Iris fishing tool overshot catch
A gripping assembly for a fishing tool which includes first and second end members and a plurality of gripping members which are retained by the first and second end members and which are moveable between a radially expanded configuration and a radially restricted configuration by rotation of the second end member with respect to the first end member.
1. A gripping assembly of a fishing tool to grip a fish within a wellbore, the gripping assembly comprising:
a first end member;
a second end member;
a plurality of gripping members that are retained by the first and second end members and which are moveable between a radially expanded configuration and a radially restricted configuration by rotation of the second end member with respect to the first end member; and
wherein rotation of the second end member moves the gripping members radially inwardly by moving a pin on each gripping member along a slot within the second end member.
2. The gripping assembly of claim 1 wherein the second end member further comprises a lug extending radially outwardly to move within a helical track such that the second end member is rotated with respect to the first end member as the gripping assembly is moved axially within the outer housing.
3. The gripping assembly of claim 1 further comprising:
slots formed within the first end member;
a first pin extending from an axial end of each gripping member; and
the first pin of each gripping member extends within and is moveable within the slot of the first end member to retain the gripping member within the first end member.
4. The gripping assembly of claim 1 wherein the gripping members each present a gripping face to contact and engage the fish.
5. The gripping assembly of claim 4 further comprising at least one projection upon the gripping face to form a biting engagement with the fish.
6. The gripping assembly of claim 1 further comprising a J-slot mechanism to control movement of the gripping assembly with respect to a surrounding outer housing.
7. A fishing tool for gripping a fish within a wellbore, the fishing tool comprising:
an outer housing which is securable to a running string;
a gripping assembly retained within the outer housing for gripping the fish, the gripping assembly having first and second end members and a plurality of gripping members that are retained by the first and second end members and which are moveable between a radially expanded configuration and a radially restricted configuration by rotation of the second end member with respect to the first end member; and
wherein the gripping assembly is moved axially with respect to the surrounding outer housing by moving an arm operably associated with the gripping assembly along a J-slot formed within the outer housing.
8. The fishing tool of claim 7 further comprising:
a lug extending radially outwardly from the second end member; and
a helical track formed within the outer housing and wherein the lug moves within the helical track such that the second end member is rotated with respect to the first end member as the gripping assembly is moved axially within the outer housing.
9. The fishing tool of claim 7 further comprising:
slots formed within the first end member;
a first pin extending from an axial end of each gripping member; and
the first pin of each gripping member extends within and is moveable within the slot of the first end member to retain the gripping member within the first end member.
10. The fishing tool of claim 7 further comprising:
a plurality of curved slots formed within the second end member; and
a second pin extending from each of the gripping members, each second pin residing within a curved slot in the second end member and moveable within the curved slot between a radial outer position and a radially inner position.
11. The fishing tool of claim 7 wherein the gripping members each present a gripping face to contact and engage the fish.
12. The fishing tool of claim 11 further comprising at least one projection upon the gripping face to form a biting engagement with the fish.
13. A method of gripping a fish within a wellbore comprising the steps of:
disposing a fishing tool into a wellbore, the fishing tool having a gripping assembly retained within the outer housing for gripping the fish, the gripping assembly having first and second end members and a plurality of gripping members that are retained by the first and second end members and which are moveable between a radially expanded configuration and a radially restricted configuration by rotation of the second end member with respect to the first end member;
surrounding a portion of the fish with the gripping assembly; and
moving the gripping assembly from the radially expanded configuration to the radially restricted configuration to grip the fish, wherein rotation of the second end member moves the gripping members radially inwardly by moving a pin on each gripping member along a slot within the second end member.
14. The method of claim 13 wherein the second end member is rotated by moving the gripping assembly axially with respect to a surrounding outer housing.
15. The method of claim 14 wherein the step of moving the gripping assembly axially with respect to the surrounding outer housing further comprises moving an arm operably associated with the gripping assembly along a J-slot formed within the outer housing.