U.S. patent application number 11/509752 was filed with the patent office on 2006-12-21 for saw blade for cutting fiber cement.
Invention is credited to John R. Curtsinger, Stephen C. Dassoulas, Dean Edwards, Laura Lindberg, Michael Lindberg, Steve McClaskey, Stefan Nock.
Application Number | 20060283436 11/509752 |
Document ID | / |
Family ID | 22371193 |
Filed Date | 2006-12-21 |
United States Patent
Application |
20060283436 |
Kind Code |
A1 |
Dassoulas; Stephen C. ; et
al. |
December 21, 2006 |
Saw blade for cutting fiber cement
Abstract
An improved circular saw blade designed for cutting fiber cement
workpieces, which are becoming more and more prevalent on the
construction site, includes a PCD/carbide tip mounted in the rim of
a saw blade at six, rather than the usual four locations, equally
spaced around the blade. The tips are mounted adjacent a relatively
large-diameter, semi-circular gullet, which itself is preceded by a
chip and dust minimizer. The minimizer includes several alternating
hills and valleys formed in the rim of the saw blade, each hill and
valley having the same radius, producing a sinuous array
essentially centered on the rim of the blade. It has been
discovered that such a dust and chip minimizer reduces the level of
dust and chips produced by the blade and clears the same from the
kerf generated in the blade-workpiece interface. Ideally, all of
the parameters and relief angles for the surfaces on the saw blade
tip can be generated by cutting an array of such tips from a
large-diameter blank of PCD fused to a layer of tungsten carbide,
and by mounting the tips onto the blade in such an orientation as
to present, preferably, a negative hook or rake angle to the
workpiece.
Inventors: |
Dassoulas; Stephen C.;
(Lutherville, MD) ; Curtsinger; John R.;
(Shelbyville, KY) ; Nock; Stefan; (Baltimore,
MD) ; Edwards; Dean; (Bel Air, MD) ; Lindberg;
Michael; (Rockville, MD) ; Lindberg; Laura;
(Rockville, MD) ; McClaskey; Steve; (Baltimore,
MD) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
22371193 |
Appl. No.: |
11/509752 |
Filed: |
August 24, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09890164 |
Mar 22, 2004 |
7117863 |
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PCT/US00/01609 |
Jan 24, 2000 |
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11509752 |
Aug 24, 2006 |
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60117145 |
Jan 25, 1999 |
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Current U.S.
Class: |
125/13.01 |
Current CPC
Class: |
A01K 15/02 20130101;
A01K 15/026 20130101; B23D 61/021 20130101; B28D 1/121 20130101;
B23D 61/04 20130101; B23D 65/00 20130101; A63H 33/18 20130101; A01K
5/0114 20130101 |
Class at
Publication: |
125/013.01 |
International
Class: |
B28D 1/04 20060101
B28D001/04 |
Claims
1-20. (canceled)
21. A process for making a saw blade tip, comprising: cutting an
array of tips from a PCD blank; the PCD blank having a PCD layer
pre-joined to a carbide layer; each tip having two diverging
radially-relieved side surfaces; and wherein the array is formed by
a plurality of adjacent tips oriented such that one of said
relieved side surfaces of one tip is adjacent the opposite relieved
side surface of another tip.
22. The process claimed in claim 21, wherein the base of one tip is
adjacent the top of another tip.
23. A process for making a saw blade, comprising: cutting all of
the relief surfaces into a PCD blank to form a saw blade tip; and
mounting a plurality of said cut tips on rim shoulders adjacent a
corresponding plurality of gullets formed in the rim of a circular
saw blade, the tips being mounted at a negative rake angle.
24. A circular saw blade formed by the process claimed in claim 23,
and further comprising: a dished area formed in said shoulder to
underlie a corner of said tip.
25. A circular saw blade formed by the process claimed in claim 23,
further comprising a chip and dust minimizer formed at a plurality
of sites in said rim of said saw blade.
26. The circular saw blade claimed in claim 25, further comprising
a plurality of gullets formed in the rim of said circular saw
blade, each chip minimizer being formed in front of each said
gullet in the direction of rotation of the saw blade.
27. The circular saw blade claimed in claim 25, wherein at least
one gullet is annular and having a constant radius.
