Research On Optimization Of Marching Allowance And Feedrate Based On Measured Blanks

With the rapid development of national economy and manufacturing industry,complex curved surface parts are widely used in key equipment of ships,aviation,and molds because of their unique geometric shapes and performance.Among them,the large-scale whole propeller is a typical complex surface type part,whose machining performance and shape accuracy directly affect the efficiency and service life of the ship’s thruster.The propeller processing standard can’t be determined easily because of casting generally used to make large whole propeller and complicated shape structure of the blades,whose rough spot margins often occurs,leads to product overshoot and scrapped,and causes great economic loss.After determining the processing standard,due to the unclear of the distribution of the machining allowances of various parts,in order to control the processing distortion and ensure the processing quality,more conservative cutting processing parameters are often used.This can not fully exploit the potential of the machine tool,low production efficiency,and poor processing quality.Based on the appeal problem,this paper proposes the determination of propeller optimal machining standard based on the actual measurement of propeller blank and the use of surface matching technology.Based on this,the machining allowance is extracted,and then the propeller processing method is optimized according to the actual machining allowance of the propeller.In order to ensure the quality of processing and improve processing efficiency.The main work of this article is summarized as follows:1.Determination of the optimum processing standard of the propeller.The free-surface matching method was used to find the optimum machining standard of the propeller.Principal component analysis was used to preliminary calculate the optimum processing standard of the propeller.The iterative closest point was used to accurately calculate the optimum processing standard of the propeller.After the propeller optimum processing standard is determined,the machining allowance is calculated along the tool movement trajectory,and the machining allowance distribution map is drawn.2.Analysis of propeller machining deformation.After calculating the size of the cutting force in the process of propeller production via finite element method,a finite element model of the deformation of the propeller under the action of the cutting force was established.The cutting force was converted and loaded into the propeller deformation finite element model to calculate the deformation of the propeller.The deformation law of the propeller under the action of cutting force was analyzed,and during the process,the easily deformable region of propeller was found out.3.Optimization of propeller processing parameters.The influence of cutting parameters on cutting force was analyzed through numerical simulation experiment,and the machining cutting parameters were optimized.According to processes vary in deformation in different position due to different stiffnesses,different processingparameters are selected in different processing areas during propeller processing.A feed rate optimization method based on measured allowance is proposed,which controls the deformation amount as the optimization goal,according to the allowance in the actual processing of the propeller,different feedrates are selected so that the cutting force is constant during the processing.4.Compiling processing software of propeller processing standard and feed parameter optimization.Based on Open CASCADE and OpenGL,the program for the determination of the optimum processing standard for the propeller,the extraction of the machining allowance and the optimization of the feedrates were programmed,and the feasibility of the method was verified.