U.S. patent application number 10/266149 was filed with the patent office on 2004-04-08 for diamond tip point-attack bit.
Invention is credited to McAlvain, Bruce William.
Application Number | 20040065484 10/266149 |
Document ID | / |
Family ID | 32042611 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040065484 |
Kind Code |
A1 |
McAlvain, Bruce William |
April 8, 2004 |
Diamond tip point-attack bit
Abstract
A rotatable point-attack bit retained for rotation in a block
bore, and used for impacting, fragmenting and removing material
from a mine wall. An improved elongated tool body having at the
front end a diamond-coated tungsten carbide wear tip that is
rotationally symmetric about its longitudinal axis and contiguous
with a second section steel shank at the rear end. The two distinct
parts are joined by a high impact resistant braze at ratios that
prevent tool breakage. The method of making such a diamond-coated
section comprises of 1) placing within a reaction cell, the diamond
powder and the carbide substrate and 2) simultaneously subjecting
the cell and the contents thereof to temperature and pressure at
which the diamond particles are stable and form a uniform
polycrystalline diamond surface on the tip of the carbide substrate
thus forming a diamond-coated insert providing both cutting edge
and steel body protection for increased durability and extended
cutting tool life.
Inventors: |
McAlvain, Bruce William;
(Henderson, KY) |
Correspondence
Address: |
Bruce William McAlvain
5110 Heathfield Ct
Houston
TX
77084
US
|
Family ID: |
32042611 |
Appl. No.: |
10/266149 |
Filed: |
October 8, 2002 |
Current U.S.
Class: |
175/434 ;
175/293; 175/425 |
Current CPC
Class: |
E21C 35/1831 20200501;
E21C 35/183 20130101 |
Class at
Publication: |
175/434 ;
175/425; 175/293 |
International
Class: |
E21B 010/38; E21B
004/00 |
Claims
What I claim as my invention is:
1. A rotatable cutting bit for impacting, fragmenting and removing
material such as asphalt, concrete, rock, and minerals, the
rotatable cutting bit comprised of: a polycrystalline diamond tip,
affixed to a cemented carbide substrate by high temperature and
pressure bonding, forming a diamond-coated unitary body, positioned
at the forward central axis extremity of the cutter bit, having
coaxially aligned, rotationally symmetric about its longitudinal
axis a tip section, and a base section, having a maximum diameter
at said base section, and having a flat surface or a convex
protrusion or partial continuously varying radiused extension at
its rearward section. a ferrous body with a head section and
elongated shank having a circular cross section, said body
depending from said protective diamond-coated unitary body along a
longitudinal axis, said head portion having a flat surface or
concave seat or partial continuously varying radiused socket at the
forward end.
2. The rotatable cutting tool of claim 1 wherein the forward
section is coated with polycrystalline diamond, cubic boron
nitride, wurtzite boron nitride or mixtures thereof formed by a
method that comprises the placing within a reaction cell
pre-pressed forms of abrasive particles affixed to the tip of the
cemented carbide substrate and simultaneously subjecting the cell
and the contents thereof to temperature and pressure conditions at
which the diamond, cubic boron nitride or wurtzite boron nitride
particles form a super hard abrasion resistant polycrystalline
layer permanently sinter reaction bonded to the tip of the cemented
carbide substrate.
3. The rotatable cutting tool of claim 1 wherein the forward
section has a cemented carbide substrate, which at its forward end
has from 1-5 staggered concentrically layered rounded radiused
protuberances that serve to support the diamond layer.
4. The rotatable cutting tool of claim 1 wherein the forward end of
the steel shank contains a flat surface or seat or partial
continuously radiused socket defining a surface area, having an
overall depth of 0.001 to 2.00 inches.
5. The rotatable cutting tool of claim 1 wherein the axially
rearward section of said diamond-coated insert has a flat surface
or protruding or radiused extension that generally corresponds to,
and fits into the shape of the flat surface or seat or partial
continuously radiused socket of said steel shank.
6. The rotatable cutting tool of claim 1 with a braze joint joining
the surface area of the flat or protruding or radiused extension
axially rearward section of said diamond-coated insert body to the
flat surface, mating seat or radiused socket of the axially forward
section of said ferrous shank by means of a medium to high impact
resistant braze alloy.
