US20010027686A1 - Method of measuring shear friction factor through backward extrusion process - Google Patents
Method of measuring shear friction factor through backward extrusion process Download PDFInfo
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- US20010027686A1 US20010027686A1 US09/783,542 US78354201A US2001027686A1 US 20010027686 A1 US20010027686 A1 US 20010027686A1 US 78354201 A US78354201 A US 78354201A US 2001027686 A1 US2001027686 A1 US 2001027686A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/02—Measuring coefficient of friction between materials
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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
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
Definitions
- the present invention relates to a method of measuring the representative shear friction factor at the interface between a workpiece material and forming dies during bulk forming processes and, more particularly, to a method of more easily, effectively, and accurately measuring such representative shear friction factor through the backward extrusion process.
- bulk forming processes have been typically and widely used for producing a variety of mechanical parts having different structures and operational functions. Particularly, such a bulk forming process can produce intermediate products having a shape and size similar to those of the desired final product, and so the bulk forming process reduces the number of operations for production and leads to material saving. In addition, bulk forming processes lead to good mechanical properties of the final products due to work hardening of the material during forming. In order to more effectively, or even optimally design such bulk forming processes, numerical analyses are frequently used while designing the process.
- Frictional stress m f ⁇ shear yield stress (1)
- the frictional stress is in proportion to the shear yield stress of the material, with the shear friction factor “m f ” determining the ratio of the proportional relationship.
- this value is locally varying, depending on the surface quality, the type of lubrication, and the deformation condition at the interface.
- a ring compression test has been most typically and widely used for measuring such shear friction factors.
- One such a measuring method using the backward extrusion process predicts the shear friction factor by measuring the forming load during the process depending on the friction condition.
- this method of measuring the shear friction factor by measuring the difference in forming loads can be problematic in that the forming load has a direct connection with flow stress of the workpiece material, and thus it is necessary to accurately know flow stress of the material.
- Such a forming load can be considered only as an indirect measure of the friction condition.
- the objective of the present invention is to provide a method of measuring the representative constant shear friction factor at the interface between the workpiece material and forming dies during bulk forming processes through a backward extrusion process as a single value. This method can easily and effectively measure the constant shear friction factors for a variety of friction conditions and is suitable for estimating the friction condition of the complex bulk forming process.
- the present invention uses a backward extrusion process, comprised of the following steps: positioning the workpiece material at a predetermined groove location within the forming die and pressurizing the workpiece material to form an extruded product with an apex formed on the backward extruded end; measuring the perpendicular distance “d” from the external side surface of the extruded product to the apex; and calculating the shear friction factor “m f ” using the measured perpendicular distance “d”.
- the representative shear friction factor “m f ”, which has a range of 0.0 ⁇ 1.0, is calculated from the fact that the perpendicular distance “d” has a linear relationship with the shear friction factor “m f ”.
- FIG. 1 is a sectional view of the backward extrusion tool set-up designed to perform the backward extrusion process in accordance with the preferred embodiment of the present invention
- FIG. 2 is a sectional view showing the position of a workpiece material within the backward extrusion tool set-up of FIG. 1;
- FIGS. 3 a to 3 d are sectional views showing the four stages of the backward extrusion process performed to measure the shear friction factor in accordance with the present invention
- FIG. 4 is a sectional view showing the apex of an extruded product formed by the backward extrusion process of FIGS. 3 a to 3 d and the perpendicular distance “d” to this apex from the external side surface of the extruded product along with the thickness “t” of the extruded end;
- FIGS. 5 a and 5 b are experimental results showing the apexes of extruded products from this invention, with the position of the apexes changing in accordance with lubrication conditions during the backward extrusion process of FIGS. 3 a to 3 d ;
- FIG. 6 is a graph showing the linear relationship between shear friction factor “m f ” and “d/t”, where “d” is the perpendicular distances from the apex to the external side surface of the extruded product and “t” is the thickness of the extruded end.
- FIG. 1 is a sectional view of the backward extrusion tool set-up designed to perform the backward extrusion process in accordance with the preferred embodiment of the present invention.
- FIG. 2 is a sectional view showing the position of a workpiece material within the backward extrusion tool set-up of FIG. 1.
- FIGS. 3 a to 3 d are sectional views showing the four stages of the backward extrusion process performed to measure the representative shear friction factor in accordance with the present invention.
- FIG. 4 is a sectional view showing the apex of an extruded product formed by the backward extrusion process of FIGS.
