Note: Descriptions are shown in the official language in which they were submitted.
CA 02506671 2006-03-22
MODIFIED INTERLOCKING SOLID STICK
FIELD OF INVENTION
[0001 ] The present invention relates to a modified interlocking solid
composition stick for use
with steel surfaces that are in sliding or rolling-sliding contact.
BACKGROUND OF THE INVENTION
[0002] The control of friction and wear of metal mechanical components that
are in sliding or
rolling-sliding contact is of great importance in the design and operation of
many machines and
mechanical systems. For example, many steel-rail and steel-wheel
transportation systems
including freight, passenger and mass transit systems suffer from the emission
of high noise
levels and extensive wear of mechanical components such as wheels, rails and
other rail
components such as ties. The origin of such noise emission, and the wear of
mechanical
components may be directly attributed to the frictional forces and behaviour
that are generated
between the wheel and the rail during operation of the system.
[0003] Systems are known for lubricating or otherwise modifying the
coefficient of friction
between steel surfaces in sliding contact, for example, the flanges of rail
car wheels and a track,
or fifth-wheels. One type of system uses a liquid lubricant, such as oil or
grease, to lubricate the
flanges of the rail car wheels. A problem associated with these liquid
lubrication systems,
however, is the inability to meter the amount of the liquid lubricant applied
in a controlled
manner. In attempting to overcome the above problems experienced with liquid
lubrication
systems, solid lubricant or friction modifier compositions in the form of
sticks, for example US
6,136,757, have been used to apply compositions to the flanges of rail car
wheels or to the
interface between the top of the rail and the wheel tread.
[0004] Solid stick lubricants or friction modifiers known in the art can be
interlocking,
wherein the sticks nest one on top of the other. A number of nesting sticks
are typically loaded
into an applicator (such as a spring-loaded applicator) and bracket assembly
attached to the
bogie or axle of a rail car for application of the solid stick lubricant or
friction modifier. The
sticks are generally applied directly to a passenger rail or locomotive wheel
by the spring-loaded
applicator. As the wheels turn, the solid stick rubs off onto the wheel and
leaves a dry thin film.
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This thin film transfers to the rail face. Use of interlocking solid sticks
allows for a seamless
transition from one stick to the next and ensures that no part of a stick is
wasted. It also
minimizes the risk that small residual stubs of material can fall out through
the gap between the
mouth of the applicator and the wheel.
[0005] Known interlocking solid composition sticks generally comprise a
rectangular block
having a cavity at one end and a nib attached to the other end. The internal
wall of the cavity has
approximately the same dimensions as the outer surface of the nib, such that a
nib of one stick
can snugly fit into the cavity of a second stick. Interlocking solid sticks
may be used in both
transit and freight rail systems where the stick is subjected to high
vibration and shock
conditions, which can cause failure of the stick. Either or both of the cavity
or nib can fail in the
field, however failure usually occurs at the cavity end. The nib of the stick
applies loads to the
cavity end resulting in high stresses at the two corners of the cavity and the
top surface of the
stick at the base of the nib. This failure results in loss of the composition
stick and can reduce
the effective life of application of the composition onto the steel surface
requiring frequent
replacement. The failed stick may also jam the system and cause damage.
[0006] An interlocking solid stick with increased resistance to failure
through vibration and
shock is required.
SUMMARY OF THE INVENTION
[0007] The present invention relates to a modified interlocking solid
composition stick for
applying to a surface, the surface being in sliding or rolling-sliding contact
with another surface.
[0008] It is an object of the present invention to provide a modified
interlocking solid
composition stick.
[0009] The interlocking solid stick of the present invention comprises a body
member with four
side faces, a first end and an opposed second end, and a nib member joined to
the first end of the
body member, the nib member having four side faces connected by substantially
curved side
edges, wherein the second end of the body member contains a cavity with
substantially curved
side walls dimensioned to snugly receive a nib member of a corresponding
interlocking solid
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stick and wherein a length of one side face of the nib member (nl) and a
length of the side face
of the body member (1) in the same plane has a ratio nl/l from about 0.6 to
about 0.75.
Preferably the ratio nl/l of the interlocking solid stick is from about 0.67
to about 0.73.
Furthermore, the cross-sectional shape of the nib member of the interlocking
stick of the present
invention is preferably substantially oval.
[0010] The interlocking solid stick of the present invention preferably
comprises a composition
having a Low Coefficient of Friction (LCF).
[0011 ] The present invention also provides the interlocking solid stick as
defined above where
the nib member of the interlocking stick of the present invention preferably
tapers away from
the body member at an angle of taper. The angle of taper is preferably from
about 7.0 to about
40.0 degrees.
[0012] At least one of the side edges of the body member of the interlocking
stick of the present
invention is preferably substantially curved. Preferably all of the side edges
of the body member
are substantially curved. Furthermore, at least one of the edges of the first
end of the body
member is preferably substantially curved. Preferably all of the edges of the
first end of the
body member are substantially curved.
[0013] The nib member of the interlocking solid stick of the present invention
is preferably a
substantially flattened truncated cone.
[0014] Another aspect of the present invention provides an interlocking solid
stick comprising
a body member with four side faces, a first end and an opposed second end, and
a nib member
joined to the first end of the body member, the nib member having four side
faces connected by
substantially straight side edges, wherein the second end of the body member
contains a cavity
with substantially straight side walls dimensioned to snugly receive a nib
member of a
corresponding interlocking solid stick and wherein a length of one side face
of the nib member
(nl) and a length of the side face of the body member (1) in the same plane
has a ratio nl/l from
about 0.75 to about 0.95. Preferably the ratio nl/l of the interlocking solid
stick is from about
0.8 to about 0.9; more preferably the ratio nl/l is from about 0.82 to about
0.87. Furthermore,
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the cross-sectional shape of nib the member of the interlocking stick of this
aspect of the present
invention is preferably substantially rectangular.
[0015] The interlocking solid stick of the second aspect of the present
invention preferably
comprises a composition having a Low Coefficient of Friction (LCF).
[0016] The present invention also provides the interlocking solid stick of the
second aspect of
the invention as defined above where the nib member preferably tapers away
from the body
member at an angle of taper. The angle of taper is preferably from about 7.0
to about 40.0
degrees.
[0017] At least one of the side edges of the body member of the interlocking
stick of the second
aspect of the present invention is preferably substantially curved. Preferably
all of the side edges
of the body member are substantially curved. Furthermore, at least one of the
edges of the first
end of the body member is preferably substantially curved. Preferably all of
the edges of the
first end of the body member are substantially curved.
[0018] According to a third aspect of the present invention, there is provided
an interlocking
solid stick comprising a body member with four side faces, a first end and an
opposed second
end, and a nib member with four side faces joined to the first end of the body
member, wherein
the second end of the body member contains a cavity dimensioned to snugly
receive a nib
member of a corresponding interlocking solid stick and wherein the dimensions
of the stick are
selected from the group consisting of:
(i) a width of one side face of the nib member (nw) and a width of the side
face of
the body member (w) in the same plane has a ratio nw/w from about 0.30 to
about 0.48; and
(ii) the cross-sectional area of the nib member (An) and the cross-sectional
area of
the body member (Ab) has a ratio An/Ab of about 0.19 to about 0.35.
[0019] Preferably the ratio nw/w of the interlocking solid stick is from about
0.30 to about 0.48
and the ratio An/Ab of the interlocking solid stick is from about 0.19 to
about 0.35. More
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preferably the ratio nw/w of the interlocking solid stick is from about 0.30
to about 0.45 and the
ratio An/Ab of the interlocking solid stick is from about 0.19 to about 0.30.
