Note: Descriptions are shown in the official language in which they were submitted.
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Device and method for grinding a profile
The invention relates to a mobile device which is
designed, in particular, as a rail-bound vehicle for
grinding a profile with a convex running surface and a
side surface defining the profile, in particular a rail
track intended for rail-bound vehicles, wherein the
device is movable in a feed direction along the profile
and has at least one grinding body which can be driven
in a rotationally movable and/or oscillating manner about
an axis of rotation and which is arranged on a support.
The invention further relates to a method for grinding
the profile in which at least one grinding body, which
is arranged on a support, is driven in a rotationally
movable or oscillating manner about an axis of rotation.
DE 69 201 811 T2 has already disclosed a mobile device
which is designed as a rail-bound vehicle and which has
a plurality of grinding wheels for grinding a rail track
with a convex running surface and a defining side
surface. The device is movable in the feed direction
along the rail track, while the grinding wheels can be
driven at the same time in a rotationally movable manner
about an axis of rotation. The grinding wheels have in
each case an inclined axis of rotation which does not
intersect the rail profile, the grinding wheels being
arranged on a frame of the rail-bound vehicle which is
displaceable transversely to the rail track and being
guided by means of rollers which bear against the rail
track. The frame serves to displace the support both in
a transverse direction and perpendicular to the
longitudinal axis of the rail. The support has at least
one support roller which is arranged in the immediate
vicinity of the axis of the corresponding grinding wheel.
These support rollers are applied against the inner face
of the rail head.
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DD 219 230 A5 describes a device for re-profiling a rail
head, wherein the axis of rotation of the grinding wheel
is inclined relative to the vertical and the horizontal
plane. The grinding wheel is guided vertically and
laterally relative to the rail on a grinding frame by
means of grinding shoes or rollers. The grinding wheel
has a planar grinding surface which is post-machined by
a pin serving for dressing the grinding wheel during the
grinding process. The convex rail head is thus only
partially machined, so that facets are generated thereby
and the rail transverse profile is provided with a
discontinuous path.
Inclined counter-rotating grinding wheels with offset
axes which do not intersect the profile are disclosed in
DE 26 12 173 Al, the grinding wheels being mounted on
tool supports which are vertically and transversely
displaceable by means of a tracking system assigned to
each rail. The grinding tools arranged on each rail side
act on the rail head upper face with the same delivery
movement, wherein the transverse displaceability of the
two frame parts relative to one another results in a
centering relative to each rail independently of one
another.a
Moreover, a grinding device is disclosed in DE 32 27 343
Al in which a tool support is arranged in a height-
adjustable manner below a chassis for each of the rails,
the tool support guiding a rotatable machining tool, in
particular a cup grinding wheel, in a defined manner via
lateral rollers which run on the profile, the axis of
rotation of the machining tool intersecting the profile
of the rail.
In a rail-bound vehicle according to EP 2 791 422 Bl,
face milling profiling wheels are arranged on a chassis
on a machining plate which is adjustable in terms of
angle relative to the rail in the vertical and transverse
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direction as a compound slide in a linear manner and
additionally about the longitudinal and vertical axis,
wherein measuring sensors sliding on the rail supply the
reference variable for the adjustment. The tracking of
the tool on the rail can take place, for example, by
means of an articulated robot.
The device disclosed in US 4 583 893 A comprises a support
element which can be displaced in a linear manner
relative to a rail and which comprises a contoured
milling cutter. A cutting depth reference guide for the
tool bearing can be applied against the upper face of the
running surface of the rail and a lateral cutting depth
reference guide can be applied against the side surface.
The two cutting depth reference guides are rotatably
mounted about a common shaft and are arranged in the feed
direction in front of the milling cutter.
Due to relatively high axle loads and high travel speeds
rails are often stressed up to the yield point of the
rail material, and thus are subjected to wear which has
a negative effect on the profile of the running surface
of the rail head.
Due to ongoing wear, the running surfaces of railroad
tracks do not remain straight but form corrugations of
different lengths over time. These corrugations are
removed by grinding the rails, wherein corrugations of
longer lengths cause certain problems for the device.
To remove the ripples and corrugations produced on the
running surface of rail tracks during operation, which
stimulates the wheel sets of the vehicles to vibrate,
disrupts the smooth running of the vehicles, causes an
excessive wear of the track superstructure and the
vehicles and can produce whistling driving noises, it is
necessary to grind the heads of the railroad tracks flat
from time to time.
