Design And Research Of NC Multitools Pipethread Lathe Headstock

At present, the domestic mannufacturers of pipe thread normally use appropriative pipe NC lathes, with the workpiece's rotation and the tool's linear feed motion. when encountered by processing larger diameter tubes (greater thanφ200mm) and long (5000-10000mm), great vibration occurs during the pipe's rotation because of its cylindrical shape error, leading to lower production. What's more, when the shape error is too large, the pipe even bend serously in the axis derection, which might cause the bracket's damage. Labor intension happens when workers operate the traditional type of pipe thread lathe.To improve product efficiency and product quality of the pipe thread lathe, design of a new type pipe thread lathe is proposed in this thesis, with composite movement of rotation and feed movement of tools, stationary workpiece and multitools simultaneous coporation under NC control. Based on aborative analysis of existent techonology, tenet of motion composition of the planetary gear mechanism is used to realise synthesis of rotating the tool in the primary campaign, while commitment to achieve radial feed movement; Electro-kinematical chain is used to replace the mechanical contact within the transmission chain, aimed to realise the NC control of lathe during the machining of pipe thread. Further more, three absolute radial feeding chains are used to make sure the tools work in double harness.In this thesis, focused on the design of headstock, the following problems are discussed:(1) The defection in the machining of large aliber-long pipe thread on normal equipment is analysised, technical difficulties are identified, finally, a lathe with still workpiece, composite movement of cutting and feeding, and simultaneous multitools cooperation is conceived, which provides higher efficiency.(2) According to the current design rules of lathes, the overall plan is designed, and the main parameter as well as the control model of the lathe is determined.(3) Focused on the design objective and the transmission demand, key drive parts in the headstock including principle subassembly, gear drive groups, feeding mechanism, anti-backlash gear are designed. (4) Flowing the demand of NC drive system, the main drive chain and feeding transmission chain are designed and the arithmetic of movement compostion based on electron transmission chain is discussed.(5) Finite-element models of the principle axis and headstock parts are built, with appropriate element type and the describtion of loads and constraint condition. Static, modal and harmonic response analysys of the principle are all processed.