Mining or in situ disintegration of hard material – Cutter tooth or tooth head – Wear shield or replaceable wear sleeve
Patent
1997-12-15
2000-05-09
Lillis, Eileen Dunn
Mining or in situ disintegration of hard material
Cutter tooth or tooth head
Wear shield or replaceable wear sleeve
299106, 299110, E21C 3518
Patent
active
060593733
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
THIS INVENTION relates to extracting a pick holder from a pick box in a continuous miner drum; to extraction means for carrying out the method of the invention, to a pick holder, and to an extraction tool.
In one kind of continuous miner, for example a continuous miner manufactured by the firm Voest Alpine, there is provided a plurality of pick boxes arranged in predetermined fashion on a drum of the continuous miner. Each pick box has a substantially blind socket within which a pick holder is replaceably received. A shank of a pick is in turn replaceably received within the pick holder such as to allow rotation of the pick relative to the pick holder in use. Receipt of the pick holder in the pick box is by means of a tight, frictional, press fit. The pick holder is to be removable to allow replacement, reconditioning, and the like.
In known pick holders there is provided an internal circumferential groove to retain a pick in use via a retaining ring on a shank of the pick. One way to remove the pick holder from the pick box (when the pick has been removed), is by dilating a collar on a shank of an extracting tool to locate in said internal circumferential groove and to apply an extraction force on the shank. The force is then transmitted via a shoulder of the internal circumferential groove to extract the pick holder from the pick box.
Although this method is generally used, it has at least two problems. First, the integrity of locating the collar of the extracting tool in the internal circumferential groove is not good. It does happen that the internal collar slips, which may result in a very unsatisfactory and possibly dangerous situation and possible damage to equipment. Second, the collar of the extracting tool is to be dilatable to enable it to engage the internal circumferential groove, thus requiring a composite (more than one part) design which is expensive to manufacture. Such extracting tool becomes worn fairly quickly and has to be reconditioned or replaced after a relatively small number of extracting operations.
An alternative, known, method is to provide an external circumferential groove in a portion of the outer surface of the pick holder which protrudes from the pick box. This method has generally the same disadvantages as the first mentioned known method. In addition, the external circumferential groove is exposed to the working conditions and becomes worn and unusable for locating purposes fairly quickly. Furthermore , the protruding portion or head may shear of f, which renders extraction by means of the external groove impossible.
It is an object of this invention to provide a method, an extracting means, a pick holder and an extraction tool which improve on the prior art and which do not suffer, or at least suffer to a smaller degree, from the problems of the prior art.
SUMMARY OF THE INVENTION
In accordance with a first aspect of this invention, there is provided a method of extracting a pick holder from a pick box of a continuous miner drum, the method including providing an internal rotary fastening formation in a bore of the pick holder, providing a complemental external rotary fastening formation on a shank of an extraction tool, interengaging the complemental rotary fastening formations by relative rotation between the pick holder and the extraction tool and applying an extraction force to the pick holder via the shank and via the engaged rotary fastening formations.
In a preferred method, the rotary fastening formations may be screw threads and interengaging the complemental rotary fastening formations may be by screwing them together. In other methods, mere twisting or pivoting may be required.
The method may include centering the shank of the extraction tool relative to the pick holder when applying the extraction force. Centering may be effected by supporting the shank in the mouth or bore of the pick holder with little clearance. Supporting the shank in the mouth or bore may be via a sleeve received over the shank and fitting into the mouth
REFERENCES:
patent: 4586229 (1986-05-01), Pendola
patent: 5067775 (1991-11-01), D'Angelo
patent: 5119556 (1992-06-01), Hseu
Holtshausen Richard George
Wright Noel G.
Kennametal Inc.
Kreck John
Lillis Eileen Dunn
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