Configuration synthesis and preference study of steel arch looping mechanism with multiple closed-chain end-effectors

Steel arches are an important support structure for tunnel boring machines (TBM) to pass through the broken formation, each piece of which has a mass of more than 200 kg. Traditional manual looping of steel arch is difficult, which can easily lead to untimely support or unstable quality, and even cause collapse accidents. It is necessary to design a simple and reliable steel arch looping mechanism. In this paper, the algebraic solution model of single-degree-of-freedom planar closed-chain mechanism is firstly established, and the design method of closed-chain end-effector based on input constraints and output requirements is proposed, based on which, twelve tree-type opened and closed chain steel arch looping mechanism configurations are deduced. Then, in the absence of dimension parameters, a performance evaluation model of the open and closed chain mechanism containing motion/force transfer performance and complexity dimensions is established, and a method for optimizing the steel arch looping mechanism configurations is proposed from the perspective of topology. Finally, the prototype experiment of steel arch looping operation was carried out to verify the feasibility of the optimal configuration of steel arch looping mechanism, which can provide a theoretical basis for the configuration design of other tree-type open and closed chain mechanisms.