U.S. patent application number 12/474257 was filed with the patent office on 2010-06-10 for cutting tool for breaking or excavating machines.
Invention is credited to Xiaojun Yang.
Application Number | 20100141016 12/474257 |
Document ID | / |
Family ID | 40629661 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100141016 |
Kind Code |
A1 |
Yang; Xiaojun |
June 10, 2010 |
CUTTING TOOL FOR BREAKING OR EXCAVATING MACHINES
Abstract
A cutting tool for breaking or excavating machines, comprising:
a tool body,a main tip (1), and a plurality of ancillary tips (3),
wherein the ancillary tips (3) comprises a plurality of tapered
cutting tips (7) or a plurality of cutting edges (8) for breaking
operation; and the ancillary tips (3) are disposed on the tool body
(2) around the main bit tip (1). The cutting tool for breaking or
excavating machines of the invention is capable of increasing and
elongating the wear resistance capability without sacrifice its
penetrating ability so as to extend the service life of the bit, as
well as increase its working efficiency and safety.
Inventors: |
Yang; Xiaojun;
(Shijiazhuang, CN) |
Correspondence
Address: |
MATTHIAS SCHOLL
14781 MEMORIAL DRIVE, SUITE 1319
HOUSTON
TX
77079
US
|
Family ID: |
40629661 |
Appl. No.: |
12/474257 |
Filed: |
May 28, 2009 |
Current U.S.
Class: |
299/101 |
Current CPC
Class: |
E21C 35/1833 20200501;
E21C 35/18 20130101 |
Class at
Publication: |
299/101 |
International
Class: |
E21C 35/18 20060101
E21C035/18; E21B 10/58 20060101 E21B010/58 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2008 |
CN |
200810079978.6 |
Claims
1. A cutting tool for breaking or excavating machines, comprising:
a tool body (2); a main tip (1); and a plurality of ancillary tips
(3); wherein said ancillary tips (3) comprise a plurality of
tapered cutting tips (7) or a plurality of cutting edges (8) for
breaking operation; and said ancillary tips (3) are disposed on
said tool body (2) around the main bit tip (1).
2. The cutting tool of claim 1, wherein said cutting tips (7) are
in the shape of a cone, a frustum, a semi-ellipsoid, or a spherical
dome, and the sectional area of the ancillary tip (3) becomes
smaller along its axis.
3. The cutting tool of claim 1, wherein said cutting edges (8) have
a single wedge or multiple wedges.
4. The cutting tool of claim 2, wherein said tool body (2) has a
front surface (5), and ends of said cutting tips (7) are installed
above said front surface (5).
5. The cutting tool of claim 3, wherein said tool body (2) has a
front surface (5), and ends of said cutting edges (7) are installed
above or flush with said front surface (5).
6. The cutting tool of claim 1, wherein the ratio between radius of
said ancillary tip (3) and length of said ancillary tip (3) is in
the range of between 1:1.5 and 1:5.
7. The cutting tool of claim 1, wherein between 3 and 50 ancillary
tips (3) are installed around the main tip (1).
8. The cutting tool of claim 1, wherein between 6 and 20 ancillary
tips (3) are installed around the main tip (1).
9. The cutting tool of claim 1, wherein the buried length of said
ancillary tip (3) is more than one third of the length of said main
tip (1).
10. The cutting tool of claim 1, wherein the buried length of said
ancillary tip (3) is more than one third of the maximum diameter of
said main tip (1).
11. The cutting tool of claim 1, wherein the buried portion of said
ancillary tip (3) is in the shape of a cylinder, a cone, or a
truncated cone.
12. The cutting tool of claim 1, wherein said main tip (1) is made
of a first material; said ancillary tips (3) are made of a second
material; said tool body (2) is made of a third material; said
first material is harder than said third material; and said second
material is harder than said third material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority benefits to Chinese Patent
Application No. 200810079978.6 filed Dec. 9, 2008, the contents of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to cutting bits for wall breaking,
tunneling, trenching, coal mining, and road milling machines, and
more particularly to a tool comprising more than one ancillary
cutting tip in additions to a main cutting tip.
