DRILLING EQUIPMENT AND ITS FEMALE AND MALE PARTS Russian patent published in 2012 - IPC E21B17/42 F16L15/00 

FIELD: construction.

SUBSTANCE: drilling equipment comprises a female and a male parts, connected to each other by means of a threaded joint. The threaded joint comprises an inner trapezoidal thread in the female part and an outer trapezoidal thread on the male part. Each thread has a shape of a spiral ridge limited with the top and two lateral sides, a groove with a bottom. The groove stretches between two tops, besides, the thread ridge goes along multiple turns between the front and rear ends of the drilling equipment. The individual top of the thread touches upon an imaginary cylinder or a cone concentric with a central axis. At the same time the bottom of the groove of at least one of threads has a concave and a partially circular shape of a cross section at least along a part of the groove length. The individual top of the thread is transformed into lateral sides via concave radius transitions. These radii reduce in the axial direction from one end of the spiral ridge of the thread to the other end. At the same time the radius of the groove bottom increases in the same direction.

EFFECT: higher strength and service life of a threaded joint.

13 cl, 10 dwg