Drill bit according to their different material, structure, purpose, etc., can be divided into the following, come together long knowledge of it!

1. Twist

Twist is the most widely-processing tool. A diameter in the range of usually 0.25 to 80 mm. It is mainly composed of the working portion and a shank portion. Work section has two helical grooves, shape twist, hence the name. In order to reduce the wall of the guide portion of the hole when drilling friction, twist drill tip to self-direction is gradually reduced shank diameter inverted cone. Helix angle of twist mainly affects the front corner of the size of the cutting edge, edge flap strength and chip performance, typically 25 ° ~ 32 °. Spiral groove available milling, grinding, hot rolling or hot extrusion processing methods, the cutting portion is formed by grinding after the front end of the drill. Apex of the cutting portion 118 of a standard twist drill, the chisel edge angle is 40 ° ~ 60 °, the clearance angle of 8 ° ~ 20 °. For structural reasons, the front corner at the outer edge of a large, gradually decreases toward the middle of the chisel at a negative rake angle (up to about -55 °), from the squeezing action when drilling. In order to improve the cutting performance of twist drills, according to the nature of the material to be machined part repair ground cutting various shapes (such as drilling group). Shank twist drills with and handle the form of two straight shank taper, when caught in the drill chuck machining former, the latter is inserted in the machine spindle or tailstock taper in. General manufacturing high-speed steel twist drill. Inserts welded carbide blade or twist the crown suitable for machining cast iron, hardened steel and non-metallic materials, solid carbide twist drills for machining small parts and printed circuit boards and other instrumentation.

2. flat drill

Flat part of the drill cutting spade, simple structure, low manufacturing costs, cutting fluid introduced into the hole easily, but cutting and chip performance is poor. Flat drill monolithic structure and assembly of two. The overall formula of the major diameter for drilling micropores of 0.03 to 0.5 mm. Fabricated flat diamond blade can be changed, can be used to cool inside, mainly for large hole drilling 25 to 500 mm in diameter.

3. Deep Hole Drilling

Deep hole drilling process usually refers to the ratio of hole depth and aperture larger than the hole cutter 6. Commonly used gun drilling, BTA deep hole drilling, injection drilling, DF deep hole drilling. Nesting drilling also commonly used in deep processing.

4. reamer

The reamer 3 to 4 teeth, better rigidity than the twist, to expand the existing hole, and to improve the machining accuracy and finish.

5. countersink drill

Countersink drill has more teeth to the machined hole side molding into a desired shape, for processing a variety of countersunk head screws spigot, or outer face flattened hole.

6. center drill

Center drills for center hole drilling shaft parts used, it is essentially a small twist by helix angle and countersink drill composite, so called composite center drill.

7. hollow drill

The middle is hollow drill bit, drilling material mainly used for coring.

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