7. The brazed surface areas in claim 6 of said steel shank axially
forward section flat surface, seat or radiused socket and said
rearward diamond-coated insert body section flat surface,
protruding or radiused extension to be at a ratio of steel shank
surface area to diamond-coated insert body lateral cross sectioned
area of 1.0 to 6.5.
8. The rotatable cutting tool of claim 1 wherein the tip is made of
a polycrystalline diamond affixed in situ to the carbide substrate
by high temperature and high pressure.
9. The rotatable cutting tool of claim 1 wherein the tip is made of
a polycrystalline cubic boron nitride affixed in situ to the
carbide substrate by high temperature and high pressure.
10. The rotatable cutting tool of claim 1 wherein the
diamond-coated insert cemented carbide substrate is made of a
composition containing grains of carbide of group IVB, VB, or VIB
metals pressed and sintered in the presence of a binder such as 5.0
to 18.0% cobalt, nickel, iron or alloys thereof.
11. The rotatable cutting tool of claim 1 wherein the
diamond-coated insert cemented carbide substrate is made of a
composition containing carbide of group IVB, VB, or VIB metals
having grain sizes from 0.01 to 30 microns as measured on a
sintered, polished and etched part at 100 to 1500.times. optical
magnification.
12. The rotatable cutting tool of claim 1 wherein said
diamond-coated insert protective cemented carbide substrate has an
overall length of 0.01 to 3.0 inches.
13. The rotatable cutting tool of claim 1 wherein said
diamond-coated insert cemented carbide substrate section has a
plurality of even numbered peripherally spaced, laterally
projecting surfaces or vanes extending generally longitudinally
along the bit, each surface or vane being substantially triangular
with a narrow leading end and a wider trailing end, and having
relatively diverging sides that extend from the leading end to the
trailing end, the purpose of which is to effect a positive rotation
of the bit upon contact with material being impacted, fragmented or
removed.
14. The rotatable cutting tool of claim 1 wherein said steel shank
has a means for holding a loosely resilient retainer on the steel
body that allows the cutter bit to rotate about its longitudinal
axis in a mounting block.
Description
REFERENCES CITED
[0001] U.S. Patent Documents
1 3,519,309 July 1970 Engle et al. 299/86 4,065,185 December 1977
Elders 299/86 4,497,520 February 1985 Ojanen 299/86 4,592,433 June
1986 Dennis 175/329 4,604,106 August 1986 Hall et al. 51/293
4,784,023 November 1988 Dennis 175/428 X 4,865,392 September 1989
Penkunas 299/86 4,911,503 March 1990 Stuffler et al. 299/79
5,011,515 April 1991 Frushour 51/307 5,161,627 November 1992
Burkett 175/427 5,837,071 November 1998 Andersson et al. 148/528
6,029,760 February 2000 Hall 175/432 6,051,079 April 2000 Andersson
et al. 148/318
BACKGROUND OF THE INVENTION
[0002] The invention is directed to a rotatable cutting tool having
an enlarged diamond-coated cemented carbide protective tip and a
second steel body segment. The design of the invention is to
provide improved performance and safety characteristics. These
characteristics include a longer performance cycle through
increased wear and fracture resistance resulting in a more
efficient continuously penetrating material removal cycle and an
improvement in safety, due to a full diamond tipped carbide
segment, that results in less chance for methane gas ignition and
explosion. The large protective carbide substrate has a high
temperature and high pressure bonded diamond-coated tip covering
the entire exposed carbide surface that not only results in
increased wear life of the bit body but also serves to protect the
lower steel shank in tougher milling conditions.
[0003] Examples of rotatable cutting tools are on applications with
long wall miners, continuous miners, and road planers. A long wall
mining machine is used for mining coal seems underground. The
machine includes two rotating drums having a plurality of blocks
affixed thereto. Long wall mining tools typically comprise an
elongated steel body with a hard cemented carbide tip brazed into a
socket contained in the forward end of the steel body. One such
point attack bit is described in U.S. Pat. No. 4,065,185. Attempts
to improve performance have been made by hardening the insert tips
of mining attack tools by the use of diamond compacts. One such
diamond compact for use in cutting, machining, drilling and like
operations is disclosed in Hall et al U.S. Pat. No. 4,604,106.
Mining bits incorporating diamond tips brazed onto steel inserts
and subsequently brazed into steel bodies are shown in Anderson et
al U.S. Pat. Nos. 5,837,071 and 6,051,079.
