U.S. patent number 3,852,874 [Application Number 05/423,259] was granted by the patent office on 1974-12-10 for method of inserting buttons in a drilling head.
This patent grant is currently assigned to Smith-Williston, Inc.. Invention is credited to Bernard A. Pearson.
United States Patent |
3,852,874 |
Pearson |
December 10, 1974 |
METHOD OF INSERTING BUTTONS IN A DRILLING HEAD
Abstract
A button and sleeve have matching tapers and are pressed
together so that in a working configuration the external diameter
of the sleeve is stretched to slightly exceed the diameter of the
bore into which the combined assembly is to be inserted. The sleeve
is then partially removed from the button to relax its external
diameter so that the combined assembly can be placed into the bore.
The bit and sleeve are then pressed into the working configuration
in the bore until the sleeve has expanded radially into tight
contact with the inner wall of the bore and the button has seated
itself on the end wall of the bore. A button and sleeve assembly
are pressed together and have matching surfaces which cause the
exterior dimension of the sleeve to exceed that of the bore into
which the assembly is to be inserted when the button and sleeve are
combined together in a working configuration. The sleeve and button
matched surfaces, however, are dimensioned to allow the external
dimension of the sleeve to shrink to a dimension less than the
inner dimension of the bore when the sleeve is partially removed
from the button.
Inventors: |
Pearson; Bernard A. (Bothell,
WA) |
Assignee: |
Smith-Williston, Inc. (Seattle,
WA)
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Family
ID: |
27398332 |
Appl.
No.: |
05/423,259 |
Filed: |
December 10, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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303334 |
Nov 3, 1972 |
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232695 |
Mar 8, 1972 |
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Current U.S.
Class: |
29/525;
29/525.01; 175/413; 175/426 |
Current CPC
Class: |
E21B
10/56 (20130101); B23P 11/02 (20130101); E21B
10/62 (20130101); B23P 11/005 (20130101); Y10T
29/49945 (20150115); Y10T 29/49947 (20150115) |
Current International
Class: |
B23P
11/02 (20060101); B23P 11/00 (20060101); E21B
10/56 (20060101); E21B 10/00 (20060101); E21B
10/46 (20060101); E21B 10/62 (20060101); H01H
1/027 (20060101); H01H 1/02 (20060101); B23p
019/02 () |
Field of
Search: |
;29/525,526 ;76/17A
;175/410,413,374 ;403/276,277,282,284 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Moon; Charlie T.
Attorney, Agent or Firm: Seed, Berry, Vernon &
Baynham
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 303,334, filed Nov. 3,
1972 which in turn is a continuation-in-part of application Ser.
No. 232,695, filed Mar. 8, 1972, now abandoned.
Claims
The embodiments of the invention in which a particular property or
privilege is claimed are defined as follows:
1. A method of installing and holding an externally tapered button
in a cylindrical bore in a drilling head by means of an internally
tapered metal expansion sleeve, comprising;
forming the sleeve with its outer surface oversized relative to the
sidewall surface of the bore and with its inside surface generally
the same shape as the tapered outer surface of the button and
undersized relative thereto,
axially pressing the sleeve and button together into a normal
working relationship and, while in said relationship, shaping the
outer surface of the sleeve to generally the same shape as the
sidewall surface of the bore and to a size that is oversized
relative to said sidewall surface while the sleeve and button are
fully pressed together and that is undersized relative to said
sidewall surface when the sleeve is in a relaxed state,
less than fully pressed together, moving the button and sleeve
relative to one another sufficiently to permit the sleeve to shrink
to said undersize whereat its outer surface is small enough to
permit the sleeve to enter the bore without interference and
then pressing the button and internally tapered metal sleeve
together in the cylindrical bore until the sleeve is elastically
expanded by the button tightly between the button and the sidewall
surface of the bore.
2. The method of claim 1, said cylindrical bore having an inner
seat said internally tapered metal sleeve being annular and having
a generally cylindrical outer surface, said step of pressing the
button and sleeve together in the bore including abutting the
button against said inner seat.
3. The method of claim 2, said seat including an inner end wall of
the bore, the taper of said sleeve inner surface converging toward
the end wall of the cylindrical bore and said step of pressing the
button and sleeve together in the cylindrical bore including first
pressing until the sleeve rests against the end wall of the bore
and second pressing until the button rests against the end wall of
the bore.
