Low Stress Threadform with a Non-conic Section Curve
In one aspect of the present invention a threadform has a load bearing flank and a non-load bearing flank joined by a thread root. The load bearing flank tangentially joins the thread root at a first angle, and the non-load bearing flank joins the root to a second angle. The root is made of a single non-conic section curve.
1 . A threadform, comprising:
a load bearing flank and a non-load bearing flank joined by a thread root;
the load bearing flank joins the thread root at a first angle and the non-load bearing flank joins the root to a second angle; and
the root comprising a single non-conic section curve.
2 . The threadform of claim 1 , wherein a sharpest section of the curve is between a midpoint of the curve and the load bearing flank.
3 . The threadform of claim 1 , wherein the curve comprises a constantly changing radius of curvature.
4 . The threadform of claim 1 , wherein the first angle is 55 to 65 degrees.
5 . The threadform of claim 1 , wherein the non-load bearing flank joins the root tangentially.
6 . The threadform of claim 1 , wherein the second angle is 55 to 65 degrees.
7 . The threadform of claim 1 , wherein the threadform is an internal or external thread form.
8 . The threadform of claim 1 , wherein the threadform is tapered.
9 . The threadform of claim 1 , wherein a sharpest portion of the thread root is a deepest portion of the root thread.
10 . The threadform of claim 1 , wherein the loading flanks tangentially joins the thread root.
11 . A threadform formed on tool string component, comprising:
a load bearing flank and a non-load bearing flank joined by a thread root;
the load bearing flank tangentially joins the thread root at a first angle of 55 to 65 degrees and the non-load bearing flank joins the root at a second angle of less than 55 to 65 degrees; and
the root comprising an single non-conic curve.
12 . The threadform of claim 11 , wherein the threadform is formed proximate an end of the tool string component.
13 . The threadform of claim 11 , wherein the threadform is formed in between tool joints connected to ends of the tool string component.
14 . The threadform of claim 11 , wherein a sharpest section of the curve is between a midpoint of the curve and the load bearing flank.
15 . The threadform of claim 11 , wherein a sharpest portion of the thread root is a deepest portion of the root thread.
16 . A threadform, comprising:
a load bearing flank and a non-load bearing flank joined by a thread root;
the load bearing flank joins the thread root at a first angle and the non-load bearing flank joins the root to a second angle; and
the root comprising at least one non-conic section curve.
17 . The threadform of claim 16 , wherein the threadform is a semi-buttressed threadform.
18 . The threadform of claim 16 , wherein the threadform is a tapered threadform.
19 . The threadform of claim 16 , wherein a sharpest portion of the thread root is a deepest portion of the root thread.
20 . The threadform of claim 16 , wherein at least two non-conic section curves are separated by a flat.