Research On 3-Dof High-Speed Hybrid Thread Milling Machine Tool

At present, there are many problems in the process of small-diameter internal thread machining such as hard processing, low efficiency, low precision and lack of special equipment etc.. High-speed thread milling can manufacture internal threads in different materials and parts with high efficiency, low consumption and high precision. However, there are many problems in the application of high-speed thread milling in China. This article develops a new high-speed small-diameter internal thread milling machine with a hybrid approach of planar 5R parallel mechanism and series machine tool, studies systematically the parallel mechanism kinematics and static and dynamic characteristics of complete appliance, and lays a foundation for the application of internal thread milling process.This article studies the working principle and features of high-speed internal thread milling, proposes the kinematic implementation sheme of 3-dof small diameter, high-speed hybrid thread milling based on the planar 5R parallel mechanism, establishes the kinematics model of planar 5R parallel mechanism, deduces its inverse kinematics velocity Jacobian matrix, and studies the work space and performance index of parallel mechanism, raises the combination principles of the type and position of drive rods, and figures out the inverse position solution of circular movement. This article optimizes the rod length of 5R mechanism under the workspace and performance index of 5R parallel mechanism, confirms the main technical parameters of the hybrid machine, divides the main functional modules under the direction of modularization design, takes the mechanical analysis of the main components of each module, design selection and check calculation, and then develops the hybrid machine. Finaly PRO/E is used for the three-dimensional physical design and virtual assembly of hybrid machine modules.Kinematics simulation analysis of the hybrid institutions is performed with ADAMS, which verifies the validity of theoretical calculation and the rationality of machine design and provides the theoretical basis for practical design, manufacture and application of the machine. The statics and modal analysis of 3-DOF hybrid machine tool is completed with ANSYS, from which deformation and distribution of equivalent stress pattern are obtained, and then the strength and stiffness of the machine tool are analyzed. Through analysis, the natural frequency and vibration characteristics of each order are obtained, vibration mode of each order is analyzed, and then the weakness of the machine is obtained. It provides a theoretical basis for further optimization. The results show that the hybrid machine tool is expected to meet the requirements of actual thread milling trajectory and the safety coefficient in most regions of the whole structural is high, the intensity meets the processing requirements under dangerous working conditions; The Excited frequency of forced vibration diverge from the Natural frequency of the machine tool, and the machine tool can be put on the practical application.