25 September 2022, Volume 47 Issue 9
    

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  • Wear analysis and process parameter optimization on hexagon punch based on orthogonal test
    MO Jie, LIU Jian, LI Xuan, ZHENG Qiong-e
    Forging & Stamping Technology. 2022, 47(9): 1-6. https://doi.org/10.13330/j.issn.1000-3940.2022.09.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to reduce the wear amount of the cold upsetting punch at the head of hexagonal bolt for a vehicle, the Archard wear theory was used to research it. Then, taking reducing the punch wear amount as the main objective and selecting cone angle of punch, punch hardness, friction factor and feeding speed as the test factors, L16(44) orthogonal test was designed, and finite element simulation was performed by DEFROM. Furthermore, the influence degree order of each factor on the punch wear was obtained by the range analysis and variance analysis of the test results, that is cone angle of punch>punch hardness>friction factor>feeding speed, and the optimal process parameter combination was the punch cone angle of 25°, the punch hardness of 67 HRC, the friction factor of 0.10, and the feeding speed of 100 mm·s-1. Under the optimal parameter combination, the wear amount of punch was reduced from 3.39×10-6 mm to 2.16×10-6 mm. The results show that the punch wear mainly occurs at the connection between conical surface of punch and ligament of punch. Thus, the optimized process parameters reduce the wear amount of punch, which has reference significance for the research on the wear of the same type of punch.
  • Forming technology of steering knuckle based on reasonable volume distribution for circular arc upsetting die
    CAO Hong, XUE Shi-bo, XUE Chuan-mei, SHI Wen-chao, SONG Zhong-jiang, YIN Xi-bing
    Forging & Stamping Technology. 2022, 47(9): 7-11. https://doi.org/10.13330/j.issn.1000-3940.2022.09.002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to reduce the fold defect and forming load of steering knuckle forgings and realize the reasonable distribution of metal, for the automobile steering knuckle with complex grade of S-class, the forming process scheme of free forging billet(upsetting-rod flattening), pre-forging and final forging were adopted, and the forming process was simulated numerically by software Deform-3 D. Then, the metal flow laws, the distributions of equivalent stress and equivalent strain, and the load change laws during the forming process were studied by experimental verification. The results show that the designed circular arc shape in the middle of upsetting upper die plays a good role in metal distribution, and the defects of flash and folding for the pre-forged head are reduced. When the arc radius of upsetting upper die is 150 mm, the damage peak value of drum surface is the smallest. Using the forging method of circular arc upsetting upper die and free forging billet-pre-forging-final forging, the forgings obtained by the simulation have no obvious forming defects, which provides theoretical guidance for the actual production of steering knuckle forgings.
  • Influence of forging temperature on microstructure and impact property for M2-1.6Si high speed steel in machine tool
    YANG Feng, TANG Jing, ZHAO Li-ling
    Forging & Stamping Technology. 2022, 47(9): 12-17. https://doi.org/10.13330/j.issn.1000-3940.2022.09.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the influences of forging temperature on the microstructure and impact property for M2-1.6 Si high speed steel, the forging tests were carried out at different forging temperatures, and the microstructure and impact property were tested and analyzed. The results show that when the initial forging temperature increases from 1130 ℃ to 1210 ℃ or the final forging temperature increases from 790 ℃ to 870 ℃, the carbides in the sample are refined first and then coarsened, and the impact properties are improved first and then decreased. Under the condition that the other process parameters remain unchanged, when the initial forging temperature is 1130 ℃, the carbides inside the sample are in the form of coarse “bone-like” shape, while the initial forging temperature is 1170 ℃, the carbides inside the sample are fine particles, and the impact toughness increases by 33.7% compared with that at the initial forging temperature of 1130 ℃. When the other process parameters remain unchanged and the final forging temperature is 790 ℃, the carbides inside the sample present a “bone-like” shape with different sizes, while the final forging temperature is 830 ℃, the carbides inside the sample are fine particles, and the impact toughness increases by 21.7% compared with that at the final forging temperature of 790 ℃.
  • Design on forging die of connecting rod for type-12 marine engine and forging process verification example
    LIU Jiang, XU Hao
    Forging & Stamping Technology. 2022, 47(9): 18-22. https://doi.org/10.13330/j.issn.1000-3940.2022.09.004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For the connecting rod of type-12 marine engine, 500 t double crank mechanical press and 2500 t hot die forging press were adopted for production, and the billet-making dies of three steps were designed, analyzed and demonstrated respectively by analyzing and expounding the shape and structure of the forgings. Then, the small batch production verification was carried out by the three-step billet making and die forging compound forming process to obtain that the design of step 3 for the preformed billet making die was particularly critical, which not only determined the metal filling performance of the final forging die, but also had a direct impact on the material utilization rate of the forgings, and prevented the forgings from producting folding defects. After optimizing the forging process of the connecting rod for type-12 marine engine, the trial production of sample on site was conducted. The results show that the material utilization rate for connecting rod of for type-12 marine engine is 81.2%, the qualified rate is 99.4%, and the forging process is scientific, reasonable and feasible. Thus, the research conclusion is of great significance to the research, development and trial manufacture of small batch and multi-variety forgings.
  • Study on powder forging of Fe-Ni-Cu-C-Mo-V alloy for NC machine tool gears
    LIU Bo, LIU Jun-qiang
    Forging & Stamping Technology. 2022, 47(9): 23-29. https://doi.org/10.13330/j.issn.1000-3940.2022.09.005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the feasibility of powder forging for new NC machine tool gear material Fe-Ni-Cu-C-Mo-V alloy and explore the influences of initial forging temperature on the wear and corrosion resistance properties for the gear material, the powder forging test of gear material was carried out at different initial forging temperatures, and the wear resistance property, corrosion resistance property and density were tested and analyzed. The results show that the gear material with better comprehensive properties can be prepared by powder forging method. When the initial forging temperature increases from 800 ℃ to 1200 ℃, the wear volume of gear material first decreases and then increases, the corrosion potential first moves positive and then negative, the density first increases and then decreases, and the wear and corrosion resistance properties of gear material first increase and then decrease. Compared with the initial forging temperature of 800 ℃, the wear volume of powder forged gear material at the initial forging temperature of 1100 ℃ is reduced by 28.4%, the corrosion potential moves positive by 23.1%, and the density increases by 7.0%. Thus, the initial forging temperature of powder forged new NC machine tool gear material Fe-Ni-Cu-C-Mo-V alloy is preferably at 1100 ℃.