[0004] During the milling operation, the drums rotate so as to
cause the rotatable cutting tools to impact the mine wall surface.
The tools impact and fracture the wall surface. The surface
fragments of coal chunks and powder are collected by a continuously
moving conveyor belt and carried to the surface of the mine for
processing. During the rotation of a drum, each rotatable cutting
tool rotates about its central longitudinal axis. It is important
that the tools continue to rotate because without adequate rotation
a conventional tool will be locked into position and start an
uneven wear pattern that leads to rapid tool degradation and
ultimate tool failure. Due to the higher wear resistance of the
large diamond-coated cemented carbide body segment of the present
invention, if the tool fails to rotate, the uneven wear pattern
shown by conventional tools is greatly diminished or not noticeable
when the tool clears and resumes its rotation.
[0005] The steel cutting tool body includes a reduced diameter
portion adjacent to the rearward end thereof. A retainer is
adjacent the reduced diameter portion of the steel body. The
retainer functions to retain the rotatable cutting tool within the
bore of the mounting block during the milling operation. Each block
contains a central bore therein. This and other resilient retainer
means useful with the present invention are described in U.S. Pat.
Nos. 3,519,309 and 4,201,421.
[0006] A common mode of failure of polycrystalline diamond
compacts, is the delamination of the diamond from the metal carbide
substrate. Different attempts have been made to find a true bond
that would resist delamination under the severe conditions
employed. U.S. Pat. No. 5,011,515 discusses numerous attempts by
previous inventors to solve the problem of delamination of the
diamond layer from the carbide substrate. U.S. Pat. Nos. 4,592,433
and 4,784,023 teach parallel grooving of substrates to form ridges
for increased bonding. U.S. Pat. No. 6,029,760 teaches the use of
rounded cylindrical posts as support for diamond surfaces in rock
drilling and machining wear resistant materials. These designs
actually produce higher stresses in some portions of the cutter
than that exhibited in the planar interface mounted PCD to carbide.
However, all of the previous patents refer to rock and oil drilling
or machining of parts where the stresses are not the same as for
the application of this invention. This invention specifically
addresses the use of diamond-coated picks, usually mounted on a
rotating drum, for road pavement removal and recycling and coal
mining, such as for continuous and long wall mining machines. A
feature of this invention is the enlarged diamond tip supported by
rounded radiused protuberances located near the tip of the carbide
substrate. The diamond tip is fully immersed into the cutting
media, thus serving to decrease the frictional forces placed on the
load stress concentrations and distribute them evenly over the
surface, thereby minimizing the potential for diamond
delamination.
[0007] Other features of this invention are provided by a method
for making a fully coated diamond carbide, which method comprises
the placing within a reaction cell pre-pressed forms of diamond
particles affixed to the tip of the carbide substrate and
simultaneously subjecting the cell and the contents thereof to
temperature and pressure conditions at which the diamond particles
solidify and are permanently reaction bonded to the cemented
carbide substrate. The methods of making polycrystalline diamond in
high temperature, high-pressure presses are well known in the art
and further detailed description thereof is not considered
necessary.
[0008] Another method of failure of previous inventions that use a
small carbide, or small diamond-coated carbide tip bonded to a
steel shank is braze failure at the carbide tip to steel shank
junction, where the severe application forces exceed the tensile
strength of the braze alloy causing bond failure of the small
contact area between two dissimilar metals. This invention, having
a diamond tipped larger and longer extended carbide portion, makes
the surface area where the carbide post is brazed to the steel
shank of much larger diameter than previous inventions further
increasing the surface area with a partial continuously varying
radius that matches the profile of the steel shank pocket where it
is bonded by a medium to high impact resistant braze. The larger
brazed surface area ensures that the braze joint will not fail
under most severe loading conditions, thus extending the life of
the bit and contributing to safety by minimizing catastrophic tool
failure.
[0009] Another method of failure is due to using diamond-coated
carbide tips limited in size as compared to the size of the diamond
tip of the present invention. Having only a limited size carbide or
diamond-coated carbide tip results in bit failure when the steel
holding the carbide or diamond-coated insert is eroded away during
application, exposing the cutting insert and allowing fracture
thereof followed by catastrophic failure of the bit. In addition to
the much larger protective surface area, the profile of this
invention is so designed as to guide the cuttings away from the
ferrous shank preventing erosion of the steel body below the
diamond tip, thus significantly extending the life of the tool.
