25 September 2023, Volume 48 Issue 9
    

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  • Improvement and optimization on upset-extrusion forming process for bottom step of new energy battery shell based on DEFORM-3D
    Sun Rumeng, Zhou Liju, Si Daqiang, Huang Yao, Wang Leigang
    Forging & Stamping Technology. 2023, 48(9): 1-6. https://doi.org/10.13330/j.issn.1000-3940.2023.09.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For the new energy battery shell of 4680 series, in order to ensure the sealing effect, an upset-extruded step structure was designed at the bottom of battery shell, and after the process test verification, the forming of bottom step required a three-step process of prepunching of bottom hole, forging and fine-punching of bottom hole. Then, aiming at the problem of burrs in one-time forming of the bottom step, an improved process of first forging and then shaping was proposed based on the original process, and the forming effect and load change of the bottom step structure in the two different process schemes were analyzed by software DEFORM-3D. Furthermore, since the diameter of prefabricated hole had a great influence on the subsequent fine-punching hole, three prefabricated holes with different diameters were designed and numerically simulated, and according to the forming law and load change as well as the forming requirements of the bottom prefabricated hole, the comparison and analysis were conducted to choose the best prefabricated hole diameter. The results show that the improved process of first forging and then shaping is beneficial to reduce the mold load and make the forming effect of the step structure better.When the prefabricated hole diameter is Φ8.5 mm, the load is smallest, which is more conducive to the subsequent fine-punching process.Finally, the rationality of the optimization results and the improved process are verified by actual production.
  • Analysis and finite element simulation on quenching cracking for automotive high-strength steel forgings
    Chen Rongchuang, Lyu Jiajun, Deng Qingwen, Tao Peng, Zhang Yunjun
    Forging & Stamping Technology. 2023, 48(9): 7-14. https://doi.org/10.13330/j.issn.1000-3940.2023.09.002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    High-strength steel forgings for an automobile face the problem of quenching cracking in production, and it is urgent to trace the cause of cracking from the production process. Therefore, the high-strength steel forgings after quenching for an automobile were dissected, and the crack morphology, metal streamlines, microstructure and element distribution were observed. Then, it was found that the material flow at the fracture was extremely uneven, and the severe slip and shear during the forging deformation were the main causes of cracking. Furthermore, the quenching process of an automotive SAE5137H high-strength steel forgings for an automobile in PAG quenching liquid with the mass fraction of 9% (water-based quenching medium containing 9% polyalkylene glycol)was simulated, and it was found that the maximum equivalent stress at the location of quenching cracking was much lower than the tensile strength of material, the quenching stress is low. Comprehensive crack analysis test result and finite element analysis result show that the material flow is not uniform during the forging process of forgings, and severe slip occurs locally, which reduces the plasticity of material. Although there is no direct cracking after forging, the lack of plasticity under the action of quenching thermal stress leads to cracking. According to the reason of cracking, by reducing the local die fillet of pre-forging mold cavity at cracking position A to R8 mm, and local heating at position B of the forgings, the quenching cracking ratio of the forgings is significantly reduced, and the cracking problem is solved.
  • Research on forging process and optimization on die structure for an automotive flange part
    Song Zhifeng, Lu Yunjie, Ma Lei, Zhu Jie
    Forging & Stamping Technology. 2023, 48(9): 15-22,48. https://doi.org/10.13330/j.issn.1000-3940.2023.09.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to solve the problems of low efficiency, low material utilization, high production cost and poor product performance in the traditional manufacturing process of an automotive flange part, a three-station hot die forging process was designed, which consists of preforming, pre-forging and final forging in sequence. Then, to ensure the process quality, the forming process of flange part was simulated by software Deform-3D, and the hidden defects in the process were determined based on the metal deformation process. Furthermore, the pre-forging die structure was optimized, and two improvement schemes were proposed. At the same time, the forming inspection was carried out in turn, and the temperature distribution of final forgings, the forging force of pre-forging and final forging stations, and the die wear conditions of the two improved schemes were compared. The results show that the improved process solves the forging defects, and the improvement scheme 2 is more helpful to improve the quality of flange forgings and prolonging the life of die. Finally, hot die forging tests of flange parts are carried out, and the expected flange parts are obtained, which effectively solves the current problems.
  • Research and application on near net forming process for automobile transmission shaft bushing
    Gao Lin, Shi Haihong, Ren Yan
    Forging & Stamping Technology. 2023, 48(9): 23-31. https://doi.org/10.13330/j.issn.1000-3940.2023.09.004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to solve the problems of low production efficiency and high cost in the cutting of an automobile transmission shaft bushing, two new machining processes were designed according to its structural characteristics and plastic forming theory, namely, the billet was made by cold heading firstly, and then the final forming was completed by a small amount of cutting, which increased the material utilization rate from 26.9% to 86.1%. Then, the forming of the cold heading part for the two processes was simulated by finite element software Deform-3D, respectively, the feasibility of the two processes was evaluated, and the equivalent stress, forming force and damage value of each station for the two processes were compared. The results show that the two processes can meet the forming requirements and obtain the expected billet parts. When the scheme 2 is adopted, the distributions of equivalent stress and damage values are better and the required forming force is smaller, which is beneficial to improve the quality of billet part and reduce the mold shock. Finally, the scheme 2 was applied to the machining of the shaft bushing, and production experiments were completed. The final billet part is well formed without defects, which is similar to the simulation results. After a small amount of final cutting, the size of shaft bushing fully meets the requirements, and compared with the previous process, the efficiency and cost are significantly improved.