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To this end, grinding devices are known, the grinding
devices having at least two cup wheels which are arranged
one behind the other in the longitudinal direction of the
rail head and which are applied against the running
surface on the front face on opposing sides of the rail
head, and which have a grinding profile corresponding to
the running surface profile.
To this end, for example, a method for machining railroad
tracks is known in which a plurality of rotating grinding
wheels is used, the grinding wheels being arranged
adjacent to one another and one behind the other, wherein
some of the grinding wheels are inclined according to the
original profile of the rail heads. Only an approximation
to the original profile of the rail heads can be achieved
by such a grinding method.
EP 0 315 704 B1 has already described a grinding machine
for re-profiling rail heads with a grinding head which
can be adjusted by a lifting device, wherein the grinding
heads can be lifted and lowered successively and offset
to one another.
An arrangement of grinding modules in a rail grinding
machine is disclosed in WO 00/58559 Al which takes into
account the radial offset in the case of narrow radii of
curvature of the rails without the presence of
constraining forces and permits the re-profiling of the
rail in a simple manner. The grinding tool has five
degrees of freedom in which each grinding module is
mounted with a frame so as to be at least approximately
vertically adjustable and is mounted on the frame so as
to be at least approximately horizontally adjustable with
a chassis.
So-called cup grinders are also known, the cup grinders
being brought into engagement on the front face with the
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rail surface and preferably being set with a tilting
angle relative to the rail surface to be ground.
In so-called offset grinding, a front surface of the
grinding tool is also used for machining the rail but is
contoured according to the rail geometry. This is made
possible by the axis of rotation not running through the
rail but with a lateral spacing thereto. The grinding
zone is thus not located in front of the axis of rotation
in the direction of the feed movement but transversely
between the axis of rotation and the rail. In order to
achieve a sufficient removal capacity, a high rotational
speed and/or high pressing force is set. In practice,
this leads to flying sparks and thus to the risk of fire.
EP 2 525 933 B1 relates to a device for material-removing
post-machining of the running surface of a rail head with
a frame guided along the rail head. The machining tools
are configured as face milling cutters which can be
driven so as to rotate in opposing directions, the axes
of rotation thereof running in a common plane and the
cutting regions thereof overlapping one another
transversely to the longitudinal direction of the rail
head.
Further devices for grinding are described in the
publications US 4,583,895 Al, DE 32 27 343 Al, DE 28 01
110 Al and EP 1 918 458 Al.
Devices for grinding a rail with a grinding belt running
parallel to the rail longitudinal axis have already been
disclosed in CH 670 667 AS, US 5,997,391 A, DE 41 19 525
Al and JP 2003-053655 A. During the grinding process, the
grinding belt is pressed against the rail to be ground
by a profiled sliding shoe, a movable pressure shoe, or
by a pressure element. Moreover, DE 20 2005 012 147 U
also relates to a device for grinding a rail with a
contact roller which is shaped according to the rail head
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and by which a grinding belt is pressed against the rail
head.
A device for grinding a rail running surface with a
grinding belt aligned parallel to the rail longitudinal
axis is also disclosed in EP 0 444 242 Al, wherein a
further belt which is configured as a pressure belt is
arranged between the pressure rollers and the grinding
belt.
So-called sliding stones are also used for profile-
grinding the heads of railroad tracks. In this case
grinding trains are used, grinding stones being arranged
on the underside thereof and being guided under pressure
over the rail surfaces. Grinding by sliding stones is
based on an oscillating translatory movement of the
grinding body along the rail during the movement of the
vehicle. By contouring the grinding bodies, which during
use also substantially maintain their shape even with
increasing wear, in principle a good surface quality and
dimensional accuracy is achieved.
A drawback of the grinding method using sliding stones
is that after a short time the sliding stone is already
adapted to the worn profile of the rail surface, so that
while a removal of ripples and corrugations in the rail
surface is achieved, it is not possible to restore the
original profile of the rail head.
