Geometric modelling of face processing surfaces by planetary executive devices of tunnelling machines

Abstract

Purpose. To identify characteristic surface forms generated by the movement of a cutting tool located on the working disks of a planetary executive device depending on its main parameters in various implementation schemes. This will contribute to a more accurate determination of rational values for the structural and kinematic parameters of the executive device for specific design schemes and operating conditions. Methodology. A scheme was used to provide a general definition of the surface formed while processing the face with the system of working tools of a planetary executive device, which integrates all the existing and theoretically possible options of a planetary executive device with two rotational motions and a translational one. The generalized model of the planetary executive device is based on an arbitrarily oriented moving working disk which rotates, with a system of working tools positioned on it. Findings. In the work, modelling and geometric analysis are performed of the characteristic forms of surface carriers (processing surfaces) of the trajectories of the working tool installed on the disks of the planetary executive devices of tunnelling machines. The characteristic peculiarities are revealed of the change in the shape of the processing surface when varying the values of the parameters of the executive device and the nature of the impact of each of them on the shape of this surface, taking into account the peculiarities of the interaction of the working tool with the rocks being destructed. Originality. Geometric analysis of surface carriers formed by numerous trajectories of movement of working tools of various designs of the planetary executive device shows that, in general, the processing surface is a section of a helical cylindrical helicoidal surface. When simplified, it turns into a section of a toroidal surface, with a second-order closed curve, whose shape depends on the values of the orientation angles of the working disk. To identify the characteristic peculiarities of the face surface formation, assessment was performed of the impact of each of these parameters separately on the shape of the surface carriers of the working sections of the tool trajectories (processing surfaces), considering the case of maximum processing of the face surface with the working disks of the executive device to ensure the commonality of the results. Practical value. The results of the studies conducted in the work provide the theoretical basis for solving the engineering issues of the interaction of the working tool of planetary executive devices with rocks being destructed, where the geometric parameters of this interaction are of paramount importance.