Study On Complex Helical Drill Grinding Theory And Technology

Drilling is greatly applied in metal cutting. The hole-machining is one of the most methods for material machining. Drilling sequence amount achieves 20-40% of total machining sequences. Therefore, drilling technology is important research project in machining area.Nowadays, the usual drill is the conical drill. But the grinding motions of the machine tools are very complex for the conical drill and can't exactly control geometric parameters of the drill points. This thesis is to study helical drill, which the motions of grinding are simple; the grinding parameters can be exactly control. The thesis study on the following area:Firstly, developing history of drill and grinding technology are reviewed. Grinding methods of flank surfaces of several usual drill points are discussed. The necessity and feasibility for researching complex helical drill are proposed.Secondly, drill point is the most important part of a drill for drilling. To research of drill is mainly to research of drill point. According to the defects of common drill points, analyzing of grind principle and its motion relation, a new kind of drill, which is called as complex helical point drill is established. The mathematical models of helical point are established.Thirdly, the relation of the grinding parameters and geometric parameters is analyzed.Fourthly, analyzing geometric parameters of complex helical drill point and developing their mathematic models, achieving distribution reasonability of geometric angles of the helical drill, it is helpful to analyze and exactly control the parameters of drill point.Fifthly, experiment analyzes. Complex helical drill point and common drill points are used in the drilling experiment, changing their grinding parameters in the contrastive experiment. We will analyze different drill points on the drilling force and drilling quality.It is clear that complex helical drill point has an "S" contour with a radiuses crown chisel, which reduces the thrust force and makes the drills self-centering. The S-shape chisel edge has a lower negative rake angle than a conventional chisel edge.