U.S. patent application number 13/320170 was filed with the patent office on 2012-03-22 for cutting device for a mining machine.
This patent application is currently assigned to Sandvik Mining and Construction G.m.b.H. Invention is credited to Jan Akerman, Roman Gerber, Ralf Grief, Nikolaus Sifferlinger.
Application Number | 20120068528 13/320170 |
Document ID | / |
Family ID | 42236615 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120068528 |
Kind Code |
A1 |
Grief; Ralf ; et
al. |
March 22, 2012 |
CUTTING DEVICE FOR A MINING MACHINE
Abstract
In a cutting device for a mining machine, in particular a
shearer, including a tool carrier, in particular a shearer drum,
that is rotatably mounted about a rotational axis and at least one
cutting tool (1) that is fixed to the tool carrier, the cutting
tool (1) comprises a tool base body (3) and a cutting insert (1)
made of a diamond composite material or a harder material and fixed
in a receiving bore (6) of the tool base body. The cutting tool is
oriented on the tool carrier at an incident cutting angle (.beta.)
of 45-58.degree., preferably 47-54.degree., preferably 49.degree..
The tip (2) of the cutting insert (1) is substantially conically
designed, with the nose angle being 60-75.degree..
Inventors: |
Grief; Ralf; (Zeltweg,
AT) ; Gerber; Roman; (Zeltweg, AT) ; Akerman;
Jan; (Knittelfeld, AT) ; Sifferlinger; Nikolaus;
(St. Stefan, AT) |
Assignee: |
Sandvik Mining and Construction
G.m.b.H
Zeltweg
AT
|
Family ID: |
42236615 |
Appl. No.: |
13/320170 |
Filed: |
May 6, 2010 |
PCT Filed: |
May 6, 2010 |
PCT NO: |
PCT/AT2010/000155 |
371 Date: |
November 11, 2011 |
Current U.S.
Class: |
299/113 ;
299/79.1 |
Current CPC
Class: |
E21C 35/183 20130101;
E21C 35/1837 20200501 |
Class at
Publication: |
299/113 ;
299/79.1 |
International
Class: |
E21C 35/183 20060101
E21C035/183 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2009 |
AT |
A 750/2009 |
Claims
1. A cutting device for a mining machine, in particular a shearer,
including a tool carrier, in particular a shearer drum, that is
rotatably mounted about a rotational axis and at least one cutting
tool that is fixed to the tool carrier and comprises a tool base
body and a cutting insert made of a diamond composite material or a
harder material and fixed in a receiving bore of the tool base
body, characterized in that the cutting tool is oriented on the
tool carrier at an incident cutting angle (.beta.) of 45-58.degree.
and the tip (2) of the cutting insert (1) is substantially
conically designed, with the nose angle being 60-75.degree..
2. A cutting device according to claim 1, characterized in that the
tip (2) of the cutting insert (1) has a tip radius of 2-5 mm.
3. A cutting device according to claim 1, characterized in that the
cutting insert (1) comprises a cylindrical base body (3) having a
diameter of preferably 10-18 mm and carrying the conical tip (2),
wherein a transition radius of 35-45 mm is provided between the
cylindrical base body (3) and the conical tip (2).
4. A cutting device according to claim 1, characterized in that the
diameters of the cutting insert (1) and the receiving bore (6) are
dimensioned such that the cutting insert (1) is held in the
receiving bore (6) by a shrink-press fit.
5. A cutting device according to any one of claim 1, characterized
in that the cutting insert (1) is held in the receiving bore (6) by
the aid of a soldered joint, preferably by using a solder,
preferably a metal solder, introduced into the receiving bore
(6).
6. A cutting device according to claim 5, characterized in that the
cutting insert (1) comprises an electrolytic copper coating whose
thickness is preferably between 0.1 and 0.2 mm.
7. A cutting device according to claim 6, characterized in that a
copper-silver solder is chosen as said solder.
8. A cutting device according to any one of claim 1, characterized
in that the diamond composite material is comprised of diamond
crystals that are interconnected by a silicon carbide matrix.
9. A cutting device according to claim 1, wherein the incident
cutting angle (.beta.) is 47-54.degree..
10. A cutting device according to claim 1, wherein in the incident
cutting angle (.beta.) is 49.degree..
11. A cutting device according to claim 2, when the tip (2) of the
cutting insert (1) has a tip radius of 4 mm.
12. A cutting device according to claim 3, wherein the transition
radius is 40 mm.
