Analysis and research on quality Defects of threaded machining of oil casing

In the process of exploration and development in petroleum enterprises, the processing quality of casing thread is closely related to the benefit of exploration and development. This is mainly because the thread belongs to the connection part, so it is the weakest link, so it is often the area of high incidence of accidents, in the process of oil casing thread processing, there are often some or other quality defects. Based on this background, combined with our own practice, this paper analyzes the quality defects of the threaded machining of oil casing, and puts forward some suggestions for strengthening the threaded machining of oil casing.
Oil casing thread; Machining quality defect
1. Analysis of common quality defects in thread processing of oil casing
The common quality defects of oil casing thread processing are as follows: one is black buckle; The second is ripple; Three is close distance, etc.
As far as black buckle is concerned, it is mainly due to the serious shortage of processing capacity in the part of the silk buckle, which leads to poor finish. It is mainly related to the diameter of the steel pipe itself and the thickness of the pipe wall, the ovality and accuracy, and the flatness of the pipe end. When there is black buckle in the pipe body, it is mainly caused by the small outer diameter of the pipe body, the flatness of the pipe end is not enough, and the large ellipticity.
And with the thread appears after black buckle, there will be wire buckle wall defects, mainly for steel pipe after wire processing, one side is thinner and the other side is uneven wall thickness. The reason why the silk buckle will deviate from the wall is the same as the reason why the black leather buckle is formed by the thread, which is caused by the uneven wall thickness of the steel pipe end and the large ellipticity and bending. In addition, the deviation wall exists in the thread processing, and the processing quantity is not reasonably controlled, leading to the excessive negative difference of the bottom wall thickness of the wire. So both are the quality defects of thread processing.
However, tight pitch, tooth height, taper and pitch are thread parameters, which often lead to poor connection and sealing performance because of their parameters exceed the standard. Among them, the close distance and the whole lot of single parameter fluctuation in thread, so when any one single parameter is unqualified, will effect the close distance, so it is not only related to steel pipe material, and the way and processing and processing machine type and stability with the precision of machine tools and other closely related [1].