  • Forging process optimization and process simulation analysis on disc steering knuckle
    Qi Yi, Xue Xiyun, Jiao Fei, Yang Junhuang, Yu Zhen, Yang Jianquan
    Forging & Stamping Technology. 2023, 48(9): 32-40. https://doi.org/10.13330/j.issn.1000-3940.2023.09.005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    During the forging process of a certain type of automobile disc steering knuckle, there are quality problems such as high crack rate of 10.00% and high scrap rate of 7.36%. After analysis, due to the design defects of the original forging process, defects such as forging folds, cracks and insufficient filling of mold cavity are prone to occur. Therefore, it was necessary to carry out forging process optimization, including forging process analysis, drawing of forgings diagram, equipment tonnage selection, forging process step optimization, blank design and selection, hot forging mold optimization design, etc. Then, two groups of process optimization schemes were designed, scheme 1 was blanking (size of Φ150 mm×280 mm)-upsetting (upsetting amount of 20 mm)-pre-forging (material section placed horizontally in the cavity)-final forging-trimming, and scheme 2 was blanking (size of Φ150 mm×280 mm)-upsetting (upsetting amount of 50 mm)-pre-forging (material section placed vertically in the cavity)-final forging-trimming. Furthermore, combined with the finite element process simulation, the simulation quality results of the two process schemes were compared and analyzed, and the process schemes were optimized. The comparison between results of process simulation and small batch trial production verification proves that the quality of the products obtained by the two groups of process optimization schemes improves compared with the original production process. The effect of scheme 2 is better, and the scrap rate after forging is reduced from about 7.36% of the original production process to about 1.01%, which is given priority. Compared with the actual trial production results, the process simulation results are basically consistent with the actual situation, which is credible. Finally, an ideal process scheme is proposed as a research direction of mass production development and breakthrough of forging technology in the future.
  • Modeling algorithm on complex fillets in die surface engineering of automobile covering panels
    Zhang Afei, Liu Yuqi, Zhang Zhibing, Wang Zhen
    Forging & Stamping Technology. 2023, 48(9): 41-48. https://doi.org/10.13330/j.issn.1000-3940.2023.09.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The existing fillet modeling algorithms are suitable for a single scene, and when modeling in complex areas, there are problems of low stability and poor modeling surface quality, which affects the design efficiency and overall quality of die surface. So it is necessary to study an efficient and stable fillet modeling algorithm to improve the design quality and shorten the development cycle. Therefore, a complex fillet modeling algorithm based on section curve rounding was proposed to achieve the stable creation and flexible editing of free fillet surface, and the algorithm converted the complex surface rounding into the section curve rounding, which significantly reduced the complexity of the algorithm. Then, through the section curve interference inspection algorithm, the self-intersection areas of section curve were searched and reconstructed to ensure the stability and quality of the constructed fillet. Furthermore, based on the custom object technology of NX platform, the fillet modeling function was developed, which realized the high efficient creation and stable updating of the fillet surface. The results of the actual automobile covering panel model test prove that the proposed algorithm is stable and reliable, with high editing efficiency and rich adaptation scenarios, which effectively improves the efficiency of designers and shortens the product development cycle.
  • Influence of pre-forming amount on forming quality of parts in indirect hot forming
    Tang Ziming, Gu Zhengwei, Li Yi, Li Xin, Yu Ge
    Forging & Stamping Technology. 2023, 48(9): 49-55. https://doi.org/10.13330/j.issn.1000-3940.2023.09.007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to better grasp the indirect hot forming technology, for 22MnB5 steel material, the indirect hot forming processof boxshaped parts was studied by combining two methods of numerical simulation and experiment, and the influence of pre-forming amount on the forming quality of parts and the design principles of pre-forming amount were discussed. The results show that in indirect hot forming, when the stamping stroke is used as the designed reference object of the pre-forming amount, the box-shaped parts satisfy the law that the maximum thinning rate gradually decreases with the increasing of the pre-forming amount, and when the pre-forming amount is ≥ 90%, the part formability is better and the thickness distribution is more uniform. For the indirect hot forming, the role of the final forming is more about shaping and forming local features of pre-formed sheet. In addition, different pre-forming amounts do not have a significant effect on the mechanical properties of part.
  • Stamping process optimization on automobile stainless steel plate based on scoring function
    Wang Ya
    Forging & Stamping Technology. 2023, 48(9): 56-63. https://doi.org/10.13330/j.issn.1000-3940.2023.09.008
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    For a stainless steel plate for automobile, considering the problems of production efficiency and cost, a stamping process of onedie producing two-piece was designed, and in order to improve the forming quality and reduce the stamping force, the stamping process of stainless steel plate was studied by numerical simulation technology. Then, taking the minimum thickness, the maximum thickness and the maximum stamping force of plate as the inspection indexes, the scoring function was established, and the forming effects of integral blank holder with constant blank holder force, zonal blank holder with constant blank holder force and zonal blank holder with variable blank holder force were compared. The results show that the integral blank holder with constant blank holder force mode has a greater risk of cracking and wrinkling, and cannot obtain the plate that meets the size requirements, while the zonal blank holder mode can effectively avoid the risk of cracking and wrinkling, and the variable blank holder force loading mode is better which requires a smaller stamping force in the forming. Finally, the forming test of stainless steel plate was carried out by using zonal blank holder with variable blank holder force mode, and the plate without defects such as cracking and wrinkling was obtained to verify the effectiveness of the process.