4. The method of claim 2, said seat including an end wall of the
bore, said taper of said sleeve inner surface diverging toward the
end wall of the cylindrical bore and said step of pressing the
button and sleeve together in the cylindrical bore including first
pressing until the button rest aggainst the end wall of the bore
and second pressing until the sleeve rests against the end wall of
the bore.
5. The method of claim 1 wherein said button and sleeve are in the
same exact rotational alignment with each other during pressing in
the bore as when pressed together into said normal working
configuration.
6. The method of claim 1, said step of forming a sleeve with a
tapered inner surface including cold forming the inner surface on a
die, said step of reducing the diameter of the combined button and
sleeve including grinding the exterior surface of the sleeve to the
desired diameter.
7. The method of claim 5, said step of forming a sleeve with a
tapered inner surface including cold forming the inner surface on a
die, said step of reducing the diameter of the combined button and
sleeve including grinding the exterior surface of the sleeve to the
desired diameter.
8. The method of claim 7 wherein the taper of said inner surface
converges toward the end wall of the cylindrical bore and said step
of pressing the button and sleeve together in the cylindrical bore
includes first pressing until the sleeve rests against the end wall
of the bore and second pressing until the button rests against the
end wall of the bore.
9. The method of claim 7 wherein said taper of said sleeve inner
surface diverges toward the end wall of the cylindrical bore and
said step of pressing the button and sleeve together in the
cylindrical bore includes first pressing until the button rests
against the end wall of the bore and second pressing until the
sleeve rests against the end wall of the bore.
10. A method of installing a button assembly having an externally
tapered button and an internally tapered metal sleeve, in a
cylindrical bore of a rock drillinghead assembly, said button
assembly having an outer diameter slightly larger than the
cylindrical bore, comprising;
forming a hollow metal sleeve having a tapered inner surface and an
outer surface,
forming a solid button having a tapered outer surface of
substantially the same shape as said sleeve tapered inner surface,
a working end surface and an abutment end surface,
elastically expanding the hollow sleeve outside of the bore to a
normal working position and, while expanded, shaping the outside of
the sleeve to a desired interference fit diameter greater than the
bore diameter,
relaxing the sleeve partially into an intermediate position to
reduce the sleeve to a diameter less than the bore diameter,
with the sleeve in said intermediate position, inserting said
button and sleeve into said bore until the abutment end of the
button engages the end of the bore, and
moving the sleeve from said intermediate position into engagement
with the end of the bore whereby the sleeve is expanded against the
button and the bore to hold the button tightly within the bore.
11. A method of installing a button assembly having an externally
tapered solid button and an internally tapered metal sleeve
surrounding the button into a cylindrical bore of a drilling head
assembly, said bore having side and end walls, comprising;
forming the sleeve to a desired size and shape with the outside of
the sleeve being of a first size smaller than the bore side
wall,
placing the formed internally tapered sleeve and the solid button
in said bore, and
moving the internally tapered sleeve and button further relative to
each other with a force which does not exceed the elastic limit of
the sleeve while simultaneously radially elastically expanding the
sleeve from said first size to a second larger size in tight
engagement with the bore sidewall so that the button is held
tightly in the bore by the friction between the sleeve and the bore
sidewall.
12. The method of claim 11, said sleeve having a hardness of at
least 38' 40 Rc.
13. The method of claim 11, said step of moving the sleeve
including pressing the sleeve until it seats against the end wall
of the bore.
14. The method of claim 11, said step of forming the sleeve
including expanding the inside of the sleeve to match the size and
shape of the button outer surface, and forming the outer surface of
the sleeve while expanded fully over the button outside of the bore
to a shape corresponding to the shape of the sidewall of the bore
and to a size exceeding the size of the sidewall of the bore by the
desired interference fit, said step of placing the formed sleeve
and the button in the bore including relaxing the sleeve to reduce
its outer size to less than the size of the sidewall of the
bore.
15. The method of claim 14, said step of forming the outer surface
of the sleeve while expanded outside of the bore including pressing
the sleeve over the button into a working configuration, said step
of relaxing the sleeve including withdrawing the sleeve along the
button from its working configuration.
16. The method of claim 15, said bore outer surface converging
toward the outer end of the bore.