In order to increase the travel speed which is achievable
with sliding stones, DE 21 32 220 A proposes to provide
a grinding means support which can be fastened to the
grinding train and which has individual guide channels
which face toward the rail surface for a relatively
coarse-grained grinding means with loose grit which is
supplied through the channels under pressure to the rail
surface and held there by the channel walls, wherein the
lower defining edges of the guide channels have a spacing
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relative to the rail surface which is smaller than the
grain size of the grinding means. As a result, only
relatively small and short chips are formed, the chips
being able to be removed in a simple manner. Heat build-
up due to plaque formation and any risk of rupture are
thus effectively avoided.
To increase the machining speed, it is disclosed in DE
32 22 208 Al, for example, to use milling cutters, the
cutting edges thereof which are distributed in a
plurality of axial groups over the periphery of the
cutter head replicating the rail head profile.
The arcuate cutting path of the individual cutting edges
of the milling cutter caused by such peripheral milling,
however, leads to a surface of the rail head which is
corrugated in the rail longitudinal direction, wherein
the surface quality is impaired with an increasing feed
rate due to the increasing distance between the material
removal of successive cutting edges.
These drawbacks are remedied by face milling cutters, as
disclosed in US 4,583,893 A for example, the face milling
cutters being arranged on one side of the rail head and
being used with a complex guide which has a freely
rotatably mounted guide wheel and a plurality of guide
rollers on the opposing rail side.
Similar drawbacks occur in a device according to EP 0 148
089 A2 in which the running surface is machined on both
sides of the longitudinal center by a milling head, which
is configured as a face milling cutter but has to be used
with a correspondingly inclined axis, since peripheral
milling cutters for the longitudinal sides of the rail
head have to be arranged upstream or downstream of this
common milling head.
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WO 02/06587 Al also describes a method for re-profiling
at least the convex part of the rail head cross-sectional
profile of a rail by peripheral milling, with more than
five milling tracks adjacent to one another in the
longitudinal direction of the rail.
Further devices for material-removing post-machining, in
particular for milling rail heads laid in the track, are
described in the publications EP 0 952 255 Bl, US
5,549,505 A, EP 0 668 398 Bl, EP 0 668 397 Bl, US
4,275,499 A and DE 32 22 208 C2.
Devices are also known in which the rail heads are
machined with a so-called rail planer. The publication
DE 28 41 506 C2 discloses such a device in which the
material-removing planer blades machine the rail with a
continuous feed movement. Flat surfaces can be generated
by means of the planer, the surfaces having only
negligible machining marks relative to milling. A
drawback with planing, primarily compared to the milling
method, is a relatively long machining time due to the
repeated passes required over the rail portion to be
machined.
In order to obtain a flat surface, EP 2 177 664 Al
proposes to move the cutting edge along a straight path
during the material-removing machining of the workpiece.
When machining a rail track by means of milling cutters,
a significant amount of material is removed but the
surface quality thus generated requires post-machining
by finishing. In contrast, a smaller amount of material
is removed by the known grinding method than by milling.
However, higher feed rates can be achieved during
grinding, so that in practice due to the respective
boundary conditions both milling and grinding methods are
used.
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Thus it is currently usual to machine the rails in one
operation with a milling cutter and to reduce the
machining marks which occur on the machined surface as a
result of the milling, such as corrugations or track
patterns, by grinding.
The object of the invention is to improve substantially
the removal capacity when grinding profiles, at the same
time with high demands for the surface quality and the
dimensional accuracy of the profile thus machined.
This object is achieved according to the invention by a
device for grinding a rail track according to the
features of claim 1. The further embodiment of the
invention can be found in the dependent claims.
According to the invention, therefore, a device for
grinding is provided, in which the axis of rotation can
be positioned to be inclined with an orientation relative
to the vertical plane and/or relative to the horizontal
plane, and the axis of rotation does not run through the
profile, and in which the support is arranged in a
transverse plane on the device, in particular, so as to
be movable in a translatory manner relative to the
transverse plane to the feed direction, and the support
is kinematically coupled to at least one contact element
which can be applied non-positively against the profile
as lateral copying and/or vertical copying, by which the
support with the grinding body is automatically aligned
in the transverse plane relative to the profile and
relative to the device.
The invention is based on the recognition that it is
possible to maintain exceptionally small tolerances when
machining the profiles by means of the mobile device
designed as a rail-bound vehicle, by the support of the
grinding body being movable both relative to the profile
and relative to the mobile device and being automatically
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aligned during use of the device. At the same time, the
working result is achieved irrespective of wear occurring
on the grinding body, which thus does not have a negative
effect on the quality of the surface machining.
