| The camshaft of marine diesel engine has heavy weight,large length-to-diameter ratio,special shape and high machining accuracy requirements.A company has some urgent problems to be solved,machining DE-18 series camshafts through CNC machine tools: the drilling of the camshaft center oil hole drill bit was severely worn or even damaged,burrs on the edge of the milling cam,and burns on the surface of the high-speed grinding cam.Therefore,this article takes the DE-18 series camshaft CNC machining process as the research object,and aims to solve the problems encountered by a company in the production and processing of camshafts.The work completed in this article includes the following aspects:(1)The characteristics,processing technology and processing difficulties of DE-18 series camshaft are analyzed as well as the main research content of this paper is determined.The lifting data of the cam are analyzed,the nominal velocity and the nominal acceleration of the cam are calculated,and the original data is smoothed.The cubic spline fitting method is used to interpolate the lift data.(2)Compared the deep hole drilling processing system,a finite element model of BTA single tube drilling was established.The variance method was further used for studying the influence of drilling parameters on the temperature and wear depth of the drill.Research shows that: the maximum temperature and maximum wear depth of the drill bit appear near the cutting edge.The influence order of processing parameters on bit temperature and wear depth is as follows: drill speed,feed rate,the initial temperature.But the initial temperature has almost no effect on processing.The optimal processing parameters are selected based on the comprehensive balance method,verifying in actual processing.(3)Study milling processing methods,burr formation mechanism and milling force model.Based on the numerical model of the milling cam,the influence of processing parameters on the size of the burr and the maximum X-direction milling force is studied.The results show that the thickness and height of the burr and the maximum X-direction milling force gradually decrease with the increase of the milling speed.The thickness and height of the burr and maximum X-direction milling force increase with the increase of milling depth and feed.Choosing appropriate milling parameters can control the generation of burrs.The conclusion is verified by practical production.(4)The principle of cam grinding is studied and the X-C linkage mathematical model of cam grinding is analyzed.The grinding process,grinding force and grinding temperature are analyzed by establishing the single diamond grits high-speed grinding finite element model.The generation of a temperature control strategy for grinding temperature.Finally,a grinding temperature prediction model was established based on BP neural network.The results show that the cutting force is mainly affected by the cutting speed,and the machining temperature is mainly affected by the feed speed.The optimal grinding parameters are selected and the accuracy of the simulation is verified in machining.The error values of training samples and verification samples are combined,which shows that the neural network has good grinding temperature prediction ability,which provides a certain reference value for grinding temperature control. |