[0004] 2. Description of the Related Art
[0005] Most popular conventional bits for breaking or excavating
machines are generally comprised of an alloy steel bit body and a
carbide alloy bit tip. The carbide alloy bit tip is welded to the
head of the bit body using soldering technology. During cutting or
breaking, the head of the cutter undergoes strong stresses and is
subjected to friction. Thus, the bit body around the carbide alloy
bit tip will progressively wear out, generally resulting in the
falling off of and catastrophic failure of the bit tip. In
underground coal mining application, sparks are created when the
tool collides with the rock. Spark must be reduced or eliminated
for safety reasons. Various technologies have been developed to
elongate the service lifetime of the tool, while trying to improve
the safety and penetrating ability thereof. Currently, a majority
of cutting bits adopts the three structures shown in FIGS. 1-3.
Still, 85 percent failures of the tools adopting the above
mentioned designs are due to a fall-off of the carbide tip,
resulting from a wear out of the steel body.
[0006] German Patent DE19821147A1 discloses a cutting tool design
(FIG. 4). The design suggests installing wear-resistant elements
around the main cutting tip. However, the design is not optimized,
and there is still much room for improvement. Although the design
reduces the wear out of the steel body to some extent, it also
shows the following weaknesses: [0007] The front area disposed
toward the working direction has to be widened to accommodate the
additional wear resistant elements. The shoulder of the bits with
such arrangement becomes wide and square, which brings about the
problem of heavy pounding and high power consumption. [0008] The
flat top surface of the claimed cylindrical wear resistant body
also increases resistance against the tool during work. In
addition, the sharp right-angled edges of the wear resistant
elements are fragile and break easily in collision with the
material to be removed. The breakage diminishes the protection
effect of the elements. [0009] The necessary length of the wear
resistant body, as well as radius to height ratio of the
cylindrical wear resistant element, have not been elucidated or
optimized. From what is illustrated in the drawings, the radius to
height ratio of the cylindrical wear resistant element is very
close to 1:1. Obviously, elements with such a configuration can
only provide only limited protection to the square part of the tool
shoulder. However, in practical working conditions, the entire
front part of the tool is often buried beneath the material to be
removed. The material to be removed will wear against the front
part of the tool, including the metal around and beneath the bottom
of the wear resistant element. In this case, the short fat wear
resistant element will rapidly lose support and fall out due to
wear out of the surrounding metal (see FIG. 13). As a result, such
configuration actually cannot provide lasting protection for the
steel tool body.
[0010] There have been other solutions adopting slimmer and longer
wear resistant elements than the above mentioned German patent.
However, these solutions can only prolong the service life to a
limited extend, while they do not give satisfying results life
respect to the problems discussed above.
SUMMARY OF THE INVENTION
[0011] Therefore, it is one objective of the present invention to
provide a bit tool for breaking or excavating machines capable of
increasing the wear resistance capability without sacrificing its
penetrating ability so as to extend the service lifetime of the
bit, as well as increase its working efficiency and safety.
[0012] To achieve the above objective, there is provided a cutting
bit for breaking or excavating machines, comprising: a tool body; a
main tip; and a plurality of ancillary tips, the ancillary tips
comprising a plurality of tapered cutting tips or a plurality of
cutting edges for breaking operation; and the ancillary tips being
disposed on the tool body around the main bit tip.
[0013] In certain embodiments of the present invention, the cutting
tips of the ancillary tips are in shape of a cone, a frustum, a
semi-ellipsoid or a dome, e.g., a spherical dome, with the
sectional area of the ancillary tips becoming smaller along their
axis.
[0014] In certain embodiments of the present invention, the cutting
edges of the ancillary tips are single-wedge or multiple-wedge.
[0015] In certain embodiments of the present invention, the ends of
the cutting tips are installed above the front surface of the tool
body.