17. A method of installing an externally tapered button in a
cylindrical bore of a drilling head, said bore having an inner end,
a sidewall and an outer end, comprising;
forming a sleeve with an inside taper smaller than the external
taper of the button by a first predetermined amount and forming the
sleeve with an outside diameter of a size which is smaller than the
diameter of the sidewall of the bore by a second predetermined
amount which is smaller than the said first predetermined amount,
and
axially moving the internally tapered sleeve and button relative to
one another in the bore so as to elastically radially stretch the
sleeve by the button against the sidewall of the bore to an extent
greater than said second predetermined amount and by a force that
does not exceed the elastic limit of the sleeve, thereby retaining
the combined button and sleeve in the bore by the friction between
the sleeve and the side wall of the bore caused by the elastic
compressive load in the sleeve and sidewall of the bore.
18. The method of claim 17, said tapers of said button and sleeve
converging toward the outer end of the bore.
19. The method of claim 17, said tapers of said button and sleeve
diverging toward the outer end of the bore.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to button and sleeve assemblies for rock
drill heads or the like and to methods of installing the combined
button and sleeve assembly in a head.
2. Description of the Prior Art
As stated in my earlier application, one of the problems with prior
art rock drilling heads is that the buttons in many cases are not
replaceable resulting in the necessity of replacing the entire head
at a cost of several times the cost of the individual button when
only a few bits are actually in need of replacement. One prior art
attempt at providing replaceable buttons was unsuccessful since the
buttons were difficult to remove, often became loose, and in some
cases caused cracking of the head under percussive loading. This
prior art technique employed buttons mounted in sleeves which were
fitted in bores in the head assembly. These sleeves were split so
that they expanded against the inside wall of the bores. The bores
were provided of necessity with an internal central opening
accessible from the interior of the head assembly so that a worn
sleeve and button could be driven out from within. The placement of
the buttons in the head was thus primarily determined by the
availability of access from within the head to drive out the
buttons and was not designed for optimum drilling configurations.
Furthermore, the necessity of numerous access holes weakened the
structure of the head assembly. Still further, the sleeves did not
firmly hold the button in the head and under percussive loading the
buttons would become loosened or broken.
Other prior art attempts at replacing the buttons without the use
of sleeves have proven extremely expensive since the buttons are
difficult to machine to the exact tolerances of the bores in the
head and often fractured the metal around the bore when being
pressed into the bore. In addition, the percussive loading on the
buttons is transmitted directly to the edges of the bores, causing
damage of the edges and requiring that a bore be recut to a larger
size before a replacement button can be installed. Furthermore, the
replacement bottom is then an odd size making it expensive to
manufacture.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a button and sleeve
assembly comprising a bit and a sleeve which can be manufactured
and stored as an integral unit and adapted for installation in
various size holes in a rock drill head or the like.
Basically, the button and sleeve assembly comprises a button having
an outer surface and a sleeve having a matching inner surface such
that when combined in a working configuration the exterior
dimension of the sleeve is stretched to exceed the inner dimension
of the opening in which the button and sleeve assembly are to be
inserted. "Working configuration" for the purposes of this
description means a button pressed within a sleeve to the same
extent as when finally pressed into the opening in the head. The
matching surfaces are dimensioned such that upon partial removal of
the sleeve from the button the exterior surface of the sleeve is
reduced to a dimension less than the dimension of the opening. This
configuration allows a button and sleeve assembly to be accurately
formed to a desired external dimension and thus be matched to the
dimension of a hole in a drill head. Thus the bit button and sleeve
can be stored in a partially disassembled (but not completely)
condition and can then be inserted into the opening of the drill
head and pressed into the working configuration such that the
sleeve will be expanded into tight engagement between the button
and the sidewall of the opening.
The method of this invention comprises forming a bore in a drilling
head with an inner end wall, combining a button and a sleeve into a
working configuration with the button within the sleeve, forming
the conbined bit and sleeve while in said working configuration to
reduce the external dimensions of the sleeve, moving the button and
sleeve slightly relative to each other to reduce the external
dimension of the sleeve and button, placing the bit and sleeve into
the opening, and then moving the button and sleeve relative to each
other to expand the sleeve radially until the button and sleeve are
returned to their combined working configuration with the sleeve
being pressed tightly against the button and the bore.
