Aiming at problems such as cracking and de-welding of t […]
Aiming at problems such as cracking and de-welding of the spiral fins when the welded auger pipe is combined with wind pressure to drill into the soft coal seam, which can lead to problems such as difficulty in hole formation or even scrapping, spiral grooves are processed in thick-walled pipes by milling chips. Improved drill pipe joints, surface treatment of threads, and developed integral spiral drill pipe.
Problems encountered in drilling soft coal seams
The soft coal seam refers to the coal seam with the coal hardness coefficient f<1. It has the characteristics of soft coal, poor permeability, high gas content, and high pressure. In the process of gas drainage drilling construction, accidents such as blowholes, hole collapses, and holding drills are prone to occur, resulting in shallow drilling depths, low hole formation rates, and poor gas drainage effects. These problems have become urgent for coal mining. Problems solved.
In the long-term drilling practice, some domestic coal mine enterprises have successively conducted experiments and applications of air drilling technology in soft coal seams. With the use of wide blade spiral drill pipes and air pressure drilling technology, the hole formation depth and hole formation rate of soft coal seams have been greatly improved, and the medium air pressure air drilling technology has become an effective and feasible drilling construction in soft coal seams.
At present, wide blade spiral drill rods are widely used in China, and the spiral blades are mostly processed by hot-melt welding. This kind of processing method has higher requirements on the welding technology level, and the controllability and stability of the welding quality in the actual processing process is poor. Affected by the level of welding technology, problems such as "over-welding" or "de-soldering" will inevitably occur. "Over-welding" will cause damage to the rod body, and breakage along the welding seam between the spiral fin and the rod body is likely to occur during use;
In addition, hot-melt welding places higher requirements on the material of the rod body and the spiral fin. In order to ensure good weldability between the spiral fin and the drill pipe body, the material properties of the two. If selected at random, in addition to abnormal phenomena such as over welding and desoldering, it will also cause excessive wear of the drill pipe spiral fins, which greatly reduces the service life of the drill pipe.
Manufacturing process of integral spiral drill pipe
This kind of drill rod adopts the integral milling method to mill out the thick-walled pipe. The integral spiral drill rod is developed and applied with parameterized spiral grooves to form spiral fins. Because it is processed by a CNC milling machine, it can effectively control the processing accuracy of the spiral groove. The formed spiral blade and the rod body are integrated, and the material is the same as the drill pipe parent body. The performance is greatly improved, which solves the problem of traditional welded spiral drill rods. Problems such as welding, weak welding, and fast wear of spiral fins.