- FIGS. 5 a and 5 b are experimental results showing the apexes of extruded products from this invention, with the position of the apexes changing in accordance with lubrication conditions during the backward extrusion process of FIGS. 3 a to 3 d .
- FIG. 5 a and 5 b are experimental results showing the apexes of extruded products from this invention, with the position of the apexes changing in accordance with lubrication conditions during the backward extrusion process of FIGS. 3 a to 3 d .
- FIG. 6 is a graph showing the linear relationship between the shear friction factor “m f ” and “d/t”, where “d” is the perpendicular distances from the apex to the external side surface of the extruded product and “t” is the thickness of the extruded end.
- the backward-extruding tool set-up designed to perform the backward extrusion process in accordance with the preferred embodiment of this invention, comprises two parts: a die part 10 and a punch part 20 .
- the punch part 20 which moves vertically with the movement of the upper press, contains the punch 21 that is used for applying extrusion force to a workpiece material 30 .
- the die part 10 supports the workpiece material 30 when the material 30 within the die part 10 is pressed down by the punch 21 .
- the above die part 10 comprises an external die 11 , a lower die 13 , a die mounting flange 15 and a lower die housing 19 L.
- the external die 11 has a hollow cylindrical shape provided with a central opening for receiving the vertically movable punch 21 therein, while the lower die 13 is firmly positioned at the bottom of the central opening of the external die 11 .
- the lower die 13 with a groove at the center thus creates the forming die of the tool-set in cooperation with the external die 11 .
- the annular die-mounting flange 15 is firmly set around the external die 11 , thus holding the external die 11 in place.
- the lower die housing 19 L is positioned under and supports the external die 11 , the lower die 13 and the die-mounting flange 15 . Hydrostatic pressure pads 17 L are set within the lower die housing 19 L.
- the punch 21 of the punch part 20 can freely move into and out of the central opening of the external die 11 of the die part 10 .
- An upper die housing 19 H surrounds the upper portion of the punch 21 , with hydrostatic pressure pads 17 H set within the cavity of the upper die housing 19 H.
- the workpiece material 30 is positioned on the groove of the top surface of the lower die 13 .
- This workpiece material 30 has a cylindrical shape, with the diameter of the workpiece material 30 set as the average of the outer diameter of the punch 21 and the inner diameter of the external die 11 .
- the above workpiece material 30 must be positioned on the top groove of the surface of the lower die 13 such that the central axis of the material 30 is precisely aligned with the central axes of both the punch 21 and the external die 11 .
- the punch 21 is moved downward to apply the required extrusion pressure to the material 30 .
- FIGS. 3 a to 3 d show the initial non-pressure position, wherein the punch 21 does not apply any extrusion pressure to the material 30 .
- FIG. 3 b shows the barreling position, wherein the punch 21 applies the pressure to the material 30 such that barreling of the material 30 occurs.
- FIG. 3 c shows the initial apex forming position, wherein the continuously applied pressure by the punch 21 forms the apex 33 on the material 30 .
- FIG. 3 d shows the final apex position, wherein the formation of the apex 33 on the material 30 is completed.
- the extruded end of the completely processed material 30 has a cross-section similar to a triangle, with the top apex 33 of the extruded end being positioned at a certain perpendicular distance “d” from the external side surface of the workpiece 30 .
- the thickness of the extruded end of the workpiece 30 is represented by “t”.
- the above perpendicular distance “d” between the top apex 33 of the extruded end and the external side surface of the workpiece 30 is the value that can be used as an effective measure of the representative shear friction factor.
- the characteristics of the perpendicular distance “d” are described in detail herein below with reference to FIGS. 5 a and 5 b.
- FIG. 5 a shows the apex 33 of the material 30 when the material 30 was backward extruded under a low lubrication condition, free of any lubricant.
- FIG. 5 b shows the apex 33 of the material 30 when the material 30 was backward extruded under a high lubrication condition using a proper lubricant, namely, a mixture of grease and MOS 2 .
- the perpendicular distance “d” of the embodiment of FIG. 5 a is about 1.65 mm, while the perpendicular distance “d” in the embodiment of FIG. 5 b is about 0.75 mm.
- the perpendicular distance “d” is related inversely to the lubrication condition of the backward extrusion process. That is, the high lubrication condition results in a short perpendicular distance “d”, while the low lubrication condition results in a long perpendicular distance “d”. Particularly, the perpendicular distance “d” increases linearly in proportion to increases in the representative shear friction factor.
