At present,iron and steel enterprises mainly use“after spot test ward”to control final product quality.However,it is impossible to realize on-line quality predetermining for all products by this traditional approach...At present,iron and steel enterprises mainly use“after spot test ward”to control final product quality.However,it is impossible to realize on-line quality predetermining for all products by this traditional approach,hence claims and returns often occur,resulting in major eco-nomic losses of enterprises.In order to realize the on-line quality predetermining for steel products during manufacturing process,the predic-tion models of mechanical properties based on deep learning have been proposed in this work.First,the mechanical properties of deep drawing steels were predicted by using LSTM(long short team memory),GRU(gated recurrent unit)network,and GPR(Gaussian process regression)model,and prediction accuracy and learning efficiency for different models were also discussed.Then,on-line re-learning methods for transfer learning models and model parameters were proposed.The experimental results show that not only the prediction accuracy of optimized trans-fer learning models has been improved,but also predetermining time was shortened to meet real time requirements of on-line property prede-termining.The industrial production data of interstitial-free(IF)steel was used to demonstrate that R2 value of GRU model in training stage reaches more than 0.99,and R2 value in testing stage is more than 0.96.展开更多
Hubei Tianmen Textile Machinery Co.,Ltd.is a well-known enterprise and key high-tech enterprise in China textile industry.The company's leading product,drawing frame,has completely independent intellectual propert...Hubei Tianmen Textile Machinery Co.,Ltd.is a well-known enterprise and key high-tech enterprise in China textile industry.The company's leading product,drawing frame,has completely independent intellectual property rights,among which TM 11 is well received by users and has a high market share in China.展开更多
The inherent teaching approach can no longer meet the demands of society.In this paper,current issues within the teaching landscape of architectural engineering technology in higher vocational colleges as well as the ...The inherent teaching approach can no longer meet the demands of society.In this paper,current issues within the teaching landscape of architectural engineering technology in higher vocational colleges as well as the policies and teaching demands that formed the basis of this model were analyzed.The study shows the importance of the implementation of the teaching model“promoting teaching and learning through competitions.”This model puts emphasis on the curriculum and teaching resources,while also integrating the teaching process and evaluation with competition.These efforts aim to drive education reform in order to better align with the objectives of vocational education personnel training,while also acting as a reference for similar courses.展开更多
Cinderella National Ballet of China.Date:Febuary 2-4,2024.Venue:National Center for the Performing Arts.Rooted in romance and decorum,Cinderella is a tale of courage,hope,and heart that is suitable for audiences of al...Cinderella National Ballet of China.Date:Febuary 2-4,2024.Venue:National Center for the Performing Arts.Rooted in romance and decorum,Cinderella is a tale of courage,hope,and heart that is suitable for audiences of all ages.Founded in December 1959,the National Ballet of China has top-notch artistic personnel trained at professional art institutes and keeps drawing on the strengths of different art genres with Russian skills as its core.In addition to ushering in a high number of world classics,it has independently produced numerous masterpieces with distinct national characteristics,featureing an amazing fusion of the classical with the modern and the national with the international.展开更多
In the vast Xizang Autonomous Region,numerous small villages and towns are scattered at the foot of snow-capped mountains and deep in the grasslands,drawing people from afar with their unique social and cultural tapes...In the vast Xizang Autonomous Region,numerous small villages and towns are scattered at the foot of snow-capped mountains and deep in the grasslands,drawing people from afar with their unique social and cultural tapestry.展开更多
1. Sketch素描.Sketching is a monochrome drawing that uses lines to depict the light and shade of objects with materials such as charcoal, pencils, or pens. Monochrome watercolor and monochrome oil paintings can also b...1. Sketch素描.Sketching is a monochrome drawing that uses lines to depict the light and shade of objects with materials such as charcoal, pencils, or pens. Monochrome watercolor and monochrome oil paintings can also be considered sketches;traditional Chinese fineline paintings and ink wash paintings can also be called sketches. Usually, sketching refers to pencil and charcoal drawings.展开更多
In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and co...In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.展开更多