  • An automatic cold upsetting process for automobile non-standard parts based on computer numerical analysis
    BO Shi-bing
    Forging & Stamping Technology. 2022, 47(9): 30-38. https://doi.org/10.13330/j.issn.1000-3940.2022.09.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to change the current situation of multipre processes, low production efficiency and large differences of product performance in curvent production process for an automobile non-standard part, two kinds of automatic cold upsetting schemes were proposed, and the Johnson-Cook constitutive model of 10 B21 steel was established by Deform-3 D. Then, based on the model, the simulated forming of the parts in each station for the two schemes were conducted, and the deformation law, equivalent stress distribution and load situation of the material were analyzed. Furthermore, the process inspection and optimization were carried out, and the final forming scheme was determined, namely, blanking-diameter reducing and inner hole pre-forming-head pre-upsetting-flower head upsetting-head shaping-head final forming-punching, and the process test was completed. Production tests show that the finite element analysis results are accurate, the optimized cold upsetting process is reliable, and the mass production of the non-standard parts can be realized. The obtained parts have complete forming, good surface quality and no problems of scraping, folding, potholes and so on, and the dimensional accuracy meets the production requirements.
  • Influence of billet preheating method on microstructure and properties for AZ80 magnesium alloy wheel hub
    HU Mei-xie, DI Shi-lei
    Forging & Stamping Technology. 2022, 47(9): 39-44. https://doi.org/10.13330/j.issn.1000-3940.2022.09.007
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    The influences of direct forging and hot forging after 410 ℃/23 h homogenization treatment on the microstructure and properties of wheel hub were studied by means of contrast. The results show that the direct forging after homogenization treatment can improve production efficiency and save energy, the surface quality of wheel hub after forging is better, and there are no forging defects such as surface cracks and folding. However, its mechanical properties are obviously lower than those of the wheel hub after homogenization treatment and hot forging, the grain size is not uniform in the microstructure, the recrystallized grain is small on the grain boundary, and the single-phase solid solution in the grain is relatively coarser. After the homogenization treatment, the microstructure of the forged wheel hub after re-heat treatment at 435 ℃ for 7.5 h before forging is uniform and fine with fine grain boundary and obvious forging texture. The mechanical properties of all parts for the wheel hub are higher than those of the wheel hub that is homogenized treatment and then directly forged, especially, the mechanical properties of rim and spoke are different greatly.
  • Application of numerical simulation technology for metal flow velocity in eliminating folding defect of hot die forgings
    WANG Fei, JIN Chao-hui, XU Bao-guo, SONG Jia-bing
    Forging & Stamping Technology. 2022, 47(9): 45-50. https://doi.org/10.13330/j.issn.1000-3940.2022.09.008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The metal flow velocity change of billet during hot die forging process was analyzed by numerical simulation technology, the metal flow velocity change at the forging folding and other defect positions was analyzed and summarized, and the relationship between multiplied difference of flow velocity and forging folding and other defects was obtained. Then, using this connection, the problems of folding and other defects encountered in the hot die forging process were analyzed from the multiplied difference of flow velocity, and the solution to the folding problems of hot die forgings such as disc forgings, steering knuckle forgings and so on were verified by production. The results show that the folding and other defect problems of hot die forgings can be solved by environmental factors such as mold optimization, control of mold temperatures and lubrication, etc. to affect the change of multiplied difference of flow velocity in the hot die forging process. Thus, in the forming process of hot die forgings, good metal fluidity, uniform flow velocity change and small multiplied difference of flow velocity are beneficial to the hot die forging and avoid forging folding and other defects. On the contrary, if the metal flow is too violent and turbulent, and the multiplied difference of flow velocity changes greatly, the forming possibility of folding and other defects for forgings becomes greater.
  • Simulation and experiment research on chain-die forming of EV seat beam
    LIU Yang, ZOU Tian-xia, LIANG Zhen-ye, QIAN Zhen, LI Da-yong, XIAO Hua, SHI Lei, ZHOU Guo-wei
    Forging & Stamping Technology. 2022, 47(9): 51-57. https://doi.org/10.13330/j.issn.1000-3940.2022.09.009
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    In order to solve the problems of many forming defects and low dimensional accuracy for the seat beam of ultra-high strength steel by traditional thin sheet forming process, a two-pass chain-die forming process scheme was proposed, and the corresponding finite element model was established by Abaqus/Standard. Then, the strain distribution, forming load and section shape of part during the chain-die forming process were analyzed. The simulation results show that there are no wrinkles and cracks on the part after chain-die forming, and the dimensions of the transverse and longitudinal sections for the part are relatively consistent with the target. Based on the exiting chain-die forming unit, the two-pass chain-die forming experiment of EV seat beam was carried out, and the key dimensions of formed parts were measured. The dimensional deviation of flange outer contour is less than ±0.5 mm, which meets the requirement of welding. The research results show that the chain-die forming process can form variable-section beam parts of ultra-high strength steel body at room temperature, which is helpful to promote its application in the ultra-high strength steel market.
  • Influence of workpiece thickness non-uniformity on curvature radius for roll bending
    ZHENG Zi-jun, TAO Yu-mei
    Forging & Stamping Technology. 2022, 47(9): 58-65. https://doi.org/10.13330/j.issn.1000-3940.2022.09.010
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    Due to the influence of manufacture process, the thickness of original workpiece is nonuniform, which can affect the shape of roll bending product. A finite element model based on Eulerian grid was proposed to conduct the Monte Carlo simulation of three-roll bending process, in which the local thickness of workpiece had normal-distributed error. Comparing with the conventional Lagrangian grid finite element model, the roll bending simulation scheme could reduce the grid number and simplify the contact treatment obviously. Then the statistic laws of curvature radius for roll forming was analyzed, and experiments of relationship between blank thickness non-uniformity and curvature radius of roll bending were conducted by using the 3 D printing. The results show that with the increasing of blank thickness non-uniformity, the distribution of local radius for product gets wider, and the macro radius of product becomes smaller, which is verified by the experimental result. For a given goal produce shape, the influence of blank thickness non-uniformity on roll bending is more significant when a smaller roller distance or a thinner nominal thickness is employed.