- FIG. 6 is a graph showing the linear relationship between the representative shear friction factors “m f ” and the perpendicular distance “d”, which is non-dimensionalized by the thickness “t” of the extruded end of the workpiece 30 . Since the thickness “t” of the extruded products is 3.4 mm, “d/t” for the embodiment of FIG. 5 a can be calculated to be 0.49, while it is 0.22 for the embodiment of FIG. 5 b . This linear relationship is expressed by the following equation (2).
- the representative shear friction factor for the embodiment of FIG. 5 a extruded under low lubrication condition can be calculated to be about 0.46, while the representative shear friction factor for the embodiment of FIG. 5 b extruded under high lubrication condition can be calculated as 0.09.
- the present invention based on backward extrusion provides a method of measuring the representative shear friction factor at the interface between a workpiece material and forming dies during bulk forming processes.
- the measuring method is very simple and suitable for estimating the friction conditions of complex bulk forming processes as a single value.
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a method of measuring the representative shear friction factor at the interface between a workpiece material and forming dies during bulk forming processes and, more particularly, to a method of more easily, effectively, and accurately measuring such representative shear friction factor through the backward extrusion process.
- 2. Description of the Prior Art
- As well known to those skilled in the art, bulk forming processes have been typically and widely used for producing a variety of mechanical parts having different structures and operational functions. Particularly, such a bulk forming process can produce intermediate products having a shape and size similar to those of the desired final product, and so the bulk forming process reduces the number of operations for production and leads to material saving. In addition, bulk forming processes lead to good mechanical properties of the final products due to work hardening of the material during forming. In order to more effectively, or even optimally design such bulk forming processes, numerical analyses are frequently used while designing the process.
- In order to use the numerical analysis in the design of a target bulk forming process effectively, it is necessary to accurately describe a variety of numerical parameters. Of such parameters to be estimated, the friction condition at the interface between the workpiece material and forming dies is very important since it directly influences both flow of the workpiece material and forming load during the target bulk forming process. In the end it will affect the success or failure of the process.
- In order to express the friction condition quantitatively in bulk metal forming, a constant shear friction model is typically used in numerical analyses as expressed by the following equation (1).
- Frictional stress=m f×shear yield stress (1)
- wherein,
- mf: shear friction factor
- In the above equation (1), the frictional stress is in proportion to the shear yield stress of the material, with the shear friction factor “mf” determining the ratio of the proportional relationship. In general, this value is locally varying, depending on the surface quality, the type of lubrication, and the deformation condition at the interface.
- Therefore, it is necessary to accurately measure the representative shear friction factor “mf” as a single value in order to properly estimate the friction conditions in the target bulk forming process for simplicity and convenience for the process simulation.
- A ring compression test has been most typically and widely used for measuring such shear friction factors.
- In such ring compression test, variation in the inner diameter of an annular test specimen is measured during the compression of the test specimen to estimate the friction condition. This ring compression test is advantageous in that it is simple in its testing process. However, because this ring compression test is so exceedingly simple in its testing process, it may not be suitable for estimating the friction conditions in more complex bulk forming processes. In addition, the free surface generated during the ring compression test is quite small when compared with those of typical bulk forming processes. Another disadvantage of the ring compression test resides in that it is necessary to use nonlinear calibration curves to determine the desired shear friction factors. According to this method, since the shear friction factor is dependent on the deformation history, it is not easy to determine the representative constant shear friction factor.
- Several methods of measuring shear friction factors that overcome the above-mentioned problems experienced in ring compression tests have been recently proposed and implemented. Of those recently proposed methods, various methods based on the backward extrusion process that is capable of generating a large amount of free surfaces have been preferred.
- One such a measuring method using the backward extrusion process predicts the shear friction factor by measuring the forming load during the process depending on the friction condition. However, this method of measuring the shear friction factor by measuring the difference in forming loads can be problematic in that the forming load has a direct connection with flow stress of the workpiece material, and thus it is necessary to accurately know flow stress of the material. Such a forming load can be considered only as an indirect measure of the friction condition.
- Another method of measuring the shear friction factor based on a simultaneous forward and backward extrusion process has been proposed and used. This method is designed to determine the shear friction factor by measuring the ratio of material flow in the forward and backward ends in accordance with the friction condition. However, this measuring method is problematic in that it is insensitive at high levels of friction.
