Collapsible casing tightener and method of use
A collapsible casing tightener comprising an outer body with hollow cylindrical main section open at one end and closed at the other at a shoulder. A reduced neck protrudes from the shoulder to a collar for attachment to a drill rig. The cylindrical main section is defined by a radial array of angularly spaced notches each comprising a narrow aperture through the wall. Internally, a hollow pipe section extends coaxially within from the neck to a distal cylindrical receptacle with a threaded female joint. An extendable inner body is telescopically inserted into the outer body between the cylindrical main section and hollow pipe section, the inner body having pins affixed therein and carried within the notches for guided extension. The collapsible casing tightener replaces time consuming, inefficient hand tightening of multiple drill rod segments and casing segments with a wrench with telescopic extension and retraction followed by drill-assisted rotation.
1 . A collapsible casing tightener, comprising:
an outer body having a hollow frustoconical main section open at one end and leading to a shoulder at another end, said shoulder leading to a reduced neck, a collar on said neck having a radial array of angularly spaced upward-facing non-threaded joints for bolt attachment to a drill rig, the main section of the outer body having a radial array of angularly-spaced notches each comprising an elongated aperture through a wall of the main section, a hollow pipe section extending coaxially within the main section; and attached to the neck, the hollow pipe section extending to a distal cylindrical receptacle having a threaded female joint; and
an extendable inner body telescopically inserted into the outer body between the main section and hollow pipe section, the inner body having a plurality of pins affixed therein and carried within said notches for guided extension.
2 . The collapsible casing tightener of claim 1 , wherein each notch comprises a lengthwise elongate segment running a majority of the length of the main section and two short segments extending at approximately a right angle from a terminus end of a lengthwise elongate segment, wherein the length of the elongate segments defines a maximum extension distance of the extendable inner body.
3 . The collapsible casing tightener of claim 1 , wherein the at least one notch of the radial array of angularly spaced notches comprises a safety lock configured to block a corresponding pin from entering the lengthwise elongate segment of the corresponding notch.
4 . The collapsible casing tightener of claim 3 , wherein the safety lock comprises opposing flanges flanking the uppermost short segment of the at least one notch, the opposing flanges containing through holes for insertion of a hitch pin, wherein the hitch pin straddles the two flanges when inserted through the through holes blocks the corresponding pin of the inner body from entering the lengthwise segment of the at least one notch, thereby preventing inadvertent extension.
5 . The collapsible casing tightener of claim 1 , wherein the inner body is formed with a male threaded joint configured to engage with a casing section.
6 . The collapsible casing tightener of claim 1 , wherein the neck continues through the shoulder into the main section, where it is attached to the hollow pipe section, which in turn continues to a distal cylindrical receptacle having a threaded female joint.
7 . The collapsible casing tightener of claim 6 , wherein the threaded female joint is configured for screw-insertion of a drill rod.
8 . The collapsible casing tightener of claim 6 , wherein the threaded female joint is configured for screw-insertion of a drill segment.
9 . A method of installing a micropile, the method comprising:
drilling a first casing segment and first drill rod segment into the ground and below an upper clamp using drill string that comprises an interlocking ring bit and pilot bit, then releasing the pilot bit by reversing and extracting the pilot bit, wherein the first casing segment is left-hand-threaded and the first drill rod segment is right-hand-threaded;
utilizing the collapsible casing tightener according to claim 1 to a drill rig at the collar by bolt attachment to the non-threaded joints;
loading a second drill rod segment into the collapsible casing tightener and rotating the second drill rod segment clockwise into engagement with the first drill rod segment in a lower clamp;
disengaging the second drill rod segment from the collapsible casing tightener by counterclockwise rotation;
inserting a second casing segment over the second drill rod segment;
lowering the collapsible casing tightener into engagement with the second casing segment, wherein the inner body of the collapsible casing tightener is telescopically extended until the collapsible casing tightener engages with the second casing segment, preventing the hollow pipe section of the collapsible casing tightener from engaging with the second drill rod; and
rotating the drill rig and collapsible casing tightener counterclockwise to engage the second casing segment with the first casing segment.
10 . The method of claim 9 , further comprising repeating the steps of claim 9 until enough casing and drill rod segments have been utilized as needed to form the micropile.