  • Design and optimization on preforming process for high-capacity diesel engine oil pan
    YUE Feng-li, ZHANG Xin, CHEN Da-yong, XU Yong, SONG Hong-wu, MA Yan, ZHANG Shi-hong, LI Jing-ming, LI Yong-hui
    Forging & Stamping Technology. 2022, 47(9): 66-74. https://doi.org/10.13330/j.issn.1000-3940.2022.09.011
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    Due to the appearance features of thin wall, large size and asymmetric deep cavity for the new type large-capacity diesel engine oil pan, the traditional forming process of oil pan is no longer applicable. Therefore, the billet used in final bulging was formed by hydro-mechanical deep drawing process, and the hydro-mechanical deep drawing process was developed into two steps, that is first partial deep drawing, and then overall deep drawing. With the help of finite element simulation software, the calculation model was established, and combined with the response surface method and orthogonal test method, the influences of the crucial process parameters such as die fillet radius, friction factor between blank and punch, friction factor between blank and die, blank holder force and hydraulic pressure on the hydro-mechanical deep drawing for oil pan were investigated. Furthermore, taking the maximum thinning rate and the maximum thickening rate as the optimization goals, the best combination of process parameters was obtained and verified, and a new type of gantry-type preformed part that met the quality requirements was successfully manufactured, and the maximum thinning rate was basically consistent with the simulation results, which verified the correctness of the process plan and the reliability of the simulation.
  • Numerical simulation and process parameter optimization on tank head forming based on orthogonal test
    SHU Zhi-hang, HUANG Ben-sheng, LI Tian-ning, LIU Jun-qi, ZHENG Jian-neng
    Forging & Stamping Technology. 2022, 47(9): 75-82. https://doi.org/10.13330/j.issn.1000-3940.2022.09.012
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    In order to explore the optimal combination of process parameters for the tank head stamping, improve efficiency and save time, the Dynaform finite element software was used for numerical simulation. Then, the three factors of punching speed, blank holder force and friction coefficient were selected as optimization variables, and the maximum thinning rate, the maximum thickening rate and the maximum springback amount of head were used as forming indicators. Furthermore, the orthogonal test scheme was designed, and the optimal combination of process parameters with the punching speed of 4000 mm·s-1,the blank holder force of 590 kN and the friction coefficient of 0.08 was determined by range analysis and variance analysis. Finally, the actual production test was carried out according to the optimal combination of process parameters, and the ovality of head port was used as the verification standard. The results show that the simulation results are consistent with the actual production results, and the final forming quality of head meets the requirements.
  • Finite element simulation and springback prediction on whole process for CNC stretch forming process of nose cone skin
    ZHANG He-gang, WANG Zhi-cheng, WANG Xiao-chen, DU Jian-ning, PENG Hao-yun, ZHU Li, LI Xiao-qiang, YANG Xiao-jun
    Forging & Stamping Technology. 2022, 47(9): 83-89. https://doi.org/10.13330/j.issn.1000-3940.2022.09.013
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    In order to improve the aerodynamic performance for new generation of aircraft, the requirements on the surface shape accuracy have been significantly increased, so it is necessary to control the springback of parts after the skin is stretched. Therefore, based on the self-developed domestic skin stretch forming simulation software AISF, the whole process of CNC stretch forming, trimming, springback for the nose cone skin was simulated numerically. Then, the key motion mechanism of VTL1000 CNC skin stretch forming machine was measured, and a finite element simulation model of skin stretch forming considering the actual motion of machine tool was established. Furthermore, the CNC stretch forming code of the actual parts was directly input into the finite element simulation model to ensure that the simulation boundary conditions were completely consistent with the experiment. Considering the actual production conditions, a simulation model of stretch forming-springback-trimming-pressing was established to realize the simulation prediction of springback. According to the optimized CNC stretch forming code, the actual parts were formed and digitally inspected. The results show that the springback prediction is basically consistent with the actual situation, which verifies the accuracy of the finite element simulation model.
  • Optimized trajectory without undersurface bump based on single-point NC incremental forming method of sheet metal
    WU Jian, CENG Xu-cheng, WU Han-yu
    Forging & Stamping Technology. 2022, 47(9): 90-98. https://doi.org/10.13330/j.issn.1000-3940.2022.09.014
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    In order to study the best path in NC incremental forming of flat-bottomed parts to improve forming accuracy, surface quality and forming efficiency. Therefore, for the circular truncated cone model, four kinds of forming paths were used for comparative experiments, which were contour line path, path of each layer from inside to outside, path of contour line+bottom from inside to outside and path of contour line+multi-layer bottom from inside to outside, and three different step distances were set on the bottom layer for the path of multi-layer bottom. The results show that the path of contour line+bottom from inside to outside causes the conical surface to sink on the bottom of part, while the path of each layer from inside to outside and the path of contour line+multi-layer bottom from inside to outside can not only eliminate the bulging on the bottom, but also avoid sinking phenomenon on the bottom. When the step distance of the bottom layer for the path of multi-layer bottom is set to 0.2 mm, the maximum error of the part bottom is 0.16 mm, and replacing the path of each layer from inside to outside with the path of multi-layer bottom from inside to outside can significantly shorten the forming time. Reducing the step distance of the bottom layer for the path of multi-layer bottom can not only improve the surface quality of the part bottom, but also improve the geometric accuracy of the part.
