CN108801801A - A kind of assay method of sheet alloy hot forming limit curve - Google Patents
A kind of assay method of sheet alloy hot forming limit curve Download PDFInfo
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- CN108801801A CN108801801A CN201810619971.2A CN201810619971A CN108801801A CN 108801801 A CN108801801 A CN 108801801A CN 201810619971 A CN201810619971 A CN 201810619971A CN 108801801 A CN108801801 A CN 108801801A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/18—Performing tests at high or low temperatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
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- G01N2203/0226—High temperature; Heating means
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Abstract
The present invention provides a kind of assay methods of sheet alloy hot forming limit curve, belong to Alloy Forming limit curve fields of measurement.The present invention is transmission medium using silicon nitride ceramic ball and molybdenum disulfide, has the advantages that heat safe, it can be achieved that higher pressure, can be used for broader temperature range；The differently strained load path in double stretching strain areas is realized jointly by changing transmission medium composition and mold；Strain measurement is realized by online vision measurement technology in sheet alloy deformation process, and shaping limit curve under the conditions of by above 3 points combination realization sheet alloys in broader temperature range, under more load paths, more accurate strain measurement tests acquisition methods.
Description
Technical field
The present invention relates to Alloy Forming limit curve field of measuring technique, and in particular to a kind of sheet alloy hot forming limit
The assay method of curve.
Background technology
In the fields such as aerospace and automobile making, high tensile metal sheet alloy (aluminium alloy plate, magnesium alloy plate, titanium alloy
Plate etc.) with have become realize component lightweight and ensure sufficient intensity one of main path.However, High-strength plate is in room
Plastic deformation ability force difference under the conditions of temperature, it is difficult to obtain complex-shaped part by punch process.Therefore, the plasticity of such plank
Processing generally require to carry out under the high temperature conditions, low then 200 DEG C~300 DEG C, it is high then close to 1000 DEG C.How hot conditions are obtained
Under shaping limit curve come to assess maximum crystallized ability of such plank under special process temperature condition be one relatively tired
Difficult and significant work.
In general, the method for obtaining shaping limit curve mainly has theoretical method and test method.Theory obtains forming
The method of limit curve is limited to the applicability and accuracy of theory used, often will appear the theoretical and prodigious feelings of actual deviation
Condition.Therefore, in the industrial production for different raw material, adopt experimentally obtain shaping limit curve be it is most effective,
Reliable method.In traditional cold punching pressing formation, the method that experiment obtains shaping limit curve mainly has cylindrical male experiment
Method, hemispherical punch-pin test method and hydraulic bulge test method.In first two rigidity punch-pin test method, pass through change
Lubricating status when sample is contacted with punch-pin realizes the differently strained load path in double stretching strain areas to obtain the forming limit diagram right side
Side region, still, the selection of the lubricant medium under high temperature are limited, the change of lubricant effect cannot make the range of strain of test specimen compared with
Region required by more ground drape forming limiting figure.Hydraulic bulge test method realizes double stretching strains by changing cavity plate shape
The different loading paths in area still, are limited to liquid medium and device sealing to obtain more complete forming limit diagram right area
The temperature capacity of original paper limits, and the deformation temperature range that this method is applicable in is usually no more than 300 DEG C, and therefore, it is difficult to obtain high temperature
Under the conditions of Forming Limit of Sheet Metals curve.
In the experiment for obtaining shaping limit curve, strain is mainly obtained by network analysis technology.In plate before experiment
It prints that size is identical rectangular or roundness mess on material, the change of constriction and rupture location and its neighbouring size of mesh opening is measured after experiment
Change, then obtains first principal strain and the second principal strain at failure moment by a series of mathematical processing methods.Common printing net
The method of lattice has：Ink screen method for printing, electrochemical erosion method, laser incising candle method.No matter which kind of method, grid under hot conditions
Clarity can all be affected, the precision of follow-up strain analysis is just difficult to ensure.
In conclusion the main reason for existing test method for obtaining shaping limit curve is difficult to carry out under the high temperature conditions
Following two points can be attributed to：First, the load mode in differently strained path is difficult to realize under hot conditions；Second is that under hot conditions
Strain measurement be difficult to ensure precision.
Invention content
The object of the present invention is to provide a kind of assay methods of sheet alloy hot forming limit curve, for wider deformation temperature
The shaping limit curve for spending section tests assay method, is that the shaping limit curve under aluminium or magnesium alloy plate hot conditions is drawn
A kind of practicable test method is provided.