During 28-29, September 2005, water was drawn from Hanjiang River and Houguan Lake to the Yangzi River via Sanjiao Lake and Nantaizi Lake in Wuhan in order to provide favorable conditions for ecosystem restoration. To...During 28-29, September 2005, water was drawn from Hanjiang River and Houguan Lake to the Yangzi River via Sanjiao Lake and Nantaizi Lake in Wuhan in order to provide favorable conditions for ecosystem restoration. To evaluate the feasibility and validity of drawing water as a means of ecosystem restoration, zooplankton populations were studied 3 times (before, immediately after finishing and a month after drawing water) at seven locations from 27 Sept. 2005 to 2 Nov. 2005. Water quality in the lakes was mostly improved and zooplankton species richness decreased as soon as drawing water had finished but increased a month after drawing water. Zooplankton density and biomass was reduced in the lakes by drawing water but was increased at the entrance to Sanjiao Lake because of landform geometry change. Before drawing water, most species in Sanjiao Lake e.g., Brachionus sp. and Keratella sp. were tolerant of contamination. After drawing water oligotrophic-prone species such as Lecane ludwigii and Gastropus stylifer emerged. We conclude that drawing water could be important for improving water quality and favour ecosystem restoration. Dilution of nutrient concentrations may be an important role in the effect.展开更多
In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead ...In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.展开更多
The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other...The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.展开更多
Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ul...Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ultralow carbon (ULC) steel slabs and two low carbon (LC) aluminum-killed steel slabs were sampled to study the relationship between hooks and subsurface macro-inclusions, which were detected on the cross-sections of steel samples with an area of 56058 mm2 using an automated scanning electron microscopy/energy-disper-sive X-ray spectroscopy system. Results show that subsurface inclusions larger than 200 μm were almost entrapped by hook structures, whereas the location of other inclusions smaller than 200μm had no obvious dependence on the location of solidified hooks. Furthermore, the number density (ND) of subsurface inclusions larger than 200μm decreased from 0.02 to 0 cm-2 in ULC steel as the mean hook depth decreased from 1.57 to 1.01 mm. Similar trends were also observed in LC steel. In addition, the detected inclusions larger than 200μm were concentrated in the region near the slab center (3/8 width-5/8 width), where hook depths were also larger than those at any other locations. Therefore, minimizing the hook depth is an effective way to reduce inclusion-induced sliver defects in deep-drawing steels.展开更多
The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress ...The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ=κΕn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.展开更多
In order to meet the forming demands for low plasticity materials and large height-diameter ratio parts, a new process of hydrodynamic deep drawing (HDD) with independent radial hydraulic pressure is proposed. To in...In order to meet the forming demands for low plasticity materials and large height-diameter ratio parts, a new process of hydrodynamic deep drawing (HDD) with independent radial hydraulic pressure is proposed. To investigate the effects of loading paths on the HDD with independent radial hydraulic pressure, the forming process of 5A06 aluminum alloy cylindrical cup with a hemispherical bottom was studied by numerical simulation. By employing the dynamic explicit analytical software ETA/Dynaform based on LS-DYNA3D, the effects of loading paths on the sheet-thickness distribution and surface quality were analyzed. The corresponding relations of the radial hydraulic pressure loading paths and the part's strain status on the forming limit diagram (FLD) were also discussed. The results indicated that a sound match between liquid chamber pressure and independent radial hydraulic pressure could restrain the serious thinning at the hemisphere bottom and that through adjusting radial hydraulic pressure could reduce the radial tensile strain and change the strain paths. Therefore, the drawing limit of the aluminum cylindrical cup with a hemispherical bottom could be increased significantly.展开更多
Understanding the characteristics of drawing body shape is essential for optimization of drawing parameters in longwall top coal caving mining.In this study,both physical experiments and theoretical analysis are emplo...Understanding the characteristics of drawing body shape is essential for optimization of drawing parameters in longwall top coal caving mining.In this study,both physical experiments and theoretical analysis are employed to investigate these characteristics and derive a theoretical equation for the drawing body shape along the working face in an inclined seam.By analyzing the initial positions of drawn marked particles,the characteristics of the drawing body shape for different seam dip angles are obtained.It is shown that the drawing body of the top coal exhibits a shape-difference and volume-symmetry characteristic,on taking a vertical line through the center of support opening as the axis of symmetry,the shapes of the drawing body on the two sides of this axis are clearly different,but their volumes are equal.By establishing theoretical models of the drawing body in the initial drawing stage and the normal drawing stage,a theoretical equation for the drawing body in an inclined seam is proposed,which can accurately describe the characteristics of the drawing body shape.The shape characteristics and volume symmetry of the drawing body are further analyzed by comparing the results of theoretical calculations and numerical simulations.It is shown that one side of the drawing body is divided into two parts by an inflection point,with the lower part being a variation development area.This variation development area increases gradually with increasing seam dip angle,resulting in an asymmetry of the drawing body shape.However,the volume symmetry coefficient fluctuates around 1 for all values of the seam dip angle variation,and the volumes of the drawing body on the two sides are more or less equal as the variation development volume is more or less equal to the cut volume.Both theoretical calculations and numerical simulations confirm that the drawing body of the top coal exhibits the shape-difference and volume-symmetry characteristic.展开更多