  • Simulation analysis on stamping defects for 5052 aluminum alloy thin sealing plate
    Lü Zhi-min, JIANG Hao
    Forging & Stamping Technology. 2022, 47(9): 99-104,181. https://doi.org/10.13330/j.issn.1000-3940.2022.09.015
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    For the serious cracking and high scrap rate of a 5052 aluminum alloy thin sealing plate, based on computer simulation technology, its stamping process was simulated numerically. Firstly, the mechanical property parameters and stress-strain curves of 5052 aluminum alloy were obtained by unidirectional tensile test, and the stamping material model was established by software Deform. Secondly, through the establishment of stamping simulation model, and combined with taguchi test design, the influences of stamping parameters such as stamping speed, friction coeffient, blank holder force and die fillet radius on the forming quality of thin sealing plate were studied, the evaluation function model of the maximum thinning rate and the maximum thickening rate was established by the linear weighted method, and the stamping parameters were optimized by small feature model. The optimization results show that the maximum thinning rate and the maximum thickening rate of sealing plate are improved obviously, the risk of cracking and wrinkling is reduced.And the verification was conducted by the stamping test. The cracking defects in the original process are eliminated, and the quality of sealing plate meets the design requirements.
  • Numerical simulation and process optimization on NC bending for stainless steel continuous multi-bend tube
    YANG Rui-meng, YUE Tao, LIN Lei, LI Li, CHEN Yong, ZHENG Sen-mu
    Forging & Stamping Technology. 2022, 47(9): 105-111. https://doi.org/10.13330/j.issn.1000-3940.2022.09.016
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    For the problems of poor forming quality and low dimensional accuracy for 0Cr18Ni9 stainless steel continuous multi-bend tube in the practical production, the process parameters were optimized by numerical simulation method of NC bending to improve the forming quality of products. Then, based on the finite element simulation platform, a three-dimensional finite element model of tube NC bending, mandrel retracting and springback was established, and the accuracy of the model was verified by comparing the simulation and test results. Since the continuous multi-bend tube was composed of multiple bending sections, the influences of key process parameters in the forming process for each elbow on the forming results were studied firstly, and the combination of process parameters was optimized. Based on this, the forming simulation of continuous multi-bend tube was carried out. The results show that the qualified tube cannot obtained by simply using the optimal process parameter combination of each single bend tube to form continuous multi-bend tube. However, by adjusting the combination of bending angles for two bends before and after to compensate the influence of stress interference between two bend elbows on the forming accuracy, and the qualified product with the forming quality meeting the requirements is obtained.
  • Analysis and optimization on wrinkling defect in bending process for a car chassis frame bending pipe
    HU Xiao, YIN Jing-jing, WANG Chuang-wei, WANG Fei-long
    Forging & Stamping Technology. 2022, 47(9): 112-117. https://doi.org/10.13330/j.issn.1000-3940.2022.09.017
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    Aiming at the wrinkling problem in the bending process of a car chassis frame bending pipe, based on SIGMA module of Autoform software, the influence of material parameters on wrinkling defect was analyzed, and the parameters of material which were sensitive to wrinkling defect were determined, so as to guide the material improvement. The influence of yield strength, tensile strength, r90 and friction factor on the wrinkling defect for S355 MC steel pickling sheet material was analyzed. The simulation results show that the yield strength and tensile strength have a great influence on the wrinkling defect of bending pipe, while the friction factor and r90 have almost no influence on the wrinkling defect. It is beneficial to reduce the yield strength and the yield strength ratio to control the wrinkling defect. By adding an appropriate amount of Cr and adjusting the coiling temperature, the yield strength and the yield strength ratio of S355 MC steel pickling sheet material are effectively reduced. The average yield strength is 374.1 MPa, and the average yield strength ratio is below 0.73. By reducing the yield strength and the yield strength ratio of the material, the wrinkling problem of bending pipe is successfully solved.
  • Quality analysis on hot orbital forming for cylindrical parts with cross ribs based on response surface method
    WU Lei, FENG Wei
    Forging & Stamping Technology. 2022, 47(9): 118-125. https://doi.org/10.13330/j.issn.1000-3940.2022.09.018
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    In order to study the influence laws of geometric parameters for cross ribs on the forming quality problems of rib insufficient filling, folding and so on during the hot orbital forming process of aluminum alloy cylindrical part with cross ribs, taking the width and height of cross ribs as variables, the experimental design was carried out by Box-Behnke designing(BBD) method, and the hot orbital forming process of cylindrical parts with different rib widths and rib heights was simulated by the finite element method. Then, the filling quality and folding rate of ribs with different rib widths and rib heights at the end of forming were calculated, and taking the width and height of cross ribs as the design variables and the filling quality and folding rate of ribs as the objectives, a quadratic polynomial response surface model(RSM) was established. Furthermore, the forming quality of part with different rib width and rib heights was obtained by combining response surface model and finite element method, and the height and width of cross rib when the forming quality was the best were predicted, which were simulated and verified by finite element. The results show that the filling quality of ribs is better when the height-width ratio of high ribs is less than six, and the folding rate decreases gradually with the increasing of the rib width. After optimization, the ribs of part are filled fully, the fold defects are few, and the simulation results are consistent with the prediction results to verify the accuracy of the response surface model.
  • Optimization on structural parameters of mandrel for TA1 titanium alloy internal thread pipe based on response surface
    LI Hua-jie, LI Xu-dong, XIONG Zhen, ZHANG Zheng-hao, HUANG Dong-nan
    Forging & Stamping Technology. 2022, 47(9): 126-134. https://doi.org/10.13330/j.issn.1000-3940.2022.09.019
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    In order to obtain the optimal structural parameters of mandrel, taking thread length L, thread lift angle φ1 and attack angle of mandrel φ2 as the design variables, and taking velocity relative difference VRD1 of material head tooth in thread pipe, velocity relative difference VRD2 of pipe wall and maximum load F of extrusion forming as the optimization target parameters, the multi-response regression model was established. Then, the established multi-response regression model was globally optimized by particle swarm algorithm, and the optimal parameters of internal thread pipe mandrel were finally obtained as the thread length L=11 mm, the thread lift angle φ1=30°, and the attack angle of mandrel φ2=96°. Furthermore, after optimization, VRD1 was reduced by 50.38%, VRD2 was reduced by 44.81%, and F value was decreased by 5.10%. Finally, the mold was processed by the optimal structure parameters of mandrel, and the extrusion test was conducted to obtain the qualified TA1 titanium alloy internal thread pipe. The results show that the mandrel structure optimized by the response surface method can improve the fluidity of metal in the extrusion process, reduce the maximum forming load of mold, and improve the forming quality of internal thread pipe.