The present invention provides a kind of assay method of sheet alloy hot forming limit curve, includes the following steps：
(1) it is coated with machine silicon heat resistance paint in the single side of sheet alloy, makes spot, obtain pretreatment sheet alloy, institute
It is aluminum alloy plate materials or magnesium alloy plate to state sheet alloy；
(2) transmission medium is provided, the transmission medium includes silicon nitride ceramic ball and molybdenum disulfide, the silicon nitride ceramics
The grain size of ball is 0.1,0.3 or 0.5mm, and the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide is 9:1 or 8:2；
(3) by hot forming limit curve measuring device to the pretreatment sheet alloy, transmission medium and mold point
It is not preheated, the preheating temperature of the pretreatment sheet alloy, transmission medium and mold independently is higher than the alloy sheets
10~20 DEG C of material forming temperature；The mold is oval expanding die, and the major diameter of the mold is 100mm, and short axle is straight
Diameter is respectively 100,90,80,60 and 40mm；
(4) apply side pressure, the pressure rate of the side pressure is 0.0045 or 0.045MPas-1；
(5) strain data is recorded by online vision measurement system, is calculated using online vision measurement system software different
The first principal strain and the second principal strain of failure critical moment be as limit principal strain under the conditions of transmission medium and different mold,
Obtained limit principal strain is plotted in forming limit diagram, sheet alloy hot forming limit curve is obtained；
To the step (1) and (2) without temporal restriction.
Preferably, sheet alloy is circle in the step (1), and a diameter of 180~200mm of the sheet alloy is thick
Degree is 1~1.5mm.
Preferably, the pre-heating temperature elevation rate of sheet alloy, transmission medium and mould is pre-processed independently in the step (3)
For 5~10 DEG C/min.
Preferably, preheating temperature independently is 260~270 DEG C or 230~240 DEG C in the step (3).
Preferably, online vision measurement system is located at the upper mold of hot forming limit curve measuring device in the step (5)
Top.
Preferably, limit principal strain is calculated in the step (5) to include the following steps：It is extracted in rupture location near zone
First principal strain and the second principal strain, averaged is as limit principal strain respectively.
The present invention provides a kind of assay method of aluminum alloy plate materials hot forming limit curve, includes the following steps：
(1) it is coated with machine silicon heat resistance paint in the single side of sheet alloy, makes spot, obtain pretreatment sheet alloy, institute
It is aluminum alloy plate materials or magnesium alloy plate to state sheet alloy；
(2) transmission medium is provided, the transmission medium includes silicon nitride ceramic ball and molybdenum disulfide, the silicon nitride ceramics
The grain size of ball is 0.1,0.3 or 0.5mm, and the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide is 9:1 or 8:2；
(3) by hot forming limit curve measuring device to pretreatment sheet alloy, transmission medium and mold respectively into
Row preheating, the pretreatment sheet alloy, transmission medium and mold preheating temperature independently be higher than the sheet alloy at
10~20 DEG C of shape temperature；The mold is oval expanding die, and the major diameter of the mold is 100mm, minor axis diameter point
It Wei not 100,90,80,60 and 40mm；
(4) apply side pressure, the pressure rate of the side pressure is 0.0045 or 0.045MPas-1；
(5) strain data is recorded by online vision measurement system, is calculated using online vision measurement system software different
The first principal strain and the second principal strain of failure critical moment be as limit principal strain under the conditions of transmission medium and different mold,
Obtained limit principal strain is plotted in forming limit diagram, sheet alloy hot forming limit curve is obtained；
To the step (1) and (2) without temporal restriction.
