Investigation Intokey Design Technology Of High Precision Horizontal Machining Center

The key design technology of high-precision horizontal machining center is the common key technology of high-end CNC machine tools.It is of great practical significance to carry out these technical studies to promote the development of high-end CNC machine tools in China.To this end,this paper relies on the national863 project to develop a high-precision horizontal machining center prototype.Carry out in-depth systematic research on key design technologies of the entire machine structure,servo feed system,high-precision electric spindle,and static pressure-supported torque motor-driven turntable.The main research work is as follows:According to the needs of the project,the overall layout of the machine tool is established.Using the forward design method,the error relationship and static stiffness relationship model between the end of the machine tool and the components are established,and the static stiffness optimization of the machine tool is matched to determine the model of the guide rail and the screw of the machine tool.The static stiffness of each component is used as a constraint condition.The large parts of the structure are optimized for high rigidity and lightweight design of the entire structure from top to bottom.Based on the bidirectional repetitive positioning accuracy,reverse difference and transmission error model analysis of the ball screw pair linear feed system,a method for estimating the bidirectional repetitive positioning accuracy and reverse difference of the ball screw pair linear feed system is proposed.At the same time,the technical measures to improve the position accuracy of the system are explained.Determine the optimal matching relationship between the motor inertia and load inertia of the feed system,the optimal lead of the lead screw,and the minimum critical speed of the feed system without creeping.An optimization design method considering the dynamic characteristics,optimal lead and repeated positioning accuracy of the ball screw feed system is proposed,and the feed system of the prototype is designed.Developed a built-in motor directly drives rear-mounted split spindle unit.The transmission mode of the spindle unit,bearing selection,bearing support combination,bearing installation and positioning method,the interference interference of the motor and the spindle,the interference interference of the bearing and the spindle,and the dynamic balance technology of the spindle unit are studied.The key elements of the interference design of the spindle and the rotor of the motor and the key elements of the interference design of the spindle and the inner ring of the bearing are clarified.Design the cooling and lubricating system of the spindle unit,and perform thermal simulation on the spindle unit.Development of a high-precision CNC turntable with hydrostatic support and direct drive by a torque motor.The design calculation model of technical indicators such as oil pad flow,stiffness,friction power loss of oil pad,and oil film clearance for closed-type static pressure bearing with automatic adjustment of gap throttling for CNC turntable is established.Obtain the optimal oil film clearance at the minimum power loss,the required flow of the system,the power loss,the change of oil film stiffness with the load,the load range,etc.The design calculation method and process of the closed static pressure bearing with automatic adjustment of gap throttling are clearly defined;Design and develop a high-precision CNC turntable with hydrostatic support and torque motor direct drive and its hydraulic control system.The test of the precision horizontal machining center prototype developed based on these research results is carried out to verify the scientificity of these design methods.