The Design Method Of Metamorphic Mechanism Based On Resistance Gradient Of Metamorphic Joint

The metamorphic mechanism is a new field of the mechanism research, which brings to mechanism research a fresh air. The source metamorphic mechanism has several freedoms, metamorphic mechanism need constraint of several metamorphic joints to to ensure the movement uncertain and timing requirements when moving. The metamorphic joint is through the constraint of the resistance between two components to realize the function, so it is necessary to research the resistance relationship between several metamorphic joint, in this paper the main contents include:At first, summarizes the ways of realizing link combined and separated under non active control. The way of metamorphic mainly includes:force changed way, geometry changed way, combination changed way, etc. Using these kinds of ways of metamorphic, respectively for the revolute metamorphic joint and the sliding metamorphic joint design a variety of metamorphic joint, and analyze the resistance relationship of one metamorphic joint.Secondly, two typical metamorphic mechanisms are analyzed such as two-DOF five-bar mechanism and three-DOF six-bar mechanism. Through topology analysis of source metamorphic mechanism and basic mechanisms, analysis of kinematic pair and analysis of resistance status in configuration changing, proved that the metamorphic pair’s resistance gradient is exist and the criteria relationship it should meet, etc. Each relative motion metamorphic joint shall meet minimum resistance principle, and the restrain of the rest metamorphic joint shouldn’t change when it moving, thus to meet the task requirements of timing and uncertainty sport and introduce a kind of mathematical model, to lay a foundation for the later design method of metamorphic mechanism.Finally, describes a design method of metamorphic mechanism for a given task, based on metamorphic joint’s resistance gradient, through the example and dynamics simulation to verify the validation of the design method. First break total task action into some decomposition actions, decomposition action can be achieved through the kind of basic mechanism, all the mechanism can form a scheme combination. Through a series of screening and synthesis of mechanism, we can get a source metamorphic mechanism. Through the movement of kinematic pair, the change of configuration and the type of the pair to choose the suitable metamorphic joint, make it meet the resistance gradient criteria. To design a steel shearing mechanism using the design method of metamorphic mechanism, dynamics simulation verified the correctness of resistance gradient and fessibility of design method.