The present invention is transmission medium using silicon nitride ceramic ball and molybdenum disulfide, is had the advantages that heat safe, it can be achieved that more
High pressure can be used for broader temperature range, be the alloy in shaping limit curve experiment acquisition process under the high temperature conditions
Plank free bulge provides on-load pressure；Constituted by changing transmission medium realizes with mold that pair stretching strain area is different answers jointly
Become load path, avoids and obtain strain paths area existing for different loading paths by changing Frotteurism under hot conditions
Not unconspicuous phenomenon efficiently solves prior art measurement result and the problems in more collects in double stretching strain areas, can be effective
Promote the accuracy that shaping limit curve is drawn；In sheet alloy deformation process strain measurement by online vision measurement technology come
It realizes, limit principal strain is determined according to the change histories of the first principal strain and the second principal strain during sheet metal deformation so that
The determination of shaping limit curve is more accurate, overcomes ink screen method for printing, electrochemical erosion method, laser incising and lights up method in high temperature
The problem that condition is difficult to carry out or measurement error is big, and determine limiting strain according to strain historical variations, it can be obtained with synchronous
Loading curve comparative analysis, can accurately recognize sheet deformation unstability start and be broken occur moment plate face principal strain number
Value is answered by above 3 points combination realization sheet alloys in broader temperature range, under more load paths, more accurately
The shaping limit curve become under measuring condition tests acquisition methods.
Description of the drawings
Fig. 1 is the structure chart for the mold that the assay method of aluminum alloy plate materials hot forming limit curve of the present invention uses；
Fig. 2 is the structure chart of hot forming limit curve measuring device and online vision measurement system that the present invention uses；
Fig. 3 is first test data point diagram that the embodiment of the present invention 1 obtains；
Fig. 4 is the limit principal strain point diagram under 1 differently strained path of the embodiment of the present invention；
Fig. 5 is the shaping limit curve of 17075 aluminum alloy plate materials of the embodiment of the present invention；
Fig. 6 is first test data point diagram that the embodiment of the present invention 2 obtains；
Fig. 7 is the limit principal strain point diagram under 2 differently strained path of the embodiment of the present invention；
Fig. 8 is the shaping limit curve of 2AZ31 magnesium alloy plates of the embodiment of the present invention.
Specific implementation mode
The present invention provides a kind of assay method of sheet alloy hot forming limit curve, includes the following steps：
(1) it is coated with machine silicon heat resistance paint in the single side of sheet alloy, makes spot, obtain pretreatment sheet alloy, institute
It is aluminum alloy plate materials or magnesium alloy plate to state sheet alloy；
(2) transmission medium is provided, the transmission medium includes silicon nitride ceramic ball and molybdenum disulfide, the silicon nitride ceramics
The grain size of ball is 0.1,0.3 or 0.5mm, and the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide is 9:1 or 8:2；
(3) by hot forming limit curve measuring device to pretreatment sheet alloy, transmission medium and mold respectively into
Row preheating, the pretreatment sheet alloy, transmission medium and mold preheating temperature independently be higher than the sheet alloy at
10~20 DEG C of shape temperature；The mold is oval expanding die, and the major diameter of the mold is 100mm, minor axis diameter point
It Wei not 100,90,80,60 and 40mm；
(4) apply side pressure, the pressure rate of the side pressure is 0.0045 or 0.045MPas-1；
(5) strain data is recorded by online vision measurement system, is calculated using online vision measurement system software different
The first principal strain and the second principal strain of failure critical moment be as limit principal strain under the conditions of transmission medium and different mold,
Obtained limit principal strain is plotted in forming limit diagram, sheet alloy hot forming limit curve is obtained；
To the step (1) and (2) without temporal restriction.
The present invention is coated with machine silicon heat resistance paint in the single side of sheet alloy, makes spot, obtains pretreatment sheet alloy,
The sheet alloy is aluminum alloy plate materials or magnesium alloy plate.In the present invention, the sheet alloy is preferably circular, the conjunction
The diameter of golden plate material is preferably 180~200mm, more preferably 185~195mm, and thickness is preferably 1~1.5mm.
The present invention does not have the source of the aluminum alloy plate materials, magnesium alloy plate and organosilicon heat-resistant lacquer special limit
It is fixed, using commercial goods well known to those skilled in the art.
The present invention does not have special restriction to the size of the spraying, quantity for spray, spot, ripe using those skilled in the art
The spraying method and spraying dosage known.
The present invention preferably sprays spot completely in the single side of the sheet alloy.In the present invention, the effect of the spot
It is the Strain Distribution cloud atlas for facilitating on-line measurement system to be calculated using image recognition technology in sheet alloy deformation process.
In the present invention, preferably further include before sheet alloy spraying organosilicon heat-resistant lacquer using bar stock cutting by punching or
Machine cuts, cut-out sheet alloy edge, polishing deburring.