Description
[0001] The invention relates to a cutting device for a mining
machine, in particular a shearer, including a tool carrier, in
particular a shearer drum, that is rotatably mounted about a
rotational axis and at least one cutting tool that is fixed to the
tool carrier and comprises a tool base body and a cutting insert
made of a diamond composite material or a harder material and fixed
in a receiving bore of the tool base body.
[0002] Cutting tools for mining machines are, for instance, known
in the form of so-called chisels, which are, for instance, used in
coal mining or in tunnelling. Chisels are usually disposed about
the periphery of a cutting or shearing drum, wherein, by selecting
the appropriate incident cutting angle, it will be achieved that
the usually tapering chisels, due to the rotating movement of the
cutting or shearing drum, will engage with the material to be
extracted, or the rock to be removed, in such a manner that
material, or rock, will be detached from the surface of the mine
face by cutting or scraping. Chisels, as a rule, are each comprised
of a base body and a cutting insert fixed in a receiving bore of
the base body. In order to also enable the efficient removal of
harder rock, the cutting insert is made of a particularly hard and
wear-resistant material. In this respect, tungsten carbide or a
tungsten-carbide-cobalt composite has, for instance, been proposed
as a material for the cutting insert.
[0003] A particularly wear-resistant configuration will be achieved
by using cutting tools or chisels including tips of diamonds or
polycrystalline diamond composites. The cutting insert of the
cutting tool in such cases may just be provided with an outer
coating of a diamond composite material or be completely comprised
of such a diamond composite material.
[0004] U.S. Pat. No. 5,161,627, for instance, shows and describes a
round-shaft chisel including a cutting insert that is designed to
be conical with a rounded-off tip. A layer of a polycrystalline
diamond composite is applied on the surface of the cutting insert.
The layer is about 0.04 inch (0.1 cm). A conical cutting insert
coated with a polycrystalline diamond material can also be taken
from U.S. Pat. No. 4,811,801. In respect to the subject matter of
U.S. Pat. No. 6,733,087, diamond, a polycrystalline diamond
material, a cubic boronitride binder, free carbide or combinations
thereof are cited as materials to be used for a wear-resistant
coating of a cutting insert.
[0005] Based on a new generation of diamond composite materials,
which are described in WO88/07409 A1 and WO90/01986 A1, a cutting
tool including a tapering cutting insert made of diamond crystals
that are interconnected by a silicon carbide matrix has been
proposed in EP-1283936 B1. To connect the cutting insert with the
tool base body, a metal matrix composite is indicated.
[0006] A diamond composite material has a higher hardness than any
substance naturally occurring on earth and, therefore, is ideal for
an application as a cutting insert. It is, however, also a very
expensive material. In recent times, materials harder than diamond
have also become known. Barium titanate with tin is, for instance,
said to be higher than diamond, wherein it is to be anticipated
that this material will, in future, be less expensive than diamond
because of its producibility.
[0007] In addition to the material of the cutting tool, the
respective cutting geometry is decisive for the cutting performance
to be achieved. A cutting geometry is defined by the shape of the
chisel bit, on the one hand, and by the peripheral force occurring
on the chisel bit and the rock-dependent normal force, on the other
hand. In order to optimize a cutting system, i.e. in order to
largely reduce bending forces on the cutting chisel, the cutting
geometry should be devised such that a resulting cutting force that
coincides with the cutting axis, i.e. the axis of the chisel, will
form. In this respect, it is to be taken care that the cutting
geometry, due of the wear of the cutting insert, does not change to
the effect that a resulting cutting force enclosing an angle with
the chisel axis will form, which will result in a tilting load or
tilting movement of the chisel and, in particular, the chisel base
body.
[0008] Cutting tests have demonstrated that cutting inserts coated
with diamond composite materials involve the disadvantage that the
wear layer will chip off within a very short time such that the
originally defined and optimized cutting geometry will no longer be
provided. Better results have been achieved with cutting inserts
comprised of the diamond composite materials described in the
documents WO88/07409 A1 and WO90/01986 A1, since the wear is
crucially reduced because of the improved wear properties and any
possible wear will occur uniformly such that the cutting geometry
will not be substantially changed.
[0009] These basic considerations have led to the conclusion that,
in order to maintain a constantly high cutting performance, it will
be of essential importance to use a cutting insert that is
completely made of a diamond composite material as is, for
instance, the case with the subject matter of EP-1283936 B1, while,
at the same time, selecting a cutting geometry by which tilting
moments on the cutting insert or the tool base body will be avoided
as largely as possible.
