Types and uses of drill bits

What are the types of drill bits

A. Classification according to structure

(1) Integral drill bit: drill top, drill body and drill shank are made of the same material as a whole.

(2) End welding drill bit, the top bit is welded by carbide.

B, according to the drill shank classification

(1) Straight shank drill bit: if the diameter of drill bit is less than or equal to 13.0mm, straight shank shall be used.

(2) Taper shank drill bit: the drill shank is taper shaped, generally its taper is Morse taper.

This picture is provided by the registered user "Ni Zi's text", feedback of copyright statement

C. Classification by use

(1) center drill bit: generally used for drilling before the center point, the front cone has 60°, 75°, 90°, etc., lathe operation in order to use the tail seat support, holding should use 60° center drill and lathe tail seat center 60°.

(2) Twist bit: the most widely used bit for industrial manufacturing, we generally use twist bit.

(3) Super hard bit: the front end or all of the drill body is made of super hard alloy cutting material, which is used for drilling materials.

(4) oil hole drill bit: there are two holes in the drill body, through which the cutting agent reaches the cutting edge part to take away heat and chips. The work of the drill bit is generally rotating, while the drill bit is stationary.

(5) Deep hole drill: the first used for barrel and stone drilling processing, also known as barrel drill. The deep hole bit is of a groove type, with more than a quarter of the bit cut off in a round tube to produce cutting chip removal.

(6) drill reamer: in order to mass production, the front end of the drill, the rear end of the reamer, the diameter of the drill and the diameter of the reamer only difference in the margin of reaming, there are also drills in screw tapping mixed use, so it is also known as mixed drill.

(7) Taper bit: When machining the feed port of the mould, taper bit can be used.

(8) Cylindrical hole drill bit: we call it countersunk head milling cutter, this kind of drill bit has a small diameter part called the shaft.

(9) conical hole drill: for drilling conical hole, its front Angle is 90°, 60° and so on, we use a chamfering knife is a conical hole drill.

(10) Triangular bit: a drill bit used in electric drills, the shank of which has a triangular face so that the collet can secure the bit.

The characteristics and usage of various types of drill bits are introduced

Twist drill

Twist drill is the most widely used hole machining tool. The usual diameter range is 0.25 to 80 mm. It is mainly composed of bit working part and shank. The working part has two spiral grooves, shaped like a twist, hence the name. In order to reduce the friction between the guide part and the hole wall when drilling, twist drill from the drill tip to the handle direction gradually reduce the diameter of the inverted cone. The screw Angle of twist drill mainly affects the size of cutting edge Angle, edge edge strength and chip removal performance, which is usually 25° ~ 32°. Spiral grooves can be processed by milling, grinding, hot rolling or hot extrusion, and the front end of the drill bit forms a cutting part after grinding. The cutting Angle of the standard twist drill is 118, the bevel Angle of the cross edge is 40° ~ 60°, and the back Angle is 8° ~ 20°. Due to structural reasons, the rake Angle is large at the outer edge and gradually decreases to the middle, and the transverse edge is negative rake Angle (up to about -55°), which acts as extrusion when drilling.

In order to improve the cutting performance of twist drill, the cutting part can be ground into various shapes according to the properties of processed materials (such as group drill). Twist drill shank form has straight shank and cone shank two kinds, processing the former clip in the drill chuck, the latter inserted in the machine tool spindle or tail seat of the cone hole. The general twist drill is made of high speed steel. Insert welding carbide blade or crown twist drill for the processing of cast iron, hardened steel and non-metallic materials, such as the whole cemented carbide small twist drill for the processing of instrument parts and printed circuit boards.

Flat drill

The cutting part of flat drill is spade form, structure is simple, manufacturing cost is low, in cutting fluid leads into hole easily, but performance of cutting and discharge chip is poorer. Flat drill structure has two types of integral and assembled. The whole is mainly used for drilling 0.03 ~ 0.5 mm diameter micro hole. Prefabricated flat drill blade can be changed, can use internal cooling, mainly used for drilling 25 ~ 500mm diameter of large holes.

Deep hole drilling

Deep hole drilling is usually refers to the processing of hole depth to aperture ratio greater than 6. Commonly used gun drill, BTA deep hole drill, jet drill, DF deep hole drill and so on. Sleeve drills are also commonly used for deep hole machining.

Reaming drill

Reaming drill has 3 to 4 cutter teeth, its rigidity is better than twist drill, used to expand the existing hole and improve processing accuracy and finish.

Economic drill

Shaving drill has more cutter teeth, in order to form the hole end processing into the required shape, used for processing various countersunk head screw hole, or flat hole outer end face.

Center drill

The center drill is used for drilling the center hole of shaft type workpieces. It is essentially composed of screw Angle small twist drill and countersink drill, so it is also called compound center drill.