Trepanning is a kind of drill with deep hole processing on solid material by ring cutting. The nesting process can leave the core, save material and reduce the power consumption of machine tools. When it is necessary to take the sample from the material Center for performance test, the sleeve drill can not be replaced by other tools. Sleeve drills are usually used to process holes over 60 mm in diameter, and the depth of the blank can reach more than ten meters.
There are two kinds of trepanning ：
one is external chip removal and the other is internal chip removal (see deep hole drill). The main advantage of the external chip removal sleeve drill is that the equipment of the cutting fluid system is simple, but the diameter of the drill pipe is small, so the strength and stiffness of the drill pipe are poor, and it is mostly used in small batch production.
The internal chip removal trepanning relies on the pressure of the cutting fluid to flush chips out of the drill pipe, so it needs to equip a more complex fluid supply system and solve the sealing problem, but the productivity is high, and it is suitable for batch production.
The trepanning may have one or more high-speed steel or carbide cutter heads, and the cutter body is equipped with guide blocks to prevent vibration during cutting and reduce hole deflection. The guide block is made of cemented carbide, bakelite or nylon. The cutter body and tubular drill pipe can be joined by welding or special square thread. In order to ensure the smooth removal of chips and reduce cutting load, the cutting edges of each tool head of the trepanning are designed in different shapes, so that the chips can be divided narrowly. At the same time, a chip breaker is rubbed on the front of each tooth to break the chips. For large diameter blind hole nesting, a special cutting device is needed to separate the core from the body.
Material drilling deep hole processing matters needing attention - deep hole processing manufacturers come to tell you:
1: At the beginning of drilling, the cutter should be slowly lowered and the edge of the cutter should touch the steel plate slowly. When the bit is drilled into about 1-2 mm, the cutter will feed normally after stabilizing the feed.
2: When drilling, the force should not be too strong or too small, the force should be moderate and the feed should be uniform.
(1) Too much force and machine load will affect the service life of the machine and chip removal at the same time.
(2) If the force is too small, the friction of the cutting edge will be increased and the passivation speed of the bit will be accelerated.
(3) The appropriate thickness of iron chips is 0.10-0.15 mm.
3: When approaching perforation, feed speed should be slowed down to avoid excessive instantaneous penetration force, damage of blade and core jamming.
4: In the process of drilling, there will be chip phenomenon, which can be caused by excessive force or passivation of small cutters, hardness and softness of workpiece materials, impurities, rotational speed and so on. 5: Chips manifestation: abnormal sound when drilling, vibration feeling on hand, increase of motor load and other phenomena
Approaches:
1) Return the knife in time and many times so that the excess and stuck iron chips can be discharged.
2) Remove the wrapped iron chips with hooks in time (no (no hands, lest scratches)
3) Check whether the bit is passivated and replace the new bit in time.
4) If debris removal is not emphasized and debris removal is not smooth, it will be easier for debris and core to be jammed, which will lead to the phenomenon of bit edge collapse and fracture.
