Since when the welded water well drilling tools cooperate with the air pressure to drill into the soft coal seam, the spiral fins are prone to cracking, de-welding, and wear resistance, which leads to problems such as difficulty in forming holes or even scrapping. Helical grooves were machined, drill pipe joints were improved, threads were surface treated, and integral water well drilling tools were developed. The field test results show that the integral water well drilling tools have good comprehensive mechanical properties, strong hole-forming ability, and long service life. They can not only replace the welded water well drilling tools for pneumatic drilling in soft coal seams, but also Conventional flat drill pipe construction rock drilling.

　　Problems encountered in drilling soft coal seams

　　Soft coal seam refers to the coal seam with a coal hardness coefficient , which has the characteristics of soft coal, poor permeability, high gas content, and high pressure. During the construction of gas drainage drilling, in-hole accidents such as injection holes, collapsed holes, and drilled holes are prone to occur, resulting in problems such as shallow drilling depth, low hole formation rate, and poor gas drainage effect. Safe and efficient mining of coal mines is an urgent problem to be solved.

　　In the long-term drilling practice, some domestic coal mining enterprises have successively carried out the test and application of air drilling technology in the soft coal seam. After the wide-foil water well drilling tools are used in combination with the air pressure drilling technology, the pore depth and porosity of the soft coal seam have been greatly improved, and the medium wind pressure air drilling technology has become effective and feasible for drilling in the soft coal seam. construction process.

　　At present, water well drilling tools with wide fins are widely used in China, and the spiral fins are mostly processed by hot-melt welding. This processing method has high requirements on the welding process level, and the controllability and stability of the welding quality in the actual processing process are poor. Affected by the level of the welding process, problems such as "over-soldering" or "de-soldering" are inevitable. "Over-welding" will cause damage to the rod body, and fractures along the welding seam between the helical fins and the rod body are prone to occur during use; In addition, hot melt welding has higher requirements on the material of the rod body and the helical fins. To ensure good weldability between the helical fin and the drill pipe body, the material properties of the two should be optimized. If selected randomly, in addition to abnormal phenomena such as over-welding and de-soldering, it will also cause excessive wear of the drill pipe helical fins, which greatly reduces the service life of the drill pipe.

　　This kind of drill pipe adopts the integral milling method to mill out the thick-walled pipe. The development and application of integral water well drilling tools have helical grooves with certain parameters to form helical fins. Because it is processed by a CNC milling machine, it can effectively control the machining accuracy of the spiral groove. The formed spiral fin and the rod body are integrated, and its material is the same as that of the parent body of the drill pipe, and the wear resistance is greatly improved, which completely solves the problem of traditional welding water Problems such as over-welding of well drilling tools, weak welding, and rapid wear of spiral fins.