ECCENTRIC CONES FOR ROCK CUTTING
A backreaming assembly having an elongate rotatable tool shaft and a plurality of cutting elements. The tool shaft is disposed on a tool axis and has a first end and a second end. Each cutting element is supported on the shaft in side-to-side relationship. Each cutting element is rotatable with respect to the shaft and with respect to each other. Each cutting element has a center offset from the tool axis.
1 . A tool, comprising:
an elongate rotatable tool shaft disposed on a tool axis and having a first end and a second end; and
a plurality of cutting elements supported on the shaft in side-to-side relationship, each cutting element rotatable with respect to the shaft and with respect to each other and having a center offset from the tool axis.
2 . The tool of claim 1 in which each cutting element is rotatable about a bit axis that is not parallel to the tool axis.
3 . The tool of claim 2 in which each bit axis is tilted by an angle of less than about 30 degrees from parallel relationship to the tool axis.
4 . The tool of claim 2 in which each bit axis is tilted by an angle of about 3 degrees from parallel relationship to the tool axis.
5 . The tool of claim 1 in which each cutting element is shaped as a conical frustum and in which cutters are formed on the side walls of the frustum.
6 . The tool of claim 4 , in which each cutting element has its maximum cross-sectional dimension adjacent the second end of the tool shaft.
7 . The tool of claim 1 in which the cutting elements are situated intermediate the first and second ends of the tool shaft and in which a threaded connection is formed at the first end of the tool shaft and a towing connection is formed at the second end of the tool shaft.
8 . The tool of claim 7 in which the towing connection is a towing eye formed on a swivel that is maintained in a non-rotating configuration when the tool shaft is under rotation.
9 . The tool of claim 1 in which each cutting element is angularly offset about the tool axis relative to its adjacent cutting elements.
10 . The tool of claim 9 in which the angular spacing of adjacent cutting elements is uniform.
11 . A system comprising:
the tool of claim 1 ;
an underground drill stem attached to the tool adjacent the first end of the shaft; and
a product pipe attached to the tool adjacent the second end of the shaft.
12 . A tool, comprising:
an elongate rotatable tool shaft disposed on a tool axis and having a first end and a second end; and
a plurality of cutting elements supported on the shaft in side-to-side relationship, each cutting element rotatable with respect to the shaft and with respect to each other and having a center offset from the tool axis; and
a product pipe towing connection formed at the second end of the elongate rotatable tool shaft.
13 . The tool of claim 12 in which the towing connection is maintained in a non-rotating configuration when the tool shaft is under rotation.
14 . The tool of claim 12 in which each cutting element is shaped as a conical frustum and in which cutters are formed on the side walls of the frustum
15 . The tool of claim 12 in which each cutting element is angularly offset about the tool axis relative to its adjacent cutting elements.
16 . The tool of claim 15 in which the angular spacing of adjacent cutting elements is uniform.
17 . The tool of claim 12 in which each cutting element is rotatable about a bit axis that is not parallel to the tool axis.
18 . The tool of claim 17 in which each bit axis is tilted by an angle of less than about 30 degrees from parallel relationship to the tool axis.
19 . The system of claim 12 having a central bore formed in the tool shaft and a radial fluid passage in fluid communication with the central bore formed in each of the cutting elements.