The Modular Design And Optimization Of The Frame Of The C-shaped Gantry Parallel Machine Tool

In this thesis,the machine tool is divided into several modules by the idea of modular design,and the corresponding structural design of these modules is carried out.Then,these modules are combined into machine tools with different layouts in different ways to meet different processing needs.The horizontal C-shaped gantry parallel machine tool was selected as the main research object.The static analysis,the dynamic analysis and the optimization design of the frame are implemented,and the influence of the frame deformation on the position error of the moving platform is analyzed.The main work is as follows.Firstly,the definition and method of modular design are briefly introduced,and the frame is divided into different modules from the perspective of structural analysis.The structure of each module is well-designed.With different bases(or covers),these modules are combined into horizontal parallel machine(C-shaped gantry parallel machine tools),gantry parallel machine tools and vertical parallel machine tools.Secondly,the structural parameters and characteristics of the parallel machine tool are introduced.The force Jacobian matrix of the parallel mechanism is deduced.Under the proposed machining conditions and machining trajectories,the relationship between the force of the six hinges on the frame and the position of the moving platform are obtained.Then,the deformation of the frame is analyzed under the given machining conditions and machining trajectories.It is found that the Z-direction stiffness of the horizontal parallel machine tool frame is slightly deficient,and the corresponding optimization design makes the static stiffness of the frame meet the requirements,which lays a foundation for good dynamic performance.In addition,the corresponding static analysis of the gantry parallel machine frame and the vertical parallel machine frame is performed,and it is found that the stiffness basically meets the machining requirements of the machine.Finally,the dynamic model of the bolt joint surface is established,and the modal and harmonic response analysis of the horizontal parallel machine tool frame with the bolt joint surface is carried out.In order to study the influence of the mechanical properties of the frame on the machining precision,the error model of the machine tool is established.The influence of the frame deformation on the position error of the moving platform is also analyzed.