  • Prediction of cold heading punching force and optimization of punch structure parameters for superalloy A286 thin-walled pipe fittings
    Mo Ningning, Feng Zhiguo, Tao Liang, Jiang Yulian, Wang Chengmin
    Forging & Stamping Technology. 2023, 48(9): 64-70. https://doi.org/10.13330/j.issn.1000-3940.2023.09.009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The prediction of punching force and optimization of punch parameters of thin-walled pipe fittings are important issues to be considered in the punching process. Therefore, the punching process of thin-walled pipe fittings was numerical simulated by software DEFORM, and the influence degrees of front angle A of punch, fillet radius r and punching clearance C on the maximum punching force Fmax were analyzed by using the range analysis. Then, the BP neural network model was established to predict the maximum punching force in the punching process of thin-walled pipe fittings, and the correlation coefficient R reached 0.97608. Furthermore, minimizing the maximum punching force in the punching process as the optimization objective, the genetic algorithm was used to optimize the punching structural parameters, such as front angle A of punch, fillet radius r and punching clearance C, and the optimum punching structural parameters were obtained that the front angle A of punch was 12.8°, the fillet radius r was 0.2 mm and the punching clearance C was 0.12 mm.Finally, based on the simulation experiments, the optimized punch structural parameters were verified to be accurate, which provides a basis for the optimization on the punching process of thin-walled pipe fittings and the selection of punch structural parameters.
  • Optimization on upsetting process for superalloy A286 thin-walled tube
    Lei Xiaoye, Jiang Yulian, Feng Zhiguo, Tao Liang
    Forging & Stamping Technology. 2023, 48(9): 71-80. https://doi.org/10.13330/j.issn.1000-3940.2023.09.010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A study was conducted to investigate the occurrence of folding, incomplete filling and flashing during the thin-walled characteristic upsetting process of superalloy A286 thin-walled tube, and two material flow modes, namely forward extrusion and reverse extrusion, were proposed. Then, the forming processes were numerical simulated by finite element software Deforn-3D, respectively, and a comparative analysis was performed to assess the forming effects, equivalent stress, equivalent strain, streamline and material flow law during the forming process of the two upsetting processes. The numerical simulation results indicate that compared with the reverse extrusion, the stress concentration of the forward extruded parts is obvious, the streamline is disorderly, and it is accompanied by obvious defects, so it is more reasonable to adopt the reverse extrusion upsetting process. The upsetting experimental results show that the parts formed by the reverse extrusion upsetting process have good geometric characteristics, and there are no defects such as incomplete filling, folding and flashing. The experimental results are consistent with the numerical simulation results.
  • Product and process development on hydroforming structure rear sub-frame for a certain vehicle
    Liu Ning, Feng Jinghui, Li Huan, Zhou Liang, Wang Yuqi
    Forging & Stamping Technology. 2023, 48(9): 81-88. https://doi.org/10.13330/j.issn.1000-3940.2023.09.011
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    In order to realize the lightweight and low-cost design of passenger vehicle chassis sub-frame, based on the punching and welding structure of rear sub-frame for a certain vehicle, the hydroforming structure rear sub-frame was newly developed, and the finite element simulation technology of product was used to verify that the durability and strength of the hydroforming structure rear sub-frame meet the requirements. Then, for the hydroforming longitudinal beam, a low-cost process design method which realized one die producing two S-typed pieces was proposed to improve the manufacturing efficiency, and the material utilization rate was increased from 91.0% to 93.5%. Furthermore, the finite element simulation technology of process forming was used to verify the good manufacturability of the one die producing two S-typed pieces for hydroforming longitudinal beam, the maximum thinning rate was 18.0% to meet the requirements, and the whole process scheme was formulated. Finally, the design of structure lightweight, low-cost and manufacturability were driven by the finite element simulation technology of product and process, and the cost difference between the two structures was evaluated in detail by the cost model. The results of the trial production of assembly sample and the assembly bench test show that the feasibility of the product and process development for hydroforming structure rear sub-frame is verified, the weight reduction is 15.1%, and the manufacturing cost is reduced by 15.8%.
  • Extrusion process on 20MnCr5 steel thin-walled shell based on numerical simulation
    Wang Yong, Ni Zhibing
    Forging & Stamping Technology. 2023, 48(9): 89-97. https://doi.org/10.13330/j.issn.1000-3940.2023.09.012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For a complex thin-walled shell, in order to solve the problem of large amount of material removal and serious waste in cutting production and realize the near net forming, a new process scheme of multi-station extrusion combined with a small amount of cutting was proposed, and the material utilization rate increased from 35.49% to 90.54%. Then, the blank-making processes of three different cold extrusion schemes were numerically simulated by software Deform-3D, and the filling effect of parts, streamline state, extrusion force and equivalent stress were compared in an all-round way. The results show that when the scheme 1 is adopted, not only the defects are effectively controlled, but also the forming quality of parts at each station is better, the filling is full, and the maximum extrusion force is also smaller. Finally, the on-site extrusion test was carried out, and the test results are consistent with the simulation test results. All the thinwalled shells are fully filled, the formed appearance is good without defects such as scratches and cracks, and the dimensional test results are within the required range.
