CN108801801B - A kind of measuring method of sheet alloy hot forming limit curve - Google Patents
A kind of measuring method of sheet alloy hot forming limit curve Download PDFInfo
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- CN108801801B CN108801801B CN201810619971.2A CN201810619971A CN108801801B CN 108801801 B CN108801801 B CN 108801801B CN 201810619971 A CN201810619971 A CN 201810619971A CN 108801801 B CN108801801 B CN 108801801B
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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
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Abstract
The present invention provides a kind of measuring 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 resistant to high temperature, 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 measuring method of curve.
Background technique
In the fields such as aerospace and automobile manufacture, high tensile metal sheet alloy (aluminium alloy plate, magnesium alloy plate, titanium alloy
Plate etc.) utilization have become realize component lightweight and guarantee sufficient intensity one of main path.However, High-strength plate is in room
Plastic deformation ability is poor under the conditions of temperature, is difficult to obtain complex-shaped part by punch process.Therefore, the plasticity of such plate
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 forming capacity of such plate under the conditions of special process temperature 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 very big 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 test obtains shaping limit curve mainly has cylindrical male test
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 and punch-pin contact 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 part 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 test for obtaining shaping limit curve, strain is mainly obtained by network analysis technology.In plate before test
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 test
Change, then obtains the first principal strain and the second principal strain of 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 subsequent 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 is that the loading method in differently strained path is difficult to realize under hot conditions；Second is that under hot conditions
Strain measurement be difficult to ensure precision.
Summary of the invention
The object of the present invention is to provide a kind of measuring methods of sheet alloy hot forming limit curve, for wider deformation temperature
The shaping limit curve for spending section tests measuring 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 measuring method of sheet alloy hot forming limit curve, comprising 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
Stating sheet alloy 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 ceramics
The partial 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
Fail under the conditions of transmission medium and different mold critical moment the first principal strain and the second principal strain as limit principal strain,
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 the diameter of the sheet alloy is 180~200mm, 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) the following steps are included: extracting 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 measuring method of aluminum alloy plate materials hot forming limit curve, comprising 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
Stating sheet alloy 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 ceramics
The partial 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
Fail under the conditions of transmission medium and different mold critical moment the first principal strain and the second principal strain as limit principal strain,
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 resistant to high temperature, it can be achieved that more
High pressure can be used for broader temperature range, under the high temperature conditions be the alloy in shaping limit curve test acquisition process
Plate 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 candle method in high temperature
The problem that condition is difficult to carry out or measurement error is big, and limiting strain is determined 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 in broader temperature range, under more load paths, more accurately by above 3 points of combinations realization sheet alloy
The shaping limit curve become under measuring condition tests acquisition methods.
Detailed description of the invention
Fig. 1 is the structure chart for the mold that the measuring 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 the differently strained path of the embodiment of the present invention 1；
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 the differently strained path of the embodiment of the present invention 2；
Fig. 8 is the shaping limit curve of 2AZ31 of embodiment of the present invention magnesium alloy plate.
Specific embodiment
The present invention provides a kind of measuring method of sheet alloy hot forming limit curve, comprising 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
Stating sheet alloy 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 ceramics
The partial 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
Fail under the conditions of transmission medium and different mold critical moment the first principal strain and the second principal strain as limit principal strain,
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 special limit to the source of the aluminum alloy plate materials, magnesium alloy plate and organosilicon heat-resistant lacquer
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 in the single side of the sheet alloy completely.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 in sheet alloy deformation process using image recognition technology.
In the present invention, before sheet alloy spraying organosilicon heat-resistant lacquer it is also preferable to include using bar stock cutting by punching or
Machine cuts, cutting 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 partial size of silicon nitride ceramic ball is 0.1,0.3 or 0.5mm, the volume ratio of the silicon nitride ceramic ball and molybdenum disulfide be 9:1 or
8:2.The present invention does not have special restriction to the source of the silicon nitride ceramic ball and molybdenum disulfide, using those skilled in the art
Well known commercial goods.In the present invention, the molybdenum disulfide is preferably the molybdenum disulfide for being used as lubricant.
In the present invention, the transmission medium preferably includes: (partial size is for silicon nitride ceramic ball that 1. volume ratio is 9:1
0.1mm) and molybdenum disulfide, the silicon nitride ceramic ball (partial size 0.3mm) and molybdenum disulfide, 3. volume ratio that 2. volume ratio is 9:1
For the silicon nitride ceramic ball (partial size 0.5mm) and molybdenum disulfide of 9:1, (partial size is for silicon nitride ceramic ball that 4. volume ratio is 8:2
0.1mm) and molybdenum disulfide, the silicon nitride ceramic ball (partial size 0.3mm) and molybdenum disulfide, 6. volume ratio that 5. volume ratio is 8:2
For the silicon nitride ceramic ball (partial size 0.5mm) and molybdenum disulfide of 8:2.
The present invention does not have special restriction to the preparation method of the transmission medium, and use is 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 independently preferably 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 of 100mm for major and minor axis, 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 independently preferably 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 rod
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
Sheet alloy 4 is moved between in upper and lower molding flange, molds rapidly and apply flanging by the type chamber that flange 5 and pressure head 9 are formed
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, guarantee heating efficiency 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, calculates different pressure transmissions 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: extracting in rupture location near zone
First principal strain and the second principal strain, averaged is as limit principal strain respectively.