The present invention provides transmission medium, and the transmission medium includes silicon nitride ceramic ball (Si3N4) and molybdenum disulfide, it is described
The grain size of silicon nitride ceramic ball is 0.1,0.3 or 0.5mm, and the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide is 9:1 or
8:2.The present invention does not have the source of the silicon nitride ceramic ball and molybdenum disulfide special restriction, using those skilled in the art
Well known commercial goods.In the present invention, the molybdenum disulfide is preferably the molybdenum disulfide as lubricant.
In the present invention, the transmission medium preferably includes：1. volume ratio is 9:(grain size is 1 silicon nitride ceramic ball
0.1mm) and molybdenum disulfide, 2. volume ratio be 9:1 silicon nitride ceramic ball (grain size 0.3mm) and molybdenum disulfide, 3. volume ratio
It is 9:1 silicon nitride ceramic ball (grain size 0.5mm) and molybdenum disulfide, 4. volume ratio are 8:(grain size is 2 silicon nitride ceramic ball
0.1mm) and molybdenum disulfide, 5. volume ratio be 8:2 silicon nitride ceramic ball (grain size 0.3mm) and molybdenum disulfide, 6. volume ratio
It is 8:2 silicon nitride ceramic ball (grain size 0.5mm) and molybdenum disulfide.
The present invention does not have the preparation method of the transmission medium special restriction, use well known to those skilled in the art
The preparation method of composition is made.
The present invention distinguishes pretreatment sheet alloy, transmission medium and mold by hot forming limit curve measuring device
It is preheated, the preheating temperature of the pretreatment sheet alloy, transmission medium and mold independently is higher than the sheet alloy
10~20 DEG C of forming temperature；The mold is oval expanding die, and the major diameter of the mold is 100mm, minor axis diameter
Respectively 100,90,80,60 and 40mm.In the present invention, the preheating liter of the pretreatment sheet alloy, transmission medium and mould
Warm rate is preferably independently 5~10 DEG C/min.
Fig. 1 is the structural schematic diagram of mold that the present invention uses, in Fig. 1：1 is the mold that major and minor axis is 100mm, and 2 are
The mold that long axis is 100mm, short axle is 90mm, 3 be the mold that long axis is 100mm, short axle is 80mm, 4 be long axis be 100mm,
Short axle is the mold of 70mm, and 5 be the mold that long axis is 100mm, short axle is 60mm.
In the present invention, the preheating temperature is preferably independently 260~270 DEG C or 230~240 DEG C.
There is no special restriction to the source of the hot forming limit curve measuring device in the present invention, using this field skill
Hot forming limit curve measuring device known to art personnel.
Fig. 2 is the structure chart of hot forming limit curve measuring device and online vision measurement system that the present invention uses,
In Fig. 2：1 is upper mold, and 2 be thermocouple, and 3 be upper mold blank holder, and 4 be sheet alloy, and 5 be lower die blank holder, and 6 be resistance heating
Stick, 7 be thermal insulation layer, and 8 be lower die, and 9 be pressure head, and 10 be transmission medium, and 11 be online vision measurement system.Pass through resistance heating stick
6 heating upper mold blank holders 3 and lower die blank holder 5 are simultaneously monitored temperature by thermocouple 2, sheet alloy 4 and granule medium
10 are heated by external heating furnace, this three's Synchronous Heating, and after the completion of heating, transmission medium 10 is packed into lower molding rapidly
The cavity that flange 5 is formed with pressure head 9 molds rapidly between moving to sheet alloy 4 in upper and lower molding flange and applies flanging
Power.In heating process, between upper mold blank holder 3 and upper mold 1, between lower die blank holder 5 and lower die 8, upper and lower mould blank holder periphery
And thermal insulation layer 7 is equipped in pressure head 9, ensure the efficiency of heating surface and temperature-controlled precision.
In the present invention, the online vision measurement system is preferably placed in the upper mold of hot forming limit curve measuring device
Side.
Apply side pressure, the pressure rate of the side pressure is 0.0045 or 0.045MPas-1.The present invention is to the application
The specific method of side pressure does not have special restriction, by the way of the pressure of application side well known to those skilled in the art.
Strain data is recorded by online vision measurement system, different pressure transmissions are calculated using online vision measurement system software
The first principal strain and the second principal strain of failure critical moment are incited somebody to action as limit principal strain under the conditions of medium and different molds
To limit principal strain be plotted in forming limit diagram, obtain sheet alloy hot forming limit curve.
In the present invention, the calculating limit principal strain preferably includes following steps：It is extracted in rupture location near zone
First principal strain and the second principal strain, averaged is as limit principal strain respectively.
