Boring or penetrating the earth – With magazine for successively moving unconnected – oriented...
Reexamination Certificate
2000-02-10
2001-10-09
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With magazine for successively moving unconnected, oriented...
C175S085000
Reexamination Certificate
active
06298926
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to blasthole drills, and more particularly to a deck wrench for holding a drill pipe section against rotation.
BACKGROUND OF THE INVENTION
Blasthole drills are large earth drilling machines typically used in mining operations to drill holes for explosives. A conventional blasthole drill comprises a frame supported by crawlers for movement over the ground, and a mast supported by the frame for movement between a substantially vertical position and a number of angled or non-vertical positions. A rotary head moves along the mast. The rotary head engages the upper end of a drill pipe for rotating the drill pipe and driving the drill pipe into the ground. When drilling a blasthole that is deeper than the height of the mast, more than one section of drill pipe must be used. After the first section of drill pipe is driven into the ground, the rotary head moves back to the top of the mast and another section of drill pipe is connected to the top of the first section. The rotary head then drives the second drill pipe section into the ground. It is not unusual to use multiple sections of drill pipe. Such a deep blasthole is commonly referred to as a “multi-pass” blasthole. The various sections of drill pipe are usually supported relative to the mast and moved into position at the appropriate time by a device known as a pipe rack. One such pipe rack is disclosed in U.S. Pat. No. 5,622,232, which is incorporated herein by reference.
When drilling a multi-pass blasthole, a considerable amount of time is spent in adding and removing individual drill pipe sections from the overall drill pipe string. In the art of earth drilling machines, the process of separating drill pipe sections has long been one in which improvements have been sought. The problem of disconnecting or unthreading tightly connected joints between drill pipe sections has resulted in numerous devices for clamping and holding one drill pipe section while rotating the other drill pipe section.
Typically, an attempt is made to break the joint between two drill pipe sections by rotating the upper drill pipe section with the rotary head while the lower drill pipe section is held by the drill pipe holding wrenches. More often than not, the joint between the drill pipe sections is stronger or tighter than the joint between the rotary head and the upper drill pipe section. As a result, when using the rotary head to try and loosen the joint between two drill pipe sections, the joint between the rotary head and the upper drill pipe section usually breaks instead. Thus, if the joint between the drill pipe sections cannot be broken loose with the rotary head, a breakout wrench is commonly used to rotate the upper drill pipe section while a deck wrench holds the lower drill pipe section against rotation. An automatic breakout wrench is disclosed in U.S. Pat. No. 5,653,297, which is incorporated herein by reference. The automatic breakout wrench turns the upper drill pipe section while the lower drill pipe section is held by the deck wrench. This type of change-out procedure usually adds undesirable downtime to an overall blasthole drilling operation.
Conventional deck wrenches generally include a pair of opposed drill pipe holding members which are disposed on a drill deck and which are aligned with each other on opposite sides of an opening in the drill deck through which the drill pipe extends. Each drill pipe holding member is slideably mounted in a respective housing. Each section of the drill pipe generally includes a pair of recesses on opposite sides thereof. When it is desirable to unthread an upper drill pipe section from a lower drill pipe section, each drill pipe holding member engages a respective recess in the lower drill pipe section. The mating action of the members and recesses holds the lower drill pipe section against rotation in a single direction so that the upper drill pipe section can be unthreaded or disconnected from the lower drill pipe section.
SUMMARY OF THE MENTION
Although the conventional method of using a breakout wrench in cooperation with a deck wrench to facilitate the separation of two drill pipe sections is effective for such a purpose, there is still a need in the art for new equipment and methods for more easily and efficiently separating drill pipe sections. The invention provides an improved deck wrench. Unlike conventional deck wrenches, the deck wrench according to the invention is able to substantially prevent rotation of a drill pipe in either direction. As a result, the deck wrench is able to hold a drill pipe section so that a joint between the drill pipe section and another drill pipe section can be tightened or loosened as desired.
The invention provides a blasthole drill comprising a frame supported for movement over a ground surface, the frame including a drill deck having an opening, a mast supported by the frame, a drill pipe which is supported relative to the mast and which extends through the opening, the drill pipe having a longitudinal axis and further having an engagement surface, a rotary head movable along the mast for rotating and longitudinally moving the drill pipe, and a deck wrench mounted on the drill deck, the deck wrench having an engagement surface which is selectively engageable with the drill pipe engagement surface to substantially prevent rotation of the drill pipe in either direction about the longitudinal axis.
The invention also provides a blasthole drill comprising a frame supported for movement over a ground surface, the frame including a drill deck having an opening, a mast supported by the frame, a drill pipe which is supported relative to the mast and which extends through the opening, the drill pipe having a longitudinal axis, a rotary head movable along the mast for rotating and longitudinally moving the drill pipe, and a deck wrench mounted on the drill deck, the deck wrench including a movable member having opposite facing engagement surfaces each of which is engageable with an opposite side of the drill pipe to hold the drill pipe against substantial rotation.
To unthread an upper drill pipe section from a lower drill pipe section, the deck wrench first engages the lower drill pipe section. The rotary head then rotates the upper drill pipe section in one direction to tighten the joint between the rotary head and the upper drill pipe section. Thereafter, the deck wrench is disengaged from the lower drill pipe section so that the next or lower drill pipe section can be raised out of the blasthole. The deck wrench then engages the lower drill pipe section. The rotary head then rotates the drill pipe in the opposite direction to break the joint between the drill pipe sections. Because the deck wrench can substantially prevent rotation of the drill pipe in either direction, the joint at the rotary head and the upper drill pipe section can be made stronger or tighter than the joint between the upper and lower drill pipe sections before an attempt is made to break the joint between the two drill pipe sections. According to the present invention, it is no longer necessary to use a breakout wrench when disconnecting two drill pipe sections, thereby decreasing the downtime normally associated with a drill pipe change-out procedure in a blasthole drilling operation.
Although the engagement between the deck wrench and the drill pipe substantially prevents rotation of the drill pipe about its longitudinal axis, the engagement between the deck wrench and the drill pipe also allows the drill pipe to have a limited range of pivotal movement in either direction about its longitudinal axis when the drill pipe is positioned within the U-shaped recess. This limited range of pivotal movement allows the rotary head to provide some momentum to the drill pipe to enhance the tightening or loosening effect of the particular joint.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals
Dalkert Marcia H.
Kaphingst David A.
Nelson Jack W.
Silvestri Curt L.
Earl Lowe, Jr. James
Harnischfeger Technologies Inc.
Pezzuto Robert E.
Price David R.
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