  • Change law on composite thickness ratio in electrically assisted rolling for stainless steel/carbon steel
    Lin Jibin, Ruan Jinhua, Zhang Hongyu, Xiang Boyang
    Forging & Stamping Technology. 2023, 48(9): 98-107. https://doi.org/10.13330/j.issn.1000-3940.2023.09.013
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The electrically assisted rolling process of stainless steel/carbon steel was simulated by the finite element method, and the current field, temperature field and metal flow law were analyzed. Then, the influences of initial thickness ratio, reduction ratio, current density and rolling speed as single variables on the composite thickness ratio of stainless steel/carbon steel composite plate were studied.The results show that when each factor acts alone, reducing the initial thickness ratio, reducing the reduction ratio, increasing the current density and increasing the rolling speed can all reduce the composite thickness ratio. But when all factors act, reducing the reduction ratio can increase the current density on stainless steel plate, thus increasing its temperature and reducing the composite thickness ratio. The initial thickness ratio has the greatest effect on the composite thickness ratio, followed by the current density, and finally the reduction ratio and the rolling speed.
  • Numerical simulation on internal void closure behavior in reciprocating rolling process for generous square billet
    Yang Qing, Zhang Liwen, Zhang Chi, Ding Haochen, Luo Yalong
    Forging & Stamping Technology. 2023, 48(9): 108-112. https://doi.org/10.13330/j.issn.1000-3940.2023.09.014
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    The void is one of the unavoidable defects in the square billet. Due to the larger size of the generous square billet, the closing process of void is very difficult. Therefore, the thermal-mechanical coupling model of rolled parts with void in the rolling process was established by finite element software Deform, and the local subdivision of mesh for the void part was conducted to mainly simulate the void closure behavior in reciprocating transverse rolling process. By simulating the evolution conditions of the void with the diameter of Φ9-Φ12 mm, it is found that the smaller the void is, the easier it is to close. In addition, by analyzing the evolution laws of the void at different positions, it can be known that the closer to the surface of rolled parts, the greater the impact of rolling force on the void closure.When the void is close to the surface, the void closure is not only affected by the rolling force, but also by the temperature. The voids at a distance of 102 mm from the centerline are closed quickly when the equivalent strain is less than 0.3, and when the equivalent strain is greater than 0.3, the voids are closed slowly due to the decreasing of temperature around the voids. In summary, reducing the number of steel transfers, increasing the rolling force and controlling the temperature of rolled parts are beneficial to the void closure in the reciprocating rolling process of generous square bille.
  • Research and simulation prediction on crack propagation behavior for cast aluminum self-piercing riveting joints
    Hu Xiaoya, Huang Li, Chen Qiuren, Zhang Jingyi, Tan Guobi, Zhang Yongfa, Han Weijian, Wang Xianhui
    Forging & Stamping Technology. 2023, 48(9): 113-118,141. https://doi.org/10.13330/j.issn.1000-3940.2023.09.015
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the crack propagation behavior of cast aluminum in self-piercing riveting process, for a self-piercing riveting joint composed of 5754 aluminum plate and Aural2 cast aluminum, the location of the crack in joint profile and the morphology of crack were approximately restored by interrupted experiments. Then, the crack propagation mechanism of cast aluminum material inside the joint during the self-piercing riveting process was discussed, and the simulation and analysis was conducted to predict the geometric morphology and crack. The results show that there are two main locations where the cracks of cast aluminum self-piercing riveting joints occur, one is located on the side where the bottom surface of the self-piercing riveting joint is in contact with the mold, and the cracks occur when the rivets just contact the lower plate, and increase as the rivets are pressed in. The other is on the cast aluminum material of the lower plate where the rivet legs interlock with the upper and lower plates, and the cracks occur during the interlocking process and continue to grow as the rivets are pressed down. The riveting simulation model based on GISSMO damage failure is established, the morphology and contour of the simulation results are consistent with the geometric morphology of the test section profile, and the unit damage is consistent with the joint crack, which can accurately predict the geometric morphology and crack location of the joint profile.
  • Forming quality and static mechanical properties for self-piercing riveted joints of DP590 steel and AA6061 aluminum alloy
    Jia Yinglian, He Shisong, Li Xiaoyang
    Forging & Stamping Technology. 2023, 48(9): 119-129. https://doi.org/10.13330/j.issn.1000-3940.2023.09.016
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To investigate the forming quality and static mechanical properties for self-piercing riveted (SPR)joints of DP590 steel and AA6061 aluminum alloy, the simulation of self-piercing riveting was conducted by the finite element software Simufact Forming, and the self-piercing riveting test verification was conducted by using self-piercing riveting equipment. Then, the static tensile tests were also carried out on the joints.The results show that when the stacking order of connecting sheets is the same, the forming quality of joint has a better changing trend as the rivet leg length increases within a certain respectively range. When the rivet leg length is the same, the self-locking length of the joint whose upper and lower connecting sheets are DP590 steel and AA6061 aluminum alloy respectively is greater than the self-locking length of the joint after the stacking order is interchanged. When the rivet leg length is 6.0 mm, the self-locking length of group No.2 point is greatest. The stacking order of the connecting sheets is the most important factor affecting the self-locking length of the joints, and the finite element simulation result is consistent with the test verification result. The maximum static load values of group No.2 and No.3 joints are greater than those of group No.2E and No.3E joints, respectively, and group No.2 joint has the best tensile resistance. The self-locking length is the most important parameter affecting the static mechanical properties of the joints. From the macroscopic morphological observation, the tensile failure mode of the joints is self-locking failure, and from the microstructure of the typical tensile failure fracture, it is found that the fracture of the upper connecting sheet has a dimple structure and there are a large number of micro-particles in the self-locking area of the rivet hole on the lower connecting sheet, this is because that a serious fretting wear in the self-locking area when the self-piercing riveted joint fails in tension.