- Accordingly, the present invention has been made with the aforementioned problems in mind. The objective of the present invention is to provide a method of measuring the representative constant shear friction factor at the interface between the workpiece material and forming dies during bulk forming processes through a backward extrusion process as a single value. This method can easily and effectively measure the constant shear friction factors for a variety of friction conditions and is suitable for estimating the friction condition of the complex bulk forming process.
- In order to accomplish the above objective, the present invention uses a backward extrusion process, comprised of the following steps: positioning the workpiece material at a predetermined groove location within the forming die and pressurizing the workpiece material to form an extruded product with an apex formed on the backward extruded end; measuring the perpendicular distance “d” from the external side surface of the extruded product to the apex; and calculating the shear friction factor “mf” using the measured perpendicular distance “d”.
- In the above measuring method, the workpiece material has a diameter equal to the average of the outer diameter of the punch and the inner diameter of the forming die, and is positioned such that its central axis is aligned with the central axes of both the punch and the forming die.
- In addition, the representative shear friction factor “mf”, which has a range of 0.0˜1.0, is calculated from the fact that the perpendicular distance “d” has a linear relationship with the shear friction factor “mf”.
- Typically, numerical analyses are attractive for the design of bulk forming processes since they improve design efficiency, save both production time and material resources, and improve the quality of final products of the process. It is necessary to describe the friction condition properly and accurately in order to improve the reliability of numerical analyses of bulk forming processes. When the representative shear friction factor can be properly measured for the whole process as described above, it will be possible to select proper lubricants for target bulk forming processes.
- Proper lubrication in bulk forming processes can lead to reduction of forming loads, extension of die life, and reduction of energy consumption. Also, such an efficient and accurate measurement of friction conditions can aid the development of environment friendly lubricants for general use in bulk forming processes.
- The objectives, features, and other advantages of the present invention will be more clearly understood from the following detailed description given in conjunction with the accompanying drawings, in which:
- FIG. 1 is a sectional view of the backward extrusion tool set-up designed to perform the backward extrusion process in accordance with the preferred embodiment of the present invention;
- FIG. 2 is a sectional view showing the position of a workpiece material within the backward extrusion tool set-up of FIG. 1;
- FIGS. 3a to 3 d are sectional views showing the four stages of the backward extrusion process performed to measure the shear friction factor in accordance with the present invention;
- FIG. 4 is a sectional view showing the apex of an extruded product formed by the backward extrusion process of FIGS. 3a to 3 d and the perpendicular distance “d” to this apex from the external side surface of the extruded product along with the thickness “t” of the extruded end;
- FIGS. 5a and 5 b are experimental results showing the apexes of extruded products from this invention, with the position of the apexes changing in accordance with lubrication conditions during the backward extrusion process of FIGS. 3a to 3 d; and
- FIG. 6 is a graph showing the linear relationship between shear friction factor “mf” and “d/t”, where “d” is the perpendicular distances from the apex to the external side surface of the extruded product and “t” is the thickness of the extruded end.
- FIG. 1 is a sectional view of the backward extrusion tool set-up designed to perform the backward extrusion process in accordance with the preferred embodiment of the present invention. FIG. 2 is a sectional view showing the position of a workpiece material within the backward extrusion tool set-up of FIG. 1. FIGS. 3a to 3 d are sectional views showing the four stages of the backward extrusion process performed to measure the representative shear friction factor in accordance with the present invention. FIG. 4 is a sectional view showing the apex of an extruded product formed by the backward extrusion process of FIGS. 3a to 3 d and the perpendicular distance “d” to this apex from the external side surface of the extruded product along with the thickness “t” of the extruded end. FIGS. 5a and 5 b are experimental results showing the apexes of extruded products from this invention, with the position of the apexes changing in accordance with lubrication conditions during the backward extrusion process of FIGS. 3a to 3 d. FIG. 6 is a graph showing the linear relationship between the shear friction factor “mf” and “d/t”, where “d” is the perpendicular distances from the apex to the external side surface of the extruded product and “t” is the thickness of the extruded end.
