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Original Title: [Technical Dry Goods] Down-the-Hole Drilling and Casing Drilling Technology (I) 1. Overview Air Dth hammer simultaneous casing drilling technology is a new drilling technology which uses compressed air as power, and the simultaneous casing drilling tool carries out percussive rotary drilling under the action of air Dth hammer and drill torque, and realizes synchronous follow-up of casing.After the hole is finished, the simultaneous casing drilling tool is lifted out of the casing, and the casing is used to protect the wall. 1. Overview Air Dth hammer simultaneous casing drilling technology is a new drilling technology which uses compressed air as power, and the simultaneous casing drilling tool carries out percussive rotary drilling under the action of air Dth hammer and drill torque, and realizes synchronous follow-up of casing.After the hole is finished, the simultaneous casing drilling tool is lifted out of the casing, and the casing is used to protect the wall. 1.1 Characteristics of air down-the-hole hammer drilling with casing It is mainly used for the broken stratum where it is difficult to form a hole,mining dth bit, such as gravel layer, quicksand layer, overburden,mining drill bit, deluvium, etc.; the drilling speed is fast and the efficiency is high, generally up to 5m/H; dry (air) drilling is of great significance to the construction of water-deficient areas and landslides where water cannot be used; the casing can be recovered and reused; The hole depth of single-stage simultaneous casing drilling is generally 40m, and some can reach more than 80m; When the mud content in the formation is very high, it is easy to block the pores; The drilling rig requires low speed (less than 50 rpm) and large torque, preferably a long-stroke multi-function drilling rig, water well drilling rig, mining dth bit ,dth drilling hammer, etc. If the geological drilling rig needs to be able to reduce the speed. 1.2 Application field of air down-the-hole hammer drilling with casing Geological exploration Land Disaster Control and Emergency Rescue (Chongqing Wulong Landslide Rescue Project) Water well drilling (Yunnan drought-resistant well drilling project, Shandong drought-resistant well drilling project) Hydropower Station Construction (High Slope Emergency Project of Xiaowan Hydropower Station in Yunnan) Foundation Treatment of Urban High-rise Building Expressway and railway construction project Construction of tunnel pipe shed Petroleum geophysical drilling, etc. Expand the full text GK-4 hole rock core (local) GK-4 hole rock core (local) 2. Working principle of air Dth hammer drilling with casing Structure type of drilling tool with casing Air Dth hammer drilling tool with casing is the most important tool for drilling with casing. At present, there are many structural types at home and abroad, mainly including eccentric, concentric, centering, There are four types of coring and casing drilling tools with different structures and different working principles. 2. Working principle of air Dth hammer drilling with casing Structure type of drilling tool with casing Air Dth hammer drilling tool with casing is the most important tool for drilling with casing. At present, there are many structural types at home and abroad, mainly including eccentric, concentric, centering, There are four types of coring and casing drilling tools with different structures and different working principles. 2.1 Principle of air Dth hammer eccentric simultaneous casing drilling The eccentric casing drilling tool shall have two functions: 1. It can realize underreaming drilling. 2. Synchronous follow-up casing 2.2 Principle of air Dth hammer concentric drilling with casing The concentric casing drilling tool shall have two functions: 1. It can realize underreaming drilling 2. Synchronous follow-up casing 2.3 Centering and casing drilling principle of air Dth hammer Torsion moment: drill rod impactor center drill bit groove annular drill bit shoulder; annular drill bit and pipe shoe are connected by circlip The purpose of the ring bit rotating while the shoe and casing do not. 2.4 Coring and casing drilling principle of air Dth hammer It is mainly composed of center coring drilling tool and casing shoe assembly. The drilling tool is equipped with advance drilling mechanism, air shunt mechanism, torque transmission mechanism, pressure transmission mechanism, transfer mechanism and coring device to realize specific functions. 2.5 Coring and casing drilling principle of air Dth hammer During drilling, the coring and casing drilling tool realizes percussive rotary drilling, and the core enters the core tube while drilling; the casing follows up synchronously. At the end of the drilling round, the central drilling tool is directly lifted to the surface for coring, and the casing is left in the hole. This article originates from the network, and the copyright belongs to the original author. Reprinted from the network,Borehole Drill Bits, the copyright belongs to the original author, if there is infringement, please contact to delete! Read this article with. Return to Sohu to see more Responsible Editor:. wt-dthtools.com