  • Analysis and optimization on acroscopic forming defect for profiled section ring rolling based on response surface method
    MA Jun-hui, WU Yun-xin, GONG Hai, ZHANG Tao, HAO Tie-wen, LIU Lei
    Forging & Stamping Technology. 2022, 47(9): 135-144. https://doi.org/10.13330/j.issn.1000-3940.2022.09.020
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    Insufficient filling is a problem of forming defects that are easily generated during the rolling process for profiled section rings, and the relationship between the degree of insufficient filling and the geometric parameters of profiled section rings is very complicated. Therefore, the numerical model of asymmetric profiled section ring rolling for 2219 aluminum alloy was established, and the influences of groove depth and groove angle of profiled section ring on the forming quality of ring were analyzed. Then, by analyzing the forming mechanism of insufficient filling defects, the method of optimizing blank size parameters was proposed to suppress the defects. Furthermore, based on the response surface method, taking groove depth, groove angle and blank angle as the design variables and the insufficient filling coefficient as the design goal, the response surface model to characterize the insufficient filling coefficient was established, and the regression test was carried out. The results show that the larger the groove depth is and the smaller the groove angle is, the easier it is to produce forming defects. Using the established response surface model, the blank angle of ring with the target groove depth of 45 mm and the groove angle of 70° is optimized. The result shows that the optimized blank can better suppress the insufficient filling defects.
  • Cold rolling mechanism on automobile engine pulley
    MA Hou-liang, SUN Bao-shou, SHU Xue-dao, YUAN Jia-yao, XU Zhen-wei
    Forging & Stamping Technology. 2022, 47(9): 145-151. https://doi.org/10.13330/j.issn.1000-3940.2022.09.021
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    In order to realize the precise forming of cold rolling for engine pulley, a two-pass cold rolling finite element model of engine pulley was established based on Simufact software, the evolution laws of equivalent stress field and equivalent plastic strain field in the cold rolling process of pulley were analyzed, and its deformation mechanism was clarified. Then, according to the finite element simulation of cold rolling for pulley, the cold rolling experiment was carried out. The research shows that during the two-pass cold rolling process of pulley, the contact area between roller and pulley is the main deformation area, the deformation is the most severe, and the equivalent stress and equivalent plastic strain values at the groove are the largest. Properly increasing the time of finishing stage in the second pass of cold rolling for pulley can effectively eliminate the widening defect in the end face of ring. Thus, the automobile engine pulley is formed by two-pass cold rolling process, the cold rolling process is stable, and the ring with small width end face and high dimensional accuracy is obtained, which verifies the correctness of the finite element simulation.
  • Interfacial diffusion behavior on multi-pass hot rolling for automobile 310S/GH4169 steel-nickel composite plate
    QIN Cheng, XIA Yuan, TAN Li-jian, LI Jun, XU Xiao-yuan
    Forging & Stamping Technology. 2022, 47(9): 152-157. https://doi.org/10.13330/j.issn.1000-3940.2022.09.022
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    In order to improve the interfacial properties of automobile 310 S/GH4169 steel-nickel composite plate, the hot rolling method was used to strengthen it. Then, the interface microstructure change of the steel-nickel composite plate in the rolling stage was analyzed by the sampling method at the end of rolling, and the selective oxidation state near the interface area was tested. The research results show that there are many chain-like microstructures in the junction area between GH4169 nickel-base alloy and 310 S stainless steel, and the width dimension decreases rapidly from 3-10 μm to 1-2 μm. At the interface during the rolling process, fewer chain oxides are formed, which significantly improve the bonding performance of the interface. After increasing the rolling passes, the 310 S stainless steel grains are deformed to a greater extent, resulting in a large number of broken grains. Ni, Fe and Cr diffuse obviously, reaching the longest diffusion distance, which has exceeded 10 μm. However, Mo and Mn only diffuse in a short distance. After gradually increasing the rolling amount, Fe, Cr and Ni diffuse to deeper position. At the rolling interface, Mn oxides are mainly formed, which limits the diffusion of elements and reduces the bonding strength.
  • Influence of coiling temperature on microstructure and properties for low carbon steel rolled by CSP ferrite
    WANG Cheng-jian, HU Xue-wen, PENG Huan, WU Zhi-wen, YU Xuan-xun
    Forging & Stamping Technology. 2022, 47(9): 158-162. https://doi.org/10.13330/j.issn.1000-3940.2022.09.023
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    Low carbon steel was produced by CSP ferrite rolling process under different coiling temperatures, and the influences of coiling temperature on the microstructure and properties of CSP ferrite-rolled low carbon steel were studied by microstructure, micro-precipitation, dislocation density and performance tests. The research results show that the sample structure is composed of coarser ferrite and a small amount of pearlite, the precipitates are oxides or nitrides of Al, Ti and Si, and some are also compounded with MnS. When the coiling temperature drops from 700 ℃ to 620 ℃, the yield strength and the tensile strength increase by 31.6 and 25.9 MPa, respectively, and the hardness fluctuation range increases from 12 HRB to 25 HRB. Thus, increasing the coiling temperature can promote the growth and homogenization of ferrite grains, reduce the dislocation density, effectively reduce the strength and improve the uniformity of performance.
  • Finite element simulation and experiment on rolling of longitudinal rib plate in wind power tower
    CAO Han, LU Yang-hui, LI Gao-sheng
    Forging & Stamping Technology. 2022, 47(9): 163-167. https://doi.org/10.13330/j.issn.1000-3940.2022.09.024
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    The wind power tower plays an important role in the economic evaluation of wind turbine. Therefore, in order to study the rolling process of the integrally formed longitudinal rib plate, the simulation calculation was conducted by finite element method, and the influence laws of various factors such as rolling process parameters and hole-type parameters on the height of rib were analyzed. Then, rolling experiments of small-sized longitudinal rib plate were carried out, and a batch of longitudinal rib plates with the rib height greater than 2 mm, the base plate thickness of 3 mm, the width of 200 mm and the length of 700 mm were obtained. The research shows that increasing the reduction rate under certain conditions is an effective way to increase the height of rib, too high heating temperature and too long holding time will increase the burning loss, and the increased iron oxide scale will reduce the friction factor, which is not conducive to biting and rib formation. The experimental results are in good agreement with the finite element simulation results, which can provide a theoretical basis for the application of tower with ribs.