  • Simulation study on temperature field for WC 12Co composite material by selective laser melting
    Xie Yingxing, Jiang Wuji, Wu Shengfu
    Forging & Stamping Technology. 2023, 48(9): 130-141. https://doi.org/10.13330/j.issn.1000-3940.2023.09.017
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    To improve the forming quality of WC 12Co hard composites material by selective laser melting (SLM), the numerical simulation study of the temperature field in the forming process of WC 12Co hard composites material by SLM was conducted by finite element simulation software Ansys 2021R1, and the temperature distribution in the forming temperature field and the influences of forming process parameters (laser power, scanning speed, scanning spacing and substrate preheating temperature)on the temperature field were studied, which provided experimental basis for optimizing the forming of WC 12Co hard composite material. The results show that with the increasing of laser power, the temperature of forming area increases, and the peak temperature of position point 3 increases from 3507.47℃ to 3837.52℃.With the increasing of laser scanning speed, the temperature of forming area decreases, the peak temperature of position point 5 decreases from 3592℃ to 2897℃, and the peak temperature decreases by 695℃. With the increasing of scanning spacing, the temperature of each scanning area decreases, and the peak temperature of position point 3 gradually decreases from 3330℃ to 3123℃. Under the same forming process parameters, the former path of laser scanning has a pre-heating effect on the latter path, and with the increasing of scanning path, the temperature of forming area shows a gradual upward trend. Pre-heating the substrate to 120℃ can increase the internal temperature of molten pool, reduce the temperature difference between the formed parts, and reduce the temperature gradient difference. When the laser power increases, the width and depth of molten pool increase, and when the laser scanning speed increases, the width of molten pool first increases and then decreases, and the depth of molten pool decreases linearly and reversely. With the increasing of scanning spacing, both the width and depth of molten pool decrease. The temperature field simulation conclusion obtained by simulation can roughly reflect the change trend of the surface quality of formed samples and the melting state of alloy powder with the forming process parameters.
  • Study on performance of hydraulic buffer device for forging manipulator
    Chen Kejie, Liu Yanyan, Zhang Qiliang, Wang Zhiqiang
    Forging & Stamping Technology. 2023, 48(9): 142-148,183. https://doi.org/10.13330/j.issn.1000-3940.2023.09.018
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    The structural characteristics and buffering principle of hydraulic buffer device commonly used in forging manipulator were introduced, and according to the flow continuity equation and Bernoulli equation, combined with the force changes of two-way buffer cylinder and accumulator, the relationship for the external loads of the two-way buffer cylinder at any time was obtained. Then, the hydraulic buffer device was simplified into a stiffness-damping system, and the mathematical model of dynamic stiffness and dynamic damping for buffer device was obtained through differential derivation. Furthermore, the influences of initial inflated pressure and initial inflated volume of accumulator and stroke of buffer cylinder on the stiffness of buffer device, and the influence of oil chamber ringshaped cross-sectional area of buffer cylinder and cross-sectional area of damping hole on the damping were analyzed by Matlab. Finally, based on genetic algorithm (GA), the initial inflated volume and the initial inflated pressure of accumulator in the buffer device were optimized to obtain a group of Pareto non-inferior solution set, and the Pareto non-inferior solution set was optimized based on the ideal solution sorting method to obtain the best matching scheme of the initial inflated pressure and the initial inflated volume of accumulator for the buffer device.
  • Automation transformation on aluminum profile production process
    Gao Shengyun, Jiang Kaiyu, Bai Jingfang
    Forging & Stamping Technology. 2023, 48(9): 149-155. https://doi.org/10.13330/j.issn.1000-3940.2023.09.019
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    At the present stage, there are common problems such as poor working environment, low production efficiency and many safety hazards in aluminum profile production enterprises in China. Therefore, in order to improve the extrusion production efficiency of aluminum profile and reduce the labor cost of enterprise, the actual process flow of aluminum profile extrusion forming production process for small and medium-sized aluminum profile enterprise was analyzed. Then, compared with the current situation of enterprise and the existing technology, the coordinate mechanical arm, positioning mechanism for stretching and straightening, feeding mechanism for fixed-length sawing, positioning mechanism for automatic framing and spacer were designed to replace the manual operation, and the relevant mechanisms of the production line were adjusted and optimized. The results show that the redesigned and optimized production line reduces six labor without greatly changing the existing production layout, ensuring the stability and reliability of the production process, and improving the production efficiency. The kinematics simulation of the main functional modules is verified by Adams, and the rationality of the mechanical structure is verified at the theoretical level.
