www.88doc88.comScience in China Series E: Technological Sciences 2007 Science in China PressSpringer-VerlagStudy of utilizing differential gear train toachieve hybrid mechanism of mechanicalpressHE YuPeng1, ZHAO ShengDun2, ZOU Jun2 & ZHANG ZhiYuan21 School of Mechanical Engineering, Nanjing University of Science & Technology, Nanjing 210094, China;2 School of Mechanical Engineering, Xian Jiaotong University, Xian 710049, ChinaThe problems of hybrid input of mechanical press are studied in this paper, withdifferential gear train as transmission mechanism. It is proposed that “adjustable-speed amplitude” or “differential-speed ratio” is the important parameters forthe hybrid input mechanism. It not only defines the amplitude of the adjustablespeed, but also determines the ratio of the power of the servomotor to the power ofthe conventional motor. The calculating equations of the ratio of transmission in allaxes, the power of two motors, and the working load distribution are deduced. Thetwo kinds of driving schemes are put forward that the servomotor and the conventionalmotor simultaneously drive and the servomotor and the conventional motorseparately drive. The calculating results demonstrate that the latter scheme canuse much lower power of the servomotor, so this scheme makes manufacture anduse cost much lower. The latter scheme proposes a feasible way to apply the hybridmechanism of mechanical press in practice engineering.mechanical press, hybrid mechanism, differential gear train, adjustable-speed1 IntroductionAt present there are many research papers about the hybrid mechanism of mechanical press, and ithas become a hot research topic. The hybrid mechanism is a mechanism with 2-degree-of freedom(also called differential speed mechanism), and when two independent motions are input at thesame time, the output that can satisfy some motion requirements is obtained through the motioncomposition of the mechanism. The hybrid mechanism is also called controllable mechanism, orhybrid machine. The purpose of research on hybrid mechanism of mechanical press is using conventional motor with big power carrying flywheel to finish stamping work pieces; and uses ser vomotor with low power to adjust the slider speed. The advantages of the hybrid mechanism applied in the mechanical press are that it not only can reduce much lower manufacturing cost than servo press, but also has a flexible working velocity of slider1. So the mechanical press of hybrid mechanism arouses many researchers interest in working on it; and these studies are mainly focused on the multi-bar hybrid mechanism. Du and Guo1, 2 have comprehensively discussed the seven-bar hybrid mechanism of mechanical press, including the feasible conditions of composition of the linkage mechanism, the slider motion analysis, and the torque and power distribution between the two motors as well as the optimal design. The trajectory planning based on polynomial interpolation is also investigated, and the computer simulation shows that the result is indeed attractive. In addition, Meng3 has also investigated the kinematical analysis of the seven-bar mechanism, and the optimal design has been completed based on the minimum power of the servomotor motor, and Meng has proposed that the hybrid mechanism is a research direction of the mechanical press. Tokuz4 first put forward of the hybrid mechanism and analyzed the velocity synthesis by using the differential gear train. His experiment confirmed the feasibility of his conception. The concepts of the adjustable-speed amplitude and differential-speed ratio are not mentioned in their works, and the relationship between the velocity variation and the power of the two motors were not clearly given58. But these concepts are very important and absolutely necessary for the hybrid mechanism to select the two motors power and determine the working load distribution between conventional motor and the servomotor. In refs. 13 they used linkage mechanism to implement the hybrid input of mechanical press. The method is very complex because the change of the length and position of the each bar in linkage mechanism will have an effect on the motion of the slide of the mechanical press. So some principal problems are usually ignored in research hybrid mechanism course, and the research results don not always coincide with the practice engineering conditions911. The gear differential train has two freedoms, and the ratios of transmission between arbitrary two axes are a constant. In order to simplify the mechanical model and make the problems much projected, the differential gear train is used as transmission mechanism to study the hybrid problems of the mechanical press in this paper. This paper addresses the relationship between the adjustable-speed amplitude and the power of the two motors, the working load distribution between the two motors, and puts f