Abstract: Through analyzing the low-speed kinematical principle of the slide of Stephenson's six-bar linkage, it is pointed that the low-speed motion of the slide is determined by the low-speed segment of the linkage curve. The conditions which can create the low-speed segment of the coupler curves are that the length of the connecting bar of the hinge four-bar linkage is short, the length of rocking bar and the length of the framework is equal or proximity, and point P which creates coupler curves approaches the instantaneous center C. The main parameters of the slide which creates low-speed motion are the length of the connecting bar and the distance of point P to point C. Based on the technology parameters of the JH23- 200 type mechanical press, the Stephenson's six-bar mechanical press is designed. Comparing the original mechanical press, the low-speed forging-stamping performances of this mechanical press are high promoted.

Key words: Slider velocity, Coupler curves, Mechanical press, Stephenson's chain