  • Dynamic characteristics of blade rolling mill transmission system driven by hydraulic cylinder
    Zhang Yu, Hou Lyuyuan, Zhao Fei
    Forging & Stamping Technology. 2023, 48(9): 156-167. https://doi.org/10.13330/j.issn.1000-3940.2023.09.020
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    In order to analyze the influence of nonlinear dynamic characteristics for hydraulic cylinders on the vibration of transmission system for blade rolling mill, the coupled vibration model of hydraulic cylinder and transmission system for blade rolling mill was established. Considering the elastic deformation of rack matrix under load effect, the time-varying meshing stiffness of secondary gear-rack for upper roll was derived. The Runge-Kutta method was used to obtain the dynamic characteristics of system. The effect of parameters such as initial effective length of rodless cavity and meshing stiffness of gear-rack on the dynamic characteristics of transmission system for rolling mill were studied. The results show that the increasing of the initial effective length of rodless cavity causes the system to gradually move from periodic motion to multiplier motion, and eventually to chaotic motion. Besides, the meshing stiffness of gear-rack causes the fluctuation for vibration displacement of primary gear and secondary gear-rack of upper roll at the initial moment, and has less effect on the movement state of primary gear of lower roll.
  • Design on automatic stamping system for flat top chain plate
    Liu Shuqing, Sun Jian, Wang Xiaomin, Wang Yongming
    Forging & Stamping Technology. 2023, 48(9): 168-176. https://doi.org/10.13330/j.issn.1000-3940.2023.09.021
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    In order to improve the accuracy and production efficiency of flat top chain plate, according to the stamping process and production efficiency requirements of flat top chain plate, a multi-station automatic stamping system was designed, including the design of stamping die structure and feeding system, and the design of stamping die structure included the structural design of pre-bending die, bending die and rolling die. Then, the stamping simulation was carried out by finite element analysis software ABAQUS to improve the die size and the forming accuracy of chain plate, and the design of feeding system included the structural design of storage device, automatic feeding device and selection of related equipment. In order to realize the automatic stamping production, the automatic feeding device adopted a three-degree-of-freedom cross-bar structure. Furthermore, the prototype production and experiments were completed, the qualified rate of the trial produced flat top chain plate reached 97.83%, and the production efficiency reached nine pieces per minute. The result shows that the designed automatic stamping system for flat top chain plate meets the production accuracy and production efficiency requirements of chain plate.
  • Research and design on split blanking and shearing system
    Li Gang, Li Xiaobo, Zhu Shanshan, Si Jianxi, Nan Wenhu, Wang Youliang
    Forging & Stamping Technology. 2023, 48(9): 177-183. https://doi.org/10.13330/j.issn.1000-3940.2023.09.022
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    In order to solve the problem of using multiple sets of cutting tools when cutting the same series of plates with different widths, a split shearing device that could adapt to cutting plates with various widths was studied to solve the problems of multiple cutting tools and frequent tool replacement caused by traditional shearing modes, and the split shearing system was studied by the method of combining the oretical design calculation with test. Then, a three-dimensional model of split shearing device was established, and the strength and stiffness of critical structural components were analyzed and calculated. Furthermore, according to the function and action requirements of cutting tool, the corresponding high and low pressure hydraulic system and electrical protection device were designed. On the manufactured test machine, the various functional action indicators and production efficiency of the system were tested, and the shearing quality of cut ting tool was tested. The test results show that the split shearing system realizes the function of using a pair of cutting tool to cut plates with various widths, and its production efficiency and shearing quality meet the design requirements.
  • Development on monitoring system for stamping receiving line based on visual inspection technology
    Shi Lei, Wang Jianyu, Sun Shengwei, He Guijin, Zhang Hongjie, Zhao Shaoxin
    Forging & Stamping Technology. 2023, 48(9): 184-189. https://doi.org/10.13330/j.issn.1000-3940.2023.09.023
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    In the traditional production mode, the stamping production of automobile body panels is carried out on the closed production line, and the stamping receiving line cannot be monitored in real time during the production process. Therefore, a monitoring system for the stamping receiving line was built by the visual non-contact detection technology combined with image AI algorithm, and the six highspeed lenses arranged inside the production line were triggered by the signal of production line press to take pictures and automatically perform template matching with the reference image, which could realize the real-time monitoring of receiving line in different areas of drawing parts in the environment of strong vibration and high beat, output the deviation values of receiving lines in eighteen monitoring areas, and give early warning to the parts exceeding the set threshold. Then, the production and maintenance personnel could adjust the pressure values in the corresponding area according to the curve deviation without stopping the machine, and the waste and return rates of parts for production line and the loss of shutdown efficiency were greatly reduced. The result shows that after the system is put into operation, it is expected to save 260000 yuan in annual waste and return parts and 90000 yuan in shutdown efficiency.
  • Movement balance criterion and optimization on automobile cover panel die
    Cao Biao, Qiao Xiaoyong, Xu Bingfeng, Qin Ce
    Forging & Stamping Technology. 2023, 48(9): 190-196. https://doi.org/10.13330/j.issn.1000-3940.2023.09.024
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    For the deflection problem occurred in the upper die of tailgate inner and outer panel closing die for a certain project during the process of disassembling the die, the mutual motion relationship between upper die and slider of press and the torque on both sides of the upper die were analyzed in detail. It was found that the fundamental reason for the deflection of the upper die was the obvious torque difference on both sides of the upper die base during the ascent process. Then, a rapid judgment method for the force balance of the upper die with asymmetric structure was proposed. Through the actual field data verification of twenty eight sets of dies, when the resultant torque ratio on both sides of the upper die was within (1.0±0.1), the possibility of deflection was low. Furthermore, according to the results of this study, the checklist for the force balance of the upper die movement was established to quickly judge the movement balance of the upper die and guide the die design of new projects. After multiple project verifications, the results show that the method provides a reference for analyzing and solving the balance problems of upper die and achieves good results.