[0010] The invention, therefore, aims to provide a cutting geometry
that is devised for the described cutting inserts made of diamond
or a diamond composite material and that is optimized so as to
improve the cutting performance, wherein the service lives of the
cutting tools are, at the same time, extended at a possibly
unchanged cutting geometry.
[0011] To solve this object, the invention, departing from a
cutting device of the initially defined kind, essentially consists
in that the cutting tool is oriented on the tool carrier at an
incident cutting angle of 45-58.degree., preferably 47-54.degree.,
preferably 49.degree., and the tip of the cutting insert is
substantially conically designed, with the nose angle being
60-75.degree.. By incident cutting angle, the angle between the
axis of the cutting tool or cutting insert, respectively, and the
tangent to the circle swept by the tip of the cutting insert at a
rotation of the cutting device, in particular shearer drum, is to
be understood. The nose angle is the angle between two
diametrically opposite generatrices of the cone of the cutting
insert tip. The cutting geometry according to the invention results
in a cutting tool orientation that is optimized in regard to the
cutting performance, whereby the so-called clearance angle .gamma.,
i.e. the angle between the rock face to be worked and the cutting
tool blade, can at the same time be kept within the limits required
to achieve a high cutting performance.
[0012] Unlike with cutting inserts made of conventional hard-metal
materials, wear phenomena need hardly, or not at all, be taken into
consideration with cutting inserts made of diamond composite
materials when devising the cutting geometry, since wear will
hardly occur. By contrast, with cutting inserts made of
conventional hard-metal materials it had to be taken into account,
when devising the cutting geometry, that the rapidly occurring wear
during the cutting of hard, abrasive rock caused a flattening of
the original nose angle, and hence an enlargement of the contact
surface of the cutting insert, which in turn led to an increase in
the normal force of cutting. After a certain operating period, the
original cutting geometry was thus no longer ensured and led to a
decrease of the cutting performance. With cutting inserts made of
hard-metal materials, a smaller incident angle of, in particular,
45.degree. had to be selected from the start in order to compensate
for such phenomena.
[0013] Now, if and when a homogenous diamond cutting insert is used
according to the invention, the incident cutting angle can be
selected to be larger than with hard-metal materials. According to
the invention, the incident angle is, however, upwardly limited, on
the other hand. If the cutting angle is, in fact, selected within a
range larger than 60.degree., the direction of the resulting
cutting force will again be shifted, thus resulting in a bending
load on the cutting chisel and a tilting load on the cutting holder
in the other direction.
[0014] Particularly optimum conditions on the contact point between
the chisel tip and the rock will result, if the tip of the cutting
insert has a tip radius of 2-5 mm, preferably 4 mm, as in
correspondence with a preferred further development.
[0015] A particularly advantageous configuration will result, if
the cutting insert comprises a cylindrical base body having a
diameter of preferably 10-18 mm and carrying the conical tip,
wherein a transition radius of 35-45 mm, preferably 40 mm, is
provided between the cylindrical base body and the conical tip.
[0016] When using cutting inserts completely comprised of diamond
composite materials, the additional problem of a sufficiently
stable connection of the cutting insert with the tool base body
will arise. Due to the atomic bonds of diamonds, the latter cannot
be readily wetted and bonded with conventional soldering materials.
High soldering temperatures, moreover, bear the risk of a possible
damage to the diamonds and, in addition, can lead to a
decomposition of the diamonds on the interface with the soldering
material because of the formation of corresponding reaction
layers.
[0017] The cutting device according to the invention in this
respect is preferably further developed such that the diameters of
the cutting insert and the receiving bore are dimensioned such that
the cutting insert is held in the receiving bore by a shrink-press
fit. This further development is based on the surprising finding
that shrink-press fits in cutting inserts made of diamond composite
materials will provide sufficient retaining forces and enable a
durable and stable fixation of the cutting inserts even at
extremely high loads on the cutting tool, for instance when cutting
hard rock. In this respect, a further improvement of the fixation
will result according to a preferred further development in that
the cutting insert is additionally held in the receiving bore by
the aid of a soldered joint, preferably by using a solder,
preferably a metal solder, introduced into the receiving bore,
wherein a particularly stable connection will be achieved on the
interface between the cutting insert and the solder, if the cutting
insert comprises an electrolytic copper coating whose thickness is
preferably between 0.1 and 0.2 mm, as in correspondence with a
further preferred configuration. The solder and, in particular, the
electrolytic copper coating of the cutting insert are incipiently
melted when soldering the cutting insert in the bore of the tool
base body, wherein the cooling of the tool base body and the thus
formed shrink-press fit of the cutting insert in the receiving bore
will cause the incipiently melted solder or electrolytic copper
coating to penetrate into the surface of the cutting insert, thus
forming kind of a micro-gearing between the tool base body and the
cutting insert, which will result in an extremely strong and
durable connection between the cutting insert and the tool base
body. In this respect, a copper-silver solder is preferably chosen
as said solder.
