In the 3 D free bending forming system,the bending die can be designed either in a sliding type or rolling friction type.Bending die-based sliding friction type is often called normal bending dies;however,the bending ...In the 3 D free bending forming system,the bending die can be designed either in a sliding type or rolling friction type.Bending die-based sliding friction type is often called normal bending dies;however,the bending dies-based rolling friction type includes bending die-based roller type and ball type in structure.In the current study,the impact of three bending dies on the forming force,and the bent tube quality was investigated.The obtained results showed that the tangential stresses and strains of the tubes formed by the bending die-based roller type were the smallest among the three bending dies.Besides,the spherical bearing force PUwas reduced drastically after using the roller type and ball type compared to the sliding friction type.Moreover,the uniformity of the wall thickness distribution of the tubes formed by the roller type and ball type was better than those obtained from the sliding friction type.In addition,the cross-section distortion rate was reduced by 2.8%using the roller type,and 1.8%using ball-type compared to the sliding friction type.展开更多
Bending process is one of the most significant fields of application of sheet metal die. Sheet metals are ex posed to some spring back or spring-forward depending on elastic deformation following bending process. S235...Bending process is one of the most significant fields of application of sheet metal die. Sheet metals are ex posed to some spring back or spring-forward depending on elastic deformation following bending process. S235JR （1. 003 8） materials having a thickness of 4 mm were bent with 90° punches having 5 different tip radiuses. The ben- ding process was carried out by making the punch waited on the material for 30 s （30 s wait bending） and by remo ving the punch without waiting （direct bending）. Specimens were prepared in three forms as non-heat-treated, nor- malized and tempered. At the same time, all experiments were performed at a deformation speed of 25 mm/min. As a result, it was determined that as punch tip radius increased, the amount of spring-forward decreased. Although normalizing process applied to specimens increased the amount of spring-forward, tempering process decreased it. The amount of spring-forward was decreased in 30 s wait bending process.展开更多
基金supported from the Jiangsu Province Key Research and Development Project(No.BE2019007-2)Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology of China(No.ASMA201903)National Natural Science Foundation of China(No.U1937206)。
文摘In the 3 D free bending forming system,the bending die can be designed either in a sliding type or rolling friction type.Bending die-based sliding friction type is often called normal bending dies;however,the bending dies-based rolling friction type includes bending die-based roller type and ball type in structure.In the current study,the impact of three bending dies on the forming force,and the bent tube quality was investigated.The obtained results showed that the tangential stresses and strains of the tubes formed by the bending die-based roller type were the smallest among the three bending dies.Besides,the spherical bearing force PUwas reduced drastically after using the roller type and ball type compared to the sliding friction type.Moreover,the uniformity of the wall thickness distribution of the tubes formed by the roller type and ball type was better than those obtained from the sliding friction type.In addition,the cross-section distortion rate was reduced by 2.8%using the roller type,and 1.8%using ball-type compared to the sliding friction type.
文摘Bending process is one of the most significant fields of application of sheet metal die. Sheet metals are ex posed to some spring back or spring-forward depending on elastic deformation following bending process. S235JR （1. 003 8） materials having a thickness of 4 mm were bent with 90° punches having 5 different tip radiuses. The ben- ding process was carried out by making the punch waited on the material for 30 s （30 s wait bending） and by remo ving the punch without waiting （direct bending）. Specimens were prepared in three forms as non-heat-treated, nor- malized and tempered. At the same time, all experiments were performed at a deformation speed of 25 mm/min. As a result, it was determined that as punch tip radius increased, the amount of spring-forward decreased. Although normalizing process applied to specimens increased the amount of spring-forward, tempering process decreased it. The amount of spring-forward was decreased in 30 s wait bending process.