[0020] The side faces of the nib member of the third aspect of the
interlocking stick of the
present invention are preferably connected by substantially curved side edges.
Furthermore,
the cross-sectional shape of the nib member of the interlocking stick of this
aspect of the present
invention is preferably substantially oval.
[0021 ] The interlocking solid stick of the third aspect of the present
invention preferably
comprises a composition having a High Positive Friction (HPF), or a Very High
Positive
Friction(VHPF).
[0022] The nib member of the interlocking stick of this aspect of the present
invention
preferably tapers away from the body member at an angle of taper. The angle of
taper is
preferably from about 7.0 to about 10.0 degrees
[0023] At least one of the side edges of the body member of the interlocking
stick of the third
aspect of the present invention is preferably substantially curved. Preferably
all of the side edges
of the body member are substantially curved. Furthermore, at least one of the
edges of the first
end of the body member is preferably substantially curved. Preferably all of
the edges of the
first end of the body member are substantially curved.
[0024] The nib member of the interlocking solid stick of the third aspect of
the present
invention is preferably a substantially flattened truncated cone
[0025] This summary of the invention does not necessarily describe all
features of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] These and other features of the invention will become more apparent
from the following
description in which reference is made to the appended drawings wherein:
[0027] FIGURE 1 shows examples of prior art interlocking solid Low Coefficient
of Friction
(LCF) composition sticks. Figure 1A shows a perspective view of a prior art
LCF interlocking
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solid stick with curved nib side edges and Figure 1 B shows a perspective view
of a prior art LCF
interlocking solid stick with straight nib side edges.
[0028] FIGURE 2 shows an example of the interlocking solid stick of the first
aspect of the
present invention. Figure 2A shows a side view of the stick, Figure 2B shows
an end view of the
stick and Figure 2C shows a top view of the stick.
[0029] FIGURE 3 shows an additional example of the interlocking solid stick of
the first
aspect of the present invention. Figure 3A shows a perspective view of the
stick and Figure 3B
shows a side view of the stick.
[0030] FIGURE 4 shows a side view of an additional example of the interlocking
solid stick
of the first aspect of the present invention.
[0031 ] FIGURE 5 shows finite element analysis (FEA) output for the prior art
LCF
interlocking stick shown in Figure 1B. Figure 5A shows FEA output of the
cavity and Figure
5B shows FEA output of the nib.
[0032] FIGURE 6 shows finite element analysis (FEA) output for the
interlocking stick of the
first aspect of the present invention shown in Figure 3. Figure 6A shows FEA
output of the
cavity and Figure 6B shows FEA output of the nib.
[0033] FIGURE 7 shows a schematic view of a loading assumption of a bending
moment
applied to an interlocking solid stick. Figure 7A shows the assumed point of
highest stress on
the nib (point N) when a bending moment is applied to the nib and Figure 7B
shows the
assumed point of highest stress on the cavity (point C) when a bending moment
is applied to the
cavity.
[0034] FIGURE 8 shows a schematic view of an alternative loading assumption of
forces
applied to an interlocking solid stick. Figure 8A shows the assumed point of
highest stress on
the nib (point N) when forces are applied to the nib and Figure 8B shows the
assumed point of
highest stress on the cavity (point C) when forces are applied to the cavity.
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[0035] FIGURE 9 shows interlocking solid stick models as tested in Example 2
described
herein for optimization the design of an interlocking solid composition stick.
Figure 9A shows
a top view of Model A where the nib and the block have straight side edges and
tl = t2. Figure
9B shows a top view of Model B where the nib and the block have straight side
edges and the
ratio tl/t2 =1/w. Figure 9C shows a top view of Model C where two opposed side
edges of the
nib are semi-circular and the ratio of tl/t2 =1/w.
[0036] FIGURE 10 shows graphs of bending stress factor for the cavity and the
nib for the
interlocking solid stick models shown in Figure 9. Figure l0A shows the cavity
and nib stress
factor (1/mm3) for different lengths of tl (mm) in Model A. Figure lOB shows
the cavity and
nib stress factor (1/mm3) for different lengths of tl (mm) in Model B. Figure
10C shows the
cavity and nib stress factor (1/mm3) for different lengths of tl (mm) in Model
C.
FIGURE 11 shows a perspective view of an example of an applicator used for
application of
the interlocking solid stick of the present invention to the rail-wheel of a
passenger rail or
locomotive.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0037] The present invention relates to a modified interlocking solid
composition stick for
applying to a surface, the surface being in sliding or rolling-sliding contact
with another surface.
[0038] The interlocking solid stick of the first embodiment of the present
invention comprises
a body member with four side faces, a first end and an opposed second end, and
a nib member
joined to the first end of the body member, the nib member having four side
faces connected by
substantially curved side edges, wherein the second end of the body member
contains a cavity
with substantially curved side walls dimensioned to snugly receive a nib
member of a
corresponding interlocking solid stick and wherein a length of one side face
of the nib member
(nl) and a length of the side face of the body member (1) in the same plane
has a ratio nl/1 from
about 0.6 to about 0.75. Preferably the ratio nl/l of the interlocking solid
stick is from about 0.67
to about 0.73. Furthermore, the cross-sectional shape of nib member of the
interlocking stick
of the present invention is preferably substantially oval.
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[0039] As used herein, the term "substantially curved side edges" and
"substantially curved
side walls" it is meant that the side edges of the nib member and sidewalls of
the cavity are
substantially rounded and do not comprise sharp defined side edges. By side
edges it is meant
the edges between the four side faces of the nib member, and not other edges,
such as an edge
between one side and one end of the nib member. Without wishing to be bound by
theory,
provision of rounded or curved edges for the nib and cavity may reduce stress
on the cavity.
However, the use of rounded edges alone will not produce a solid composition
stick that
exhibits increased resistance to failure arising from vibration while in use.
[0040] As used herein, the term "snugly receive", "snugly fit" it is meant
that the nib member
of one stick is releasably received in the cavity of a corresponding stick,
such that there are no
substantial gaps between the nib and the cavity walls.
[0041 ] By the term "length of one side face" or "length of the side face" as
used herein it is
meant the distance from one side edge to the opposed side edge of one side
face. As described
herein by side edges it is meant the edges between the four side faces of the
nib member or body
member.
[0042] According to a second embodiment of the present invention, there is
provided an
interlocking solid stick comprising a body member with four side faces, a
first end and an
opposed second end, and a nib member joined to the first end of the body
member, the nib
member having four side faces connected by substantially straight side edges,
wherein the
second end of the body member contains a cavity with substantially straight
side walls
dimensioned to snugly receive a nib member of a corresponding interlocking
solid stick and
wherein a length of one side face of the nib member (nl) and a length of the
side face of the body
member (1) in the same plane has a ratio nl/l from about 0.75 to about 0.95.
Preferably the ratio
nl/l of the interlocking solid stick is from about 0.8 to about 0.9; more
preferably the ratio nl/l
is from about 0.82 to about 0.87. Furthermore, the cross-sectional shape of
nib member of the
interlocking stick of this aspect of the present invention is preferably
substantially rectangular.
[0043] As used herein, by the term "substantially straight side edges" and
"substantially straight
side walls" it is meant that the side edges of the nib member and side walls
of the cavity are not
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curved or rounded but are generally sharp defined edges. As hereinbefore
described, by side
edges it is meant the edges between the four side faces of the nib member, and
not other edges,
such as an edge between one side and one end of the nib member.