  • Discussion on rationality of hot stamping equipment for aluminum alloy sheet
    GAO Jing-zhou, ZHAO Sheng-dun, DU Wei, JIANG Fei, ZHENG Zhen-hao
    Forging & Stamping Technology. 2022, 47(9): 168-173. https://doi.org/10.13330/j.issn.1000-3940.2022.09.025
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    For many problems of narrow hot forming process window, solution treatment, special die and forming equipment for heat-treatable aluminum alloy sheet, through the reference and comparison of hot stamping forming technology of high strength steel plate and combined with the plastic forming properties of hot stamping for aluminum alloy, the rationality of the hot stamping technology for aluminum alloy from the aspects of aluminum alloy material and forming process, hot stamping production line and main stamping equipment were discussed. The problems existing in the current hot stamping technology for aluminum alloy and the core technical requirements for its special hot stamping die were pointed out. In addition, the development statuses of hot stamping equipment at home and abroad were discussed and analyzed, and the main representative machines were listed. Through the discussion on the rationality of the hot stamping forming process and equipment for aluminum alloy sheet, the development trends of the hot stamping technology for aluminum alloy were put forward, which was helpful to the popularization and application of this technology in our country.
  • Research on vibration prediction for tandem cold rolling mill based on EEMD-LSTM
    ZHANG Rui-cheng, CAO Zhi-xin
    Forging & Stamping Technology. 2022, 47(9): 174-181. https://doi.org/10.13330/j.issn.1000-3940.2022.09.026
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    For the characteristics of non-linear and non-stationary for vibration of tandem cold rolling mill, and it is closely related to the current and historical states, based on Ensemble Empirical Mode Decomposition(EEMD)-Long and Short Term Memory Recurrent Neural Network(LSTM), a rolling mill vibration prediction model was proposed. Then, the rolling mill vibration acceleration was decomposed into several IMF modal components and residual components with single frequency and relative stability by the EEMD method, and the complexity of vibration acceleration signal was reduced effectively. Furthermore, the prediction model of rolling mill vibration was established by using LSTM network with memory unit, and the prediction accuracy of rolling mill vibration was significantly improved by introducing historical vibration information. The simulation results show that the prediction accuracy of EEMD-LSTM model is 11% higher than that of LSTM model, and it has a good prediction effect on the rolling mill vibration. Meanwhile, the quantitative relationship between each process parameter and rolling mill vibration is analyzed, which provides a reference for quickly suppressing the rolling mill vibration and optimizing the rolling schedule.
  • Structural design and finite element analysis on multi-station automatic ink-jet device for CNC screw press
    Lü Zong-yang, ZHAO Zhi-you, ZHAO Guo-yong, ZHU Yuan-gang, CHEN Wei
    Forging & Stamping Technology. 2022, 47(9): 182-187. https://doi.org/10.13330/j.issn.1000-3940.2022.09.027
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    The lubrication of mold spraying graphite demoulding agent plays a key role in the forging production process. In the automatic production line of multi-station CNC screw press, the mode of manual spraying graphite demoulding agent often results in uneven spraying and poor spraying effect, which affects the demoulding of workpiece and reduces production efficiency, and makes the automatic production line of forging run poorly. Therefore, combined with the forging process, a multi-station automatic ink-jet device for CNC screw press was designed, which was composed of graphite supply and graphite spraying. Then, the device was driven and controlled by pneumatic transmission and PLC control technology. Furthermore, the device was debugged and verified, and the finite element analysis of universal wheel roller frame in the graphite spraying components was conducted. The experimental results show that the device can realize the controllable quantity and position of ink-jet, uniform ink-jet, simple structure and low cost, and can be popularized in the automatic production line of multi-station CNC screw press.
  • Experimental and numerical simulation study on wear behavior of forming die for automobile front axle beam
    YANG Zi-shuai, WU Bo-ya, LI Qi-ying, LI Jun-wan
    Forging & Stamping Technology. 2022, 47(9): 188-195. https://doi.org/10.13330/j.issn.1000-3940.2022.09.028
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    In order to improve the wear resistance and service life of die, and provide reference for the optimization of die material selection, the high temperature friction characteristic for three types of hot forging die steels including 5 CrNiMo, AISI H13 and SDDM were researched, meanwhile the potential wear failure mechanism was analyzed. According to the high temperature friction wear experiment, the Archard wear model was constructed, then the influences of the key foctors such as die pre-heating temperature, forging rate and die material on the die wear of automobile front axle beam roll-forging was studied by finite element method. The results show that the SDDM steel mainly suffers from abrasive wear, adhesive wear and oxidation wear at 300-500 ℃; compared with 5CrNiMo steel and AISI H13 steel, the wear weight loss and wear rate of SDDM steel at the same conditions are the least, which indicates that SDDM steel has the best high temperature wear resistance. When the die material is SDDM steel, the pre-heating temperature is 150 ℃ and the forging rate is 15 r·min-1, the die wear reaches the lowest level and the maximum wear depth of die is reduced by 48.6%, namely decreasing from 5.7×10-5 mm to 2.93×10-5 mm.
  • Optimization on die structure with high efficient and uniform heat transfer for creep aging of large tank wall panels
    WANG Jian-guang, GONG Ji-xiang, LI Xiao-kai, HU Lan, ZHANG Song, WANG Zi-li, YANG You-liang, XU Ling-zhi, ZHAN Li-hua
    Forging & Stamping Technology. 2022, 47(9): 196-202. https://doi.org/10.13330/j.issn.1000-3940.2022.09.029
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    The heating with high-efficiency and uniformity of die surface has an important influence on the forming efficiency and forming accuracy of creep aging for tank wall panels. Therefore, for the frame die of tank wall panels, the temperature field of die for wall panels during creep aging process was simulated by software Fluent, and according to the data of die temperature field and the verification result of strength, the die structure was optimized in order to improve the high-efficiency and uniformity of die surface heating. The results show that before the optimization of die structure, the temperature field of die presents a stepped distribution, the maximum temperature difference in die surface position is 25 ℃, there is the slowest heating area(SHA), and the die weight is 2414.5 kg. However, after the optimization of die structure, under the condition that the equivalent stress and overall deformation are within a safe range, the heating rate of die is significantly increased, the maximum temperature difference in die surface position is reduced to 15 ℃ with a decrease of 40%, the temperature distribution is more uniform, the slowest heating area disappears, and at the same time, the die weight is decreased by 17%. Thus, this research work provides theoretical support for the optimal design on die with high-efficient and uniform heat transfer for creep aging.
