A new non-servo motor type automatic tool changing mechanism based on rotational transmission with dual four-bar linkages

In the non-servo motor type automatic tool changer (ATC), the rotational transmission mechanism (RTM), which converts the rotary motion with specific rotational ratio, is important. This paper presents a new design for RTM with dual four-bar linkages for the non-servo motor type ATC. This RTM is entirely different from the mechanism using single four-bar linkage, in which the motion is intermittent. In the case of the mechanism using single four-bar linkage, the shape of the trajectory of four-bar linkage is the only design consideration. However, in the case of the proposed mechanism, both the shape and the speed ratio of the contact and non-contact paths of the trajectory of the four-bar linkage have to be considered. Therefore, the four-bar linkages are designed using the new path synthesis algorithm based on the derivative of the target trajectory. Through various analyses, this paper provides the proper design of the RTM. A prototype of a machining center using the developed ATC with RTM was created to verify the feasibility and for kinematic experiments. The research shows that the new RTM with linkage mechanism is suitable for practical applications.