[0016] In certain embodiments of the present invention, the ends of
the cutting edge are installed above or flush with the front
surface of the tool body.
[0017] In certain embodiments of the present invention, the ratio
between the ancillary tips radius and length is in the range of
between 1:1.5 and 1:5.
[0018] In certain embodiments of the present invention, between 3
and 50 ancillary tips are installed around the main tip.
[0019] In certain embodiments of the present invention, between 6
and 20 ancillary tips are installed around the main tip.
[0020] In certain embodiments of the present invention, the buried
length of the ancillary tip is more than one third of the length of
the main tip.
[0021] In certain embodiments of the present invention, the buried
length of the ancillary tip is more than one third of the maximum
diameter of the main tip.
[0022] In certain embodiments of the present invention, the buried
parts of the ancillary tips body are in shape of a cylinder, a
cone, or a truncated cone.
[0023] In certain embodiments of the present invention, the main
tip is made of a first material; the ancillary tips are made of a
second material; the tool body is made of a third material; and the
first material is harder than the third material; and the second
material is harder than the third material.
[0024] The present invention provides the following solution for
the buried length of the ancillary tips: [0025] a) For tools with
plug-type main tip, the buried length of the ancillary tips must be
more than one third of that of the main tip. [0026] b) For tools
with cap-type main tip, the buried length of the ancillary tips
must be more than one third of the maximum diameter of the main
tip.
[0027] The ancillary tips in the present invention constitute an
essentially different concept from the wear resistant element
described in DE19821147A1. The wear resistant elements in
DE19821147A1 are provided mainly in order to provide limited
protection to the square part of the tool shoulder. Meanwhile, the
notch formed during cutting can, to some extend, help in rotating
the tool before it falls out. However, in DE19821147A1 not much
attention was paid to the side effects brought about by the
extended shoulder area, which is necessary to accommodate the
cylindrical element. For example, the widened shoulder part causes
turbulent flow of power and pounding vibration of the machine.
[0028] In DE19821147A1 and CN 200610102129.9, a flat shoulder is
necessary to accommodate the wear resistant elements. This flat
shoulder can cause a large resistant force against the cutting tool
during its operation. The increased resistant force is harmful.
Firstly, it will overload the machine, thus causing extra impact
and vibration, which is likely to damage the machine. Secondly, it
will increase the power consumption. Thirdly, it will produce vast
easily flammable coal dust, thus reducing safety. The ancillary
tips of this invention provide ideal solution to these problems.
The tapered ancillary tips are engaged in cutting work together
with the main tip. The tapered tip cuts through the bulk material
without causing extra resistant force. Under the same working
conditions, the energy consumption of a machine equipped with the
tool of this invention is only 50% of the energy consumption of a
machine equipped with a tool described in DE19821147A1 or CN
200610102129.9.
[0029] The ancillary tips of the present invention do not have a
cylindrical or conical body. The top surface pointed to the working
direction is not flat. Rather, the ancillary tips are in the shape
of a cylinder with tapered tip, a dome, a cone, a wedge, a
mushroom, or the like. The ancillary tips not only act as passive
wear resistant member, but also are actively involved in breaking
the material to be removed.
[0030] Comparison tests were carried out between embodiments of the
present invention and those described in DE19821147A1 and CN
200610102129.9. The results of test shown below indicate that the
former have obvious advantage over the latter.
[0031] Conditions of coal mine tests:
TABLE-US-00001 Coal seam hardness f = 6. Mining depth: 0.6 m Mining
height: 4 m Shearer haulage speed: 7.7 m/min Working face length:
100 m Shearer drum speed: 28 rpm
[0032] Normally, a miner uses a traditional single tipped tool.
Because coal seams are relatively hard, the tool consumption is
large. The traditional tools cannot survive a workload of cutting
through a full working face having 100 m in length. On average, 89
bits will be consumed in an 8 hours shift. The average output is
about 2000 T per shift. 400 pieces of tools of each type were
provided to a coal miner for test.
