CN102890054A - Method for determining forging friction coefficients of forging piece - Google Patents
Method for determining forging friction coefficients of forging piece Download PDFInfo
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- CN102890054A CN102890054A CN201210367003XA CN201210367003A CN102890054A CN 102890054 A CN102890054 A CN 102890054A CN 201210367003X A CN201210367003X A CN 201210367003XA CN 201210367003 A CN201210367003 A CN 201210367003A CN 102890054 A CN102890054 A CN 102890054A
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Abstract
The invention discloses a method for determining forging friction coefficients of a forging piece. The method is used for measuring friction coefficients of a mold and a workpiece in a forging high-temperature forming process. The method comprises the following steps of: 1) simulating an annular forging piece under different friction coefficients by using simulation software, extracting circular ring inner diameter values of a forging piece sample under the condition of different height deformations according to a simulation result, and drawing a theoretical calibration curve by using the different height deformations and corresponding inner diameter variations; 2) upsetting a forging piece blank, and thus obtaining the forging piece sample; 3) measuring the height, inner diameter and outer diameter of the forging piece sample; and 4) comparing a height measuring value and an inner diameter measuring value of the forging piece sample with the theoretical calibration curve, and determining the forging friction coefficients of a material. The forging friction coefficients of the mold and the workpiece in the forging high-temperature forming process can be measured, a metal flowing law is reproduced, and the method plays an important role in prevention of the defects of the forging piece and improvement of the forming quality of the forging piece.
Description
Technical field
The present invention relates to finite element analogy and Forging Technology in a kind of material forming engineering field, a kind of assay method of forging process for fuel friction factor is provided especially.
Background technology
All there is friction in metal between the surface of every mutual motion in plastic forming process.When friction referred to plastic yield, die surface was to the resistance of metal flow.Because the existence of friction, the deformation force during metal forming, work of deformation can increase; Forging demoulding difficulty from impression, sometimes even can produce mold sticking, impact is normally produced; Can cause that also flow of metal is inhomogeneous, crackle can appear in product when serious.Generally, production run should the reduce friction, in order to reduce resistance of deformation.Therefore, the mensuration of forging process for fuel friction factor is for guaranteeing that the forging quality tool is of great significance.
The friction that is present in simultaneously between workpiece and mould can affect wearing and tearing of deformation load, product surface quality and inner structure and mould etc.Therefore, the research friction mechanism, measure the surface of contact friction factor to understand fully under different condition with forming process in the situation that contacts between mould and workpiece, for numerical simulation software provides accurately boundary condition, thereby guarantee the degree of accuracy of forging simulation process, prevention forging defect and lifting forging forming quality are had great importance.
Forge the Theory Solution of annulus when measuring friction factor, what generally adopt at present is the Theory Solution of Avitzur and improved energy method or upper bound method or slab method calculating.These methods adopt the hypothesis such as ideal rigid plasticity model, surface of contact friction force and Deformed ring velocity field, differ greatly with actual conditions, have brought larger error for the actual measurement friction factor.Along with the developing rapidly of finite element technique, Finite Element Method has been widely used in the numerical analysis of ring compression process in recent years.Adopt the truly true stress-true strain constitutive relation of reaction material in hot procedure of finite element method.
People urgently wish to obtain the assay method of the good forging process for fuel friction factor of a kind of technique effect.
Summary of the invention
The assay method that the purpose of this invention is to provide a kind of forging process for fuel friction factor, its measurement friction factor result and actual conditions are more approaching, measure the more accurate measuring method of numerical value.
The invention provides a kind of assay method of forging process for fuel friction factor, be used for the mould of Measurement accuracy forging high-temperature forming process and the method for the friction factor between the workpiece.Its principle of measuring friction factor is outer diameter D
0, inside diameter D
iWith highly place jumping-up between parallel flat-die tool for the flat annulus of h.Metal outwards or inwardly flows during Upsetting, and according to the difference of surface of contact friction factor, the internal diameter size of annulus can present different variations.When the surface of contact friction factor equals or close to zero the time, each particle on the annulus is all done flowing radially, and internal-and external diameter all increases after the distortion; When friction factor increased, the outflow rate of metal particle descended, and compared with the previous case, and under same pressure speed, the internal-and external diameter increment is all less; When if the surface of contact friction factor surpasses a certain critical value, then can a radius occur in the annulus is R
nMinute stream interface: metal outwards flows beyond this face, with interior metal to center flow; The annulus external diameter increases after the distortion, and internal diameter dwindles.Theoretical and experimental study shows: minute stream interface R
nValue increases with the increase of friction factor.Therefore, can be according to a minute stream interface location positioning friction factor.It is relevant with the position of minute stream interface that internal radius behind the jumping-up changes, so can determine friction factor with the situation that reduces of measuring internal diameter.
