The crystal orientation and outer surface roughening of magnesium alloy tubes were evaluated to clarify the effect of the mandrel on the microstructure and outer surface roughness in die-less mandrel drawing. Locally ...The crystal orientation and outer surface roughening of magnesium alloy tubes were evaluated to clarify the effect of the mandrel on the microstructure and outer surface roughness in die-less mandrel drawing. Locally heated ZM21 tubes with an outer diameter of 6.0 mm and an inner diameter of 3.8 mm were drawn with and without a mandrel. The outer surface roughness and crystal orientation were evaluated in the same measurement area. The results indicated that the outer surface becomes rougher in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. The outer surface roughness developed when there was large difference in the pyramidal slip system Schmid factor. Therefore, the slip deformation of the pyramidal slip system seems to be mainly responsible for the outer surface roughening in the die-less mandrel drawing. Furthermore, the crystal grain with the {2110} crystal plane vertical to the normal direction of outer surface had a larger Schmid factor than the other crystal grains. The large number of crystal grains with the {2110} crystal plane in the die-less mandrel drawing is one of the reasons that the outer surface roughness develops more in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. These results will contribute significantly to the development of fabrication process of the microtube with high surface quality, which prevents rapid corrosion of biomedical applications.展开更多
The multi-pass scheduling method is a key issue in die-less spinning for determining the quality of the final products, including their shape deviations and wall thicknesses, and has drawn increasing interest in recen...The multi-pass scheduling method is a key issue in die-less spinning for determining the quality of the final products, including their shape deviations and wall thicknesses, and has drawn increasing interest in recent studies devoted to trying to improve the accuracy of the formed parts. In this paper, two main parameters, roller path profiles and deformation allocations in each pass, are considered in newly proposed multi-pass scheduling and optimizing methods in die-less spinning. Four processing methods with different roller path profiles and with three deformation allocation methods are proposed for investigating the influence of scheduling parameters on product qualities. The ＇similar geometry principle for restraining shape deviation＇ and the ＇small curvature principle for maintaining wall thickness＇ are presented for optimal design of roller path profiles; in addition, the ＇uniform allocation principle for maintaining wall thickness＇ and the ＇large deformation principle for restraining shape deviation＇ are brought forward as suggestions for deformation allocations. Based on these principles, a scheduling method denoted by RF＋（FP ＆ EHS） is presented to improve the comprehensive quality of a product of die-less spinning.展开更多
In order to produce thick plates with complicated curved surface, a prototype bending machine by the use of high frequency inductor was developed. The bending mechanism is based on the localized stresses which are in...In order to produce thick plates with complicated curved surface, a prototype bending machine by the use of high frequency inductor was developed. The bending mechanism is based on the localized stresses which are induced from the difference of temperature in thickness by the high frequency inductor. The operating speed and the thickness of plate were examined from the experiment, and the variation of the temperature was measured. Finite element analysis was carried out in the second part based on the experimentally obtained temperature distribution. The so-called Mindlin plate element was used in order to perform the simulation efficiently. The strategy to produce such curved surface in the practical process was discussed and further perspective of the production system was described. (Edited author abstract) 6 Refs.展开更多
基金supported by JSPS KAKENHI Grant Nos. 19H02476 and 20KK0321the Amada Foundation Grant No. AF-2021035-C2a project researcher under financial support from the Institute of Industrial Science of the University of Tokyo。
文摘The crystal orientation and outer surface roughening of magnesium alloy tubes were evaluated to clarify the effect of the mandrel on the microstructure and outer surface roughness in die-less mandrel drawing. Locally heated ZM21 tubes with an outer diameter of 6.0 mm and an inner diameter of 3.8 mm were drawn with and without a mandrel. The outer surface roughness and crystal orientation were evaluated in the same measurement area. The results indicated that the outer surface becomes rougher in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. The outer surface roughness developed when there was large difference in the pyramidal slip system Schmid factor. Therefore, the slip deformation of the pyramidal slip system seems to be mainly responsible for the outer surface roughening in the die-less mandrel drawing. Furthermore, the crystal grain with the {2110} crystal plane vertical to the normal direction of outer surface had a larger Schmid factor than the other crystal grains. The large number of crystal grains with the {2110} crystal plane in the die-less mandrel drawing is one of the reasons that the outer surface roughness develops more in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. These results will contribute significantly to the development of fabrication process of the microtube with high surface quality, which prevents rapid corrosion of biomedical applications.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China （No. LYI5E050003）, the National Natural Science Foundation of China （No. 51675470）, and the Fundamental Research Funds for the Central Universities, China （No. 2015QNA4003）
文摘The multi-pass scheduling method is a key issue in die-less spinning for determining the quality of the final products, including their shape deviations and wall thicknesses, and has drawn increasing interest in recent studies devoted to trying to improve the accuracy of the formed parts. In this paper, two main parameters, roller path profiles and deformation allocations in each pass, are considered in newly proposed multi-pass scheduling and optimizing methods in die-less spinning. Four processing methods with different roller path profiles and with three deformation allocation methods are proposed for investigating the influence of scheduling parameters on product qualities. The ＇similar geometry principle for restraining shape deviation＇ and the ＇small curvature principle for maintaining wall thickness＇ are presented for optimal design of roller path profiles; in addition, the ＇uniform allocation principle for maintaining wall thickness＇ and the ＇large deformation principle for restraining shape deviation＇ are brought forward as suggestions for deformation allocations. Based on these principles, a scheduling method denoted by RF＋（FP ＆ EHS） is presented to improve the comprehensive quality of a product of die-less spinning.
文摘In order to produce thick plates with complicated curved surface, a prototype bending machine by the use of high frequency inductor was developed. The bending mechanism is based on the localized stresses which are induced from the difference of temperature in thickness by the high frequency inductor. The operating speed and the thickness of plate were examined from the experiment, and the variation of the temperature was measured. Finite element analysis was carried out in the second part based on the experimentally obtained temperature distribution. The so-called Mindlin plate element was used in order to perform the simulation efficiently. The strategy to produce such curved surface in the practical process was discussed and further perspective of the production system was described. (Edited author abstract) 6 Refs.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120101130003)the Key Project of Science and Technology Program of Zhejiang Province(No.2013C01135)the Youth Fund Project of the State Key Lab of Fluid Power Transmission and Control,Zhejiang University(No.SKLoFP_QN_1301),China
