The processing method of the hole is complicated and diverse. The processing of the fastener hole on the aircraft is generally drilling, and is suitable for the through hole of the mounting screw and the part rivet mounting hole. Before drilling, first select the appropriate drill according to the type and size of the fastener to ensure that the hole size is within the allowable range. In the drilling process, first of all, to ensure the verticality of the hole, and secondly to ensure the smoothness of the hole wall, otherwise it will affect the installation quality of the fastener.
There is also a widely used fastener Hi-lock (a type of high-strength bolt) on the aircraft that requires a tight fit. Reaming is also required when making the Hi-lock hole. Reaming is one of the finishing methods of the hole. After the initial completion of the drilling, reaming is required to ensure the smoothness and tolerance of the hole wall, so the suitable drill bit And the selection of the reamer is very important. Generally, the iron filings are finely broken during the reaming, and it is easy to adhere to the cutting edge, even between the edges of the calibrated portion of the reamer of the hole wall, and the processed surface is shaved to enlarge the aperture. At the same time, the accumulation of heat generated during the cutting process easily causes deformation of the workpiece and the reamer, thereby reducing the service life of the reamer and increasing the chance of chip generation. Therefore, in the reaming, the heart must use a reasonable cutting fluid. Most of the aircraft fuselage is made of aluminum alloy. In order to prevent oxidation, the anode is also anodized after the hole is made. Some of the materials are different because the fasteners and the connecting parts are different. The hole is to be primed.
In the case of making holes for a relatively thick aluminum alloy material subjected to a large load, the cold working hardening of the inner surface of the hole is also performed, and for the smaller size hole, a "drawing" process is employed. For larger sized holes, the inner wall of the hole is "blasted". This can greatly improve the fatigue resistance of the hole and is widely used in aircraft structures.
The Buddha said: "One leaf and one bodhi, one flower and one world." For us engaged in aircraft structure work, the aircraft is another world in our eyes, a steel world consisting of one hole, one fastener and one raft. Fasteners are key components in the equipment manufacturing industry, and the fasteners on the aircraft are about a few million, and the types and sizes vary to ensure the stability and connection of the aircraft structure. If the aircraft is not properly installed, it will have unimaginable consequences, and the basis of the installation lies in the holes that are not seen.
If the big country cooks small fresh, the small holes are also the same. The processing of a hole seems to be only a few minutes on the surface, but there are many things to be aware of. When I first joined the work, the master told the apprentice that it would be enough to make this hole in the life of the structure. At that time, I thought it was a joke, until I later realized the profound meaning of the master. Aircraft structure plus modification work, hundreds of fasteners, most of the work is in the hole, this work is irreversible. One or two is not easy to make mistakes, but when there are hundreds of times, there are even thousands of times? So the attitude of each hole must be consistent, the same focus, the same serious, each must pursue perfection !
(Source: Civil Aviation Resource Network)
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