The automatic alignment could take place on the basis of
contactless distance measurements. According to the
invention, the device is provided with a contact element,
for example a sliding element, such as a slide, or an
arrangement with at least one roller or a wheel. As a
result of contact-based lateral and/or vertical copying,
the support of the grinding body is moved in its guide
in the transverse plane and thus adapted to the grinding
wheel wear. However, the contact element also ensures a
compensation of the displacement in the direction of the
outside of the curve, which occurs in practice due to the
forced guidance of the mobile device during cornering.
Such a forcibly guided lateral copying is preferably non-
positively applied against the internal or medial side
surface facing the respective other rail track.
It has already been shown to be particularly expedient
if the support bears at the same time a paired arrangement
of a plurality of grinding bodies which are arranged in
a common transverse plane of the device, such that the
grinding bodies can be aligned together both relative to
the parallel rail tracks and relative to one another.
Since a separate contact element is assigned to each
grinding body, it is also possible to compensate for
inaccuracies of the profile along its main extent or
deviations from the ideal parallel alignment of the rail
tracks. To this end, the contact element is pretensioned
with a predetermined, in particular adjustable,
pretensioning force relative to the profile, in
particular the rail track. As a result, the grinding
bodies are spread apart from one another at the same
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time, so that in particular no additional abutment is
required for receiving the bearing force.
For the height adjustment, a further contact element
which can be designed as a roller is pretensioned from
above against the running surface of the profile or the
rail track, in order to achieve in this manner an
automatic adaptation in the vertical direction. However,
the contact element can also have two bearing surfaces
in order to permit the horizontal alignment relative to
the side surface and the vertical alignment relative to
the running surface at the same time with a single contact
element.
It has already been shown that the device thus equipped
is independent of the movement of the rail-bound vehicle
during operation, due to the vertical and horizontal
guidance of the supports and the grinding bodies
connected thereto, so that for the first time a working
platform does not form the reference for the adjustment
of the tools, as in the prior art, but directly the
profile itself to be machined, which clearly leads to
substantially fewer errors.
It has been shown that the machining quality can be
further improved by an arrangement of the grinding bodies
in a common transverse plane of the device or the cross-
sectional plane of the profile with the contact element
assigned thereto. As a result, the position of the
contact element as lateral copying is directly related
to the center of rotation of the grinding body, which is
designed in particular as a cup grinding wheel, so that
no lateral offset occurs even in the case of cornering.
Rather, the contour of the grinding body always remains
in congruence with the profile.
It is particularly preferred that the axis of rotation
of the grinding body is oriented with a lateral or medial
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offset in the cross-sectional plane of the profile such
that this axis of rotation does not intersect the
profile. A negative shape of the profile is formed in the
grinding body by a setting angle and an eccentric
position of the cup grinding wheel. A contact surface
which is of variable length in terms of its contact length
is thus produced over the surface of the profile, which
is distributed over the rail transverse profile. Due to
this contact surface which is lengthened in the radius
region of the profile, the grinding tool is automatically
stabilized in the longitudinal direction which leads to
an optimal flattening of the surface, in particular the
residual corrugations of the profile.
It has also already been shown to be particularly
expedient if a plurality of grinding bodies are arranged
on one respective support one behind the other in the
feed direction, wherein the axes of rotation of the
grinding bodies are not aligned in parallel but inclined
relative to one another. Different setting angles of the
grinding bodies generate different grinding regions on
the surface of the profile. The entire transverse profile
can be ground with two grinding bodies one behind the
other at different angles, by different grinding bodies
being used for machining different surface portions
(tracks) with different inclination angles running
parallel to one another in the direction of the main
extent of the profile.
The grinding bodies can be operated in synchronism or
counter-rotating, so that the rotational direction of the
grinding bodies is identical in the feed direction and
counter to the feed direction. As a result, with the
material removal during the grinding process, a
tangential removal stream is produced which always acts
in the same direction irrespective of the direction of
movement of the device by the rotating grinding body.
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Since the rotational axes of the grinding bodies are not
arranged parallel to the cross-sectional plane of the
profile to be machined, but are oriented so as to be
inclined in the feed direction or counter thereto, the
larger surface component of the contact surface between
the grinding body and the profile is located in front of
or behind the plane of the axis of rotation. In this
manner, a trailing or leading machining relative to the
feed direction is implemented in a simple manner relative
to a cross-sectional plane of the profile.