Basing on warm mechanical property of SUS304 stainless steel and hydro-mechanical deep drawing process, warm hydro-mechanical deep drawing process is proposed and discussed with experiments in this paper. The experime...Basing on warm mechanical property of SUS304 stainless steel and hydro-mechanical deep drawing process, warm hydro-mechanical deep drawing process is proposed and discussed with experiments in this paper. The experiments are performed at four different temperatures. The results show that the formability of stainless steel is improved under the condition of warm temperature. Warm hydro-mechanical deep drawing raises limiting drawing ratio of SUS304 effectively, and limiting drawing ratio 3.3 is obtained, which is beyond 2.0 with conventional deep drawing. The temperature of 90℃ is beneficial to the forming of SUS304 stainless steel, the strain-induced martensite is controlled effectively, and the thickness distribution is more uniform.展开更多
Existing linkage-optimization methods are designed for mechanical presses; few can be directly used for servo presses, so development of the servo press is limited. Based on the complementarity of linkage opti- mizati...Existing linkage-optimization methods are designed for mechanical presses; few can be directly used for servo presses, so development of the servo press is limited. Based on the complementarity of linkage opti- mization and motion planning, a phase-division-based linkage-optimization model for a drawing servo press is established. Considering the motion-planning principles of a drawing servo press, and taking account of work rating and efficiency, the constraints of the optimization model are constructed. Linkage is optimized in two modes: use of either constant eccentric speed or constant slide speed in the work segments. The performances of optimized link- ages are compared with those of a mature linkage SL4- 2000A, which is optimized by a traditional method. The results show that the work rating of a drawing servo press equipped with linkages optimized by this new method improved and the root-mean-square torque of the servo motors is reduced by more than 10%. This research pro- vides a promising method for designing energy-saving drawing servo presses with high work ratings.展开更多
Based on the ABAQUS/Explicit finite element method,the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under ...Based on the ABAQUS/Explicit finite element method,the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to 0.22.The lubricants selected for the tests were mechanical oil,butter and dry film lubricant,and the friction coefficient of these lubricants were 0.05,0.10 and 0.15,respectively.Microstructural evolution of 6 A16 aluminum alloy plate during drawing forming was investigated by OM,SEM and EBSD.The results showed that,with the increase of friction coefficient,the stress,strain and deformation degree in deformation zone increased,while the grain size in deformation zone decreased.Thus,the hardness of the cup-typed component increased with the increase of friction coefficient.Butter-lubricated cups had the highest tensile strength and yield strength after paint-bake cycle.The combination of simulation results and microstructure analysis of 6A16 aluminum alloy plate after drawing forming indicates that the appropriate lubricant is butter.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 52175284)the State Key Lab of Advanced Metals and Materials in University of Science and Technology Beijing (No. 2021ZD08)
文摘At present,iron and steel enterprises mainly use“after spot test ward”to control final product quality.However,it is impossible to realize on-line quality predetermining for all products by this traditional approach,hence claims and returns often occur,resulting in major eco-nomic losses of enterprises.In order to realize the on-line quality predetermining for steel products during manufacturing process,the predic-tion models of mechanical properties based on deep learning have been proposed in this work.First,the mechanical properties of deep drawing steels were predicted by using LSTM(long short team memory),GRU(gated recurrent unit)network,and GPR(Gaussian process regression)model,and prediction accuracy and learning efficiency for different models were also discussed.Then,on-line re-learning methods for transfer learning models and model parameters were proposed.The experimental results show that not only the prediction accuracy of optimized trans-fer learning models has been improved,but also predetermining time was shortened to meet real time requirements of on-line property prede-termining.The industrial production data of interstitial-free(IF)steel was used to demonstrate that R2 value of GRU model in training stage reaches more than 0.99,and R2 value in testing stage is more than 0.96.
文摘Hubei Tianmen Textile Machinery Co.,Ltd.is a well-known enterprise and key high-tech enterprise in China textile industry.The company's leading product,drawing frame,has completely independent intellectual property rights,among which TM 11 is well received by users and has a high market share in China.