  • High-temperature friction model and microscopic mechanism analysis on 7A09 aluminum alloy
    Han Chuande, Xia Jiansheng, Zhao Jun, Dou Shasha, Zhu Shaohua, Liu Rongtao
    Forging & Stamping Technology. 2023, 48(9): 197-203. https://doi.org/10.13330/j.issn.1000-3940.2023.09.025
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    The influences of different loads, friction speeds and temperatures on the friction coefficient of 7A09 aluminum alloy under lubrication condition were studied by friction testing machine CFT-I, and the action mechanism of different friction factors in microscopic state was analyzed by SEM. Then, a variable friction coefficient model based on different loads, friction speeds and temperatures was established through analysis, and the accuracy of the model was verified by tests. Furthermore, the friction model was imported and simulated in finite element by using ABAQUS subroutine development interface Fric and advanced computer language Fortran, and it was verified by comparing the simulation result of Coulomb friction model with the result of stamping test. The results show that the friction coefficient decreases with the increasing of load, friction speed and temperature, the data fitting degree of the variable friction coefficient model based on different loads, friction speeds and temperatures is better, the simulation result of the variable friction coefficient model is closer to the result of stamping test, and the thinning of aluminum plate occurs on the side wall, which verifies the validity of the friction model.
  • Influence law of laser local heat treatment on uniaxial tensile and forming properties for 5052-H32 aluminum alloy sheet
    Liu Pengcheng, Ma Yan, Zhang Xiaosong, Song Hongwu, Zheng Li, Wei Zuoshan
    Forging & Stamping Technology. 2023, 48(9): 204-212. https://doi.org/10.13330/j.issn.1000-3940.2023.09.026
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    Aiming at the problem of poor formability of 5052-H32 aluminum alloy sheet at room temperature, the laser rapid heating method was used for local heat treatment on the sheet, for the first time, the forming limit experiment of sheet metal after laser local heat treatment under full strain path was carried out to study the influence of laser local heat treatment process on its formability. The results of uniaxial tensile experiment show that the laser local heat treatment on 5052-H32 aluminum alloy sheet can play a significant softening effect, the tensile strength and yield strength are reduced by 17.6% and 43.3%, respectively, and the elongation after break is increased by 117%. The value of strain hardening index n increases with the increasing of peak temperature of heat treatment. When the temperature of conventional annealing heat treatment reaches 400℃ and the peak temperature of laser local heat treatment reaches 500℃, the fiber tissue produced during the rolling process is transformed into recrystallized tissue, and the texture strength is reduced. The forming limit experiment results of H32 state, conventional annealing heat treatment and laser local heat treatment show that after laser local heat treatment (400℃), the forming limit under full strain path is increased compared with the H32 state as a whole, and the value of ultimate plane strain FLC0 is increased by 39.1%, indicating that the mechanical properties of 5052-H32 aluminum alloy sheet can be changed by laser local heat treatment, and its formability is improved effectively.
  • Influence of preheating before solution on microstructure uniformity for Ti6Al4V alloy ring forgings with thick cross-section
    Zou Chaojiang, Zheng Tengteng, Zhang Zheng, Wang Panzhi
    Forging & Stamping Technology. 2023, 48(9): 213-219. https://doi.org/10.13330/j.issn.1000-3940.2023.09.027
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    For Ti6Al4V alloy ring-rolled forgings with a cross-section thickness of more than 100 mm, the process tests of preheating treatment at 650℃ and then rising to 960℃ for solution treatment and furnace charging at the set temperature of 960℃ for solution treatment were carried out, and equivalent test blocks and load thermocouple were used to monitor the temperature change and holding time during heat treatment of Ti6Al4V alloy ring-rolled forgings with thick cross-section. Then, the macrostructure of cross-section test pieces cut from the typical positions of forgings after different heat treatments were observed, and the specimens were cut from the inner diameter, core and outer diameter areas of forgings to observe microstructure and test tensile properties at room temperature. Furthermore, the influences of the two heat treatment processes on the microstructure uniformity and the tensile strength uniformity at room temperature of ring forgings were compared and analyzed.The research results show that the microstructure uniformity and the tensile strength uniformity at room temperature of the ring forgings preheated at 650℃ before solution treatment are better than those of the forgings furnaced at the set temperature of 960℃ for solution treatment. However, limited by the hardenability of alloy, the preheating treatment can not completely eliminate the differences in the microstructure and properties of Ti6Al4V alloy ring forgings with thick cross-section at different cross-sectional positions.