In this case, a trailing or following arrangement for
hobbing or surface milling can also be implemented for
smoothing the residual corrugations.
Different positions of the grinding body are conceivable.
With a central positioning of the grinding body, i.e. if
the axis of rotation runs through the profile, in
particular the central longitudinal axis thereof,
straight facets are produced, which has already proved
expedient when rough grinding. A combination of a
plurality of grinding bodies can also be expediently
used, at least one axis of rotation thereof passing
through the profile and at least one further axis of
rotation having a lateral offset to the profile, wherein
this is not oriented in a cutting manner.
With a combined used of the grinding bodies with at least
one milling cutter, the milled rail transverse profile
can be produced with a partial oversize so that an exact
rail transverse profile is produced after grinding. This
occurs when, after the milling process, the partial
oversize protrudes in the region in which the grinding
tool also corresponds in its normal (pressing direction
= greatest grinding removal).
When carrying out the grinding process, the grinding
bodies bear relative to the profile in a force-dependent
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manner, in particular with an adjustable or limitable
pressing force or pretensioning force. The control of the
pressing force or pretensioning force is carried out
expediently by considering the relevant parameters of the
profile and the surrounding conditions, wherein the
detected torque of the grinding body and the feed rate
of the device can also be included.
In order to be able to compensate for a rapid and reliable
adaptation to different profiles, in particular rail
tracks or variable conditions of use, and associated
therewith different relative positions and orientations
between the profile and the device, the support or the
axis of rotation can be adjusted in a path-controlled
manner.
In a further embodiment of the invention, which is also
particularly promising, for introducing a superimposed
movement during the rotating and/or oscillating movement,
the support is designed to be movable in a reversable
translatory manner in a plane parallel to the main extent
of the profile or the rail track. Since at least one of
the grinding bodies, which is designed as a grinding
wheel, is moved at the same time by a reversing
translatory movement of the support provided with the
grinding body in a plane parallel to the main extent of
the rail track, during the rotating or oscillating
movement to and fro along a specific circular path, the
grinding means is repeatedly engaged in each rail
portion. As a result, a rail portion is not only reached
once by the grinding zone of the grinding body but passed
over repeatedly by the grinding body and a corresponding
high removal capacity is achieved. Surface qualities
which are comparable with a sliding stone method can be
implemented, wherein in particular corrugations in the
rail surface can be reliably eliminated.
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The shape of the rail track to be machined is not
determined by the geometry of the grinding body but by
the setting angle thereof, so that it does not lead to a
deviation in size in the context of a rotating or
oscillating movement. A combination of a plurality of
grinding bodies known per se has already proved expedient
here.
It is particularly advantageous if the axis of rotation
of at least one grinding body encloses an acute angle
with the longitudinal axis of the profile. The reference
shape of the grinding process to be generated is
accordingly achieved by a plurality of grinding bodies,
which together produce the desired profile. The axes of
rotation of different grinding bodies enclose an acute
angle relative to one another. Moreover, the setting
angle of at least one grinding body can be designed to
be adjustable, wherein preferably the angle of
inclination of the respective axis of rotation is also
designed to be adjustable during the operation of the
device.
Moreover, the setting angle can also be selected
according to the desired profile clearance, in order to
be able to achieve optimal grinding results even under
spatially restricted operating conditions.
According to a further particularly expedient embodiment
of the invention, if the axis of rotation of the grinding
body encloses an acute angle with the transverse plane
of the rail track, a rapid transport of the material
removed from the machining zone is achieved in a simple
manner, so that the removed material cannot collect in
the grinding gap.
Naturally, the grinding body has a rotationally
symmetrical shape. Particularly advantageous is a variant
of the grinding body which has at least in some portions
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a concave shape of the peripheral surface or the front
surface, wherein the concave grinding surface is adapted
to the geometry of the profile of the rail track.
In a preferred embodiment of the invention, the grinding
body and/or the support has at least one electrical
and/or hydraulic drive in order to provide the desired
drive power and also to undertake a rapid change in the
speed of the support or the grinding body by a
deceleration or acceleration, and as a function of the
respective operating conditions. The drive can be
arranged centrally on the device or decentrally on the
support, wherein a plurality of grinding bodies can be
supplied with the required drive power by a common drive.