The assay method of a kind of forging process for fuel friction factor of the present invention is used for measuring the mould of forging high-temperature forming process and the friction factor between the workpiece, and it is characterized in that: the assay method specific requirement of described forging friction factor is:
1) pre-rendered theoretical calibration curve: utilize Finite Element Simulation Software that circular forging under the different coefficients of friction is simulated, extract the internal radius value of forging sample under differing heights deflection condition according to analog result, utilize different high variable quantities and with it the internal diameter varies amount of correspondence draw theoretical calibration curve; This crosses range request and should finish before step 4 at least;
2) preparation forging sample: circular concrete forging blank is carried out jumping-up make the forging sample;
3) carry out afterwards DATA REASONING: height and the inside and outside footpath of the forging sample behind the measurement jumping-up;
4) carry out at last determining of friction factor: with height measurements and inner diameter measurement value and the contrast of theoretical calibration curve of forging sample, determine the forging friction factor of material.
The assay method of described forging friction factor is characterized in that: the specific requirement to the forging blank before the jumping-up is: the surperficial coated glass lubricant of circular forging blank, lubricant is wanted outside surface and the inner hole surface of uniform fold forging blank.
The preferred specific requirement of preparation forging sample is: the forging blank behind the coated glass lubricant is heated to forging temperature, is incubated 10-60 minute; Be 30% or 50% to carry out jumping-up according to deflection.
Forging blank satisfies following preferred requirement: the external diameter of circular forging blank: internal diameter: height=4:2:1.
Further preferred content: forging blank satisfies following requirement: circular forging blank external diameter is that 40 millimeters, internal diameter are that 20 millimeters, height are 10 millimeters.
The preferred specific requirement that data are measured is:
The internal diameter of forging sample and the measurement of external diameter require: at first along the circumferential direction measure 2 to 10 values on its equatorial plane, then get its mean value;
The height of forging sample is measured requirement: along the circumferential direction measure 2 to 10 values at the R/2 place, get its mean value.R is the large radius of circle of forging sample.
In principle, guarantee the accuracy of measurement data by repeatedly measuring to average.
The present invention is utilizing on the bases such as friction border and heat transfer boundary condition, simulate exactly the mobile and geomery Changing Pattern of metal in the ring compression process, the theoretical calibration curve of determining thus can reflect the impact that rubs in the Metal Forming process exactly.
The present invention in can Measurement accuracy forging high-temperature forming process mould and the friction factor between the workpiece, reproduce the flowing law of metal.Thereby the degree of accuracy that provides boundary condition accurately to guarantee the forging simulation process for numerical simulation software is to the prevention forging defect with promote the forging forming quality and have great importance.
According to proving for experimental study of the present invention, the present invention can make rejection rate by being reduced to more than 7.5% of traditional handicraft present less than 4.3%, the present invention also has huge economic worth and social value when improving the quality of products.
Description of drawings
The present invention is further detailed explanation below in conjunction with drawings and the embodiments:
Fig. 1 is theoretical calibration curve;
Fig. 2 is forging blank sample synoptic diagram.
Embodiment
The assay method of 1 one kinds of forging process for fuel friction factor of embodiment
Take measure TC4 material forging process friction factor as example specifies implementation process of the present invention.
1, draw theoretical calibration curve: the starting condition of finite element analogy is as follows: TC4 ring compression temperature is 940 ℃, and upper and lower mould is made as rigid die, and patrix pressing speed 150mm/s, mold preheating temperature are 220 ℃.Firm plastic constitutive relation model is adopted in simulation, and the specific heat capacity of workpiece varies with temperature and changes.The coefficient of heat convection of workpiece, mould and air is 0.02N/ (smm ℃), and the heat exchange coefficient between workpiece and the mould contact surface is 11N/ (smm ℃).Adopt shearing friction between workpiece and the mould, friction factor is got respectively m=0,0.02,0.04,0.06,0.08,0.1,0.12,0.16,0.2,0.24,0.3,0.35,0.4,0.45,0.5,0.55,0.6,0.7,0.8,0.9,1.0.
The theoretical calibration curve of drawing according to the variation of height and internal diameter after the simulation as shown in Figure 1.
2, preparation forging sample: at forging blank surface coated glass lubricant as shown in Figure 2, the whole surface of sample and endoporus are wanted evenly and covered to lubricant.Sample is heated to 940 ℃, and insulation 30min is 30% and 50% to carry out jumping-up according to deflection, make the forging sample, and each condition prepares 3 forging samples.