28. The circular saw blade claimed in claim 27, wherein said at
least one gullet is substantially defined in profile by a
semicircle, the center of the semicircle being located radially
inwardly of the perimeter of the saw blade.
Description
BACKGROUND OF THE INVENTION
[0001] Fiber cement products are becoming more and more common on
construction sites. As such there has arisen a demand for cutting
tools, particularly circular saw blades, that can cut this very
difficult material, while reducing the amount of fine dust
particles generated. A need also exists for such blades that yield
a high quality (straight and smooth) cut in fiber cement
workpieces. There has also arisen a need for such blades that are
less expensive to produce than conventional diamond blades, but
which still exhibit good wear characteristics. Finally, there is a
perception by users that conventional blades for cutting fiber
cement products, particularly blades with conventional tips formed
with polycrystalline diamond joined to tungsten carbide ("PCD")
don't "feel" right.
[0002] In the conventional manufacturing process, a PCD tip is
attached to the rim of the blade blank at four circumferentially
equidistant locations, by brazing the carbide portion to the steel
blade blank. Frequently, diamond elements are formed and machined,
then applied to pre-formed carbide substrates, or, in the
alternative, a diamond film is deposited on the carbide tips using
a chemical vapor deposition process. One relatively recent process
for forming a PCD tip is to cut several parts out of a large PCD
blank, in which the PCD has already been fused to a carbide layer
or substrate. Another conventional process is to form the PCD tip,
braze it to the blade, then machine the radial or side clearances,
the tangential clearances, and the top relief or clearance for each
tip. In view of the wear resistance inherent in the diamond and
carbide materials selected, this amount of machining is a slow,
expensive process.
[0003] As to the structure of a conventional blade for fiber
cement, conventional wisdom dictates using a positive hook angle
for the tip. This has not proved to be entirely satisfactory.
Further, the conventional design employing four tips doesn't
provide a good finish, nor does it provide the user with a good
"feel".
SUMMARY OF THE INVENTION
[0004] The present invention solves the cost problem and makes the
PCD blade capable of cutting a difficult substance like fiber
cement. It also makes it possible for the blade to be priced for
the consumer, rather than as a high-end specialty product. One way
in which the invention is created is to cut the appropriate
relieved tooth form out of the PCD/carbon-fused blank or sandwich
and then mount the PCD tooth form or tip to the saw blade blank in
such a way as to eliminate any further grinding step. Another is to
form a relatively large diameter blank of PCD/carbide, and then to
form an array of relieved saw blade tips in the blank, such as by
EDM cutting, so that, in one embodiment, radially-relieved surfaces
of each tip are immediately adjacent the opposite side
radially-relieved surface of another tip. Another embodiment of the
process of the present invention is to form a PCD/carbide tip in a
"square" configuration, such as 0.090 inches by 0.090 inches by
0.125 inches, then connecting the tip to the blade blank, and then
grinding the top, radial and tangential relief surfaces in place.
Or, it may be desirable to orient the tip on the blade in such a
way that the tip needs no grinding to form the desired top relief,
and using diamond grinding wheels to grind simultaneously the
radial and tangential clearance (relief) surfaces with the tip
fixed in place on the blade. Both approaches of the process of the
present invention eliminate the conventional need for attaching a
pre-formed PCD layer to match the configuration of each carbide
tip.
[0005] Another aspect of the process of the present invention is to
form a rounded dished portion in the shoulder of a saw blade rim
where the corner of the PCD tooth is normally mounted. This reduces
voids in the braze between the carbide portion of the PCD sandwich
and the metal rim of the saw blade. It also improves alignment of
the tip to the plate, because it eliminates the gullet that would
otherwise interfere with the sharp corner at the bottom rear of the
tip. Finally, yet another aspect of the process of the present
invention is optionally to form a shallow depression in the saw
blade rim behind the tip so that there will be sufficient clearance
in the event it is desired to top-grind both the tip and a portion
of the blade steel immediately adjacent the rear of the tips, at
the rim of the blade. This may not be necessary, if the blade is
laser-cut from steel strip or sheet. Now follows a discussion the
blade of the present invention.