  • Heat treatment process on 45 steel bar prepared by 3D-SPD
    WANG Hang-duo, PANG Yu-hua, SUN Qi, LIU Dong, ZHANG Zhe
    Forging & Stamping Technology. 2022, 47(9): 203-210. https://doi.org/10.13330/j.issn.1000-3940.2022.09.030
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    For the problem of plasticity decrease for Φ25 mm ultrafine grained bar of 45 steel obtained by single-pass intense compression-torsion composite 3 D-SPD rolling, the influence laws of different heat treatment methods on the microstructure and mechanical properties for bar were investigated by four heat treatment methods of annealing, tempering, normalizing and sub-temperature quenching. The results show that after tempering and annealing, the cementite is spheroidized with uniform distribution, the size of particle increases with the increasing of temperature, and the particle size is refined to 400 nm. After normalizing treatment, the size of pearlite clusters and the spacing of lamellar cementite gradually increase with the increasing of temperature. After sub-temperature quenching treatment, dispersing island martensite structure is obtained, and the volume fraction of martensite gradually increases with prolonging of holding time. After annealing, tempering and normalizing, the plasticity of material is obviously improved, after tempering at 600 ℃, the tensile strength and elongation of material are 785 MPa and 23.9% respectively, and the plasticity is increased by about 38%, which shows the best matching effect between strength and plasticity.
  • Influence of local forging and deformation heat treatment process on microstructure and mechanical properties for Hadfield steel frogs
    TANG Tie-bing
    Forging & Stamping Technology. 2022, 47(9): 211-217. https://doi.org/10.13330/j.issn.1000-3940.2022.09.031
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    The core rail and wing rail at the position where the Hadfield steel frog was most likely to fail during the service process were increased by 30 mm by casting technology, and the elevated area of frog was depressed and deformed by the high temperature deformation heat treatment process to make it match the height of the unelevated area. Then, the Hadfield steel frogs were treated by three different processes: immediate water toughening, water toughening after returning to furnace and holding at 1100 ℃ for 7 min, and water toughening after returning to furnace and holding at 1100 ℃ for 25 min. Furthermore, the microstructures for deformed and undeformed areas of the frogs in the three different states were observed, and their corresponding mechanical properties were tested.Results show that the microstructure of the deformed areas for frogsafter local forging and deformation heat treatment is obviously refined, and the mechanical properties are significantly improved. For the studied hadfield steel frogs in the three deformation states, the frogs with water toughening after returing to furnace and holding at 1100 ℃ for 7 min after deformation have the most obvious performance improvement at the top of the deformed area with the tensile strength of 986 MPa and the elongation of 51.1%. Compared with the undeformed area for frogs, they are increased by 34.1% and 46.8%, respectively.
  • Microstructure and performance characteristics on laser cladding layer for Co-based alloy with different B contents
    ZHANG Zhi-bin, SHU Feng-yuan, WANG Hui-peng, ZHU Peng-hua
    Forging & Stamping Technology. 2022, 47(9): 218-223. https://doi.org/10.13330/j.issn.1000-3940.2022.09.032
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    To improve the surface properties of H13 die steel, a layer of Co-based alloy powder was clad on its surface by laser, and the microstructure and mechanical properties of the cladding layer were analyzed. The results show that the microstructure of the cladding layer is mainly composed of Cr2Ni3, Fe2B, γ-Co and Co3B components. With the increasing of B content the crystalline phases of Fe, Cr and Co elements decrease, B compound increases. And from the bottom to the top of the cladding layer, B compound increases. The surfaces of the cladding layer for the samples with the B content of 7% and 19% in the alloy powder have excellent wear resistance property. Under the same wear conditions, the wear rate is low, and the wear type is mainly abrasive wear. However, the cladding layers of the samples with the B content of 11% and 15% are severely worn, and the wear types are mainly adhesive wear + peeling wear + oxidation wear. Furthermore, a large number of pores appear in the cladding layer, which reduce the wear resistance property, increase the friction factor, and increase the wear loss. When the B content is 19%, the cladding layer has a lot of cracks. Thus, comprehensive consideration, when the B content is 7%, the microstructure and performance of the cladding layer are the best.
  • Adiabatic shear behavior and crack propagation mechanism on Ti6242 titanium alloy under high-speed impact loading
    PENG De-ping, LIU Xiao, HE Dan-dan, WAN Bu-yan, CHEN Yang, LIU Wen-hui
    Forging & Stamping Technology. 2022, 47(9): 224-229. https://doi.org/10.13330/j.issn.1000-3940.2022.09.033
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    In order to study the adiabatic shear behavior and crack propagation mechanism of Ti6242 titanium alloy under different impact loading, the impact test with average impact strain rate of 3069-11337 s-1 at room temperature was carried out by split Hopkinson Bar technique. Then, the adiabatic shear behavior in microstructure was analyzed by optical microscope, and the crack nucleation and propagation model was established. The results show that the impact strength of Ti6242 titanium alloy is not sensitive to average impact strain rate, and the plasticity displays an increasing trend with the increasing of the average impact strain rate. The number of adiabatic shear bands increases with the increasing of the average impact strain rate, and α/β phase in lamellar distribution hinders the propagation of adiabatic shear band, resulting in the bifurcation phenomenon of adiabatic shear bands. Under the high-speed impact loading, the pores nucleate, grow and merge in the adiabatic shear band, and finally form micro-cracks, which continue to expand by merging with the front-end holes to form macro-cracks, resulting in fracture failure of material.