The assay method of sheet alloy hot forming limit curve provided by the invention is carried out with reference to embodiment detailed
Explanation, but they cannot be interpreted as limiting the scope of the present invention.
Embodiment 1
Several a diameter of 180mm are prepared, thickness is the 7075 aluminium alloy plectane test specimens of 1mm, uses organosilicon fire-resistant
Paint, sprays black and white speckle on a surface of test specimen, and speckle covers whole surface.
Prepare transmission medium：Transmission medium selects grain size for the silicon nitride ceramic ball (Si of 0.1mm, 0.3mm, 0.5mm3N4)
And molybdenum disulfide, prepare the transmission medium of following several specifications：1. volume ratio is 9:(grain size is 1 silicon nitride ceramic ball
0.1mm) and molybdenum disulfide, 2. volume ratio be 9:1 silicon nitride ceramic ball (grain size 0.3mm) and molybdenum disulfide, 3. volume ratio
It is 9:1 silicon nitride ceramic ball (grain size 0.5mm) and molybdenum disulfide, 4. volume ratio are 8:(grain size is 2 silicon nitride ceramic ball
0.1mm) and molybdenum disulfide, 5. volume ratio be 8:2 silicon nitride ceramic ball (grain size 0.3mm) and molybdenum disulfide, 6. volume ratio
It is 8:2 silicon nitride ceramic ball (grain size 0.5mm) and molybdenum disulfide.
Using the measuring device of hot forming limit curve shown in Fig. 2, upper mold blank holder (3) is heated by resistance heating stick (6)
Temperature is monitored with lower die blank holder (5) and by thermocouple (2), aluminium alloy plectane test specimen (4) and transmission medium (10)
It is heated by external heating furnace, this three's Synchronous Heating makes this three's temperature rise to 230~240 DEG C.After the completion of heating,
The transmission medium of the first specification (10) is packed into the cavity that lower die blank holder (5) is formed with pressure head (9) rapidly, by aluminum alloy round
Between plate test specimen (4) moves in upper and lower molding flange, molds rapidly and apply pressure-pad-force.In heating process, upper mold blank holder
(3) it is all provided between upper mold (1), between lower die blank holder (5) and lower die (8), in upper and lower mould blank holder periphery and pressure head (9)
There is thermal insulation layer (7), ensures the efficiency of heating surface and temperature-controlled precision.
The deformation history that online vision measurement system (11) prepares record plank is opened, passes through pressure head at once after the completion of molding
(9) side pressure is applied to transmission medium, until transmission medium bursts aluminium alloy plectane test specimen, the pressure rate of side pressure is
0.0045MPa·s-1。
In entire Bulging Process, the strain data recorded by online vision measurement system (11), according to systematic survey
Obtained strain cloud atlas, the first principal strain and the second principal strain averaged of selection rupture location peripheral region are as the limit
Principal strain, and it is plotted in the right side of forming limit diagram, obtain first test data point (see Fig. 3).Replace different shape upper mold
Blank holder, i.e., the structure (see Fig. 1) of different molds, in Fig. 1：1 for major and minor axis be 100mm mold, 2 be long axis be 100mm,
Short axle be 90mm mold, 3 be the mold that long axis is 100mm, short axle is 80mm, 4 be long axis be 100mm, short axle is 70mm's
Mold, 5 be the mold that long axis is 100mm, short axle is 60mm, repeats above-mentioned experimental procedure, obtains the examination under other strain paths
Test data point；The transmission medium of other specifications is replaced, the above-mentioned experiment process of repetition again obtains under more differently strained paths
Limit principal strain (see Fig. 4).The each limit principal strain obtained under all differently strained paths is plotted in forming limit diagram
Right side, smooth line obtain the shaping limit curve (see Fig. 5) in 7075 aluminum alloy plate materials region at 220 DEG C.
Embodiment 2
Several a diameter of 180mm are prepared, thickness is the AZ31 magnesium alloy circle test specimens of 1.5mm, uses the resistance to height of organosilicon
Temperature paint, sprays black and white speckle on a surface of test specimen, and speckle covers whole surface.
Configure pressure transmission substance：It is same as Example 1.
