Study Of Thrust Force And FEM Simulation In Drilling Process On Complex Helical Drill

Drilling is one of the most commonly used and important machining operations. With the development of mechanism industry, the requirement of precision machining is more exigent than before and the precision machining technology is much more important. Therefore, a lot of work is urgent to do on drilling in order to meet the needs of precision machining. In recent years, the application of finite element method (FEM) to cutting operations has proved to be effective to study the cutting process and chip formation. It can reduce the experimental cost and replace some experimental testing which may be difficult or impossible to obtain by numerical simulation on the computer. FEM was applied in machining simulation in 1970s for the first time. Many papers are available now on simulation of orthogonal and oblique cutting process but little of drilling because of the complexity of drilling processes. Though some are on drilling, they are simplified to orthogonal cutting to solve just approximately.Study of thrust force is one of the most important problems in the drilling process. In the drilling process, thrust force influence the temperature, the wear and durability of tools and the surface integrity of holes. So establishing the drill thrust force approximate mathematical model by Simplified to orthogonal cutting to deduce the factors of influence to thrust force.Mathematical model is the basic of design, manufacturing, analysis and drilling, the study of helical drill point is not an exception. Firstly, grinding mathematical model of SD grinder should be established and then the three-dimensional model of helical twist drill and conical drill should be established by Pro/Engineer.The 3D models of helical twist drill and conical drill should be imported into DEFORM 3D and then the 3D FEM model should be established. And then 3D FEM simulation of twist drilling is presented in the paper and gets the continuous chip formation and indicates the feasibility of FEM simulation of drilling processes. FEM simulation of twist drilling is carried out to identify the characteristics and to analyze the drilling quality of the twist drilling, including temperature distribution, chip formation in the workpiece, thrust force, stress and elastic deformation of drilling tools. The paper analyzes perpendicularity indirectly by comparing the elastic deformation and stress of the drilling tools reacted by the workpiece.In theory, helical drill point has better drilling capability than ordinary conical drill point, which is manifested in experiments. The study and application of helical drill has improved the drilling capability of drill and drilling quality. The "S"-shape chisel edge has a lower negative rake angle than a conventional chisel edge. Helical drill point has an "S" contour with a radiused crown chisel that reduces the thrust force and makes the drills self-centering, achieving hole with exact size.