Patent Application
20050000324
This invention relates to deck wrenches used on blasthole drills, and, more particularly, to deck wrench dies for gripping the drill pipe.
Blasthole drills are large machines used to drill holes for explosives in mining operations. 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. The mast defines a drill hole axis. A rotary head moves relative to the mast along the drill hole axis. 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 pipe then drives the second section into the ground. It is not unusual to use four sections of drill pipe. Such a deep blasthole is referred to as a “multi-pass” blasthole.
After drilling a multi-pass blasthole, it can be difficult to break the joint between two pipe sections. A blasthole drill typically includes an automatic breakout wrench for breaking a joint if the rotary head cannot do so. An automatic breakout wrench is disclosed in U.S. Pat. No. 4,128,135. The automatic breakout wrench turns the upper pipe section while the lower pipe section is held by deck wrenches.
A conventional breakout wrench includes a swing arm pivotable relative to the mast between extended and retracted positions. A wrench member pivots relative to the swing arm about the drill hole axis when the swing arm is in the extended position. The wrench member carries dies for gripping the pipe section. A clamping jaw pivots relative to the wrench, member between a clamping position and a non-clamping position. The jaw also carries a die for gripping the pipe section. When the swing arm is in the extended position, movement of the jaw to the clamping position causes the pipe section to be gripped by the dies on the jaw and on the wrench member. Thereafter, pivotal movement of the wrench member relative to the swing arm (the clamping jaw moves with the wrench member) turns the pipe section to break the joint. Pivotal movement of the wrench member is caused by a hydraulic breakout cylinder connected between the swing arm and the wrench member.
In U.S. Pat. No. 5,653,297, shims allow for adjustment of the dies to compensate for pipe wear and to accommodate different pipe sizes. More particularly, the pipe section is gripped by two dies mounted on the wrench member and by one die mounted on the clamping jaw. Each die is held in place by upper and lower fasteners. Shims can be inserted behind each die to adjust the position of the die. Each shim has therein an aperture through which the upper fastener extends to hold the shim in place. The bottom of each shim has therein an upwardly extending slot through which the lower fastener extends. The shim is removed by loosening the lower fastener and by removing the upper fastener from the shim aperture. The slot in the shim allows upward movement of the shim relative to the lower fastener, while the lower fastener maintains the position of the shim.
Two problems occur with current break out wrenches. One is that when a drill pipe wears from the abrasion of bailing rock from the hole, a reduction in pipe diameter occurs, and the amount of reduction varies and is greater near the bottom of the pipe, because the bottom of the pipe is in the hole longer, than near the top of the pipe. This results in a tapering of the pipe known as penciling. The current wrench dies do not accommodate tapered pipe, so the die does not make proper contact with the pipe and hence has difficulty gripping the worn pipe. The second problem is that current wrenches require shims to be added to the wrench as the pipe diameter reduces from wear. Typically, this is not done by the mine due to a lack of knowledge or desire to manually bolt in the shims. As a result, the wrench slips on the pipe.
One of the objects of the invention is to allow the die to match the taper of a worn pipe.
Another of the objects of the invention is to allow the die to make line contact with pipes of different diameters without using shims.
The invention provides a die assembly for a drilling machine adapted to use drill pipe with a longitudinal axis, the drilling machine including a pipe turning wrench including a first arm and a second arm pivotable about an axis spaced apart from and parallel to the pipe longitudinal axis, and a die pocket, in the one of the wrench first arm and wrench second arm, that is adapted to receive the die assembly. The die assembly is adapted to be attached to one of the wrench first arm and the wrench second arm, and the die assembly includes a die having a pipe facing front spaced apart from but parallel to the pipe longitudinal axis, a wrench facing rear, and two spaced apart opposed sides, each connected to the die front and die rear. The die is thick on one side and thin on the other side so that the die facing front has a face that recedes from the pipe from one edge to the other edge so that contact between the die facing front varies depending upon the diameter of the pipe. The die rear also has a convex curve so that the die has a thick mid section. The die assembly further includes means for attaching the die to the die pocket. The means for attaching the die to the pocket includes the die having a hole extending through the die from one side to the other opposed side, and a pin that extends through the die hole. A die assembly further includes a bracket, and the bracket is attached to the one of the wrench first arm and wrench second arm in the die pocket. The bracket has two aligned openings on the inside of each of two opposed bracket walls, and the pin extends through the die hole, and each end of the pin being received in a respective one of the bracket side wall openings.
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 are used to designate like features.
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter and the equivalents thereof.
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In this embodiment, the pocket 84 is in a separate bracket 94 bolted by bolts 102 into die pockets 108 on the breakout wrench 42. In other embodiments (not shown), the bracket 94 can be omitted and the die assembly can be received directly into the die pocket 108. The bracket 94 further has two aligned openings 96 and 98 on the inside of each of the opposed bracket walls, and means for attaching the die to the bracket 94. The die attaching means comprises a pin 100 that extends through the die hole 80, each end of the pin 100 being received in a respectively one of the bracket side wall openings 96 and 98.
The floating die assemblies 54 thus address the problems listed above. The back of the die 58 is curved which allows the die 58 to rock back and forth. This movement allows the die 58 to match the taper of a worn pipe (see
Various other features of the invention are set forth in the following claims.