[0044] The ratio "nl/1" defines the relationship between the length of one
side face of the body
member and the length of the side face of the nib member in the same plane.
The distance from
side edge to side edge of the side face of the nib member is divided by the
distance from side
edge to side edge of the side face of the body member in the same plane, to
give the ratio nl/1.
The body member and nib member may both have two opposed side faces that are
longer than
the other two opposed side faces. In this case, it is the length of one of the
longer side faces for
both the nib member and the body member that are compared to obtain the ratio
nl/1.
[0045] The third embodiment of the present invention provides an interlocking
solid stick
comprising a body member with four side faces, a first end and an opposed
second end, and a
nib member with four side faces joined to the first end of the body member,
wherein the second
end of the body member contains a cavity dimensioned to snugly receive a nib
member of a
corresponding interlocking solid stick and wherein the dimensions of the stick
are selected from
the group consisting of:
(i) a width of one side face of the nib member (nw) and a width of the side
face of
the body member (w) in the same plane has a ratio nw/w from about 0.30 to
about 0.48; and
(ii) the cross-sectional area of the nib member (An) and the cross-sectional
area of
the body member (Ab) have a ratio An/Ab of about 0.19 to about 0.35.
[0046] By the term "width of one side face" or "width of the side face" it is
meant the distance
from one side edge to the opposed side edge of one side face. As described
herein, by side edges
it is meant the edges between the four side faces of the nib member or body
member.
[0047] The ratio "nw/w" defines the relationship between the width of one side
face of the body
member and the width of the side face of the nib member in the same plane. The
distance from
side edge to side edge of the side face of the nib member is divided by the
distance from side
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edge to side edge of the side face of the body member in the same plane, to
give the ratio nw/w.
The body member and nib member may both have two opposed side faces that are
shorter than
the other two opposed side faces. In this case, it is the width of one of the
shorter side faces for
both the nib member and the body member that are compared to obtain the ratio
nw/w.
[0048] By the term "cross-sectional area of the nib member" it is meant the
length of the nib
member (nl) x width of the nib member (nw). This applies for rectangular nibs
for example
models A and B (Figures 9A and 9B). Similarly, by the term "cross-sectional
area of the body
member" it is meant the length of the body member (1) x width of the body
member (w).
[0049] A number of interlocking solid composition sticks of the present
invention may be
nested one on top of the other and loaded into an applicator for application
of the stick
composition to a steel surface. The applicator may be provided with a spring-
loaded
mechanism against which the stick is loaded. The spring-loaded mechanism
provides pressure
against the stick during application so that the stick is available for
application to a steel surface,
such as a passenger rail or locomotive wheel. As the passenger rail or
locomotive wheels turn,
the solid stick rubs off onto the wheels like a crayon and leaves a dry thin
film. This thin film
transfers to the rail face. Non-limiting examples of straight applicators
include those disclosed
in US 4,811,818, US 5,054,582, US 5,251,724, US 5,337,860, US 2003 0101897,
and those
available from Kelsan Technologies (North Vancouver, Canada). Circular
applicators may also
be used with the solid stick of the present invention. An example of a
circular applicator
includes, but is not limited to those available from Kelsan Technologies
(North Vancouver,
Canada). The interlocking solid sticks of the present invention may be curved
for application
by a circular applicator.
[0050] Wheel squeal associated with a curved track may be caused by several
factors including
wheel flange contact with the rail gauge face, and stick-slip due to lateral
creep of the wheel
across the rail head. Without wishing to be bound by theory, lateral creep of
the wheel across
the rail head is thought to be the most probable cause of wheel squeal, while
wheel flange
contact with the rail gauge playing an important, but secondary role. Studies,
as described
herein, demonstrate that different friction control compositions may be
applied to different
faces of the rail-wheel interface to effectively control wheel squeal. For
example, a
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composition with a positive friction characteristic exhibiting an
intermediate, high or very high
coefficient of friction may be applied to the head of the rail-wheel interface
to reduce lateral
slip-stick of the wheel tread across the rail head, and a low friction control
composition
exhibiting a low coefficient of friction, may be applied to the gauge face of
the rail-wheel flange
to reduce the flanging effect of the lead axle of a train car.
[0051 ] The co-efficient of friction may be measured using any suitable devise
for example a
push tribometer, or TriboRailer (H. Harrison, T. McCanney and J. Cotter
(2000), Recent
Developments in COF Measurements at the Rail/Wheel Interface, Proceedings The
5th
International Conference on Contact Mechanics and Wear of Rail/Wheel Systems
CM 2000
(SEIKEN Symposium No. 27), pp. 30 - 34).
[0052] A composition having a Low Coefficient of Friction (LCF) can be
characterized as
having a coefficient of friction of less than about 0.2 when measured with a
push tribometer.
Preferably, under field conditions, LCF exhibits a coefficient of friction of
about 0.15 or less.
A positive friction characteristic is one in which friction between the wheel
and rail systems
increases as the creepage of the system increases. As described herein, a
composition having a
High Positive Friction (HPF) can be characterized as having a coefficient of
friction from about
0.28 to about 0.4 when measured with a push tribometer. Preferably, under
field conditions,
HPF exhibits a coefficient of friction of about 0.35. A composition having a
Very High Positive
Friction (VHPF) can be characterized as having a coefficient of friction from
about 0.45 to
about 0.55 when measured with a push tribometer. Preferably, under field
conditions, VHPF
exhibits a coefficient of friction of 0.5.
[0053] When a lubricant is included in an interlocking solid stick without a
friction modifier the
composition will typically have a low coefficient of friction. Inclusion of a
friction modifier in
an interlocking solid stick generally provides compositions with an
intermediate, high or very
high coefficient of friction.
[0054] The interlocking solid stick of the first and second embodiments of the
present invention
preferably comprises a composition having a Low Coefficient of Friction (LCF)
suitable for
application to the gauge face of a rail-wheel flange. An LCF composition is
characterized as
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having a neutral friction characteristic, in that with increased creepage, a
low coeffecient of
friction is maintained. An LCF can be characterized as having a coefficient of
friction of less
than about 0.2 when measured with a push tribometer. Preferably, under field
conditions, LCF
exhibits a coefficient of friction of about 0.15 or less.
[0055] A benefit associated with the use of the LCF solid sticks of the
present invention is the
reduction of energy consumption as measured by, for example but not limited
to, drawbar force,
associated with steel-rail and steel-wheel systems of freight and mass transit
systems. The
reduction of energy consumption has an associated decrease in operating costs.
[0056] The interlocking solid stick of the third embodiment of the present
invention preferably
comprises a composition having a High Positive Friction (HPF) or a Very High
Positive
Friction (VHPF) suitable for application to the head of the rail-wheel
interface. A positive
friction characteristic is one in which friction between the wheel and rail
systems increases as
the creepage of the system increases. HPF can be characterized as having a
coefficient of
friction from about 0.28 to about 0.4 when measured with a push tribometer.
Preferably, under
field conditions, HPF exhibits a coefficient of friction of about 0.35. VHPF
can be
characterized as having a coefficient of friction from about 0.45 to about
0.55 when measured
with a push tribometer. Preferably, under field conditions, VHPF exhibits a
coefficient of
friction of 0.5 (e.g. US 5173204; US 5,308,516; US 6,136,757; US 6,759,372).
[0057] A benefit associated with the use of either an HPF or a VHPF solid
stick of the present
invention is the reduction of lateral forces associated with steel-rail and
steel-wheel systems of
freight and mass transit systems. The reduction of lateral forces may reduce
rail wear (gauge
widening) and reduce rail replacement costs.