In the preferred form the button and sleeve have matching tapers
with the taper of the sleeve diverging toward the end wall of the
bore and the step of moving the button and sleeve into the bore
includes the step of first seating the button against the end wall
of the bore and then pressing the sleeve over the button also into
engagement with the end wall of the bore. The preferred method also
includes the step of maintaining the button and sleeve in the exact
same rotational alignment with each other during pressing into the
cylindrical bore as when they are pressed together into said normal
working configuration. In this manner the irregularities in the
shape of the button are compensated for by the deformation of the
sleeve and this exact compensation is not changed since the sleeve
and button are never rotated relative to one another again during
the remainder of the installation procedure. Also in the preferred
form the taper is made in the sleeve by first cold forming it over
a die and combined with the button in its working configuration the
exterior surface of the sleeve is ground to be slightly greater
than the diameter of the bore.
As is apparent, the sleeve serves as a protection for the edge of
the hole since percussive loading on the button will damage the
sleeve rather than the edge of the hole which is less deformable
than the sleeve. The sleeve expands against the sidewall of the
bore by radial expansion and does not cause gouging or
overstressing of any portion of the bore. Furthermore, the entire
surface of the hole is expanded uniformly without over-stretching
the entrance to the bore so as to hold the sleeve tightly in the
bore. Since the sleeve is expanded uniformly against the bore it
holds the button securely and reduces the chance of breakage of the
button. The button can be easily removed by cutting the sleeve from
around the button to free the bit in the hole.
Another advantage is that the button can remain at its standard
production size and the sleeve made oversized to recover a drilling
head having an oversized hole caused from prior damage to the hole.
In prior art devices such a head was often discarded at a
tremendous cost merely because the cost of machining a carbide
button to the configuration of the oversized hole was too
expensive. Still another advantages is that since the end of the
button abuts directly against the end wall of the bore in the drill
head rather than against the sleeve as in the prior art, the sleeve
can be made much thinner thus reducing the size of the hole and
increasing the strength of the head and allowing an increased
number of buttons in the head.
Still further the invention is equally applicable for replacement
of buttons in existing conventional drilling heads or as an
original manufacturing technique for new drilling heads. It is
particularly advantageously employed as a technique for mounting
the buttons in drilling heads receiving high loading such as those
used in tunnel boring machines and the like. Not only are the
buttons more easily installed by this invention but the buttons are
held more securely and thus the drilling head and the buttons last
longer for such severe drilling applications.
In the preferred embodiment the sleeve receives a pressure during
installation rather than the button thus allowing greater
flexibility in the hardness of the button. As a result a wider
range of customer's specifications for button composition can be
maintained.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an environmental view of a typical drilling head showing
a button and sleeve assembly embodying the principles of this
invention and installed according to the methods of this
invention.
FIGS. 2A-2G are schematic operational views illustrating various
steps in the method of installation which embody the principles of
this invention. FIG. 2C, for example, specifically shows a typical
button and sleeve assembly in a working configuration prior to
being installed in the rock drilling head. FIG. 2 D specifically
shows a technique for storing the combined button and sleeve prior
to installation in the drilling head. FIG. 2F illustrates a typical
installation of a button and sleeve assembly in a drilling
head.
FIG. 3 illustrates an alternative method step for removing the
sleeve when a button is to be replaced.
FIG. 4 illustrates an alternative form of button and sleeve
assembly, the installation of which is basically the same as that
shown in the steps illustrated in FIGS. 2A-3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
My earlier patent application Ser. No. 232,695 disclosed in detail
a drilling head, a button and sleeve assembly for use in a drilling
head, and methods of installing button and sleeve assemblies in the
drilling head. This application discloses additional subject matter
incorporating improvements of the originally disclosed installation
method and expands on the description of a preferred installation
method. For this purpose, FIG. 2A illustrates a technique for cold
forming a taper on a sleeve 44. Preferably the sleeve is made from
4340 low alloy steel and is coined on a die 80 using conventional
cold forming practices. The tapered sleeve is then heat treated to
produce a hardness of about R.sub.c 38-40.
In the preferred form, a typical sleeve will initially have an
outer diameter slightly greater than the diameter of the bore in
the drilling head to which the sleeve will finally be inserted. The
cold forming step on the die 80 provides the internal taper of the
sleeve with diameters of about 0.005 of an inch less than the
corresponding top and bottom diameters of the carbide button 42
with the button having a taper of 0.20 of an inch diameter per inch
of sleeve length formed during sintering of the buttons. In a
typical example, a bit is composed of 9 1/2 to 10 1/2 percent
cobalt carbide of tungsten of the type manufactured by Diamond
Metal Alloys. The composition of the sleeve and button will vary to
some extent, however, due to the requirements of the user of the
drill head. A typical drilling head can be made from Bethlehem
Steel Corporation tool steel ASTM Grade 7, sold under the trademark
Bearcat.
