Research On Inner Helical Surface Milling Processing Technology Of Screw Drilling Tool Motor Stator

Screw drilling tool is a kind of downhole motor whose driving force is from drilling fluid and its motor is composed of the two core components that are the rotor and the stator. The rotor is a steel screw whose outer surfaces are coated with wear-resistant materials, and its level of manufacturing process is already very high. The traditional stator is a thin-walled steel pipe, and its inner surface cohere with the inner helical surface rubber bush. After repeated used, the traditional screw drilling tool is found a lot of shortcomings, such as the heat concentration and the uneven heating of the stator rubber bushing, ultimately resulted in early failure and damage, also the adhesive ability of stator bush is not strong, leading to degum and resulted in loss of utility of the pumps and so on. Respond to the problems that exist in trational screw drilling tool, a new type of screw drilling tool stator appears. This kind of stator can effectively improve the problems of the traditional screw drilling tools by changing the shape of inner surface, thereby reducing the screw drilling tool failure rate, increasing their service life. Therefore, in order to achieve low-cost, highly efficient processing of such screw drilling tools stator, this paper proposes a method of using forming milling process to achieve the inner helical surface, and do research on milling processing technology.First of all, set up the mathematical model of the inner helical surface according to the working principle of the screw drilling tools. Secondly, by comparing many domestic and foreign processing methods of the inner helical surface for the stator, propose and determine the processing method of this paper and its superiority. Then analysis of milling inner helical surface by the tool of discrete points fitting the profile replaced by arc profile, and verify the feasibility of milling inner helical surface by the tool of its profile is the replaced arc profile. Later, do research on the dynamic characteristics of the arbor and propose reliable and effective form of anxiliary for the arbor. Finally, milling experiments are carried out on independent design and development of processing equipment, and the results show that the stator having been processed meet the requirements. The facts show the feasibility of processing and the stability and reliability of milling, thus lay a solid foundation of theory and practice for successful achevement of inner helical surface by forming milling.