[0033] 1. Comparison Test of Tools Described DE19821147A1:
[0034] Single tipped tools were replaced by the tools constructed
according to DE19821147A1. As soon as the shearer was started, the
monitoring system indicated the machine was working in an
overloaded condition. The tool caused great resistance due to a
widened shoulder area. The tools could not penetrate into the coal
bulk smoothly; instead, the tools stroke the bulk like hammer. The
pounding effect caused heavy coal dust and great vibration of the
shearer. The machine operator had to shut off the shearer. In order
to carry on the test, the operator had to readjust the shearer
working parameters as follows: shearer haulage speed was slowed
down to: 4.0 m/min; shearer drum speed was lowered to 19 rpm; and
the mining depth remained at 0.6 m. The test was carried on by
sacrificing the working efficiency. After the adjustment, the
operator managed to maneuver the shearer working at the limit below
overloading. Although the wear resistant elements provided some
extent of protection to the tool body, they started to suffer
breakage soon after start of operation. Some of the wear resistant
members started to fall off after the shearer worked though 95 m
along the working face. The main tips started to drop out after 120
m. Then the machine had to be stopped for tool replacement. The
test lasted 4 working shifts (32 hours). Totally, 276 pieces of
tools had to be changed, that is 69 pieces had to be changed every
working shift, on average. During the test, coal production output
was about 2100 T every working shift.
[0035] 2. Comparison Test of Tools According to CN
200610102129.9
[0036] After replacing the tools prepared according to DE19821147A1
with those described in CN 200610102129.9, the shearer operator
restored the parameter as follows: shearer haulage speed at 7.7
m/min; shearer drum speed at 28 rpm; the mining depth remained at
0.6 m. At the initial stage, the similar problem appeared as in the
previous test. The operator had to readjust the machine the same
way as in the previous test, that is, shearer haulage speed was
slowed down to: 4.0 m/min; shearer drum speed was lowered to 19
rpm; and the mining depth remained at 0.6 m. Similar to the former
test, the wear resistant elements started to suffer breakage soon
after operation. However, the elements were held strongly in
position because they were embedded deeper into the tool body. As
the front tool body around the wear resistant element has worn out,
the tool front shoulder disappeared and the tool front became
slimmer. When the shearer reached 80 m along the working face, the
operator noticed that the working load decreased due to the better
penetrating performance of tool. Then the operator restored the
parameter to normal settings as follows: shearer haulage speed at
7.7 m/min; shearer drum speed at 28 rpm; the mining depth remained
at 0.6 m. A few wear resistant members started to fall off after
the shearer fed in 160 m along the working face. Main tips started
to drop out after 200 m. Then the machine had to be stopped for
tool replacement. The test lasted 4 working shifts (32 hours).
Totally, 220 pieces of tools had to be changed, that is 55 pieces
had to be changed every working shift in average. During the test,
coal production output is about 2350 T every working shift.
[0037] Although this test gives a better result than the previous
test, ancillary tips, which can actively get engaged in cutting
operation, were adopted for further comparison test.
[0038] 3. Comparison Test of Tools According to Present
Invention:
[0039] The operator installed the tools of the present invention on
the same shearer and started test. The shearer parameters were set
as follows: shearer haulage speed at 7.7 m/min; shearer drum speed
at 28 rpm; the mining depth remained at 0.6 m. As soon as the test
started, the operator noticed the machine was working under rated
load. The operator thought it was the result of the sharper tool
contour and high penetrating capability. So, the working parameters
were set up to as follows: shearer haulage speed at 12.8 m/min;
shearer drum speed at 28 rpm; the mining depth remained at 0.6 m.
After the adjustment, the machine worked without any
overloading.
[0040] During the test, the ancillary tips performed much better
than the positive wear resistant elements in the previous tests.
They actively got involved in cutting working and provided superior
protection to the tool body. Few breakage of the ancillary tips
occurred due to impact during their service life. No ancillary tip
fell off until the shearer reached 280 m along the working face.
