Simulation Analysis Of Knurling Connection Process And Technological Parameters For Assembled Camshaft

As one of the key parts in valve actuating mechanism of engine, camshaft has importanteffects on dynamic property, ride comfort, fuel efficiency of engine. Assembled camshaft hassignificant advantages in lightweight, materials optimization, efficient production, savingmaterial and energy, reducing cost, which meet the requirements of high power andlightweight for modern engine, they are becoming the main development direction. The keytechnical process of assembled camshaft fabrication is the connection between cam and shaft.Various connecting methods have been researched and developed such as welding, powdersintering, mechanical expanding, hydraulic expanding tube, hot interference assembly andknurling interference assembly, etc. Of these methods, the knurling inference assemblycombines the advantages of both elastic interference pressing fitting and plastic deformation,with connecting strength, strong versatility, no thermal deformation, ease of automation andother characteristics. So knurling interference assembly has been noticed widely attention andbecame a research hotspot.Main factors influencing the connection strength of knurling interference assembly arematerials and basic sizes of parts, knurling tooth shape parameters, assembly parameters andprocess control, etc. Based on the National Science and Technology Major Projects (projectnumber2012zx0409011), this paper conducted the research on camshaft knurling connectionprocess and assembly parameters to provide the basis for the development of CNC assemblymachine and manufacturing application of the camshaft. In this paper, both axial and radialknurling interference assembly processes were numerically simulated. And the maintechnological parameters effects on connection strength were systematically studied. Thecharacters and applicability were analyzed among different kinds of knurling assemblymethods, and the simulation results were compared with assembly experiments. The papercan provide reference data to realize a better selection for different varieties of the camshaftassembly technologies and assembly parameters. The major research work in the dissertationis summarized as follows:（1）The assembly process of camshaft was designed according to characters of knurlingassembly connection and the requirement of press fitting; The technological process ofknurling assembly was made that was based on the structure and working principle of CNCassembly machine. Knurling assembly separated parts clamping position, velocity control,quality of connection strength inspection and other problems were discussed deeply in theassembly process. （2）Knurling assembly connection is a special interference fitting method. In order todetermine the main influence factors and influence laws, the force of thick wall cylinderinterference connection were conducted.Then the stress field, displacement field andassembly load analytic equation were given. Besides, the connection intensity of interferenceassembly was carefully discussed.（3）Three-dimensional finite element analytical models were adopted respectively inaxial and radial knurling interference assembly. Other technical issues such as constraint,friction and loading technology of boundary and interface were deposed.（4）The axial and radial knurling interference assembly process were numericallysimulated. Both stress and strain distribution characteristics of the shaft and cam wereanalyzed during the assembly process. Many factors that have significant influences onassembly process and connection qualities were discussed deeply including the materialmatching, loading speed, the length of the connecting area, the assembly interference amount,parameters of shaft tooth, cam keyway, etc.（5）The experiments of axial and radial knurling interference assembly were conducted,which verified the validity of numerical simulation. Based on materials matchingcharacteristics of the two types of knurling connection, the scope of application werediscussed respectively. And the suggestions were proposed for choosing reasonable processparameters.