3, DATA REASONING: with height h and the inside diameter D of vernier caliper measurement forging sample
iAnd outer diameter D
0
Inside diameter D
iAnd outer diameter D
0On the equatorial plane of each forging sample, along the circumferential direction every 45 ° of measurements, measure altogether 4 values, get its mean value;
The height h along the circumferential direction at the R/2 place every 90 ° of measurements, measure 4 values, get its mean value.The measurement mean value of 3 forging samples of each condition is as the foundation (such as table 1) of measuring friction coefficient.
Table 1 measurement data
4, determining of friction factor: according to forging the contrast of annulus height measurements and inner diameter measurement value and theoretical calibration curve, determine that the TC4 material is 0.32 in that the friction factor under the lubricant condition is arranged.
Embodiment 2
A kind of assay method of forging process for fuel friction factor is used for the mould of Measurement accuracy forging high-temperature forming process and the method for the friction factor between the workpiece.Its principle of measuring friction factor is outer diameter D
0, inside diameter D
iWith highly place jumping-up between parallel flat-die tool for the flat annulus of h.Metal outwards or inwardly flows during Upsetting, and according to the difference of surface of contact friction factor, the internal diameter size of annulus can present different variations.When the surface of contact friction factor equals or close to zero the time, each particle on the annulus is all done flowing radially, and internal-and external diameter all increases after the distortion; When friction factor increased, the outflow rate of metal particle descended, and compared with the previous case, and under same pressure speed, the internal-and external diameter increment is all less; When if the surface of contact friction factor surpasses a certain critical value, then can a radius occur in the annulus is R
nMinute stream interface: metal outwards flows beyond this face, with interior metal to center flow; The annulus external diameter increases after the distortion, and internal diameter dwindles.Theoretical and experimental study shows: minute stream interface R
nValue increases with the increase of friction factor.Therefore, can be according to a minute stream interface location positioning friction factor.It is relevant with the position of minute stream interface that internal radius behind the jumping-up changes, so can determine friction factor with the situation that reduces of measuring internal diameter.
The assay method of the described forging process for fuel friction factor of present embodiment is used for measuring the mould of forging high-temperature forming process and the friction factor between the workpiece, and the assay method specific requirement of described forging friction factor is:
1) pre-rendered theoretical calibration curve: utilize Finite Element Simulation Software that circular forging under the different coefficients of friction is simulated, extract the internal radius value of forging sample under differing heights deflection condition according to analog result, utilize different high variable quantities and with it the internal diameter varies amount of correspondence draw theoretical calibration curve; This crosses range request and should finish before step 4 at least;
2) preparation forging sample: circular concrete forging blank is carried out jumping-up make the forging sample;
3) carry out afterwards DATA REASONING: height and the inside and outside footpath of the forging sample behind the measurement jumping-up;
4) carry out at last determining of friction factor: with height measurements and inner diameter measurement value and the contrast of theoretical calibration curve of forging sample, determine the forging friction factor of material.
The assay method of described forging friction factor is characterized in that: the specific requirement to the forging blank before the jumping-up is: the surperficial coated glass lubricant of circular forging blank, lubricant is wanted outside surface and the inner hole surface of uniform fold forging blank.
The specific requirement of preparation forging sample is: the forging blank behind the coated glass lubricant is heated to forging temperature, is incubated 10-60 minute; Be 30% or 50% to carry out jumping-up according to deflection.
Forging blank satisfies following requirement: the external diameter of circular forging blank: internal diameter: height=4:2:1; Forging blank satisfies following requirement particularly: circular forging blank external diameter is that 40 millimeters, internal diameter are that 20 millimeters, height are 10 millimeters.
The specific requirement that data are measured is: the internal diameter of forging sample and the measurement of external diameter requirement are: at first along the circumferential direction measure 2 to 10 values on its equatorial plane, then get its mean value; The height of forging sample is measured requirement: along the circumferential direction measure 2 to 10 values at the R/2 place, get its mean value.In principle, guarantee the accuracy of measurement data by repeatedly measuring to average.
Present embodiment is utilizing on the bases such as friction border and heat transfer boundary condition, simulate exactly the mobile and geomery Changing Pattern of metal in the ring compression process, the theoretical calibration curve of determining thus can reflect the impact that rubs in the Metal Forming process exactly.
Present embodiment in can Measurement accuracy forging high-temperature forming process mould and the friction factor between the workpiece, reproduce the flowing law of metal.Thereby the degree of accuracy that provides boundary condition accurately to guarantee the forging simulation process for numerical simulation software is to the prevention forging defect with promote the forging forming quality and have great importance.
