ABSTRACT
In modern tunnel construction, TBM (Tunnel Boring Machine) plays a very important role. In response to the needs of tunnel wall reinforcement and TBM automated construction for tunnel construction, a shotcrete mechanism mounted on the TBM is designed. In order to evaluate the kinematic performance of the mechanism, this paper studies the forward and inverse kinematics and spatial architecture of the TBM shotcrete robot. Firstly, based on the D-H parameter method, the number of joints and links is determined and structural analysis is performed to obtain the robot's forward kinematics equation, achieving the mapping between joint space and pose space. Then, by determining the joint variables, the mapping of the end tool in Cartesian space is achieved. Finally, based on the Monte Carlo random sampling method, the workspace of the robot is constructed, and its reachability and flexibility within the robot workspace are evaluated. The performance of the device is verified by building a prototype, which meets the requirements well. Through the research in this paper, it can provide theoretical basis and guidance for the design and control of the shotcrete robot.
ABSTRACT
The ice abrasive air jet is a clean surface treatment technology, which currently has limitations such as high energy consumption, uncontrollable particle size and hardness. Realizing the instant preparation and utilization of ice particles are crucial for solving the energy consumption problem. This paper based on the icing principle of heterogeneous nucleation, proposed a new method of ice making, the heat transfer mechanism of low temperature droplets was studied, and the method was proved to be feasible. Using the FLUENT solidification and melting model combined with the VOF model to calculate the freezing process of droplets, the effects of droplet particle size, initial temperature, and wall temperature on the freezing time were analyzed, and the calculation equation of the freezing time was determined, which was corrected by the icing test results. The results showed that the outside of the droplet freezes first, the liquid-solid boundary is parabolic, and the parabolic concavity increases with time and droplet size. In the freezing process, the larger the droplet size, the longer the droplet phase transition time; the higher the droplet initial temperature, the longer it took to reach the phase transition; the higher the wall temperature, the longer the ice formation time.