文摘The inherent teaching approach can no longer meet the demands of society.In this paper,current issues within the teaching landscape of architectural engineering technology in higher vocational colleges as well as the policies and teaching demands that formed the basis of this model were analyzed.The study shows the importance of the implementation of the teaching model“promoting teaching and learning through competitions.”This model puts emphasis on the curriculum and teaching resources,while also integrating the teaching process and evaluation with competition.These efforts aim to drive education reform in order to better align with the objectives of vocational education personnel training,while also acting as a reference for similar courses.
文摘Cinderella National Ballet of China.Date:Febuary 2-4,2024.Venue:National Center for the Performing Arts.Rooted in romance and decorum,Cinderella is a tale of courage,hope,and heart that is suitable for audiences of all ages.Founded in December 1959,the National Ballet of China has top-notch artistic personnel trained at professional art institutes and keeps drawing on the strengths of different art genres with Russian skills as its core.In addition to ushering in a high number of world classics,it has independently produced numerous masterpieces with distinct national characteristics,featureing an amazing fusion of the classical with the modern and the national with the international.
文摘In the vast Xizang Autonomous Region,numerous small villages and towns are scattered at the foot of snow-capped mountains and deep in the grasslands,drawing people from afar with their unique social and cultural tapestry.
文摘1. Sketch素描.Sketching is a monochrome drawing that uses lines to depict the light and shade of objects with materials such as charcoal, pencils, or pens. Monochrome watercolor and monochrome oil paintings can also be considered sketches;traditional Chinese fineline paintings and ink wash paintings can also be called sketches. Usually, sketching refers to pencil and charcoal drawings.
文摘In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.
文摘During 28-29, September 2005, water was drawn from Hanjiang River and Houguan Lake to the Yangzi River via Sanjiao Lake and Nantaizi Lake in Wuhan in order to provide favorable conditions for ecosystem restoration. To evaluate the feasibility and validity of drawing water as a means of ecosystem restoration, zooplankton populations were studied 3 times (before, immediately after finishing and a month after drawing water) at seven locations from 27 Sept. 2005 to 2 Nov. 2005. Water quality in the lakes was mostly improved and zooplankton species richness decreased as soon as drawing water had finished but increased a month after drawing water. Zooplankton density and biomass was reduced in the lakes by drawing water but was increased at the entrance to Sanjiao Lake because of landform geometry change. Before drawing water, most species in Sanjiao Lake e.g., Brachionus sp. and Keratella sp. were tolerant of contamination. After drawing water oligotrophic-prone species such as Lecane ludwigii and Gastropus stylifer emerged. We conclude that drawing water could be important for improving water quality and favour ecosystem restoration. Dilution of nutrient concentrations may be an important role in the effect.
文摘In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.
文摘The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.
文摘Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ultralow carbon (ULC) steel slabs and two low carbon (LC) aluminum-killed steel slabs were sampled to study the relationship between hooks and subsurface macro-inclusions, which were detected on the cross-sections of steel samples with an area of 56058 mm2 using an automated scanning electron microscopy/energy-disper-sive X-ray spectroscopy system. Results show that subsurface inclusions larger than 200 μm were almost entrapped by hook structures, whereas the location of other inclusions smaller than 200μm had no obvious dependence on the location of solidified hooks. Furthermore, the number density (ND) of subsurface inclusions larger than 200μm decreased from 0.02 to 0 cm-2 in ULC steel as the mean hook depth decreased from 1.57 to 1.01 mm. Similar trends were also observed in LC steel. In addition, the detected inclusions larger than 200μm were concentrated in the region near the slab center (3/8 width-5/8 width), where hook depths were also larger than those at any other locations. Therefore, minimizing the hook depth is an effective way to reduce inclusion-induced sliver defects in deep-drawing steels.
基金supported by the laboratory foundation of Tsinghua Universitythe'985'research foundation of Tsinghua University
文摘The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ=κΕn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.
文摘In order to meet the forming demands for low plasticity materials and large height-diameter ratio parts, a new process of hydrodynamic deep drawing (HDD) with independent radial hydraulic pressure is proposed. To investigate the effects of loading paths on the HDD with independent radial hydraulic pressure, the forming process of 5A06 aluminum alloy cylindrical cup with a hemispherical bottom was studied by numerical simulation. By employing the dynamic explicit analytical software ETA/Dynaform based on LS-DYNA3D, the effects of loading paths on the sheet-thickness distribution and surface quality were analyzed. The corresponding relations of the radial hydraulic pressure loading paths and the part's strain status on the forming limit diagram (FLD) were also discussed. The results indicated that a sound match between liquid chamber pressure and independent radial hydraulic pressure could restrain the serious thinning at the hemisphere bottom and that through adjusting radial hydraulic pressure could reduce the radial tensile strain and change the strain paths. Therefore, the drawing limit of the aluminum cylindrical cup with a hemispherical bottom could be increased significantly.
