Abrading – Abrading process – With critical temperature modification or control of work or...
Patent
1996-08-12
1999-03-23
Morgan, Eileen P.
Abrading
Abrading process
With critical temperature modification or control of work or...
451 48, 451450, B24B 5502
Patent
active
058851364
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for grinding buttons of a rock drilling bit, and to a flushing head for supplying flushing medium.
From Swedish Patent 460 584 a device for grinding buttons of a rock drilling bit is previously known, said device including a grinding head having a rotatably journalled spindle that receives a grinding cup. Inside the grinding head, means are provided for supplying flushing/cooling medium to a recess of the grinding cup. Said flushing/cooling medium is supplied axially within the rotatable spindle and then axially within the shank of the grinding cup until the flushing/cooling medium reaches the recess of the grinding cup. However, due to the fact that the means for supplying flushing/cooling medium to the grinding cup is located within the grinding head, considerable sealing arrangements for separating the flushing/cooling medium from the lubricating medium must be present. This complicates the design of the grinding head.
The aim of the present invention is to present a method and apparatus for grinding buttons of rock drilling bits, while simplifying the supply of flushing/cooling medium to the grinding cup.
SUMMARY OF THE INVENTION
One aspect of the present invention involves a method of grinding a button of a rock drilling bit, comprising the steps of positioning a grinding surface of a grinding cup against the button; applying a rotary force to an inner end of a shaft structure disposed within a grinding head, to rotate the grinding cup which is mounted on an outer portion of the shaft structure disposed outside of the grinding head; introducing a flushing medium to an inlet of an axial bore of the outer portion at a location disposed outside of the grinding head; and conducting the flushing fluid through the axial bore to the grinding surface for flushing the grinding surface.
An apparatus aspect of the invention comprises a grinding head, a shaft structure including inner and outer portions, the inner portion rotatably mounted in the grinding head, and the outer portion projecting out of the grinding head. A drive mechanism is connected to the inner portion for rotating the shaft structure. A grinding cup is mounted on the outer portion and includes a grinding surface for grinding a button upon rotation of the shaft structure. The outer portion of the shaft structure includes an axial bore communicating with the grinding surface. The axial bore includes an inlet situated outside of the grinding head. The inlet is adapted to communicate the axial bore with a source of flushing fluid so that flushing fluid can be conducted to the grinding surface through the axial bore for flushing the grinding surface.
Another aspect of the invention relates to a flushing head adapted to be mounted on a rotatable grinding spindle which carries a grinding cup, for conducting flushing medium to an axial bore of the grinding spindle. The flushing head comprises a radially inner part having an axial through-bore adapted to be mounted on the grinding spindle to be rotated therewith. The axially inner part includes a pair of axially spaced sleeves each carrying a seal for creating a fluid seal with the grinding spindle. The sleeves are axially separated by a cylindrical spacer which includes a first opening extending radially therethrough at a location axially between the seals. The flushing head further includes a stationary radially outer part connected nonfixedly to the sleeves in surrounding relationship to the spacer. The radially outer part includes a second opening communicating with the first opening for conducting flushing fluid thereto.
The flushing head preferably permits the sleeves to be moved axially away from one another by a force of the flushing fluid and into sealing relationship with respective portions of the radially outer portion.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the device/flushing head according to the invention is below; reference being made to the accompanying drawings where
FIG. 1 shows a s
REFERENCES:
patent: 2455597 (1948-12-01), Metzger et al.
patent: 3229427 (1966-01-01), Goodhew
patent: 4102084 (1978-07-01), Bloomquist
patent: 4616738 (1986-10-01), Shurtliff
patent: 4858388 (1989-08-01), Bice
patent: 5070654 (1991-12-01), Manqvist et al.
patent: 5637037 (1997-06-01), Bergquist
patent: 5639273 (1997-06-01), Sjolander et al.
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