How are the drills classified?
A deep hole drill usually refers to a tool for processing holes in which Kong Shen is larger than the aperture ratio of 6. Commonly used are gun drills, BTA deep hole drilling, jet drilling, DF deep hole drilling, etc.. The casing drill is also used in deep hole machining.
Twist drill is the most widely used hole cutting tool. Usually, the diameter ranges from 0.25 to 80 millimeters.
The cutting part of flat drill is shovel shaped, simple in structure and low in manufacturing cost. The cutting fluid is easy to be introduced into the hole, but the performance of cutting and chip removal is poor. The structure of flat drill is composed of two types: integral type and assembled type. The integral type is mainly used for drilling 0.03 to 0.5 millimeters in diameter. The assembled flat drill blade can be changed, and can be internally cooled. It is mainly used for drilling large holes with a diameter of 25~500 millimeters.
As a result of structural reasons, the front angle is large at the outer edge and gradually decreases to the middle. The horizontal blade is a negative front angle (up to about 55 degrees), and plays a role of extrusion when drilling. In order to improve the cutting performance of the twist drill, the cutting parts can be cut into various shapes according to the nature of the material to be processed, such as group drills. Handle form twist drills with parallel shanks and taper shank two, when processing the former clamp the drill chuck, which is inserted in the machine tool spindle or the tailstock taper hole. Made of high speed steel for general twist drills. Inlaid with hard alloy blade or crown drill for machining cast iron, hardened steel and non-metallic materials, solid carbide twist drill used for machining small instrument parts and printed circuit board etc..
The work part and the handle part constitute. The work part has two spiral grooves, similar to the "twist", hence its name. In order to reduce the drilling hole wall part and the guide friction between the drill shank twist drill to self direction decreases inverted cone diameter. The spiral angle of the twist drill mainly affects the rake angle, the blade edge strength and the chip removal performance of the cutting edge, usually 25 to 32 degrees. The spiral groove can be processed by milling, grinding, hot rolling or hot extrusion, and the cutting edge of the drill head is formed by grinding the front end of the drill bit. The cutting edge of a standard twist drill is 118, the cross edge angle is 40 degrees to 60 degrees, and the back angle is 8 degrees to 20 degrees.
