Threaded engagement device
The threaded engagement device includes a female thread portion and a male thread portion, which are engaged to each other through a plurality of threads formed along the axis direction. Each thread of the female thread portion and the male thread portion of the threaded engagement device includes a crest, a root, a stab flank and a load flank. The root of the female thread portion has a straight portion extending along the axis direction and a concave rounded portion. The root of the male thread portion has a concave rounded portion, wherein the radius of curvature of the rounded portion formed in the root of the male thread portion is larger than the radius of curvature of the rounded portion formed in the root of the female thread portion.
1. A threaded engagement device having a female thread portion and a male thread portion engaged to each other through a plurality of threads formed along an axis direction of the device;
wherein each thread in the female thread portion and male thread portion has a crest and a root formed around the circumference of the thread, and a stab flank and a load flank connecting the crest and the root;
wherein the root of the female thread portion comprises a straight portion extending along the axis direction and a concave rounded portion;
wherein the root of the male thread portion comprises a concave rounded portion; and
wherein a radius of curvature of the rounded portion in the male thread portion is larger than a radius of curvature of the rounded portion in the female thread portion.
2. A rolling mill comprising the threaded engagement device according to claim 1 .
3. The threaded engagement device according to claim 1 , wherein the rounded portion of the male thread portion is formed as substantially a full rounded shape.
4. A rolling mill comprising the threaded engagement device according to claim 3 .
5. The threaded engagement device according to claim 1 , wherein the load flank of the thread, which is placed at the rear of the threaded engagement direction opposite the stab flank, makes an angle of less than 90 degrees with the crest.
6. A rolling mill comprising the threaded engagement device according to claim 5 .
7. The threaded engagement device according to claim 1 , wherein the load flank of the thread, which is placed at the rear of the threaded engagement direction opposite the stab flank, makes an angle of 83 to 90 degrees with the crest.
8. A rolling mill comprising the threaded engagement device according to claim 7 .
9. The threaded engagement device according to claim 1 , wherein the root of the male thread portion further comprises a straight portion extending along the axis direction connected to the concave rounded portion.
10. A rolling mill comprising the threaded engagement device according to claim 9 .