Bionic Test Investigation On Thread Galling For Oil Tubing

The tubing broken accidents is a common problem in oil production, and related to the exploitation of oil directly. A main cause of tubing broken accidents is tubing thread galling. In order to improve the anti-galling ability of the tubing thread, by analysis of galling mechanism of tubing thread and research on characteristics of bionic non-smooth surface, by using the finite element method, screw together process was simulated combined with bionic technology in this paper, and the results show that, the maximum contact stress of bionic tubing thread which join the non-smooth structure was significantly lower than the common tubing thread in standard conditions, and the stress distribution is more homogeneous. In order to find the best bionic structure parameters, this paper makes an optimized design on diameter, diameter depth ratio, density and the distribution of teeth number, and find out that tubing threaded galling phenomenon was improved best when there are8bionic elements which diameter and depth are150μm on each teeth of five tooth surface in the middle of thread. According to the optimize bionic parameters, bionic tubing thread was machined, and the anti-galling ability was tested by coupling screw on machine, the result show that, anti-galling ability of the bionic tubing thread is better than the common tubing thread.