[0006] Recognizing that conventional blades for cutting fiber
cement limit the number of teeth to four, because it is believed
that fewer teeth generate smaller amounts if fine-particle dust,
and further recognizing that four teeth do not satisfactorily clear
or minimize the chips and dust packed into the blade--fiber cement
interface, the blade of the present invention includes chip and
dust minimizers preferably, one in front of each tooth (in the
direction of cut of the saw blade). The minimizers of the present
invention are created by a sinuous pattern of a plurality of
adjacent radially-extending alternating peaks and valleys formed in
the rim of the saw blade blank. In a preferred embodiment, each
minimizer includes three distinct "hills", each hill separating two
"valleys", such that the sinuous pattern begins and ends with a
valley. The result is a pattern of three hills interspersed among
four valleys. Such a minimizer has been found to reduce the amount
of chips and dust in the blade-workpiece interface. The minimizers
coact with another feature of the blade of the present invention,
namely, adjacent, substantially semi-circular, large-diameter
gullets at each tip location on the saw blade rim, to further
reduce the level of dust.
[0007] Yet a further object of the blade of the present invention
is to locate six, not four, sets of PCD tips, gullets and
minimizers about the rim of the blade. This has resulted in a
significant improvement in the quality of cut in fiber cement
workpieces.
[0008] Finally, a further object of the present invention is to
orient the PCD/carbide tips of the present invention in their
respective locations in the rim of the saw blade so that the tips
present a negative hook or rake angle to the workpiece, as opposed
to the conventional positive-hook saw blades for cutting fiber
cement. The negative-hook orientation of the saw blade tips of the
present invention also contributes to the better feel and finish of
the blades of the present invention.
[0009] Other objects, features and advantages of the present
invention will become more fully apparent from the following
detailed description of the preferred embodiments, the appended
claims, and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the accompanying drawings, in which like reference
characters in the same or in different Figures, indicate like
parts:
[0011] FIG. 1 is a top plan view of a circular saw blade formed
according to the present invention showing the minimizers, gullets
and tips of the present invention;
[0012] FIG. 2 is an enlarged detail schematic view of one portion
of the saw blade of FIG. 1, showing the shelf and dished area
adjacent a gullet, prior to installing a PCD/carbide tip therein,
and a portion of the minimizer of the present invention;
[0013] FIG. 3 is an enlarged schematic detail view of a minimizer
of the present invention adjacent a portion of a gullet;
[0014] FIG. 4A is a front elevational detail view of a square
PCD/carbide tip of the present invention;
[0015] FIG. 4B is a sectional view, taken along the line B-B of
FIG. 4A, the dashed lines indicating another embodiment of the
PCD/carbide tip of the present invention;
[0016] FIG. 5 is a side elevation of the PCD/carbide tip of FIG. 4B
placed in a saw blade blank of the present invention at a
predetermined negative hook angle, and after having the top
clearance angle ground;
[0017] FIG. 6 is a fragmentary, front elevational view of the
invention shown in FIG. 5, after the side (radial) and tangential
relief surfaces have been ground;
[0018] FIG. 7 is a side elevational view of a pre-cut PCD tip of
another embodiment of the present invention;
[0019] FIG. 8 is a side elevational view of the pre-cut PCD tip of
FIG. 7 assembled to a saw blade adjacent a gullet at a
predetermined positive rake angle;
[0020] FIG. 9 is an enlarged detail view of the radial relief of
the saw blade tooth shown in FIG. 7;
[0021] FIG. 10 is a side elevational detail view of the pre-cut tip
shown in FIG. 9 with the pre-cut top relief of 30 degrees, prior to
being rotated forwardly about 15 degrees, as shown in FIG. 8,
thereby yielding a top clearance angle of about 15 degrees;
[0022] FIG. 11 is a schematic plan view of a large circular blank
of a PCD/carbide sandwich or fusion showing an array of PCD/carbide
tips formed according to the present invention;
[0023] FIG. 12A is a top plan schematic view of another embodiment
of the saw blade tip of the present invention, in which all of the
relief angles have either been formed in the tip prior to its
connection to the saw blade blank, or are created by the
predetermined attitude of the tip when secured in place on the saw
blade blank;
[0024] FIG. 12B is a front elevational schematic view of the tip
shown in FIG. 12A;
[0025] FIG. 12C is a side elevational schematic view of the PCD saw
blade tip of FIG. 12A;
[0026] FIG. 13 is a side elevational schematic view of the tip of
FIG. 12A attached to a saw blade of the present invention in which
the tip is oriented at a negative hook angle, and in which the top
clearance angle is created by the orientation of the tip relative
to the saw blade blank.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring to FIG. 1, the saw blade of the present invention
is referred to generally as 10. The saw blade 10 rotates in the
direction shown by arrow 12 when mounted to a saw. The saw blade is
formed of a steel plate or blank 14 on which is mounted a plurality
of tips 16, where are formed of harder material, such as a fusion
of PCD and tungsten carbide (hereinafter referred to as
PCD/carbide). The thickness of the steel plate 14 is in the range
of from 0.061 inches to 0.065 inches, with the preferred thickness
being 0.063 inches. In the preferred embodiment of the circular saw
blade 10 of the present invention, the blade itself is cut from
sheet or plate steel by a laser process, and then the PCD/carbide
tips 16 are brazed to the blade rim 31 in selected locations.
