Selection of bit material
According to the processing characteristics of the materials, has the following characteristics: drill bit hardness must be greater than the workpiece hardness; the drill bit under great torsion and axial force on the workpiece, therefore must have sufficient strength and toughness; because the machined material toughness, when the cutting blade is sharp enough to ask, so the tool material must have sufficient wear resistance, so as to reduce the hardening of the workpiece; because the chemical properties must be high, so the requirement of tool material and titanium alloy affinity to poor, in order to avoid travel diffusion caused sticking knife, broken drill phenomenon.
At present, there are many kinds of materials used for cutting tools, including tool steel, carbide and superhard material.
At first, try to use ordinary high-speed steel drill coating test, ordinary high speed steel bit low price, when using coating technology, can significantly reduce the friction coefficient of the tool and the workpiece, improve the tool life. However, due to the high speed of the machine tool, the bit strength is not enough, and the drill bit is broken in the process, so the effect is not satisfactory.
Cemented carbide is a newly developed tool material suitable for roughing and finishing of most materials, including steel, cast iron, special materials and plastics. To this end, we decided to adopt the whole carbide drill.
Determination of parameters for bit grinding
1., the main auxiliary plane of twist drills
The main auxiliary planes of the twist drill are the base plane, cutting plane, middle section and column section.
If the auxiliary movement is not considered, the surface of any point on the main cutting edge of the twist drill is considered, and because of the structural features of the twist drill, the base surface of each bit of the main cutting edge of the drill bit is changed.
The cutting surface at any point on the main cutting edge is the plane that contains the point of the cutting speed and cuts it at the machined surface of the point. The cutting plane is perpendicular to the base surface, and the cutting planes of each point on the main cutting edge are different. The column section at the main cutting edge is a cylindrical surface made by this point and centered on the center line of the drill bit, and different column sections on the main cutting edge are cylindrical surfaces with different radii.