Dynamic error of multiaxis machine tools considering position dependent structural dynamics and axis coupling inertial forces

During the working process of high-speed multiaxis machine tools, inertial forces can cause vibration and deformation of mechanical structure, which lead to the dynamic error of tool center point (TCP) relative to worktable and can adversely affect the machining performance. Considering the varying feed positions and accelerations during machining, a parameter-varying multi-rigid-body dynamic model of a 3-axis gantry machine tool is proposed. This model represents the position dependent structural dynamics and inertial forces, which can simulate the dynamic error of TCP relative to worktable within the entire workspace. The results show that the dynamic error in one direction is affected by the feed motions of multiple feed axes. The magnitudes of the dynamic error significantly vary with the position of Z-axis. And the dynamic errors in Y- and Z-direction show different varying trends. Then the theoretical model is used to discuss the dynamic error and position dependency. The expressions of TCP dynamic response and inertial forces reveal the reason why the dynamic errors in Y- and Z-direction show different varying trends.

Priority order recognition method of module redesign for the CNC machine tool product family to improve green performance

In order to solve the sequencing problem of module redesign in the greening process of the CNC machine tool product family, a priority order recognition method based on fuzzy analytic hierarchy process (FAHP) and grey relational analysis (GRA) was put forward. A hierarchical model of functional modules of the CNC machine tool product family was constructed, and the types of functional modules were divided. The generality coefficient of the functional modules was proposed to reflect the influence of the module types on the redesign priority order. A green performance evaluation indicator system for module instances of CNC machine tool product family was built, based on which a life cycle-oriented green performance priority order recognition method was established. FAHP and GRA was utilized to evaluate the green performance of module instances, and then the priority order of module redesign can be determined by the ratio of green performance evaluation value and generality coefficient. The feasibility and effectiveness of the proposed priority order recognition method was verified by a applied case of module green redesign sequencing of gantry machine tool product family. The application case showed that the proposed priority order recognition method based on FAHP and GRA provides a scientific basis for companies to carry out the greening improvement project of the gantry machine tool product family.

Study on lightweight structural optimization design system for gantry machine tool

In order to improve the efficiency and effectiveness of the lightweight design of the gantry machine tool, a lightweight structural optimization design system for the gantry machine tool was constructed. Serialized gantry machine tools were parametrically modeled, and a load model with multiple operating conditions was established. A twice optimization design method integrating zero-order optimization, parameter rounding, and structural re-optimization was proposed. Using the proposed method, a lightweight structural optimization design system for gantry machine tool with parametric design, lightweight design, and other functions was developed. The developed gantry machine tool lightweight structural optimization design system was applied to complete the lightweight structural optimization design of gantry frame of a certain gantry machine tool, so the structural parameters of the gantry frame were optimized. Although the maximum stress and the maximum deformation of the gantry frame increases within the allowable range, the experimental comparison before and after the optimization shows that the mass of the whole gantry frame is reduced by 9.24%, which is beneficial to save the manufacturing cost. The research results show that the constructed lightweight structural optimization design system of the gantry machine tool has high engineering practicality.

The Statics Characteristic Analysis of Fixed Beam Gantry Machine Tool Crossbeam Based on ANSYS

In order to calculate the crossbeam’s stress and deformation under the weight of gantry machine tool, and analyze whether the deformation meets the precision of design requirements. In this paper, we will use the finite element method to get the stress and deformation in different directions with finite element analysis software-ANSYS. The result shows that the maximum deformation is 14.3 microns which appeared in the middle part of the beam towards the gravity direction and the maximum stress is 4730000 Pa which appeared in the joint of pillar and beam.