Using mould structure shown in Fig. 2, upper mold blank holder (3) and lower die blank holder (5) are heated by resistance heating stick (6)
And temperature is monitored by thermocouple (2), magnesium alloy circle test specimen (4) and transmission medium (10) by external heating furnace into
Row heating, this three's Synchronous Heating make this three's temperature rise to 260~270 DEG C.After the completion of heating, rapidly by the first specification
Transmission medium (10) be packed into lower die blank holder (5) with pressure head (9) formed cavity, magnesium alloy circle test specimen (4) is moved to,
Between in lower die blank holder, molds rapidly and apply pressure-pad-force.In heating process, between upper mold blank holder (3) and upper mold (1),
It is equipped with thermal insulation layer (7) between lower die blank holder (5) and lower die (8), in upper and lower mould blank holder periphery and pressure head (9), is ensured
The efficiency of heating surface and temperature-controlled precision.
The deformation history that online vision measurement system (11) prepares record plank is opened, passes through pressure head at once after the completion of molding
(9) pressure is applied to transmission medium, until transmission medium bursts magnesium alloy circle test specimen.
In entire Bulging Process, the strain data recorded by online vision measurement system (11), according to systematic survey
Obtained strain cloud atlas, the first principal strain and the second principal strain averaged of selection rupture location peripheral region are as the limit
Principal strain obtains first test data point (see Fig. 6).The different upper mold blank holder (see Fig. 1) of mold shape is replaced, in repetition
Experimental procedure is stated, the test data point under other strain paths is obtained；The transmission medium of other specifications is replaced, in repetition again
It states experiment process, obtains the limit principal strain under more differently strained paths (see Fig. 7).It will be obtained under all differently strained paths
Each limit principal strain be plotted on the right side of forming limit diagram, smooth line obtains AZ31 magnesium alloy plates in 250 areas DEG CXia Gai
The shaping limit curve (see Fig. 8) in domain.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (6)
1. a kind of assay method of sheet alloy hot forming limit curve, includes the following steps：
(1) it is coated with machine silicon heat resistance paint in the single side of sheet alloy, makes spot, obtain pretreatment sheet alloy, the conjunction
Golden plate material is aluminum alloy plate materials or magnesium alloy plate；
(2) transmission medium is provided, the transmission medium includes silicon nitride ceramic ball and molybdenum disulfide, the silicon nitride ceramic ball
Grain size is 0.1,0.3 or 0.5mm, and the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide is 9:1 or 8:2；
(3) by hot forming limit curve measuring device to the pretreatment sheet alloy, transmission medium and mold respectively into
Row preheating, the pretreatment sheet alloy, transmission medium and mold preheating temperature independently be higher than the sheet alloy at
10~20 DEG C of shape temperature；The mold is oval expanding die, and the major diameter of the mold is 100mm, minor axis diameter point
It Wei not 100,90,80,60 and 40mm；
(4) apply side pressure, the pressure rate of the side pressure is 0.0045 or 0.045MPas-1；
(5) strain data is recorded by online vision measurement system, different pressure transmissions is calculated using online vision measurement system software
The first principal strain and the second principal strain of failure critical moment are incited somebody to action as limit principal strain under the conditions of medium and different molds
To limit principal strain be plotted in forming limit diagram, obtain sheet alloy hot forming limit curve；
To the step (1) and (2) without temporal restriction.
2. assay method according to claim 1, which is characterized in that sheet alloy is circle in the step (1), described
A diameter of 180~200mm of sheet alloy, thickness are 1~1.5mm.
3. assay method according to claim 1, which is characterized in that pretreatment sheet alloy, pressure transmission in the step (3)
The pre-heating temperature elevation rate of medium and mold independently is 5~10 DEG C/min.
4. assay method according to claim 1, which is characterized in that preheating temperature independently is 260 in the step (3)
~270 DEG C or 230~240 DEG C.
5. assay method according to claim 1, which is characterized in that online vision measurement system position in the step (5)
Above the upper mold of hot forming limit curve measuring device.
6. assay method according to claim 1, which is characterized in that calculating limit principal strain in the step (5) includes
Following steps：The first principal strain and the second principal strain are extracted in rupture location near zone, averaged is as the limit respectively
Principal strain.
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| CN110394392A (en) * | 2019-06-12 | 2019-11-01 | 北京机科国创轻量化科学研究院有限公司 | It is a kind of based on heat-stream multi- scenarios method Forming Limit of Sheet Metals research method |
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| CN108801801B (en) | 2019-10-08 |
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