is 0.25；

Fig. 7 is the shaping limit curve of experiment dual phase steel.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the invention will be further described.

Embodiment

The present embodiment a kind of high intensity experiment is formed with dual phase steel the determination of limit curve, comprises the following steps：

S1：Carry out the experiment of different drawing heights with the slab of dual phase steel to experiment on forcing press, measure slab drawing The rupture drawing height h2 that rupturing just occur in limit drawing modulus h1 (actually measured h1 is 87mm) and drawing during success is (actual H1 is measured for 88mm), table 1 below is the actual drawing situation of the experiment dual phase steel：

Referring to Fig. 1, the cylinder of forcing press punching press drawing when slab diameter 87mm stretching height 21mm are shown in figure Part, drawing does not rupture；

Referring to Fig. 2, the cylinder of forcing press punching press drawing when slab diameter 88mm, stretching height 20mm are shown in figure Part, drawing produces rupture.

S3：The newly-built tested sheet metal in the material depot of Stamping CAE simulation-analysis software DYNAFORM softwares Material depot, the experiment that step S2 is obtained imports the material database with the stress-strain diagram of dual phase steel (as shown in figure 3, figure Middle abscissa is strain stress (%), and ordinate is stress σ (MPa)), due to the FLC curve shapes substantially one of similar metal sheet material Sample, simply FLD 0 be worth difference, can first in the newly-built material depot of DYNAFORM softwares set an initial FLD0 value, with It is stamping that actual forcing press is simulated in DYNAFORM softwares；

Fig. 4 uses the right in the shaping limit curve of initial FLD0 values, figure to be DYNAFORM softwares for experiment dual phase steel The forming limit curve of the middle dual phase steel determined according to FLC_Keeler formula, the left side sets FLD0, right according to FLD0 difference The forming curve on side is vertically moved along above and below Y-axis.

The punching press situation of cylindrical element is striking out when the different FLD0 values of setting are to slab diameter 88mm, stretching height 20mm Simulated in type simulation softward DYANFORM, physical simulation result see the table below 2：

FLD0	0.20	0.21	0.22	0.23	0.24	0.25
							Analog result	Rupture	Rupture	Rupture	Rupture	Rupture	Do not break

Fig. 5 is that the point position in the forming process simulation image that FLD0 is 0.24, circle is generation rent；

Fig. 6 is the forming process simulation image that FLD0 is 0.25, and bottom roundings represent that being in hazardous area does not break still Split place.

S5：If analog result is consistent with actual punching press situation, the initial FLD0 values set in step S3 are determined For the FLD0 values in forming limit diagram, experiment is also accordingly determined with the shaping limit curve of dual phase steel.

If analog result is not met with actual punching press situation, comparative simulation result and actual punching press result, accordingly Increase reduces FLD0 values, until the FLD0 values set in DYNAFORM softwares make analog result be consistent with actual punching press result Untill, so far FLD0 is determined, experiment also mutually should determine that with the shaping limit curve of dual phase steel.

Shaping limit curve can be gone to calculate according to Keeler formula, therefore the FLD curve shapes of a class steel will be protected As holding, differ only in FLD0 difference so that the FLD curves in figure are influenceed by FLD0 numerical value, are moved up and down.Therefore FLD0 position can be substantially determined by actual punching press, is then clicked on " export " in Fig. 4, it is each on export FLC curves Point coordinates, the curve can be drawn out by these coordinate points in excel softwares.

As can be seen that when FLD0 points are 0.24, experiment dual phase steel just ruptures from table 2, Fig. 5-6；Work as FLD0 When point is 0.25, sample does not just rupture.Hence, it can be determined that the FLD0=0.24 of experiment dual phase steel, then DYNAFORM The shaping limit curve of experiment dual phase steel is as shown in Figure 7 in material depot.

Above example is used for illustrative purposes only, rather than limitation of the present invention, about the technology people of technical field Member, without departing from the spirit and scope of the present invention, can also make various conversion or modification, therefore all equivalent Technical scheme should also belong to scope of the invention, should be limited by each claim.

Claims

1. a kind of determination method of metal sheet forming limit curve, it is characterised in that comprise the following steps：

S1:The experiment of different drawing heights is carried out to the slab for being tested sheet metal on forcing press, the success of slab drawing is measured When limit drawing modulus h1 and drawing just there is the rupture drawing height h2 ruptured；

S2:The stress-strain diagram of tested sheet metal is obtained by tension test；

S3:The material of newly-built tested sheet metal in the material depot of Stamping CAE simulation-analysis software DYNAFORM softwares Storehouse, imports material database, first in DYNAFORM softwares by the stress-strain diagram of the obtained tested sheet metals of step S2 An initial FLD0 value is set in newly-built material depot, it is stamping to simulate actual forcing press for DYNAFORM softwares；

S4:Forcing press punch test convex mould, cavity plate, slab, blank holder mathematical model are imported in DYNAFORM softwares, according to Related process parameters in forcing press punch test set the corresponding process parameters in DYNAFORM simulation softwards, and setting limit is drawn Deep height h1 and rupture drawing height h2, carries out stamping simulation respectively；

S5:If analog result is consistent with actual punching press situation, the initial FLD0 values set in step S3 are defined as shaping FLD0 values in limiting figure, by Keeler formula, calculate and obtain the shaping limit curve of tested sheet metal；

If analog result is not met with actual punching press situation, comparative simulation result and actual punching press result, increase accordingly or Reduce FLD0 values, untill the FLD0 values set in DYNAFORM softwares make analog result be consistent with actual punching press result, So far FLD0 is determined, then by Keeler formula, calculates and obtain the shaping limit curve of tested sheet metal.