It is carried out below with reference to measuring method of the embodiment to sheet alloy hot forming limit curve provided by the invention detailed
Explanation, but they cannot be interpreted as limiting the scope of the present invention.
Embodiment 1
It prepares several diameters and uses organosilicon fire-resistant for 180mm with a thickness of the 7075 aluminium alloy plectane test specimens of 1mm
Paint, sprays black and white speckle on a surface of test specimen, and speckle covers whole surface.
Prepare transmission medium: transmission medium selects partial 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: (partial size is for silicon nitride ceramic ball that 1. volume ratio is 9:1
0.1mm) and molybdenum disulfide, the silicon nitride ceramic ball (partial size 0.3mm) and molybdenum disulfide, 3. volume ratio that 2. volume ratio is 9:1
For the silicon nitride ceramic ball (partial size 0.5mm) and molybdenum disulfide of 9:1, (partial size is for silicon nitride ceramic ball that 4. volume ratio is 8:2
0.1mm) and molybdenum disulfide, the silicon nitride ceramic ball (partial size 0.3mm) and molybdenum disulfide, 6. volume ratio that 5. volume ratio is 8:2
For the silicon nitride ceramic ball (partial size 0.5mm) and molybdenum disulfide of 8:2.
Using the measuring device of hot forming limit curve shown in Fig. 2, upper mold blank holder (3) are heated by resistance heating rod (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) are packed into the type chamber that lower die blank holder (5) and pressure head (9) are formed rapidly, by aluminum alloy round
Plate test specimen (4) moves between in upper and lower molding flange, molds rapidly and applies 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)
Have thermal insulation layer (7), guarantees heating efficiency and temperature-controlled precision.
The deformation history that online vision measurement system (11) prepare record plate 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 for choosing 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 is the mold of 100mm for major and minor axis, 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 test 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
It prepares several diameters and uses the resistance to height of organosilicon for 180mm with a thickness of the AZ31 magnesium alloy circle test specimen of 1.5mm
Temperature paint, sprays black and white speckle on a surface of test specimen, and speckle covers whole surface.
Configure pressure transmission substance: same as Example 1.
Using mould structure shown in Fig. 2, pass through resistance heating rod (6) heating upper mold blank holder (3) and lower die blank holder (5)
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 the type chamber that lower die blank holder (5) and pressure head (9) are formed, 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), guarantees between lower die blank holder (5) and lower die (8), in upper and lower mould blank holder periphery and pressure head (9)
Heating efficiency and temperature-controlled precision.
The deformation history that online vision measurement system (11) prepare record plate 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 for choosing 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 test 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 plate 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 (5)
1. a kind of measuring method of sheet alloy hot forming limit curve, comprising 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
Partial 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 or 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, calculates different pressure transmissions 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, calculated in the step (5)
Limit principal strain is sought respectively the following steps are included: in rupture location near zone the first principal strain of extraction and the second principal strain
Average value is as limit principal strain；
To the step (1) and (2) without temporal restriction.
2. measuring method according to claim 1, which is characterized in that sheet alloy is circle in the step (1), described
The diameter of sheet alloy is 180~200mm, with a thickness of 1~1.5mm.
3. measuring method according to claim 1, which is characterized in that pre-process 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. measuring method according to claim 1, which is characterized in that pre-process sheet alloy, pressure transmission in the step (3)
The preheating temperature of medium and mold independently is 260~270 DEG C or 230~240 DEG C.
5. measuring 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.
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| CN102248056B (en) * | 2011-06-13 | 2014-11-12 | 北京航空航天大学 | Method for improving sheet forming limit |
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| CN102601203A (en) * | 2012-03-23 | 2012-07-25 | 哈尔滨工业大学 | Device for improving plate forming limit and method for improving plate forming limit by aid of device |
| CN103424318B (en) * | 2012-05-23 | 2017-10-10 | 上海工程技术大学 | A kind of determination method of metal sheet forming limit curve |
| CN103852388B (en) * | 2014-03-04 | 2015-09-16 | 湖南大学 | A kind of metal sheet hot forming limit experimental provision and method of testing |
| CN103920786B (en) * | 2014-04-04 | 2016-05-04 | 燕山大学 | A kind of soft punch manufacturing process of sheet material based on vibration |
| CN103909132A (en) * | 2014-04-04 | 2014-07-09 | 燕山大学 | Reverse drawing method for soft die with peripheral auxiliary thrust |
| CN104729928B (en) * | 2015-03-31 | 2017-10-10 | 吉林大学 | The test device and test method of forming limit diagram under the conditions of high temperature constant strain rate |
| CN105067455A (en) * | 2015-08-07 | 2015-11-18 | 中南大学 | Test device for acquiring plate thermoforming limit diagram |
| CN106040817B (en) * | 2016-06-02 | 2018-01-23 | 燕山大学 | A kind of thermo shaping method of high strength alumin ium alloy sheet material |
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2018
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