[0010] The present invention reduces the potential of sparking and
explosion from ignition of methane gas. The ignition of methane
gas, which is released from pockets where the gas has been trapped
in the material being mined, is a safety problem. The causes of
ignition are believed to be due to the heat generated through
friction as the bits move through the coal and rock during the
mining operation or due to sparking, which may occur when the steel
base portions of the bits strike rock. Since the coefficient of
friction of diamond is substantially lower than that of steel, less
heat is generated as the diamond tipped body of the present
invention cuts through coal and rock, thus reducing the possibility
of gas ignition.
[0011] The large protective diamond tip is preferably formed onto a
unitary member of cemented carbide or other material, which
provides suitable hardness and toughness characteristics. The term
"cemented carbide" refers to the type of material resulting when
grains of carbide of the group IVB, VB, or VIB metals are pressed
and sintered in the presence of a binder such as cobalt, nickel, or
iron as well as alloys thereof. The term "diamond" refers to
polycrystalline diamond, cubic boron nitride or wurtzite boron
nitride and mixtures thereof.
SUMMARY OF THE INVENTION
[0012] The present invention overcomes the shortcomings associated
with known rotatable cutting tools and teaches the construction and
operation of an insert for road construction or mining attack
tools. The present invention of a large fully diamond tipped
cemented carbide body segment, joined to the steel shank at a
specified braze area ratio, serves to channel the flow of material
away from the steel shank so as to significantly reduce premature
washout wear and failure, which are the most common modes of
failure with all smaller diamond tipped previous inventions.
[0013] Since the coefficient of friction of diamond is
substantially lower than that of steel, less heat is generated as
the protective body of the present invention cuts through coal and
rock thus increasing the safety of operation by reducing the
potential of sparking and explosion from ignition.
DETAILED DESCRIPTION
[0014] Referring to the drawings more particularly by reference
numbers wherein like numerals refer to like parts. FIG. 1
identifies a rotatable diamond tipped mining bit constructed
according to the teachings of the present invention. FIG. 2 shows
prior art with a bit having a typical tungsten carbide tip 1 and a
steel body 2. Shown in FIG. 3 is a preferred segmented embodiment
of the invention of a rotatable cutter bit having a diamond-coated
cemented tungsten carbide tip 3 and a steel body 2. The carbide
base 4 of the diamond-coated tip 3 is joined to the steel shank 2
at the matching recessed pocket 9 by a medium to high strength
braze alloy. The head portion 3, and the shank 2 are coaxially
aligned. The shank 2 having at its widest diameter, an enlarged
section 5, which prevents the tool from being forced into the
opening of the mounting block. The rearward steel member 2 may be
seen to include a generally cylindrical shank portion 6 having an
annular groove 7 near the rearward end and a frusto conical portion
8 adjacent forward to the shank portion 6. The frusto conical
portion 8 has a partial continuously radiused socket 9 at its
forward end.
[0015] FIG. 4 shows the present invention diamond-coated cemented
tungsten carbide tip 3, which includes a circular diamond tipped
head end portion 10 and a partial continuously varying radiused
tail end carbide section 11 which is brazed into a matching partial
continuously varying radiused socket 9 of the steel shank 2.
[0016] FIG. 5 shows the cemented carbide substrate portion of the
diamond-coated body prior to affixing the diamond. The surface 12
serves as a substrate onto which the diamond is applied. The
diamond is applied and covers the entire rounded tip surface until
it meets the widest part band 13. The nodular frusto conical
retention surface contains one or more layers of rounded radiused
protuberances 14, and the frusto conical planar surface 15 that
extends rearward until it meets a step in the carbide substrate at
a band 13.
[0017] FIG. 6 shows a longer version of a substrate of this
invention. The front includes a circular diamond tipped head end
portion 20 and a partial continuously varying radiused tail end
carbide section 11 which is brazed into a matching partial
continuously varying radiused socket 9 of the steel shank 2. The
diamond layer 20 is shown superimposed onto the carbide
substrate.
[0018] FIG. 7 shows the longer carbide substrate portion of the
diamond-coated tip prior to affixing the diamond. The diamond is
applied and covers the rounded tip surface 16, the nodular frusto
conical retention surface containing one or more layers of rounded
radiused protuberances 14, and the angular frusto conical vanes 17
leading down the side of the body until they meet the widest point
18 at band 19.
* * * * *