Main tips started to drop out only after 350 m. The test lasted 4
working shift (32 hours). Totally, 52 pieces of tools had to be
changed during the test, that is, 13 pieces had to be changed every
working shift in average. During the test, coal production output
is about 3500 T every working shift.
[0041] The following table summarizes the comparison test
results:
TABLE-US-00002 TABLE 1 Consumption Consumption per working per ton
Maintenance shift of coal output downtime Single tipped tool 89 pcs
0.045 pcs/ton 120 min/shift DE19821147A1 tool 69 pcs 0.033 pcs/ton
90 min/shift CN200610102129.9 tool 55 pcs 0.023 pcs/ton 75
min/shift Tool of present invention 13 pcs 0.004 pcs/ton 18
min/shift
[0042] As can be seen from the test result, the present invention
has vastly extended the tool service lifetime. At the same time it
remarkably improved efficiency of the cutting operation.
[0043] In this invention, ancillary tips can be made of hard
material having a lower propensity for incendiary spark production
during a cutting operation than the steel of the shank. This
arrangement reduces the contact area between material to be removed
and steel body, thus reducing the likelihood of producing a spark
during mining or excavation operations, in particular in
underground coal mining.
[0044] As described before, a wear resistant member can help to
rotate the tool during its operation. But if a member fails often,
using it has only a limited effect. Ancillary tips of this
invention stay in position for a much longer period of time and can
help to rotate the tool in operation all through its extended
service lifetime.
[0045] In underground coal mining, one of the major safety problems
is heavy coal dust, which can be trapped within the mine and is
readily ignitable. Disadvantageously, the equipment used in coal
mining can generate sparks and thus cause fires or explosion.
Therefore, it is important that all appropriate steps be taken to
minimize or eliminate the production of sparks. In this invention,
ancillary tips can be made of hard material having a lower
propensity for incendiary spark production during a cutting
operation than the steel of the shank. In addition, the tapered
ancillary tips can be installed above the shoulder surface, so that
the coal bulk can be crashed before it comes into touch with the
steel tool body. This arrangement reduce the contact area between
material to be removed and steel body, thus reduced likelihood of
producing a spark during mining or excavation operations, in
particular in underground coal mining.
[0046] Another advantage of this invention is that the concept of
ancillary tips makes it possible to realized equal-strength design
of the main tip and the cutting tool body. By adjusting the
configuration of the ancillary tip, including the tip contour, its
length and diameter, the main tip can be held for much longer time
before losing support and falling off due to wear out of the steel
tool body.
[0047] The advantages of the present invention can be summarized as
follows: [0048] 1. The ancillary tips are actively engaged in the
cutting operation; this can not only provide better protection to
the steel, but also help in reducing the cutting force. [0049] 2.