A further embodiment of the invention, which is also
promising, is also achieved by the rotational or
oscillating movement of the at least one grinding body,
on the one hand, and the translatory movement of the
support, on the other hand, taking place in a
synchronized manner by a kinematic coupling. As a result,
the rotational or oscillating movement is adapted to the
movement sequence of the support, which due to the
reversing translatory movement is decelerated in a
cyclical manner at the reversal points. The change
associated therewith in the relative movement of the
grinding body relative to the rail track is compensated
by the kinematic coupling. A superimposition of a
different drive power of the grinding body can thus also
be implemented in a simple manner by a further drive
power provided by means of the kinematic coupling. For
example toothed racks, connecting rods, coupling rods or
the like can be used for the power transmission. In
practice, an additional speed component of the rotation
or oscillation of the grinding wheel rotation is
superimposed on the at least one grinding body, primarily
in a direction of movement of the support opposing the
direction of travel. The lateral copying and the guide
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are pretensioned relative to the profile by a
pretensioning force, while the grinding body, for
example, can be lifted away on one side.
In a further particularly advantageous modification of
the invention, the drive power of the support is used as
the sole drive power for the rotation of the grinding
tool, by using the coupling.
In a further embodiment of the invention, which is also
particularly promising, the synchronized rotational or
oscillating movement of the at least one grinding body,
on the one hand, and the translatory movement of the
support, on the other hand, takes place by a hydraulic,
pneumatic or electromechanical coupling. The additional
or sole drive power for the at least one grinding body
is produced by the cyclical pressure increase or pressure
reduction of the hydraulic or pneumatic pressure of the
drive of the support, which is effective in the regions
of the reversal points of the reversing movement. A
distinction can also be made of the drive power provided
in the rear and front reversal points. In this manner,
for example, the relative speed of the grinding body
which is moved in a rotational or oscillating manner, and
also translatory manner, by means of the support relative
to the rail track can be kept constant within
predetermined limit values. To this end, a pressure
accumulator can also be provided in order to be able to
provide a drive power which is as uniform as possible.
The object according to the invention is also achieved
by a method for grinding a profile, in particular a rail
track intended for rail-bound vehicles, in which at least
one grinding body which is arranged on a support is driven
in a rotationally movable or oscillating manner about an
axis of rotation, in that during the rotational or
oscillating movement of at least one grinding body, the
support bearing the grinding body is driven at least
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temporarily in a reversing translatory manner for
introducing a superimposed movement parallel to a
longitudinal axis of the profile. Thus a repeated
engagement of the grinding body takes place in each
profile portion, in which the supports are moved to and
fro in the longitudinal direction of the rail track,
while the grinding body ensures the desired material
removal by its rotational or oscillating movement. The
axis of rotation of the grinding body is arranged, in
particular, so as to be inclined at an acute angle
relative to the plane of the surface portion to be
machined and/or to the cross-sectional plane of the rail
track. As a result, due to the inclined orientation of
the axis of rotation of the grinding body, the removed
material is transported away medially or laterally from
the rail track and thus does not collect in an undesirable
manner in the region of the grinding gap. Preferably, the
axis of rotation is inclined such that the lateral axis
portion is located in front of the medial axis portion
relative to the rail track in the direction of travel.
The medial side denotes the side facing the adjacent rail
track and the lateral side denotes the side facing away
from the adjacent rail track.
In comparison with the grinding methods known from the
prior art with rotating grinding tools, the rotational
speed can thus be reduced, whereby flying sparks are also
significantly reduced during operation, while the
relative speed can still be increased between the rail
surface of the rail track and the grinding body.
Since the translatory movement of the grinding body
follows a sinusoidal speed in the rail plane, the
rotation is preferably controlled such that the
rotational speed of the grinding body is increased in the
region of the reversal points of the translatory
reversing movement of the support. In particular, the
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rotational speed of the rotating movement of the grinding
body is adapted reciprocally to the translatory movement.
Since the translatory movement is additionally
superimposed by the traveling movement of the device
along the rail, the translatory speed is added with the
movement in the direction of travel and the translatory
speed is subtracted with the movement counter to the
direction of travel. The absolute translatory speed of
the grinding body is not zero in the region of the
reversal points during operation. Rather, the speed of
the support between the reversal points in the direction
of travel is greater than counter to the direction of
travel. To compensate, the rotational speed is further
reduced in the direction of travel but increased counter
to the direction of travel.