Preceding the tip 16 in the direction of rotation 12, is a chip and
dust limiter 18, immediately followed by a sweeping (relatively
large diameter) gullet 20 for also removing dust. The rim is
further formed with a dished area, decreasing the likelihood that
there will be any voids in the brazed itself, and assisting in
providing proper alignment between the tip and the blade. In
addition, a shallow depression 24 is formed in the rim 31
immediately behind the tip 16, in the event that, during the
manufacturing process, it is desired to grind both the top face of
the tip and a portion of the rim simultaneously. Depression 24
provides a clearance for the grinding wheel. Opening into every
other gullet is an expansion slot 26, which minimizes warpage in
the blade during the manufacturing process. In addition, heat vents
28 of a predetermined configuration and array are also formed in
the blade. In FIG. 1, all of the gullets 20, tips 16, and dust and
chip minimizers 18 are the same. At this point it should be noted,
that contrary to the conventional approach of using no more than
four teeth on a saw blade for cutting fiber cement workpieces, the
saw blade 10 of the present invention uses six equally-spaced sets
of teeth gullets and dust/chip minimizers. The use of 50% more
teeth has resulted in significantly improved quality of cut in the
workpiece, in that the cut is straighter and has a smoother finish.
For a more detailed description of this portion of the saw blade,
reference is now made to FIG. 2.
[0028] As shown in FIG. 2, gullet 20 is centered about point 29,
which lies on a radial 27 going through the center of the saw
blade, and bisecting expansion slot 26. The center 29 is located
slightly radially inwardly of the circumference of the outer rim 31
and, preferably, is substantially semicircular in profile, having a
radius 30 of about 8 mm. A shelf 32 is formed in the rim 31
adjacent the trailing end of the gullet 20 at a shelf inclination
angle 44 of about 10 degrees. The shelf is joined to a backing
portion 34 by dished area 22, and together provide the mounting
support for a tip 16 when brazed into place on the rim. The backing
34 is formed at a negative rake angle 36 of about 10 degrees, while
the top surface relief angle 38 is also about 10 degrees. The
radius of the interface 40 between the gullet rim 20 and the rim 31
is about 0.51 mm, and the radius 42 of the interface 43 between the
backing 34 and the rim 31 is about 0.25 mm. The shelf inclination
angle 44 is also set at about 10 degrees. These dimensions are
selected to coact with the various dimensions and angles of the tip
16 so that, in one embodiment of the present invention, the tip
brazed in place on the shelf 32 and against the backing 34 is at an
orientation that requires no further machining of the saw blade or
tip. On the other hand, if desired, the various dimensional
parameters and angles of the tip 16 of the present invention and
the saw blade 10 of the present invention can be selected so that
one or more grinding operations can be performed on the tip after
emplacement in the saw blade. The distance 46 from radial 27 to
center 40 of the interface 41 is approximately 8 mm, while the
distance 48 from the radial 27 to the center of the dished portion
22 is about 9.9 mm. Finally, the distance 50 from the radial to the
center of interface 43 is about 11 mm. It can be noted that the
radius 30 of gullet 20 is relatively large in comparison to the
size of the tip 16. This aids in dust and chip removal, and reduces
the amount of fine-particle dust.
