The CNC Machining Technology Of Helical Groove On Liquid Rocket Engine Nozzle

The master push engines or the booster engines and the space attitude control engines using lox/kerosene as the propellant are China's latest model of liquid rocket engine. Coolant channel of the combustion chamber's convergent-divergent nozzle is loxodrome helical groove or changed angle and variable lead helical groove. The helical groove is difficult to be machined for the complexity of the component's generatrix and low stiffness. So it's quite necessary to explore and research new manufacturing and numerical control techniques suitable for the helical coolant groove for the liquid rocket engine.Based on the principle of Differential Geometry, the text developed the mathematical model for changed angle and variable lead helical groove and analysed the function relationship between lead and helical angle in case of changes of the helical angle follow constant, linear and parabolic law. Furthermore, the spiral reinforcement discrete data was calculated through Matlab software. Finally, some new solid models of variable angle and variable lead helical groove revolution surface with straight generatrix, circular arc and spline generatrix were constructed within the UG circumstances.According to the mathematical model, movement analysis and 4-axis-simulatanous-move machining method for the loxodrome, an auto-programming system for loxodrome helical groove NC machining based on Windows using VC++ 6.0. This system includes initialization module, contour selection and data processing module, simulation and graphic display module and code generation module, among which the contour selection and data processing module is the hard core. The auto-programming system with curve auto-stitiching function can handle four typical contours:linear type, circular arc type, High-order curve-type and discrete point-type. As long as the parameter of corresponding contour segment is initialized, the system could finish data points calculation and contour splicing under continuous input mode, and check out whether the contour parameters is right in simulation and graphic display module. It also could calculate the Cutter Location separately on each contour spiral groove, using equal chord height error algorithm, and generate the NC code for numerical control manufacturing.The auto-programming system is testified to be efficient and stable through the writer' experimental verification in factories utilizing this system during the thesis's writing.