The ancillary tips ensure longer and more reliable tool rotation
throughout its service life. [0050] 3. The ancillary tips vastly
extend service life of the tool. [0051] 4. The tools in this
invention reduce likelihood of producing sparks during mining or
excavation operations, and increase safety in underground coal
mining. [0052] 5. The tools in this invention realize
equal-strength design, which helps in making full use of the
resources, especially the precious hard metals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a structural view of a conventional cutting tool
with a plug type main tip;
[0054] FIG. 2 is a structural view of a conventional cutting tool
with a mushroom type main tip;
[0055] FIG. 3 is a structural view of a conventional cutting tool
with a cap type main tip;
[0056] FIG. 4 is a structural view of a conventional cutting tool
with wear resistant elements;
[0057] FIGS. 5 and 6 are structural views of cutting tools
installed with cone-tipped ancillary tips according to one
embodiment of the present invention, wherein the ancillary cone
tips raise above the steel body;
[0058] FIG. 7 is a structural views of a bit body installed with
double-wedge ancillary tips according to one embodiment of the
present invention, wherein the cutting edges of the ancillary tips
raise above the steel body;
[0059] FIGS. 8 and 9 are structural views of a cutting tool
installed with single-wedge ancillary tips according to another
embodiment of the present invention;
[0060] FIG. 10 is a structural view of a cutting tool installed
with single-wedge ancillary tips according to another embodiment of
the present invention;
[0061] FIG. 11 is a structural view of a cutting tool installed
with cone-tipped ancillary tips according to another embodiment of
the present invention, wherein the ancillary cone tips raise above
the steel body;
[0062] FIG. 12 is a comparison drawing showing the different
protection effect between the cutting tool of the present invention
and a cutting tool according to DE19821147A1 during the initial
cutting stage of a cutting test;
[0063] FIG. 13 is a comparison drawing showing the different
protection effect between cutting tool of the present invention and
a cutting tool according to DE19821147A1 during a cutting test;
[0064] FIGS. 14-16 show other embodiments of cone-tip ancillary
tips of the present invention;
[0065] FIGS. 17 and 18 illustrate other embodiments of single-wedge
ancillary tips of the present invention; and
[0066] FIG. 19 illustrates another embodiments of double-wedge
ancillary tips of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0067] As shown in the drawings, the cutting tools of this
invention, comprise: a main carbide alloy main bit tip 1 and a bit
body 2, wherein a plurality of smaller ancillary cutting tips 3 is
installed on the bit body around the main carbide alloy bit tip 1.
The sectional area of one end of the ancillary tip 3 becomes
progressively smaller along its axis. The tapered profile of the
tip 3 forms a plurality of cutting tips 7 or cutting edges 8. The
cutting edges 8 are provided in the form of a single-wedged
cylinder or a double-wedged cylinder. In the case of cutting tool
adopting cutting tips 7, the cutting tips 7 can be positioned above
the front surface 5 of the tool, so that it can be engaged in
cutting operation from the very start. Similarly, in the case when
a tip 3 with cutting edges 8 is used, the edges 8 can be positioned
either above the front surface 5 of the tool or flush with the
surface 5. In the later case, a smoother tool profile is
achieved.
[0068] In present invention, the ratio between the radius of the
ancillary tips d and the length H is in the range of between 1:1.5
and 1:5. Between 3 and 50 pieces of ancillary tips 3 can be
installed around the main tip 1. For tools with plug-type main tip
1 as shown in FIGS. 5 and 7, the buried length of the ancillary
tips must be more than one third of that of the main tip. For tools
with cap-type main tip 1 as shown in FIGS. 9-11, the buried length
of the ancillary tips must be more than one third of the dimension
of the maximum diameter D of the main tip.
[0069] The term "buried portion", as used herein with respect to
ancillary tips, is the portion of the ancillary tip which are
disposed below the external surface of the bit body (as opposed to
protruding above the external surface of the bit body). The term
"buried length", as used herein with respect to ancillary tips, is
a length of the buried portion of the ancillary tip.
[0070] The ancillary tips in the present invention are not simply
in the form of a cylindrical or conical body. The top surface
pointed to the working direction is not flat; instead, the cutting
tip or the cutting edge is formed. The ancillary tips are in the
shape of a cylinder with tapered tip, a dome, a cone, a wedge, a
mushroom, or the like, as shown in FIGS. 14 to 19. The ancillary
tips not only act as passive wear resistant members, but also get
actively involved in breaking the material to be removed.
[0071] In DE19821147A1 and CN 200610102129.9, a flat shoulder 6 of
the cutting tool is necessary to accommodate the wear resistant
elements. This flat shoulder can cause great resistant force
against the cutting tool during its operation. This increased
resistant force is harmful, as described above.
[0072] In this invention, ancillary tips can be made of a hard
material having a lower propensity for incendiary spark production
during a cutting operation than the steel of the shank. This
arrangement reduces the contact area between material to be removed
and steel body, thus reducing the likelihood of producing a spark
during mining or excavation operations, particularly in underground
coal mining.