[0058] Figure 1 shows examples of prior art LCF interlocking solid sticks (10,
20). The sticks
(10, 20) generally comprise a rectangular shaped block (11, 21) with a tapered
nib (12, 22). The
nib (12, 22) is positioned at one end of the block (11, 21), with the opposed
end of the block (11,
21) having a cavity (13, 23) therein. The dimensions of the cavity (13, 23)
approximate the
dimensions of the nib (12, 22), such that the nib (12, 22) of one stick (10,
20) can snugly fit into
the cavity (13, 23) of a corresponding stick (10, 20). In Figure IA the nib
(12) has rounded or
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curved side edges and the cavity (13) has correspondingly curved or rounded
sidewalls. In
Figure 1B the side edges of the nib (22) are straight, sharp defined edges as
are the walls of the
cavity (23).
[0059] The interlocking solid LCF composition sticks of the prior art shown in
Figure 1 may be
applied in both transit and freight rail systems where the stick is subjected
to high vibration and
shock conditions, which can cause failure of the stick. Either or both of the
cavity or nib can fail
in the field, however failure usually occurs at the cavity end. The nib of the
stick applies loads
to the cavity end resulting in high stresses at the inside corners of the
cavity and the top of the
stick.
[0060] Referring to Figure 2, there is shown an example of an interlocking
solid stick (100) of
the first embodiment of the present invention comprising a rectangular shaped
block (110) and
an oval-shaped nib (120). The nib (120) is positioned at one end of block
(110), with the
opposed end of block (110) having a cavity (130) therein. As shown in Figure
2C, the nib (120)
has a generally oval cross-sectional shape. The nib has a flat top and rounded
side edges, and
the top of block (110) at the base of the nib (12) is flat. The cavity (130)
is also oval-shaped with
rounded walls. The internal wall of the cavity (130) has approximately the
same dimensions as
the outer surface of the nib (120), such that a nib (120) of one stick can
snugly fit into the cavity
(130) of a second stick. The height (h), width (w) and length (1) of the block
are indicated in
Figure 2, as well as the nib height (nh), nib width (nw), nib length (nl) and
radius (r) of the
semi-circular ends of the nib.
[0061 ] As hereinbefore described in more detail, the length (1) of the block
(body member) is
the distance from side edge to side edge of one side face and the nib length
(nl) is the distance
from side edge to side edge of the side face of the nib in the same plane. In
Figure 2, two
opposed side faces of the block are longer than the other two opposed side
faces. The length (1)
of the block is the length of one of the two longer side faces. Furthennore,
two opposed side
faces of the nib are longer than the other two opposed side faces. The nib
length (nl) is the
length of one of the two longer side faces.
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CA 02506671 2006-03-22
[0062] The ratio nl/1 for the interlocking solid stick of a first embodiment
of the present
invention wherein the side edges of the nib are curved, is from about 0.6 to
about 0.75, or any
ratio therebetween, for example, from about 0.62 to about 0.75, from about
0.64 to about 0.75,
from about 0.67 to about 0.73, from about 0.68 to about 0.72, from about 0.69
to about 0.71, and
any ratio therebetween, or about 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66,
0.67, 0.68, 0.69, 0.70,
0.71, 0.72, 0.73, 0.74, and 0.75 and any amount therebetween.
[0063] The ratio nl/1 for the interlocking solid stick of a second embodiment
of the present
invention wherein the side edges of the nib are substantially straight, is
from about 0.75 to about
0.95, or any ratio therebetween, for example, from about 0.76 to about 0.94,
from about 0.77 to
about 0.93, from about 0.78 to about 0.92, from about 0.79 to about 0.91, from
about 0.80 to
about 0.90, from about 0.81 to about 0.89, from about 0.82 to about 0.88, from
about 0.82 to
about 0.87, from about 0.83 to about 0.86, from about 0.84 to about 0.85, and
any ratio
therebetween, or about 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83,
0.84, 0.85, 0.86, 0.87,
0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, and 0.95 and any amount
therebetween.
[0064] As both the cavity and nib of interlocking solid sticks can fail in the
field; the cavity, the
nib, or both the nib and the cavity may be modified to ensure an optimised
composition stick
that results to reduce breakage to the cavity, nib, or both. Preferably, both
the nib and cavity are
designed in a complimentary manner.
[0065] Without wishing to be limiting in any manner, the ratio of nl/l in the
range from about
0.6 to about 0.75 has been found to be an optimal ratio for the dimensions of
the nib and cavity
when the side edges of the nib are curved or rounded, so that the maximum nib
and maximum
cavity stresses are approximately equal. From example, the ratio nl/1 of the
interlocking solid
stick where the side edges of the nib are curved maybe from about 0.67 to
about 0.73.
[0066] Without wishing to be limiting in any manner, the ratio of nl/1 in the
range from about
0.75 to about 0.95 has been found to be an optimal ratio for the dimensions of
the nib and cavity
when the side edges of the nib are straight, so that the maximum nib and
maximum cavity
stresses are approximately equal. From example, the ratio nl/l of the
interlocking stick where
the side edges of the nib are straight may be from about 0.82 to about 0.87.
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CA 02506671 2006-03-22
[0067] The length of the block (1) of the interlocking solid stick of the
present invention is
preferably from about 10 to about 70 mm, or any length therebetween, for
example from about
15 to about 70 mm, from about 20 to about 70 mm, from about 25 to about 70 mm,
from about
30 to about 70 mm, from about 32 to about 68 mm, from about 34 to about 66 mm,
from about
36 to about 64 mm, from about 38 to about 62 mm, from about 40 to about 60 mm,
from about
42 to about 58 mm, from about 44 to about 56 mm, from about 46 to about 54 mm,
from about
48 to about 52 mm, and any length therebetween, or about 10, 12, 14, 16, 18
,20 ,22 ,24 ,26 ,28,
30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66,
68, and 70 mm, or any
amount therebetween.
[0068] As shown in Figure 2B, the width of the block (w) is the distance from
side edge to side
edge of one of the two shorter opposed side faces of the block. The width of
the block (w) of the
interlocking solid stick of the present invention is preferably from about 10
to about 35 mm, or
any width therebetween, for example from about 13 to about 35 mm, from about
15 to about 35
mm, from about 17 to about 33 mm, from about 19 to about 31 mm, from about 21
to about 29
mm, from about 23 to about 27 mm, from about 24 to about 26 mm, and any width
therebetween, or about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28,
29, 30, 31, 32, 33, 34, and 35 mm, or any amount therebetween.
[0069] As shown in Figure 2A, the height of the block (h) is the distance from
the cavity end of
the block to the nib end of the block. The height of the block (h) of the
interlocking solid stick
of the present invention is preferably from about 25 to about 200 mm, or any
height
therebetween, for example from about 25 to about 175 mm, from about 25 to
about 150 mm,
from about 25 to about 125 mm, from about 25 to about 100 mm, from about 30 to
about 90
mm, from about 35 to about 80 mm, from about 40 to about 70 mm, from about 45
to about 65
mm, from about 40 to about 60 mm, and any width therebetween, or about 25, 30,
35, 40, 45,
50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160,
170, 180, 190, and 200
mm, or any amount therebetween.
