Deep hole refers to the diameter of drill bits more than times, called deep hole
In machining, the hole with a hole ratio greater than 6 is usually called a deep hole. In deep hole drilling, it is difficult to get rid of heat and chip, and it is easy to bend and vibrate because of the poor rigidity of the drill rod. Cooling and cooling systems are usually used to solve cooling and chip removal problems. The classification of deep hole drilling is divided into two types according to chip arrangement: chip and chip. There are 3 kinds of chip removal drill, deep hole flat drill and deep hole twist drill. The internal chip removal is divided into BTA deep hole drilling, jet drilling and DF deep hole drilling.
Gun drill: only one cutting part, which was first used to process barrels. During drilling, the cutting fluid enters from the middle of the drill pipe and is injected into the cutting area through a small hole in the head of the drill bit and then removed from the V groove of the drill bit with the chip. The gun drill is suitable for deep holes with a bore diameter of 2~20 mm and a ratio of Kong Shen to aperture greater than 100. BTA deep hole drilling: the cutting fluid is fed from the gap between the drill pipe and the hole wall, and the cuttings are expelled from the inner hole of the drill pipe by the pressure of the cutting fluid. BTA deep hole drilling is suitable for drilling more than 6 mm hole diameter, hole depth and aperture ratio of less than 100 of the deep hole, and its production efficiency is more than 3 times higher than the gun drilling. The jet drilling: a multi edge deep hole drilling, inside and outside two layer drill pipe, most cutting fluid from inside and outside the drill pipe into the cutting area gap, and then together with the inner tube into the chip; the crescent hole and a small portion of the cutting fluid through the inner tube into the tail end of the inner tube jet formation, effect, low pressure area, help suction chip. The jet drilling does not require a strict cutting fluid seal. It is suitable for drilling deep holes with a diameter of more than 18 mm, Kong Shen and a bore ratio of less than 100.
DF deep hole drilling: this kind of drill absorbs the advantages of BTA deep hole drilling and jet drilling, and uses single pipe, chip removal, pushing and suction to improve the chip removal ability, and can drill holes at the depth of 8 millimeters or more. Gun drills are usually made of high speed steel or hard alloy. Various kinds of inner chip removing deep hole drilling can be welded or mechanically clamped and indexable carbide inserts according to size. The guide block on the deep hole drill has the function of guiding and centering to reduce the deflection of the drill hole and the vibration during cutting. The arrangement of cutter teeth and guide blocks in deep hole drilling mainly considers the balance of radial forces during chip separation and cutting. The cutter body and the drill rod can be welded or square threaded.