[0073] In certain embodiments of the present invention, the number
of the ancillary tips 3 installed on the bit body 2 around the main
bit tip 1 is in the range of between 3 and 50, and optimally, in
the range of between 6 and 20.
[0074] In present invention, there is provided a solution to the
ratio between the radius of ancillary tips d and length H, which is
in range of between 1:1.5 and 1:5, and optimally, in the range from
between 1:2 and 1:4. The specific ratio can be decided according to
other factors, such as the type of the main tip.
[0075] In choosing the length of the ancillary tips, following
solutions are provided: (a) for tools with plug-type main tip 1 as
shown in FIGS. 5 and 7, the buried length of the ancillary tips
must be more than one third of that of the main tip; in practical
application, the bottom of the ancillary tips should be arranged at
more or less the same level as main tip; and (b) for tools with
cap-type main tip 1 as shown in FIGS. 9-11, the buried length of
the ancillary tips must be more than one third of the dimension of
the maximum diameter D of the main tip. For example, if the bottom
of the plug type main tip 1 is 15 mm down into the tool front
surface 5, according to this invention, the preferable length of
the ancillary tips should be between about 10 mm and about 16 mm,
and the diameter of the ancillary tips should be preferably about 5
mm.
[0076] In the case of a tool with a cap type main tip as shown in
FIGS. 7 and 11, the length of the ancillary tips H shall be more
than 1/3 of the bottom diameter D of the main tip. More
particularly, when D is 22 mm, the length of the ancillary tips
should be more than 7 mm and the diameter of the ancillary tips
should preferably between about 3 mm and 5.5 mm. This definition
overcomes problems encountered with wear resistant element
described in DE19821147A1. While DE19821147A1 did not provide a
detailed illustration of the wear resistant element, it can be
inferred from the provided drawings that the element is fat and
short, and the main purpose thereof is to protect the square part
of the tool shoulder. Nevertheless, in practical working
conditions, the entire top part of the tool is often buried beneath
the material to be removed. The material to be removed will wear
against the thorough top part of the tool, including the metal
around and beneath the bottom of the wear resistant element. In
this case, the short fat wear resistant element will quickly lose
the support and fall out due to wear of the surround metal. Thus,
such configuration actually cannot provide lasting protection for
the steel tool body.
[0077] In practical operation, the advantage of the ancillary tips
are more obvious, because the tapered tip can help to break the
material to be removed before it contacts the steel body, so that
it further slows down the wear process. The typical wearing pattern
of the cutting tool is disclosed in promotional materials of tool
suppliers, all the disclosed tests are a good proof of the
advantages of this invention which provides slimmer and longer
ancillary tips. In one test carried out, a cutting tool of this
invention is installed with a 22 mm diameter plug tip and 8
ancillary tips. The diameter of the ancillary tips is 6 mm and its
length is 18 mm. The tool can still provide satisfactory service
even after 15 mm of ancillary tips have been consumed. The service
life was extended by 2 to 4 times. If the short fat element of
prior art had been installed, it would have fallen off soon after
the steel around it was worn out.
[0078] FIGS. 5-11 show a cutting tool installed with different
forms of ancillary tips. The ancillary tips 3 in this invention not
only resist the wear against the steel body, but their tapered
front end is also actively engaged in cutting operation. The other
advantage is that the tapered ancillary tips make it possible to
produce the cutting tool into a very sharp shape. For example, the
tapered front of the ancillary tips in FIG. 10 vastly diminishes
the square shoulder of a tool, as shown in FIG. 4, which adopts
cylindrical wear resistant element. The sharpness of such a tool is
essential. In practical operation in underground coal mine, the
blunt front of the tool shown in FIG. 4 actually collides with the
coal bulk like a hammer, as shown in the field test. The cutting
effect is greatly weakened. The tool fails to penetrate into the
coal bulk smoothly, instead, the hammering effect causes such heavy
dust and strong vibration of the machine, that operation has to be
stopped. After installing tools according to this invention to take
the place of the blunt tools, the machine started to work smoothly
with much higher feeding speed and lower vibrations. The improved
tool of this invention can boost the working efficiency, reduce
dust production, and improve the safety of the operation. In
extreme cases, where penetration ability of the tool is emphasized,
the shoulder of the tool can be totally removed using the concept
of the present invention, as shown in FIG. 10.