- As shown in FIG. 1, the backward-extruding tool set-up, designed to perform the backward extrusion process in accordance with the preferred embodiment of this invention, comprises two parts: a
die part 10 and apunch part 20. Thepunch part 20, which moves vertically with the movement of the upper press, contains thepunch 21 that is used for applying extrusion force to aworkpiece material 30. Thedie part 10 supports theworkpiece material 30 when thematerial 30 within thedie part 10 is pressed down by thepunch 21. - The above die
part 10 comprises anexternal die 11, alower die 13, adie mounting flange 15 and alower die housing 19L. The external die 11 has a hollow cylindrical shape provided with a central opening for receiving the verticallymovable punch 21 therein, while thelower die 13 is firmly positioned at the bottom of the central opening of theexternal die 11. Thelower die 13 with a groove at the center thus creates the forming die of the tool-set in cooperation with theexternal die 11. The annular die-mountingflange 15 is firmly set around theexternal die 11, thus holding theexternal die 11 in place. Thelower die housing 19L is positioned under and supports theexternal die 11, thelower die 13 and the die-mountingflange 15.Hydrostatic pressure pads 17L are set within thelower die housing 19L. - The
punch 21 of thepunch part 20 can freely move into and out of the central opening of theexternal die 11 of thedie part 10. Anupper die housing 19H surrounds the upper portion of thepunch 21, withhydrostatic pressure pads 17H set within the cavity of theupper die housing 19H. - As shown in FIG. 2, the
workpiece material 30 is positioned on the groove of the top surface of thelower die 13. Thisworkpiece material 30 has a cylindrical shape, with the diameter of theworkpiece material 30 set as the average of the outer diameter of thepunch 21 and the inner diameter of theexternal die 11. During the backward extrusion process, theabove workpiece material 30 must be positioned on the top groove of the surface of thelower die 13 such that the central axis of thematerial 30 is precisely aligned with the central axes of both thepunch 21 and theexternal die 11. After theworkpiece material 30 is properly positioned on the top groove of the surface of thelower die 13 within theexternal die 11, thepunch 21 is moved downward to apply the required extrusion pressure to thematerial 30. - When the
punch 21 is moved downward applying extrusion pressure on theworkpiece material 30, thematerial 30 deforms as shown in FIGS. 3a to 3 d. The extruded product is formed to have a shape defined by the external shape of thepunch 21, internal shape of theexternal die 11, and top surface of thelower die 13. Such a backward extrusion process can be described in more detail with reference to FIGS. 3a to 3 d as follows. FIG. 3a shows the initial non-pressure position, wherein thepunch 21 does not apply any extrusion pressure to thematerial 30. FIG. 3b shows the barreling position, wherein thepunch 21 applies the pressure to the material 30 such that barreling of thematerial 30 occurs. FIG. 3c shows the initial apex forming position, wherein the continuously applied pressure by thepunch 21 forms the apex 33 on thematerial 30. FIG. 3d shows the final apex position, wherein the formation of the apex 33 on thematerial 30 is completed. - As shown in FIG. 4, the extruded end of the completely processed
material 30 has a cross-section similar to a triangle, with thetop apex 33 of the extruded end being positioned at a certain perpendicular distance “d” from the external side surface of theworkpiece 30. The thickness of the extruded end of theworkpiece 30 is represented by “t”. - The above perpendicular distance “d” between the
top apex 33 of the extruded end and the external side surface of theworkpiece 30 is the value that can be used as an effective measure of the representative shear friction factor. The characteristics of the perpendicular distance “d” are described in detail herein below with reference to FIGS. 5a and 5 b. - In the experimental backward extrusion results of FIGS. 5a and 5 b for measuring the characteristics of the perpendicular distance “d”, an aluminum alloy, 6061-O, was used as the
workpiece material 30. - FIG. 5a shows the apex 33 of the material 30 when the
material 30 was backward extruded under a low lubrication condition, free of any lubricant. FIG. 5b shows the apex 33 of the material 30 when thematerial 30 was backward extruded under a high lubrication condition using a proper lubricant, namely, a mixture of grease and MOS2. The perpendicular distance “d” of the embodiment of FIG. 5a is about 1.65 mm, while the perpendicular distance “d” in the embodiment of FIG. 5b is about 0.75 mm. It is thus noted that the perpendicular distance “d” is related inversely to the lubrication condition of the backward extrusion process. That is, the high lubrication condition results in a short perpendicular distance “d”, while the low lubrication condition results in a long perpendicular distance “d”. Particularly, the perpendicular distance “d” increases linearly in proportion to increases in the representative shear friction factor. Such experimental results were confirmed from analyses using an analysis program based on the rigid-viscoplastic finite element method that is widely used in the numerical analysis of bulk forming processes. - FIG. 6 is a graph showing the linear relationship between the representative shear friction factors “mf” and the perpendicular distance “d”, which is non-dimensionalized by the thickness “t” of the extruded end of the
workpiece 30. Since the thickness “t” of the extruded products is 3.4 mm, “d/t” for the embodiment of FIG. 5a can be calculated to be 0.49, while it is 0.22 for the embodiment of FIG. 5b. This linear relationship is expressed by the following equation (2). - Representative shear friction factor (m f)=1.36×d/t)−0.21 (2)
- As expressed in the above equation (2), it is possible to simply and easily measure the representative shear friction factor using the geometrical characteristics of the extruded product. By using equation (2), the representative shear friction factor for the embodiment of FIG. 5a extruded under low lubrication condition can be calculated to be about 0.46, while the representative shear friction factor for the embodiment of FIG. 5b extruded under high lubrication condition can be calculated as 0.09.
