Patent EA-002252-B1 (EA)
Title: Boring rod connector
Inventor: KRUG GERHARD
IPC: F16L15/04
Filed: 1999-05-21
Abstract: 1. Boring rod connector with a journal element that has a tapered external thread section located between an outer shoulder and a journal face, a thread-free section located between the outer shoulder and the external thread section, and a thread-free section located between the external thread section and the journal face, and with a sleeve element that can be screwed to the journal element and has a tapered internal thread section located between an inner shoulder and a sleeve face, a thread-free section located between the inner shoulder and the internal thread section, and a thread-free section located between the internal thread section and the sleeve face, whereby the threadfree sections of the journal element and the sleeve element located in the area of the inner shoulder that, when a screw connected exists, lie opposite to each other, have a different length than the thread-free sections of the journal element and the sleeve element located in the region of the inner shoulder, characterized in that the inner shoulder (3, 10) forms the primary shoulder and, after the drill pipe connector is assembled and screwed to up to 90% of its yield point, the journal face (10) tightens on the inner shoulder (3, 10) up to a pressure that exceeds the pressure exerted by the sleeve face (4) on the outer shoulder (9), whereby the sleeve face (4) tightens mainly on the outer shoulder (9) when an additional torque occurs during boring, and the thread-free sections (7, 13) located in the region of the inner shoulder (3, 10) are at least twice as long as the thread-free sections (6, 12) located in the region of the outer shoulder (9). 2. Drill pipe connector as in Claim 1, characterized in that the thread-free sections (7, 13) located in the region of the inner shoulder (3, 10) are three times as long as the thread-free sections (6, 12) located in the region of the outer shoulder (9). 3. Drill pipe connector as in Claims 1 and 2, characterized in that the distance (14) between the journal face (10) and the outer shoulder (9) is greater than the distance (15) between the sleeve face (4) and the inner shoulder (3, 10). 4. Drill pipe connector as in Claims 1 to 3, characterized in that the internal thread section (5) and the external thread section (11) is equipped with a rough standard thread, whose load flank (22) has an angle in the range of 15 degree  to 20 degree , and the guidance flank (21) has an angle of 30 degree . 5. Drill pipe connector as in Claim 4, characterized in that the load flank (22) has an angle of 18 degree . 6. Drill pipe connector as in one of the Claims 1 to 5, characterized in that the internal thread section (5) in the sleeve element (1) has a steeper taper inclination than the external thread section (11) in the journal element (2). 7. Drill pipe connector as in Claim 6, characterized in that the difference in taper inclination is 0.03 to 0.3 mm/inch. 8. Drill pipe connector as in one of the Claims 1 to 7, characterized in that the outer surface (24) of the sleeve (23) is equipped with an internal turning (25) from the face (4) to approximately over the third thread.