[0079] The ancillary tips in the present invention constitute an
essentially different concept from the wear resistant element
described in the DE19821147A1. The wear resistant elements 4 in
DE19821147A1 are provided mainly in order to provide limited
protection to the square part of the tool shoulder 6. Meanwhile the
notch formed during cutting can, to some extent, help in rotating
the tool before it falls out. However, DE19821147A1 does not pay
much attention to the side effects brought about by the extended
shoulder area, which is necessary to accommodate the cylindrical
element. For example, the widened shoulder part of the machine
causes turbulent flow of the power and pounding vibrations.
[0080] FIGS. 14 to 16 show examples of possible embodiment of the
ancillary tips 3. The dome cutting tip 7 and cone cutting tip 7
allow the ancillary tips to get involved in the cutting operation.
They are no longer passive wear resistant members. In addition,
these contours get rid of the fragile square edge of simple
cylindrical elements of prior art.
[0081] In FIGS. 17 to 19, the cutting edges 8 are made from a
cylindrical body by removing a portion of the top part of the
element. An obtuse angle cutting edge is formed. The obtuse angle
cutting edge is stronger than a right angle edge used heretofore in
terms of resisting breakage under impact. At the same time, the
sloped surface formed can help to eliminate the square, wide
shoulder of the tool. The wedged ancillary tips 3 can be installed
as shown in FIGS. 7 and 10, with its cutting edge raised a little
higher above the front surface 5 of the cutting tool. The tip can
also be installed as shown in FIGS. 8 and 9, with its slope flush
with the front surface 5 of the tool so as to realize a smother
profile. As shown in FIGS. 7-10, the tools with ancillary tips are
produced into much shaper contour, which will improve the
penetration ability of the tool.
[0082] As mentioned above, a typical wearing pattern of the cutting
tool has been described in product brochures and electronic
publications of the existing tool producers. FIGS. 12 and 13 show a
typical wear out pattern for a cutting tool. Specifically, for
comparison, each sectional view shows a typical wear out pattern of
a conventional tool in the left half and a typical wear out pattern
of a tool according to this invention in the right half of the
drawing. The outermost dotted line shows a profile of an unused
tool. The inner solid line 9 shows a typical front contour of a
heavily worn out tool before failure. A wear resistant element 4 of
invention DE19821147A1 and the ancillary tips 3 of the present
invention are put in position to give a clearer comparison of their
actual protection effect. FIG. 12 is a comparison drawing at the
initial working stage, while FIG. 13 is a drawing nearly close to
the tool failure. As can be seen from the drawings, the short fat
wear resistant element 4 will fall off soon after the steel on the
shoulder of the tool. However, the ancillary tips 3 can stay in
position for a longer period of time.
[0083] The ancillary tips 3 can be in shape of a sheet, a
rectangular parallelepiped, etc. The tapered end of the ancillary
tips can be in shape of a multihedral prism, a bi-conical
polyhedron, etc.
[0084] This invention is not to be limited to the specific
embodiments disclosed herein and modifications for various
applications and other embodiments are intended to be included
within the scope of the appended claims. While this invention has
been described in connection with particular examples thereof, the
true scope of the invention should not be so limited since other
modifications will become apparent to the skilled practitioner upon
a study of the drawings, specification, and following claims.
[0085] All publications and patent applications mentioned in this
specification are indicative of the level of skill of those skilled
in the art to which this invention pertains. All publications and
patent applications mentioned in this specification are herein
incorporated by reference to the same extent as if each individual
publication or patent application mentioned in this specification
was specifically and individually indicated to be incorporated by
reference.
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