Prove according to the experimental study for present embodiment, present embodiment can make rejection rate by being reduced to more than 7.5% of traditional handicraft present less than 4.3%, present embodiment also has huge economic worth and social value when improving the quality of products.
Claims (6)
1. the assay method of a forging process for fuel friction factor is used for measuring the mould of forging high-temperature forming process and the friction factor between the workpiece, and it is characterized in that: the assay method specific requirement of described forging friction factor is:
1) pre-rendered theoretical calibration curve: utilize simulation softward that circular forging under the different coefficients of friction is simulated, extract the internal radius value of forging sample under differing heights deflection condition according to analog result, utilize different high variable quantities and with it the internal diameter varies amount of correspondence draw theoretical calibration curve;
2) preparation forging sample: circular concrete forging blank is carried out jumping-up make the forging sample;
3) carry out afterwards DATA REASONING: height and the inside and outside footpath of the forging sample behind the measurement jumping-up;
4) carry out at last determining of friction factor: with height measurements and inner diameter measurement value and the contrast of theoretical calibration curve of forging sample, determine the forging friction factor of material.
2. according to the assay method of forging friction factor claimed in claim 1, it is characterized in that: the specific requirement to the forging blank before the jumping-up is: the surperficial coated glass lubricant of circular forging blank, lubricant is wanted outside surface and the inner hole surface of uniform fold forging blank.
3. according to the assay method of forging friction factor claimed in claim 2, it is characterized in that: forging blank satisfies following requirement: the external diameter of circular forging blank: internal diameter: height=4:2:1.
4. according to the assay method of forging friction factor claimed in claim 3, it is characterized in that: forging blank satisfies following requirement: circular forging blank external diameter is that 40 millimeters, internal diameter are that 20 millimeters, height are 10 millimeters.
5. according to the assay method of forging friction factor claimed in claim 1, it is characterized in that: the specific requirement of preparation forging sample is: the forging blank behind the coated glass lubricant is heated to forging temperature, is incubated 10-60 minute; Be 30% or 50% to carry out jumping-up according to deflection.
6. according to the assay method of forging friction factor claimed in claim 1, it is characterized in that: the specific requirement that data are measured is:
The internal diameter of forging sample and the measurement of external diameter require: at first along the circumferential direction measure 2 to 10 values on its equatorial plane, then get its mean value;
The height of forging sample is measured requirement: along the circumferential direction measure 2 to 10 values at the R/2 place, get its mean value.
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Cited By (5)
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| CN103760098A (en) * | 2014-01-22 | 2014-04-30 | 上海交通大学 | Method for measuring friction factor on basis of compressive deformation of ring with inner tendon |
| CN103760099A (en) * | 2014-01-22 | 2014-04-30 | 上海交通大学 | Quantitative test method for cold forging friction and lubrication conditions |
| CN104458568A (en) * | 2014-12-16 | 2015-03-25 | 深圳大学 | Method and device for measuring friction factor of plastic micro forming |
| CN108240963A (en) * | 2016-12-23 | 2018-07-03 | 宝钢特钢有限公司 | A kind of method that friction coefficient is measured using thermo dynamic analogy machine |
| CN111229841A (en) * | 2020-01-13 | 2020-06-05 | 中国科学院金属研究所 | Method for testing friction coefficient in high-temperature rolling process |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103760098A (en) * | 2014-01-22 | 2014-04-30 | 上海交通大学 | Method for measuring friction factor on basis of compressive deformation of ring with inner tendon |
| CN103760099A (en) * | 2014-01-22 | 2014-04-30 | 上海交通大学 | Quantitative test method for cold forging friction and lubrication conditions |
| CN103760099B (en) * | 2014-01-22 | 2015-09-23 | 上海交通大学 | The quantitative measuring method of cold forging friction and lubrication condition |
| CN103760098B (en) * | 2014-01-22 | 2016-08-17 | 上海交通大学 | Based on the friction factor assay method of muscle ring compression deformation in band |
| CN104458568A (en) * | 2014-12-16 | 2015-03-25 | 深圳大学 | Method and device for measuring friction factor of plastic micro forming |
| CN108240963A (en) * | 2016-12-23 | 2018-07-03 | 宝钢特钢有限公司 | A kind of method that friction coefficient is measured using thermo dynamic analogy machine |
| CN108240963B (en) * | 2016-12-23 | 2020-06-12 | 宝武特种冶金有限公司 | Method for measuring friction coefficient by using thermal simulator |
| CN111229841A (en) * | 2020-01-13 | 2020-06-05 | 中国科学院金属研究所 | Method for testing friction coefficient in high-temperature rolling process |
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Application publication date: 20130123 |