In FIG. 2B the now tapered sleeve 44 is positioned over the
corresponding button 42 and in FIG. 2C forced down over the button
for an interference fit of 0.002-0.004 inch using a pressure of
approximately 10,000 pounds. The dimensions illustrated in the
figures, are intended to show a typical example only it being
understood that buttons and sleeves may vary in size depending on
the user's requirements. FIG. 2C illustrates a "working
configuration" of the combined button and sleeve and is identical
to the configuration they will assume when placed within a bore of
the drilling head. While in this working configuration, the
circumference of the sleeve is machined or preferably ground to
reduce its diameter to a diameter slightly in excess of the
internal diameter of the bore 60 in the drilling head to allow a
0.0030-.0035 press fit. Several sizes will be made to allow for off
size bores in the drilling head.
FIG. 2D illustrated a button and sleeve in a storage position with
the sleeve slightly retracted from the button 42. While not
necessary to practicing the invention, it has been found desirable
to store the sleeve on its corresponding button. In this way the
sleeve is never removed, and thus its angular orientation with
respect to the button is not lost. This provides the advantage of
perfect mating between the internal surface of the sleeve and the
external surface of the button caused by the 10,000 pounds pressing
force illustrated in step 2C. All irregularities in the button
become compensated for by the ductile material in the sleeve.
Rotation of one of the members relative to the other would of
course destroy this perfect uniform fit. In the position shown in
2D the sleeve is also permitted to relax sufficiently so that its
external diameter becomes less than the internal diameter of the
bore 60.
FIG. 2E illustrates the step of placing the combined button and
sleeve in the bore 60 and applying a pressure of 24,000 pounds to
force the sleeve over the button into its working configuration
shown in FIG. 2F. The button is first placed against a seat in the
bore which may be an insert in the bore or as illustrated the end
wall of the bore. The guide 72 supports the sleeve as it is being
forced over the button 42. As shown in exaggerated form in 2E, the
small gap between the external diameter of the sleeve 44 and the
internal diameter of the button 42 allows the sleeve to be moved
relative to the button a substantial distance before the radially
outer edge of the sleeve begins to contact the sidewall of the bore
60. Expansion of the diameter of the sleeve is primarily radially
so that when it reaches its final working configuration in 2F,
there is a uniform application of force pressing outwardly against
the entire inside wall of the bore 60. The outer edge of the bore
is thus not subjected to stretching and results in a tight fit at
the outer end of the bore. The sleeve extends outwardly beyond the
bore protecting the edge of the bore from abrasive or percussive
forces. The button is seated on the inner wall 62 of the bore and
thus transmits loads directly to the drilling head to better
transfer the percussive loads between the button and the head.
FIGS. 2G and FIG. 3 illustrate two methods of removing the button
and sleeve from the bore 60. In FIG. 2G a rotary cutting tool 73 is
employed to cut the sleeve from between the button and the sidewall
of the bore thus freeing the button for removal. In FIG. 3 an
electrode 90 of an electric discharge machine, well known in the
art, is employed to erode the sleeve from between the button and
sidewall of the bore by the use of an electric charge.
FIG. 4 illustrates another embodiment of the sleeve and button
assembly. In this embodiment a bit 100 is employed with a
converging external taper similar in angularity to the taper of the
preferred embodiment. The button is fixed within a sleeve 101 of a
material similar to that of the preferred embodiment. In this form
of the invention, a button and sleeve will be formed in a working
configuration such as that shown in FIG. 2C and stored as in FIG.
2D. Insertion of the button and sleeve into the bore 60 occurs
first by seating the sleeve 101 against the end wall of the bore or
a suitable insert and finally pressing the button into the sleeve
to expand the sleeve against the sidewall of the bore 60. The
button is illustrated in a position where it is initially inserted
into the bore with an exaggerated gap between the sidewall of the
sleeve and that of the bore fror the purposes of description.
While preferred forms of the invention have been illustrated and
described it should be understood that alternatives and
modifications will be apparent to one skilled in the art without
departing from the principles of the invention. Accordingly, the
invention is not to be limited to the specific embodiments
described.
* * * * *