  • Thermal deformation behavior of 17Cr2Ni2MoVNb and 20Cr2Ni4A gear steels
    DONG Ming-zhen, YAN Yong-ming, OUYANG Xue-mei, YUAN Wu-feng, YANG Ren-qi, YANG Shao-peng
    Forging & Stamping Technology. 2022, 47(9): 230-237. https://doi.org/10.13330/j.issn.1000-3940.2022.09.034
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    The thermal deformation behavior of 17Cr2Ni2MoVNb and 20Cr2Ni4A gear steels were studied by Gleeble-3800 thermal simulation test machine, respectively, and the thermal deformation activation energy for the two kinds of gear steels was calculated to construct the constitutive equation by the work hardening curves. The results show that the two kinds of gear steels exhibit obvious dynamic recrystallization at low strain rate, while at high strain rate, 20Cr2Ni4A steel exhibits dynamic recovery at 1000 ℃ and 17Cr2Ni2MoVNb steel exhibits dynamic recovery at 1000-1150 ℃. Under the same deformation conditions, the peak stress and critical stress of 17 Cr2Ni2MoVNb steel are higher than those of 20Cr2Ni4A steel, and the thermal deformation activation energy of 17Cr2Ni2MoVNb and 20Cr2Ni4A steels are 374 and 324 kJ·mol-1, respectively. The difference between the stress characteristic values and the thermal deformation activation energy between the two kinds of gear steels is mainly due to the different contents of Ni, Mo and Nb, which have different effects on dynamic recrystallization. At low strain rate, the optional deformation temperature for the two kinds of gear steels is the same, while at high strain rate, the processing temperature of 17Cr2Ni2MoVNb steel can be selected to be more than 100 ℃ higher than that of 20Cr2Ni4A steel.
  • Development and property study of low Mo refractory steel for high-rise building
    GENG Cheng, MA You-su-fu, DONG Rui-hua
    Forging & Stamping Technology. 2022, 47(9): 238-244. https://doi.org/10.13330/j.issn.1000-3940.2022.09.035
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    In order to improve the comprehensive properties of low Mo refractory steel, the effects of alloying element content and cooling method on the microstructure and mechanical properties for low Mo refractory steel were studied. The results show that M2 refractory steel with low Mo, X1-H and X2-H refractory steels with low Mo+low(Nb+V+Ti) have high strength-plasticity, low yield ratio and good refractory properties(the ratio of yield strength at 600 ℃ to yield strength at room temperature is more than 2/3). The microstructure of air-cooled refractory steel is ferrite, pearlite and a small amount of bainite, and the microstructure of water-cooled refractory steel is bainite and ferrite. The volume fractions of bainite in air-cooled M1,M2 and X1 steels are smaller than that in water-cooled X1-H and X2-H steels, while the ferrite grain size of air-cooled refractory steel is significantly higher than that of water-cooled refractory steel. The addition of trace(Nb+V+Ti) can play the roles of the second phase strengthening and the bainite transformation strengthening, which can effectively compensate for the high temperature strengthening effect of Mo on the refractory steel. Finally, it is determined that when the final rolling temperature is 885 ℃ and the cooling mode is water-cooling, the X2-H steel has the best comprehensive performance.
  • Influence of strain on in-situ tensile microstructure evolution for automotive extruded Mg-4Zn-1.2Y alloy
    YANG Jing-jiang, ZHANG Ming, LI Gang
    Forging & Stamping Technology. 2022, 47(9): 245-249. https://doi.org/10.13330/j.issn.1000-3940.2022.09.036
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    The test of Mg-4Zn-1.2Y alloy for auto mobile lightweight was conducted by comprehensively using in-situ electron backscatter diffraction(EPD) and micro-tensile test methods, and the influence of strain on the in-site tensile microstructure evolution for alloy was analyzed. The research results show that the tensile strength of specimen is 218 MPa, the elongation is 25.3% obtained by in-situ tensile test, and the specimen breaks at the strain of 26%. With the increasing of tensile strain degree, more cracks occur in the alloy and the crack size increases. The twins produced in the tensile process can coordinate the grain deformation to a certain extent to eliminate the stress concentration phenomenon and avoid the crystal structure cracking. When the grain orientation angle of initial tensile specimen is in the range of 0°-50°, the quantitutive distribution of grain orientation angles is close to normal distribution characteristic, and the grain orientation angle is mainly in the range of 20°-30°. When the strain reaches 20%, the proportion of orientation angles in the range of 20°-30° is more than 10%, and the twinning produced in Mg-4Zn-1.2Y alloy under the in-situ tensile strain of 15% plays a good role in regulating grain orientation.
  • Microstructure evolution and mechanical properties on Mg-Li alloy in multiaxial compression
    ZHU Song-qi, ZHANG Jin-long, SHEN Hui, ZHANG Qi-ming, XU Qiang, YANG Hong-zhao, GUO Qin
    Forging & Stamping Technology. 2022, 47(9): 250-255. https://doi.org/10.13330/j.issn.1000-3940.2022.09.037
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    The microstructure of multiaxial compression for Mg-Li alloy at room temperature was characterized by OM, SEM and XRD, and the evolution of microstructure and the change of mechanical properties during multiaxial compression deformation process were analyzed. The results show that Mg-Li alloy is composed of five phases of α-Mg, β-Li, fibrous Mg17Al12, granular MgLiAl2 and spherical AlLi. During compression, β-Li phase first produces slip and forms dislocation plugging, and the grain boundary is broken through and gradually disappears, the increasing of cumulative strain triggers the activation of α-Mg phase slip surface, and α-Mg phase and β-Li phase are continuously fused at the phase interface, even integrated. Mg17Al12 phase is divided into short fibers or small particles, and MgLiAl2 phase gradually loses its straight arrangement and is finally evenly distributed in β-Li phase. The hardness increases with the increasing of deformation degree, which is significant in the initial and later stages, and gentle in the middle stage. When the cumulative strain reaches 15.8, the hardness increases by 19.8%. The elongation of Mg-Li alloy can also be greatly improved while the deformation is strengthened. When the cumulative strain is 6.22, the tensile strength of the alloy is increased by 35%, and the elongation is increased by 82%.
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