Machining holes on solid materials with a drill bit is called drilling. Except that part of the hole processing of various parts is completed by turning, boring, milling and other machine tools, a large part of it is completed by fitters using drilling machines and drilling tools (drill, reamer, reamer, etc.). When drilling on the drilling machine, generally, the drill bit should complete two movements at the same time; Main motion, namely the rotary motion of the drill around the axis (cutting motion); Auxiliary movement, that is, the drill moves in a straight line towards the workpiece along the axis direction (feed movement). When drilling, the processing quality is affected mainly due to the shortcomings of the drill structure. The processing accuracy is generally below IT10, and the surface roughness is about Ra12.5 μ m, which belongs to rough processing.
Functions of drilling: ① Obtain first-hand underground geological physical data, that is, take core, ore core, rock cuttings or liquid and gaseous samples from the drilling hole, and take additional side wall rock samples from the hole wall if necessary; ② As the channel of geophysical logging, obtain various geophysical information of rock and ore beds; ③ As an artificial channel to observe the hydrogeological dynamics of the groundwater layer; ④ Some boreholes can combine exploration with mining to exploit groundwater, geothermal, oil and gas, etc. Drilling engineering has been widely used in many sectors of the national economy. According to the purpose, boreholes can be divided into the following categories: ① geological survey or exploration boreholes, which are used to understand geological structures, find ore or prove mineral reserves; ② Hydrogeological drilling to investigate underground hydrogeological conditions; ③ Well, which is used to develop or supplement groundwater resources for industry, agriculture, national defense and life, and has the function of enriching hydrogeological data; ④ Engineering geological drilling, survey or prove engineering foundation conditions for building foundation, dam site, reservoir, bridge and road; ⑤ Oil drilling, exploration and development of oil and natural gas; ⑥ Geothermal drilling, exploration and development of underground hot water and steam resources; ⑦ Drilling for engineering foundation construction, which refers to the drilling for foundation pile or pipe pile used for strengthening and treating the foundation of building engineering; ⑧ Development of boreholes, mining of underground brine, dissolved rock salt, sulfur, burning and gasification of underground coal, etc. ⑨ Auxiliary boreholes for mining or tunnel construction, boreholes for ventilation, drainage, water exploration, gas exploration, freezing, transportation, and pipeline installation, blasting, sampling, grouting, etc. for buildings and communications during mining or tunnel construction. Geological drilling