- As described above, the present invention based on backward extrusion provides a method of measuring the representative shear friction factor at the interface between a workpiece material and forming dies during bulk forming processes. The measuring method is very simple and suitable for estimating the friction conditions of complex bulk forming processes as a single value.
- In addition, it is possible to estimate friction conditions for a large range of representative shear friction factors (mf=0.0˜1.0), and so the appropriate constant shear friction factors for a variety of lubrication conditions are easily measured. This measuring method thus improves both the reliability of numerical analyses and the design efficiency of bulk forming processes to improve the final quality of bulk forming products.
- In the above description, the preferred embodiment of the present invention for measuring the representative shear friction factor using backward extrusion has been described for illustrative purposes. That is, the method according to the preferred embodiment of this invention is designed to measure the representative shear friction factor through a backward extrusion process as a single value. However, it should be understood that the present invention is not limited to the above-mentioned embodiment and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
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KR1020000017865A KR100374507B1 (en) | 2000-04-06 | 2000-04-06 | Measuring method of shear friction factor using backward extrusion |
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GB9209137D0 (en) | 1992-04-28 | 1992-06-10 | Lucas Ind Plc | Method of and apparatus for estimating surface friction |
US5628230A (en) * | 1994-11-01 | 1997-05-13 | Flam; Eric | Method and apparatus for testing the efficacy of patient support systems |
US5992212A (en) | 1996-11-07 | 1999-11-30 | Roger D. Sims, P.E. | Device for determining coefficient of friction and level of lubrication |
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2000
- 2000-04-06 KR KR1020000017865A patent/KR100374507B1/en not_active IP Right Cessation
-
2001
- 2001-02-15 US US09/783,542 patent/US6418795B2/en not_active Expired - Fee Related
- 2001-02-23 JP JP2001048232A patent/JP3416123B2/en not_active Expired - Fee Related
- 2001-02-26 DE DE10109239A patent/DE10109239B4/en not_active Expired - Fee Related
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US20110302978A1 (en) * | 2010-06-14 | 2011-12-15 | Ati Properties, Inc. | Lubrication processes for enhanced forgeability |
US10207312B2 (en) * | 2010-06-14 | 2019-02-19 | Ati Properties Llc | Lubrication processes for enhanced forgeability |
CN102901701A (en) * | 2012-10-29 | 2013-01-30 | 哈尔滨工业大学 | Plastic micro volume forming friction scale effect evaluating method and device |
CN103612415A (en) * | 2013-11-29 | 2014-03-05 | 重庆大学 | Device and method for testing friction characteristic parameters of thermoplastic forming |
CN104181100A (en) * | 2014-08-26 | 2014-12-03 | 上海交通大学 | Upset-extruding deformation test method of hot-forging friction factor |
CN106370593A (en) * | 2016-08-30 | 2017-02-01 | 上海交通大学 | Friction factor measuring method oriented to complicated large deformation |
CN112268794A (en) * | 2020-09-29 | 2021-01-26 | 中国科学院金属研究所 | Method for determining optimal anti-armor-piercing microstructure state of metal material |
Also Published As
Publication number | Publication date |
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DE10109239B4 (en) | 2004-10-28 |
KR100374507B1 (en) | 2003-03-04 |
JP2001305045A (en) | 2001-10-31 |
KR20010094284A (en) | 2001-10-31 |
US6418795B2 (en) | 2002-07-16 |
JP3416123B2 (en) | 2003-06-16 |
DE10109239A1 (en) | 2001-10-18 |
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