基金The authors gratefully acknowledge financial support from the Natural Science Foundation of China(51674264.51574244)the National Key R&D Plan of China(2018YFC0604501)+1 种基金the China Postdoctoral Science Foundation(2018M631622)Special acknowledgements are also given to the China Scholarship Council(CSC).
文摘Understanding the characteristics of drawing body shape is essential for optimization of drawing parameters in longwall top coal caving mining.In this study,both physical experiments and theoretical analysis are employed to investigate these characteristics and derive a theoretical equation for the drawing body shape along the working face in an inclined seam.By analyzing the initial positions of drawn marked particles,the characteristics of the drawing body shape for different seam dip angles are obtained.It is shown that the drawing body of the top coal exhibits a shape-difference and volume-symmetry characteristic,on taking a vertical line through the center of support opening as the axis of symmetry,the shapes of the drawing body on the two sides of this axis are clearly different,but their volumes are equal.By establishing theoretical models of the drawing body in the initial drawing stage and the normal drawing stage,a theoretical equation for the drawing body in an inclined seam is proposed,which can accurately describe the characteristics of the drawing body shape.The shape characteristics and volume symmetry of the drawing body are further analyzed by comparing the results of theoretical calculations and numerical simulations.It is shown that one side of the drawing body is divided into two parts by an inflection point,with the lower part being a variation development area.This variation development area increases gradually with increasing seam dip angle,resulting in an asymmetry of the drawing body shape.However,the volume symmetry coefficient fluctuates around 1 for all values of the seam dip angle variation,and the volumes of the drawing body on the two sides are more or less equal as the variation development volume is more or less equal to the cut volume.Both theoretical calculations and numerical simulations confirm that the drawing body of the top coal exhibits the shape-difference and volume-symmetry characteristic.
文摘Basing on warm mechanical property of SUS304 stainless steel and hydro-mechanical deep drawing process, warm hydro-mechanical deep drawing process is proposed and discussed with experiments in this paper. The experiments are performed at four different temperatures. The results show that the formability of stainless steel is improved under the condition of warm temperature. Warm hydro-mechanical deep drawing raises limiting drawing ratio of SUS304 effectively, and limiting drawing ratio 3.3 is obtained, which is beyond 2.0 with conventional deep drawing. The temperature of 90℃ is beneficial to the forming of SUS304 stainless steel, the strain-induced martensite is controlled effectively, and the thickness distribution is more uniform.
基金Supported by National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2015ZX04003004)
文摘Existing linkage-optimization methods are designed for mechanical presses; few can be directly used for servo presses, so development of the servo press is limited. Based on the complementarity of linkage opti- mization and motion planning, a phase-division-based linkage-optimization model for a drawing servo press is established. Considering the motion-planning principles of a drawing servo press, and taking account of work rating and efficiency, the constraints of the optimization model are constructed. Linkage is optimized in two modes: use of either constant eccentric speed or constant slide speed in the work segments. The performances of optimized link- ages are compared with those of a mature linkage SL4- 2000A, which is optimized by a traditional method. The results show that the work rating of a drawing servo press equipped with linkages optimized by this new method improved and the root-mean-square torque of the servo motors is reduced by more than 10%. This research pro- vides a promising method for designing energy-saving drawing servo presses with high work ratings.
基金Funded by the National Key Research and Development Program of China(No.2016YFB0300805).
文摘Based on the ABAQUS/Explicit finite element method,the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to 0.22.The lubricants selected for the tests were mechanical oil,butter and dry film lubricant,and the friction coefficient of these lubricants were 0.05,0.10 and 0.15,respectively.Microstructural evolution of 6 A16 aluminum alloy plate during drawing forming was investigated by OM,SEM and EBSD.The results showed that,with the increase of friction coefficient,the stress,strain and deformation degree in deformation zone increased,while the grain size in deformation zone decreased.Thus,the hardness of the cup-typed component increased with the increase of friction coefficient.Butter-lubricated cups had the highest tensile strength and yield strength after paint-bake cycle.The combination of simulation results and microstructure analysis of 6A16 aluminum alloy plate after drawing forming indicates that the appropriate lubricant is butter.