[0070] As shown in Figure 2A, the nib height (nh) is the height of the nib
from the end of the
nib joined to the block to the opposed end of the nib. The nib height (nh) of
the interlocking
solid stick of the present invention is preferably from about 15 to about 30
mm, or any height
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CA 02506671 2006-03-22
therebetween, for example from about 16 to about 29 mm, from about 17 to about
28 mm, from
about 18 to about 27 mm, from about 19 to about 26 mm, from about 20 to about
25 mm, from
about 20.5 to about 24.5 mm, from about 21.0 to about 24.0 mm, from about 21.5
to about 23.5
mm, from about 22.0 to about 23.0 mm, and any height therebetween, or about
15, 16, 17, 18,
19, 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 26, 27,
28, 29, and 30 mm, or
any amount therebetween.
[0071 ] With reference to Figure 2A, tl denotes the distance between the side
edge of the block
(110) and the side edge of the nib (120). The nib length (nl) is the distance
from side edge to
side edge of one of the two longer opposed side faces of the nib. The nib
length (nl) is
represented by the following equation:
nl=1-(2xt1)
where 1 is the block length.
[0072] As shown in Figures 2B and 2C, t2 denotes the distance between the
front edge of the
block (110) and the front edge of the nib (120). The nib width (nw) is the
distance from side
edge to side edge of one of the two shorter opposed side faces of the nib. The
nib width (nw) is
represented by the following equation:
nw = w - (2 x t2)
where w is the block width.
[0073] The ratio of tl/t2 of the interlocking solid stick of the present
invention preferably
approximately equals the ratio of the block length/block width (1/w). However
variations
around this ratio may also be used. The ratio of tl/t2 of the interlocking
solid stick of the
present invention is preferably from about 1.2 to about 2.8, or any ratio
therebetween, for
example, from about 1.3 to about 2.7, from about 1.4 to about 2.6, from about
1.5 to about 2.5,
from about 1.6 to about 2.4, from about 1.7 to about 2.3, from about 1.8 to
about 2.2, from about
1.9 to about 2.1, and any ratio therebetween, or about 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 2.0,
2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, and 2.8, and any amount therebetween.
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CA 02506671 2006-03-22
[0074] For the interlocking solid stick of the present invention, tl is
preferably from about 2 to
about 13 mm, or any length therebetween, for example from about 3 to about 13
mm, from
about 4 to about 12 mm, from about 5 to about 11 mm, from about 6 to about 10
mm, from
about 7 to about 9 mm, and any length therebetween, or about 3, 4, 5, 6, 7, 8,
9, 10, 11, 12, and
13 mm, or any amount therebetween.
[0075] For the interlocking solid stick of the present invention, t2 is
preferably from about 1.5
to about 15.0 mm, or any length therebetween depending upon the size od the
stick, for example
from about 1.75 to about 4.8 mm, from about 2.0 to about 4.6 mm, from about
2.0 to about 2.5
mm from about 3.2 to about 4.4 mm, from about 3.4 to about 4.2 mm, from about
3.6 to about
4.0 mm, and any length therebetween, or about 1.5, 2.0, 2.5, 3.0, 3.1, 3.2,
3.3, 3.4, 3.5, 3.6, 3.7,
3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.8, 5Ø 6.0, 7Ø 8.0, 9.0,
10.0, 11.0, 12.0, 13.0, 14.0 and
15.0 mm, or any amount therebetween.
[0076] The ratio of nib width / block width (nw/w) for the third embodiment of
the present
invention is preferably from about 0.30 to about 0.48, or any ratio
therebetween, for example,
from about 0.30 to about 0.47, from about 0.30 to about 0.46, from about 0.30
to about 0.45,
from about 0.31 to about 0.44, from about 0.32 to about 0.43, from about 0.33
to about 0.42,
from about 0.34 to about 0.41, from about 0.35 to about 0.40, from about 0.36
to about 0.39, and
any ratio therebetween, or about 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36,
0.37, 0.38, 0.39, 0.40,
0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, and 0.48 or any amount therebetween.
[0077] The cross-sectional shape of nib member of the interlocking stick of
the first and third
embodiment of the present invention is preferably substantially oval. An
example of a nib with
an oval cross section is shown in Figure 2, where two opposed sides of the nib
member are
arched. As shown in Figure 2C, the radius (r) is the radius of the two semi-
circular ends of the
nib (120). The radius (r) is suitably from about 5.0 to about 12.0, or any
radius therebetween,
for example from about 5.5 to about 11.5, from about 6.0 to about 11.0, from
about 6.5 to about
10.5, from about 7.0 to about 10.0, from about 7.5 to about 9.5, from about
8.0 to about 9.0, and
any radius therebetween, or about 5.0, 55.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5,
9.0, 9.5, 10.0, 10.5, 11.0,
11.5, and 12.0, or any amount therebetween.
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CA 02506671 2006-03-22
[0078] The cross-sectional area of a rectangular nib (An) is the nib length
(nl) x nib width (nw).
The cross-sectional area of the block (Ab) is the length of the block (1) x
width of the block (w;
see for example Figure 9A and 9B).
[0079] The ratio of nib cross-sectional area/block cross-sectional area
(An/Ab) for the
interlocking stick of the first embodiment of the present invention wherein
the side edges of the
nib are curved is preferably from about 0.35 to about 0.50, or any ratio
therebetween, for
example from about 0.37 to about 0.48, from about 0.39 to about 0.46, from
about 0.41 to about
0.44, and any ratio therebetween, or about 0.35, 0.36, 0.37, 0.38, 0.39, 0.40,
0.41, 0.42, 0.43,
0.44, 0.45, 0.46, 0.47, 0.48, 0.49, and 0.50, or any amount therebetween.
[0080] The ratio of nib cross-sectional area/block cross-sectional area
(An/Ab) for the
interlocking stick of the second embodiment of the present invention wherein
the side edges of
the nib are straight is preferably from about 0.55 to about 0.75, or any ratio
therebetween, for
example from about 0.56 to about 0.74, from about 0.57 to about 0.73, from
about 0.58 to about
0.72, from about 0.59 to about 0.71, from about 0.60 to about 0.70, from about
0.61 to about
0.69, from about 0.62 to about 0.68, from about 0.63 to about 0.67 and any
ratio therebetween,
or about 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65,
0.66, 0.67, 0.68, 0.69,
0.70, 0.71, 0.72, 0.73, 0.74, and 0.75, or any amount therebetween.
[0081 ] The ratio of nib cross-sectional area/block cross-sectional area
(An/Ab) for the
interlocking stick of the third embodiment of the present invention is
preferably from about 0.19
to about 0.35, or any ratio therebetween, for example from about 0.19 to about
0.34, from about
0.19 to about 0.33, from about 0.19 to about 0.32, from about 0.19 to about
0.31, from about
0.19 to about 0.30, from about 0.20 to about 0.29, from about 0.21 to about
0.28, from about
0.22 to about 0.27, from about 0.23 to about 0.26, and any ratio therebetween,
or about 0.19,
0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32,
0.33, 0.34, and 0.35,
or any amount therebetween.
[0082] The dimensions of the cavity (130) are approximately equal the
dimension of the nib
(120), for example the height, length, width, radius, cross-sectional area of
the cavity (130) are
approximately equal the corresponding dimension of the nib (120).
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CA 02506671 2006-03-22
[0083] Figure 3 shows another example of an interlocking stick (200) of the
first embodiment
of the present invention. The nib (220) has semi-circular ends, such that the
cross-sectional
shape of the nib (220) is substantially oval, the nib having a flat top, and
the top of the stick (at
the base of the nib), is also flat. The nib (220) tapers away from block
(210). The cavity (230)
is corresponding shaped to approximate the dimensions of the nib (220) with
the cavity walls
tapering away from the bottom edge of the block (210). The angle of tapering
of the nib and
cavity walls is given as nib angle in Figure 3B.