[0018] According to a preferred further development, the diamond
composite material is comprised of diamond crystals that are
interconnected by a silicon carbide matrix. Such a diamond
composite material has become known from WO90/01986 A1. A method
for manufacturing such a diamond composite material has become
known from WO88/07409 A1.
[0019] For manufacturing a cutting tool and, in particular, fixing
a cutting insert of a diamond composite material in a receiving
bore of a tool base body, a method comprising the following method
steps can be used: [0020] a) heating of the tool base body to a
temperature of at least 750.degree. C., preferably 800-860.degree.
C., [0021] b) inserting of the cutting insert into the receiving
bore of tool base body, [0022] c) cooling of the tool base body in
air to about 600.degree. C., [0023] d) further cooling of the tool
base body with water, and, [0024] e) preferably, final tempering to
about 300.degree. C., wherein the cutting insert is fixed in the
receiving bore of the tool base body by a shrink-press seat due to
the heating and subsequent cooling of the tool base body.
[0025] According to a preferred method control, it is further
provided that electrolytic copper coating of the cutting insert is
performed prior to step a), and that a solder, particularly a
copper-silver solder, is introduced into the receiving bore between
steps (a) and (b) such that the fixation of the cutting insert in
the receiving bore is ensured both by the shrink-press seat and a
soldered joint. In a preferred manner, the solder is introduced
into the receiving bore in the form of a cartridge.
[0026] Overall, the configuration according to the invention
ensures applicability in highly abrasive rock up to 165 MPa.
[0027] Sparking during the cutting procedure can, moreover, be
completely avoided. Besides, a substantial reduction of dust
development takes place. The cutting forces can be reduced by about
50%. As opposed to hard-metal cutting inserts, a service life 30
times longer has been achieved. Further advantages, moreover,
comprise an enhanced cutting performance as well as a reduced
development of noise and heat, particularly when cutting hard
rock.
[0028] In the following, the invention will be described in more
detail by way of exemplary embodiments schematically illustrated in
the drawing.
[0029] Therein, FIG. 1 illustrates, in a side view, a cutting
insert made of a diamond composite material;
[0030] FIG. 2 depicts a cutting tool having a diamond composite
cutting insert inserted therein; and
[0031] FIG. 3 illustrates the cutting geometry of a cutting tool
according to the invention, which is fastened to a shearer
drum.
[0032] In FIG. 1, a cutting insert made of a diamond composite
material is denoted by 1, which is basically comprised of three
parts: a cutting insert tip 2, a cutting insert base body 3 and a
cutting insert end 4. The whole cutting insert is rotationally
symmetric about a central axis 10. Accordingly, the cutting insert
tip is substantially conical with its tip rounded off. The tip
radius denoted by r is between 2 and 5 mm and the nose angle
.alpha., i.e. the angle between the two diametrically opposite
generatrices of the cone, in this configuration is 71.degree..
[0033] FIG. 2 depicts a tool base body 5 in which a cutting insert
1 is fixed in a receiving bore 6. The chisel, which is comprised of
the tool base body 5 and the cutting insert 1, is rotationally
symmetric about the central axis 10. On its front end, the tool
base body comprises a widening portion 7 directly transitioning
into an apron 8. The conical widening in the front region of the
round-shaft chisel serves to stabilize the cutting tool. On the
rear end of the chisel is provided a groove 9, into which a snap
ring (not illustrated) can engage for fixation to a chisel
holder.
[0034] FIG. 3 schematically depicts a shearer drum 12 to which a
round-shaft chisel is fixed via a chisel holder 11. The apron 8
abuts on the front side of the chisel holder, thus sealing the
opening of the chisel holder against the penetration of dust and
rock. The radius R corresponds to the distance between the
rotational axis of the shearer drum and the tip of the cutting
insert engaged with the rock or mine face 13. The so-called
clearance angle .gamma. is defined as the angle of the free space
between the tangent to the circle R (rock face) and the cutting
tool blade (closest generatrix of the cutting insert tip). The
incident cutting angle .beta. is defined as the angle between the
central axis 10 of the chisel and the tangent to the circle with
the radius R on the point of engagement. It is, in fact, the circle
that is swept by the tip of the cutting insert at a revolution of
the shearer drum 12. In the illustrated case, this angle amounts to
51.degree..
* * * * *