Drills are the most widely used hole processing tool
The drill bit is widely used in mechanical processing hardware, it is used to drill through-hole or blind hole on solid material, and can be on the existing hole reaming tool. However, different types of drill bits are selected in different operating environments. Common drill bits mainly include twist drill, spot drill, center drill, and deep hole drill. Although reaming drill and counterboring drill can not be drilled on solid material, they are usually classified as a drill bit.
A twist drill is the most widely used hole processing tool. The diameter usually ranges from 0.25 to 80 mm. It mainly consists of the working part and the handle. The working part has two spiral-shaped grooves, shaped like twists, hence the name. The top Angle of the cutting part of the standard twist drill is 118, the bevel angle of the transverse edge is 40° ~ 60°. And the back Angle is 8° ~ 20°. The shank of the twist drill has two forms: straight shank and taper shank. The former is clamped in the drill chuck while the latter is inserted in the taper hole of the spindle or tail of the machine tool. General twist drill with high - speed steel manufacturing.
Use of Drills
A deep hole drill is usually a tool for machining holes whose ratio of hole depth to the aperture is greater than 6. Commonly used are gun drill, BTA deep hole drill, jet drill, DF deep hole drill and so on. The reaming drill has 3 ~ 4 cutter teeth, its rigidity is better than the twist drill. It is used to enlarge the existing hole and improve the machining accuracy and finish.
The countersunk drill has more cutter teeth, and the hole end is processed into the desired shape by forming a method. Which is used for machining countersunk head hole of various countersunk head screws or the outer end face of the countersunk hole.
The center drill is used for drilling the center hole of the shaft workpiece, which is essentially composed of twist drill with small spiral Angle and spot drill, so it is also called a compound center drill.