[0084] The nib member of the interlocking stick of the present invention
preferably tapers away
from the body member (block) at an angle of taper. The angle of taper for the
interlocking stick
of the present invention is preferably from about 7.0 to about 40.0 degrees,
or any angle
therebetween, for example from about 7.25 to about 9.75 degrees, from about
7.5 to about 9.5
degrees, from about 7.75 to about 9.25 degrees, from about 8.0 to about 9.0
degrees, from about
8.25 to about 8.75 degrees and any angle therebetween, or about 7.0, 7.25,
7.5, 7.75, 8.0, 8.25,
8.5, 8.75, 9.0, 9.25, 9.5, 9.75, 10.0, 15, 20, 25, 30, 35 and 40 degrees, or
any amount
therebetween.
[0085] When the nib member of the interlocking stick of the present invention
tapers away
from the body member, the length of the nib member (nl), the width of the nib
member (nw),
and the cross-sectional area of the nib member (An) are all preferably taken
at the point where
the nib member joins the block member. Therefore the maximum length of the nib
member
(nl), the maximum width of the nib width (nw) and the maximum cross-sectional
area of the nib
member (An) are preferably used to calculate the ratio nl/l, the ratio nw/w
and the ratio An/Ab
for the interlocking solid stick of the present invention.
[0086] In Figure 3, the side and top edges of the block (210) are curved.
Without wishing to be
bound by theory, sharp corners and edges may result in increased stress
concentration areas in
the cavity (230). Therefore, provision of rounded edges for the nib, cavity
and block may
advantageously reduce stress on the cavity (230). However, composition sticks
that do not
comprise a curved side edge and a curved top edge may also be prepared using
the optimisations
of the nib and cavity as described herein to produce a composition stick with
improved
properties.
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CA 02506671 2006-03-22
[0087] At least one side edge of the body member (block) of the interlocking
stick of the
present invention may be substantially curved. Preferably all of the side
edges of the body
member are substantially curved. Furthermore, at least one edge of the first
end of the body
member may be substantially curved. Preferably all of the edges of the first
end of the body
member are substantially curved.
[0088] By the term "edges of the first end of the body member" it is meant the
edges between
the first end of the body member and the four body member side faces. As
described herein by
the term "curved" it is meant that the edges are substantially rounded and not
sharp.
[0089] Figure 4 shows a further example of an interlocking stick (300) of the
first embodiment
of the present invention. In this example, the nib (320) and cavity (330) both
have a
substantially flattened truncated cone shaped.
[0090] The nib member of the interlocking solid stick of the first and third
embodiment of the
present invention is preferably a substantially flattened truncated cone.
[00911 By the term "substantially flattened truncated cone" it is meant that
the cone is flattened
such that two opposed side edges of the cone are brought in towards each other
and truncated
such that the top pointed portion of the cone is not present and is replaced
by a flat top end.
[0092] The orientation of the interlocking solid sticks shown in Figures 2 to
4 are for illustrative
purposes only and should not be used to limit the scope of the present
invention in any manner.
[0093] Figure 11 shows an example of an applicator (1) for application of an
LCF interlocking
solid stick (100, 200, 300) of the present invention to the gauge face (3) of
the flange of the
rail-wheel (2) together with an applicator (5) for application of an HPF or
VHPF interlocking
solid stick (6) of the present invention to the head (7) of the wheel (2) at
the wheel-rail interface.
Both the LCF solid stick applicator (1) and the HPF and VHPF solid stick
applicator (5) are
attached to a bogie or axle of a rail car by a bracket assembly (4).
[0094] A number of LCF interlocking sticks (100, 200, 300), nested one on top
of the other, are
loaded into the LCF stick applicator (1) block end first, so that the cavity
end of the block of the
first stick contacts the gauge face (3) of the rail-wheel (2) flange. The
applicator (1) is provided
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CA 02506671 2006-03-22
with a spring-loaded mechanism (not shown) against which the sticks (100, 200,
300) are
loaded. The spring-loaded mechanism provides pressure against the sticks (100,
200, 300)
during application. As the passenger rail or locomotive wheel (2) turns, the
LCF composition
rubs off onto the gauge face (3) like a crayon and leaves a dry thin film.
[0095] Similarly, a number of HPF or VHPF yes interlocking sticks (6), nested
one on top of
the other, are loaded into the HPF or VHPF applicator (5) block end first, so
that the cavity end
of the block of the first stick contacts the head (7) of the wheel (2). The
applicator (5) is
provided with a spring-loaded mechanism (not shown) against which the sticks
(6) are loaded.
The spring-loaded mechanism provides pressure against the sticks (6) during
application. As
the passenger rail or locomotive wheel (2) turns, the HPF or VHPF composition
rubs off onto
the head (7) of the wheel (2) like a crayon and leaves a dry thin film.
[0096] Figure 11 indicates that different loads are typically applied to the
LCF solid sticks
compared to the HPF or VHPF solid sticks, because of the different angle of
application of the
sticks. Without wishing to be bound by theory, the optimal cavity and nib
dimensions of LCF
sticks will typically be different from the optimal cavity and nib dimensions
of HPF or VHPF
sticks.
[0097] The present invention will be further illustrated in the following
examples. However, it
is to be understood that these examples are for illustrative purposes only,
and should not be used
to limit the scope of the present invention in any manner.
Example 1: Optimisation of Nib Dimensions for LCF solid sticks
[0098] As described herein, both the cavity and the nib can fail in the field;
therefore the cavity
cannot be over designed causing the nib to break prematurely or vice versa.
The nib and cavity
design need to be optimized such that the stresses applied to the nib are
approximately equal the
stresses applied to the cavity so that neither is likely to fail over the
other.
Basic Loading ssumption
[0099] As a first order analysis, the assumption was made that when the
interlocking sticks are
used for application of an LCF composition to a surface, a bending moment M is
induced in the
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CA 02506671 2006-03-22
cavity by the nib end of the front stick in the system. An equal and opposite
moment M is
applied to the nib. Although the actual dynamics and boundary conditions of
the sticks in the
field were not known, the assumption that the sticks are fixed in space as
shown in Figure 7 was
made to reduce the complexity of the problem. Given an applied moment M and
working out
the moments of inertias for both the nib and cavity, the stresses at the
points of the highest stress
on the nib (point N in Figure 7A) and cavity (point C in Figure 7B) were
calculated.
Stress calculation models
[00100] The stress factor at points C and N were calculated for different
interlocking
solid LCF composition stick models as follows:
[00101] Model A is shown in Figure 9A and comprised a rectangular block and a
rectangular nib with defined sharp edges. The width (w), length (1) and height
(h) of the block
were kept constant. The nib height (nh) also remained constant. As described
herein the nib
length (nl) is represented by the equation: nl =1- (2 x tl), where 1 is the
block length; and the
nib width (nw) is represented by the equation: nw = w - (2 x t2), where w is
the block width. In
Model A the nib length (nl) and nib width (nw) were varied by increasing tl
and t2 by 0.25mm
increments, wherein tl = t2. The internal dimensions of the cavity were
approximately equal to
the external dimensions of the nib. Stress factors at points C and N were
calculated for each
0.25mm increment increase and the results are given in Table 1.