  • Deformation behavior at high temperature and establishment of constitutive model for die steel
    Liu Yubing, Guan Yanjin, Ding Huiying, Chen Fengjiao, Lin Jun
    Forging & Stamping Technology. 2023, 48(9): 220-229. https://doi.org/10.13330/j.issn.1000-3940.2023.09.028
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    An accurate material constitutive model is the foundation and key of finite element numerical modeling and simulation. Therefore, the thermal simulation experiments of 638 die steel were carried out under the conditions of strain rate of 0.001-10 s-1and deformation temperature of 750-1150℃, and its stress-strain curves under different conditions were obtained to analysis its high temperature deformation behavior. The results show that the flow stress increases sharply with the increasing of strain, and then decreases slowly and finally tends to equilibrium after reaching the peack, which is the result of the combined effect of work hardening and dynamic softening of the material. After friction correction of the stress-strain curve, the constitutive models of 638 die steel are established based on the improved Johnson-Cook model and the strain-compensated Arrhenius model, respectively, and the average relative errors of the two are 8.03% and 7.66%, respectively. Considering the accuracy of the constructed constitutive model and the condition of high temperature and high strain rate in the actual laser heat treatment, it is recommended to use the Arrhenius constitutive model based on strain compensation.
  • Warm deformation constitutive equation and thermal processing map of 7075-T6 high strength aluminum alloy
    Peng Yu, Yang Cheng, Peng Yingjiao, Yang Haoxin, Zhao Shengdun
    Forging & Stamping Technology. 2023, 48(9): 230-238. https://doi.org/10.13330/j.issn.1000-3940.2023.09.029
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    In order to obtain the reasonable deformation process parameters of warm forming for 7075 high strength aluminum alloy, the stress-strain curve of 7075-T6 aluminum alloy was tested by thermal simulation testing machine Gleeble-3500, and the rheological behavior of 7075-T6 aluminum alloy under the conditions of the deformation temperature of 150-300℃ and the strain rate of 0.01-10 s-1was studied. Then, the thermal processing map of 7075-T6 aluminum alloy under the strain of 0.3-0.6 was established based on Arrhenius constitutive equation, and the reliability and practicability of the thermal processing map were verified by metallographic microstructure.The results show that 7075-T6 aluminum alloy is highly sensitive to deformation temperature, strain rate and strain amount, and the thermal deformation activation energy Q is 291.151 kJ·mol-1. The fitting result of the modified Arrhenius constitutive equation is good, and the correlation coefficient r value and the average absolute error AARE are 99.65% and 5.54% respectively, which can better predict the rheological behavior of 7075-T6 aluminum alloy. When the strain is 0.6, the best warm processing safe zone range is the temperature of 250-300℃ and the strain rate of 0.01-0.05 s-1.
  • Study on thermal deformation behavior and constitutive equation of 2195 Al-Li alloy
    Zhang Yijun, Feng Yalei, Guo Xiaoguang, Lu Zhian
    Forging & Stamping Technology. 2023, 48(9): 239-247. https://doi.org/10.13330/j.issn.1000-3940.2023.09.030
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    Using thermal simulation testing machine Gleeble-3800, the homogenized 2195 Al-Li alloy was subjected to thermal compression deformation at the deformation temperature of 340-500℃ and the strain rate of 0.001-10 s-1, the influence of friction on the rheological stress was investigated, the rheological stress constitutive equation was established, and the rheological stress of 2195 Al-Li alloy considering strain compensation and the rheological stress after friction correction were compared and analyzed. The results show that the dendrite segregation in the homogenized 2195 Al-Li alloy is obviously eliminated, the second phase in the grain and at the grain boundary is basically dissolved back into the matrix, and there is a small amount of fishbone Al6 (CuFeMn)phase at the grain boundary. The rheological stress after friction correction is smaller than the measured stress, the measured stress values of 2195 Al-Li alloy at different deformation temperatures and strain rates have a good correlation with the predicted values of the rheological stress constitutive equation (correlation coefficient R2=0.97). The predicted values of rheological stress of 2195 Al-Li alloy considering strain compensation is in good agreement with that of rheological stress after friction correction, the correlation coefficient R2is 0.9913, and the average relative error Δ is 1.60%, indicating that the rheological stress constitutive equations based on friction correction and strain compensation have high accuracy.
  • Crushing mechanism on coarse second-phase particles for 2219 aluminum alloy
    Mao Xianchang, Lin Tugan, Lin Haiyan, Chen Dedeng, He Hailin
    Forging & Stamping Technology. 2023, 48(9): 248-256. https://doi.org/10.13330/j.issn.1000-3940.2023.09.031
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    The compression tests at high temperature and medium-low temperature of 2219 aluminum alloy after multi-directional forging were carried out, the crushing behavior of elongated and equiaxed second-phase particles for 2219 aluminum alloy was investigated, and the crushing and refining mechanism was revealed. The research results show that when compressed bidirectionally at high temperature (T=510℃), the elongated particles have better plasticity, and the particles are bent when deformed and break when the bending limit is exceeded. When T drops to 240℃, the brittleness of the elongated particles increases, and a large number of particles are broken by brittleness to improve the refining effect significantly. The particles are mainly equiaxed, and the area fraction of equiaxed particles to the total crystal phase increases from 64% at high temperature to 79%. Due to the difficulty of breaking equiaxed particles, when high temperature compression deformation, the particle periphery is gradually dissolved and the size is reduced mainly through the formation and migration behaviors of dislocation, when medium-low temperature compression deformation, the recovery and migration of dislocation in the matrix are slow and easy to accumulate and entangle near the particles, the equiaxed particles mainly rely on the matrix strengthening effect caused by dislocation to achieve crushing and improve the crushing effect.
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CN 31-2023/U
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