[0029] Now referring to FIG. 3, a more detailed description of the
dust and chip minimizers 18 of the present invention will
follow.
[0030] It has been discovered that the use of dust and chip
minimizers of the present invention reduce the amount of dust and
chips generated or present in the blade-kerf interface. The dust
and chip minimizer 18 of the present invention, illustrated earlier
in FIG. 3, includes a plurality of hills 52 interspersed in equal
distance among valleys 54, such that, in a preferred embodiment,
there are three hills 52 interspersed equidistantly from and among
four valleys 54. It should be noted that all of the hills and
valleys 52,54 are semicircular in shape and centers 56 are spaced
apart equaldistancely. The result is a sinuous array of hills and
valley 52,54, respectively, separated from an interface with gullet
20 by a distance 60, which is about 0.364 inches. The distance 58
between centers of hills (and between centers of valleys) is about
0.172 inches. The preferred radius 61 of the hills and valleys of
the minimizer 18 of the present invention is about 0.050 inches. It
is believed that reducing the number of hills and valleys will
reduce the dust-clearing action of the minimizer 18. It is also
believed, however, that there will exist some upper limit to the
hills and valleys beyond which further increases in the quantity of
hills and valleys will result in a relatively small, if any,
reduction in dust production.
[0031] Moving now to the PCD/carbide tip of the present invention,
one embodiment is illustrated in FIGS. 4A, 4B, 5 and 6. Here a tip
16 is formed in a "square" configuration with a PCD layer 70 joined
to a tungsten carbide layer 72. In one embodiment, the length and
width of the tip shown in FIG. 4A is about 0.090 inches square, and
the depth of the embodiment shown in solid lines in FIG. 4B is
about 0.060 inches. However, it has been discovered that to provide
a greater surface area and consequently a greater amount of
interface between the bottom portion of the tip and the shelf 32,
such as by making the total depth 0.125 inches, as shown in phantom
and designated 16' and 72' in FIG. 4B, there is a better and
stronger brazed connection between the tip 16' and the saw blade
14. As shown in FIG. 5, the square tip 16' is oriented on the rim
31 of the saw blade so that the cutting edge is automatically at a
negative rake angle 74 of about negative 5 degrees and a back angle
76 of also about 5 degrees. FIG. 6 illustrates the tip 16' after
the side clearance angles 78 have been ground, these angles being
in the range of about 0.001 inches to 0.005 inches, for each side.
In addition, the tip 16' is oriented on the blade 14 that there is
an overhang 80 of about 0.013 inches on each side of the blade
14.
[0032] FIGS. 7 through 10 illustrate another embodiment of the
present invention, in which a pre-cut PCD/carbide tip 16'' is
formed to a height 86 of about 0.175 inches, a width 92 at the top
of about 0.083 inches, and a width 94 at the bottom of about 0.065
inches. Referring now to FIG. 10, the depth 96 is about 0.125
inches and the pre-cut top clearance angle 90 is about 30 degrees,
thereby providing a relieved top surface 98. With reference to FIG.
8, the tip 16'' is mounted on the blade 14 such that the hook angle
88 is at a positive 15 degrees relative to the radial 27. Although
the range of acceptable hook angles of the present invention is
from minus 7 degrees to plus 10 degrees, a negative hook angle is
preferred.
[0033] With reference now to FIG. 11, a large blank 110 of PCD
material fused to carbide is illustrated, which is then cut into an
array 112 of oppositely oriented tips 114. The large diameter blank
110 is, for example, supplied by General Electric as their Compax
Grade 1300 PCD blank.
[0034] FIGS. 12A and 13 illustrate another embodiment of the saw
blade tip of the present invention in which all of the relief
angles have either been formed in the tip prior to its connection
to the saw blade blank, or created by the predetermined attitude of
the tip when secured in place on the saw blade blank. As shown in
FIG. 12A, even the tangential relief angles 100 can be formed in
this manner. FIG. 13 shows such a tip in place on the saw
blade.
[0035] The above-described embodiments, of course, are not to be
construed as limiting the breath of the present invention.
Modifications and other alternative constructions will be apparent
which are within the spirit and scope of the invention as defined
in the appended Claims.
* * * * *