t1 & t2 Stress factor Stress factor at
w (mm) I (mm) (mm) 11 (mm4) 12 (mm ) at C(1/mm) N(1/mm3) An/Ab nl/I
24.5 49.54 1.00 248229 201455 0.000530 0.000118 0.88 0.96
24.5 49.54 1.25 248229 190829 0.000432 0.000123 0.85 0.95
24.5 49.54 1.50 248229 180608 0.000366 0.000129 0.82 0.94
24.5 49.54 1.75 248229 170783 0.000320 0.000135 0.80 0.93
24.5 49.54 2.00 248229 161344 0.000285 0.000141 0.77 0.92
24.5 49.54 2.25 248229 152280 0.000258 0.000148 0.74 0.91
24.5 49.54 2.50 248229 143583 0.000237 0.000155 0.72 0.90
24.5 49.54 2.75 248229 135243 0.000219 0.000163 0.69 0.89
24.5 49.54 3.00 248229 127249 0.000205 0.000171 0.66 0.88
24.5 49.54 3.25 248229 119594 0.000193 0.000180 0.64 0.87
24.5 49.54 3.50 248229 112266 0.000182 0.000189 0.61 0.86
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CA 02506671 2006-03-22
24.5 49.54 3.75 248229 105258 0.000173 0.000200 0.59 0.85
24.5 49.54 4.00 248229 98560 0.000165 0.000211 0.56 0.84
24.5 49.54 4.25 248229 92164 0.000159 0.000223 0.54 0.83
24.5 49.54 4.50 248229 86060 0.000153 0.000236 0.52 0.82
24.5 49.54 4.75 248229 80240 0.000147 0.000250 0.49 0.81
24.5 49.54 5.00 248229 74696 0.000143 0.000265 0.47 0.80
24.5 49.54 5.25 248229 69419 0.000139 0.000281 0.45 0.79
24.5 49.54 5.50 248229 64400 0.000135 0.000299 0.43 0.78
24.5 49.54 5.75 248229 59633 0.000131 0.000319 0.41 0.77
Table 1: Stress factor results for Model A
wherein:
Il = moment of inertia of block cross-sectional area (Ab)
12 = moment of inertia of nib cross-sectional area (An)
An/Ab = ratio of nib cross-sectional area / block cross-sectional area; and
nl/1= ratio of nib length / block length.
[00102] As tl & t2 increased, the wall of the cavity got thicker thereby
reducing the stress
at point C; meanwhile, the size of the nib decreased and increased the stress
at point N. The
stress values at point C and point N were plotted against the length of tl and
the graph is shown
in Figure 10A. The graph indicates that the point of optimization where the
stress at point C
approximately equals the stress at point N is when tl is about 3.3 mm.
[00103] Model B is shown in Figure 9B and comprised a rectangular block and a
rectangular nib with defined sharp edges. The width (w), length (1) and height
(h) of the block
were kept constant. The nib height (nh) also remained constant. In Model B the
nib length (nl)
and nib width (nw) were varied by increasing tl by 0.25mm increments, wherein
the ratio of
tl/t2 =1/w. Therefore, t2 was always smaller than tl and kept proportional to
1/w. The internal
dimensions of the cavity were approximately equal to the external dimensions
of the nib. Stress
factors at points C and N were calculated for each 0.25mm increment increase
and the results
are given in Table 2.
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CA 02506671 2006-03-22
Stress factor Stress factor
w (mm) I (mm) t1 (mm) t2 (mm) 11 (mm) 12 (mm ) at C(1/mm3) at N(1/mm3) An/Ab
ni/I
24.5 49.54 1.00 0.49 248229 210507 0.000657 0.000113 0.92 0.96
24.5 49.54 1.25 0.62 248229 201789 0.000533 0.000117 0.90 0.95
24.5 49.54 1.50 0.74 248229 193346 0.000451 0.000120 0.88 0.94
24.5 49.54 1.75 0.87 248229 185170 0.000393 0.000124 0.86 0.93
24.5 49.54 2.00 0.99 248229 177256 0.000349 0.000128 0.85 0.92
24.5 49.54 2.25 1.11 248229 169599 0.000315 0.000133 0.83 0.91
24.5 49.54 2.50 1.24 248229 162192 0.000288 0.000137 0.81 0.90
24.5 49.54 2.75 1.36 248229 155031 0.000266 0.000142 0.79 0.89
24.5 49.54 3.00 1.48 248229 148109 0.000247 0.000147 0.77 0.88
24.5 49.54 3.25 1.61 248229 141422 0.000232 0.000152 0.75 0.87
24.5 49.54 3.50 1.73 248229 134964 0.000219 0.000158 0.74 0.86
24.5 49.54 3.75 1.85 248229 128730 0.000207 0.000163 0.72 0.85
24.5 49.54 4.00 1.98 248229 122714 0.000197 0.000169 0.70 0.84
24.5 49.54 4.25 2.10 248229 116912 0.000189 0.000176 0.69 0.83
24.5 49.54 4.50 2.23 248229 111318 0.000181 0.000182 0.67 0.82
24.5 49.54 4.75 2.35 248229 105927 0.000174 0.000189 0.65 0.81
24.5 49.54 5.00 2.47 248229 100734 0.000168 0.000196 0.64 0.80
24.5 49.54 5.25 2.60 248229 95734 0.000162 0.000204 0.62 0.79
24.5 49.54 5.50 2.72 248229 90923 0.000157 0.000212 0.61 0.78
24.5 49.54 5.75 2.84 248229 86296 0.000153 0.000220 0.59 0.77
Table 2: Stress factor results for Model B
wherein:
11 = moment of inertia of block cross-sectional area (Ab)
12 = moment of inertia of nib cross-sectional area (An)
An/Ab = ratio of nib cross-sectional area / block cross-sectional area; and
nl/l = ratio of nib length / block length.
[00104] The stress values at point C and point N given in Table 2 were plotted
against the
length of tl and the graph is shown in Figure l OB. The graph indicates that
the point of
optimization where the stress at point C approximately equals the stress at
point N is when tl is
about 4.5mm.
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CA 02506671 2006-03-22
[00105] Model C is shown in Figure 9C and comprised a rectangular block and a
nib
with curved side edges. Two opposed side edges of the nib were semi-circular,
such that the
cross-sectional shape of the nib was substantially oval. The width (w), length
(1) and height (h)
of the block were kept constant. The nib height (nh) also remained constant.
In Model C the nib
length (nl) and nib width (nw) were varied by increasing tl by 0.25mm
increments, wherein the
ratio of tl/t2 =1/w. Therefore, t2 was always smaller than tl and kept
proportional to 1/w. The
radius (r) of the semi-circular ends of the nib decreased as tl increased. The
internal dimensions
of the cavity were approximately equal to the external dimensions of the nib.
Stress factors at
points C and N were calculated for each 0.25mm increment increase and the
results are given in
Table 3.
w I ti t2 Icirc 11 12 Stress factor Stress factor
(mm) (mm) (mm) (mm) r (mm) (mm) (mm4) at C (1/mm3) at N (1/mm3) An/Ab nl/I
24.5 49.54 6.00 2.97 9.28 147970.33 248229 158539 0.000276 0.000118 0.51 0.76
24.5 49.54 6.25 3.09 9.16 140243.09 248229 150260 0.000253 0.000123 0.50 0.75
24.5 49.54 6.50 3.21 9.04 132822.52 248229 142310 0.000234 0.000128 0.49 0.74
24.5 49.54 6.75 3.34 8.91 125700.41 248229 134679 0.000218 0.000134 0.47 0.73
24.5 49.54 7.00 3.46 8.79 118868.63 248229 127359 0.000205 0.000140 0.46 0.72
24.5 49.54 7.25 3.59 8.66 112319.19 248229 120342 0.000194 0.000146 0.45 0.71
24.5 49.54 7.50 3.71 8.54 106044.19 248229 113619 0.000184 0.000152 0.43 0.70
24.5 49.54 7.75 3.83 8.42 100035.87 248229 107181 0.000176 0.000159 0.42 0.69
24.5 49.54 8.00 3.96 8.29 94286.56 248229 101021 0.000168 0.000166 0.41 0.68
24.5 49.54 8.25 4.08 8.17 88788.703 248229 95131 0.000162 0.000174 0.40 0.67
24.5 49.54 8.50 4.20 8.05 83534.861 248229 89502 0.000156 0.000182 0.39 0.66
24.5 49.54 8.75 4.33 7.92 78517.704 248229 84126 0.000151 0.000190 0.37 0.65
24.5 49.54 9.00 4.45 7.80 73730.014 248229 78996 0.000146 0.000200 0.36 0.64
24.5 49.54 9.25 4.57 7.68 69164.686 248229 74105 0.000142 0.000209 0.35 0.63
24.5 49.54 9.50 4.70 7.55 64814.726 248229 69444 0.000139 0.000220 0.34 0.62
24.5 49.54 9.75 4.82 7.43 60673.252 248229 65007 0.000135 0.000231 0.33 0.61
Table 3: Stress factor results for Model C
wherein:
r = radius of semi-circular nib edges;
Icirc = moment of inertia of cross-sectional area of both semi-circular nib
ends
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CA 02506671 2006-03-22
11 = moment of inertia of block cross-sectional area (Ab)
12 = moment of inertia of nib cross-sectional area (An)
An/Ab = ratio of nib cross-sectional area / block cross-sectional area; and
nl/l = ratio of nib length / block length.
[00106] The stress values at point C and point N given in Table 3 were plotted
against the
length of tl and the graph is shown in Figure l OC. The graph indicates that
the point of
optimization where the stress at point C approximately equals the stress at
point N is when tl is
about 8.0mm.
[00107] Model C appeared to be the best optimization model as the point of
convergence
of the nib and cavity stress factors was considerably lower in Model C than
Models A and B.
For models A to C, the convergent stress factor values were 0.000186,
0.000182, and 0.000167
1 /mm3 respectively.
[00108] Model C was therefore used to calculate optimal nib dimensions for
prior art
interlocking solid LCF composition sticks. In other words, the block
dimensions (i.e. block
width (w), block length (1), and block height (h)) of known interlocking solid
sticks where
measured and entered into Model C wherein the two opposed side edges of the
nib were
semi-circular and the ratio of tl/t2 =1/w. The lengths of tl and t2, which
provided equal stress
factor values at points N and C, were calculated and are given in Table 4.
Table 4 also shows
the radius (r) of the semi-circular edge, the ratio of nib cross-sectional
area/block
cross-sectional area (An/Ab) and the ratio of nib length / block length
(nl/1).
[00109] For comparison with the results obtained for the prior art sticks
entered into
Model C, the nib and block dimensions of the prior art LCF solid stick (Rekofa
TM) shown in
Figure 1 A with curved nib edges, were entered into Table 4 and the nib and
cavity stress factors
(N & C), the ratio of An/Ab and the ratio of nl/l were calculated. These
results are given in italic
in Table 4.
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CA 02506671 2006-03-22
w I ti t2 11 12 Stress factor Stress factor
(mm) (mm) (mm) (mm) r (mm4) (mm ) at C(1/mm3) at N(1/mm3) An/Ab nl/I
Rekofa 24.41 49.39 5.05 4.80 7.41 245078 152027 0.000265 0.000129 0.44 0.80
101 RW 01
2 TM 24.50 49.54 8.05 3.98 8.27 248229 99822 0.000167 0.000167 0.41 0.68
101 RW01
0 TM 19.50 43.70 7.21 3.22 6.53 135612 54406 0.000269 0.000269 0.41 0.67
Circ III TM 28.00 39.00 5.35 3.84 10.16 138411 58228 0.000243 0.000243 0.45
0.73
MPL TM 25.40 63.50 10.57 4.23 8.47 541968 217015 0.000098 0.000098 0.41 0.67
Table 4: Prior art stick results
wherein:
r = radius of semi-circular nib edges;
I1 = moment of inertia of block cross-sectional area (Ab)
12 = moment of inertia of nib cross-sectional area (An)
An/Ab = ratio of nib cross-sectional area / block cross-sectional area; and
nl/l = ratio of nib length / block length.
[00110] Table 4 shows that the stress values for point C and point N for the
Rekofa Tm
prior art stick are not equal therefore the stick is not optimized. The stress
factor for the cavity
(C) is over twice as much as the stress factor for the nib (N), therefore the
nib has been over
designed and the cavity is the likely point of failure.
[00111] For the prior art sticks that were optimized in accordance with Model
C
(including provision of rounded nib side edges) the ratios of nl/l are in the
range 0.67 to 0.73.
The ratio of nl/l for the Rekofa TM prior art stick is 0.8, which falls
outside this range.
Example 2: Finite Element Analysis (FEA)
[00112] Finite element analysis (FEA) was performed on prior art interlocking
solid LCF
composition sticks as shown in Figures 1A and 1B and also on an example of an
optimized
interlocking solid LCF composition stick of the present invention with curved
nib side edges as
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CA 02506671 2006-03-22
shown in Figure 3. A load equivalent to 30G on a new stick was applied to the
cavity of each
model while assuming the nib to be held fixed. As the strength of the cavity
increases, the nib
tends to become weaker due to its reduction in size. FEA analysis was also
conducted on each
nib to ensure that the nib will not fail before the cavity. For the FEA
analysis the assumption
was made that when the interlocking sticks are used for application of LCF
composition to a
surface, a load is induced in the cavity by the nib end of the front stick in
the system. An equal
and opposite load is applied to the nib.
[00113] Figure 5 shows FEA output for the prior art interlocking solid LCF
composition
stick shown in Figure 1B. Figure 5A shows the FEA output of the cavity and
Figure 5B shows
the FEA output of the nib.
[00114] Figure 6 shows FEA output for an example of an interlocking solid LCF
composition stick of the present invention as shown in Figure 3. Figure 6A
shows the FEA
output of the cavity and Figure 6B shows the FEA output of the nib.
[00115] Using FEA the maximum stress in the cavity and the maximum stress on
the top
surface were calculated for both the prior art interlocking solid LCF
composition sticks and the
example of an interlocking solid LCF composition stick of the present
invention as shown in
Figure 3. The calculations are given in Table 5.
Max. Stress in Cavity (MPa) Max. Stress on Top Surface (MPa)
Prior Art Stick (FIGURE 1B) 0.64 0.47
Prior Art Stick (FIGURE 1A) 0.40 0.27
Optimized Stick (FIGURE 3) 0.33 0.13
Table 5: FEA calculations
[00116] Table 5 indicates that provision of curved or rounded nib side edges
(Figure 1B)
reduces the stresses in the cavity and on the top surface of the interlocking
solid LCF
composition stick compared to a stick with straight nib side edges (Figure 1
B). Optimizing the
design of the nib and cavity further reduces the stresses.
[00117] To confirm the indications of the FEA analysis, a number of
interlocking solid
LCF composition sticks were manufactured with the design shown in Figure 3 for
testing in the
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CA 02506671 2006-03-22
field. The sticks are loaded into an axle box system mounted on a locomotive
vehicle as shown
in Figure 11. No stick failures are observed.
[00118] The present invention has been described with regard to preferred
embodiments.
However, it will be obvious to persons skilled in the art that a number of
variations and
modifications can be made without departing from the scope of the invention as
described
herein.
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