A particularly practical development of the method
according to the invention is also achieved in that the
rotational speed or the frequency of the rotating or
oscillating movement of at least one grinding body in the
region of the reversal points of the translatory
reversing movement is changed, in particular is
increased, relative to a region between the reversal
points, in order to compensate for the deceleration of
the translatory movement of the support correspondingly
by an increase in the rotational or oscillating movement.
In particular, the change in the rotational speed or the
frequency of the rotating or oscillating movement is
adjusted in a reciprocal manner to the reversing
translatory movement.
In a mobile device, in particular designed as a rail-
bound vehicle, it has proved particularly expedient if
the rotational or the oscillating movement is adjusted
to a lower rotational speed or frequency in the direction
of travel than counter to the direction of travel. This
compensates for the intrinsic movement of the mobile
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device along the rail track which is superimposed on the
translatory movement of the support and, depending on the
movement phase of the support, accordingly increased or
reduced by this amount. In addition to this fundamental
difference in the rotational or oscillating movement in
the direction of travel and counter to the direction of
travel, naturally the deceleration and acceleration
occurring in the region of the reversal points of the
reversing movement of the support can be compensated in
this manner.
In a particularly simple variant of the method, the
rotational or oscillating movement of the at least one
grinding body, on the one hand, and the translatory
movement of the support, on the other hand, can be
introduced kinematically coupled together in order to
keep the control effort low.
In order to achieve an acceleration of the rotational or
oscillating movement of the grinding body, with a
deceleration of the support, the support can also be
connected to an energy storage device, for example a
pressure vessel, which is filled in the region of the
maximum speed of the support. In the region of the
reversal points of the movement of the support, the
stored energy can be taken and used to increase the
rotational speed or frequency of the grinding bodies.
It has also proved particularly expedient if the grinding
body is brought into contact with the surface of the rail
track with a grinding surface on the peripheral side or
front face, in order to be able to machine a large portion
of the rail head by a corresponding contouring of the
grinding body, and to ensure a high machining accuracy.
An offset grinding method is preferably used in
combination with milling.
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The invention permits various embodiments. For further
clarification of its main principle, one embodiment
thereof is shown in the drawing and is described
hereinafter. This drawing shows in a schematic view, in
fig. 1 a cross section through a profile and a
grinding body arranged inclined at an angle of
350;
fig. 2 a further view of the profile with a grinding
body arranged inclined at an angle of 5 ;
fig. 3 a front view of a support according to the
invention of a device according to the
invention with the grinding body shown in
figure 1;
fig. 4 a front view of the support with a grinding
body arranged inclined at an angle of 5 ;
fig. 5 a front view of the support during the
adjustment of the position and orientation;
fig. 6 a side view of the support during the
adjustment of the position and orientation;
fig. 7 an enlarged cross section through the profile
according to figure 1;
fig. 8 two grinding bodies with axes of rotation
inclined toward one another in a front view.
A device 1 designed as a rail-bound vehicle for grinding
a profile 2 which is designed as a rail track, in
particular for grinding a running surface 3 by means of
a grinding body 4, is explained in more detail
hereinafter with reference to a schematic view in figures
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1 to 8. The device 1 which is shown in this variant is
designed specifically for machining rail tracks which run
parallel, as profiles 2 to be ground.
For improved understanding of the invention, parallel
rail tracks and the grinding bodies 4 which are assigned
thereto and arranged mirror symmetrically and which are
arranged together on the device 1, are shown in figure 3
by way of indication, as is explained hereinafter in
further detail.
For the grinding process of the profile 2, the grinding
bodies 4 are provided with a grinding surface 5 on the
front face, with bonded grain and a geometrically
undefined cutting edge. As can be identified, in
particular, in figures 1 and 2, different inclination
angles a; p between 5 and 90 of an axis of rotation 6
of the grinding bodies 4 can be provided relative to a
central longitudinal plane 7 of the profile 2.
An essential aspect of the invention is that the axis of
rotation 6, as can be identified, is not only arranged
inclined relative to the vertical and the horizontal but
is additionally oriented eccentrically with an offset,
such that the axis of rotation 6 of the grinding body 4
does not intersect the profile 2. Thus only a circular
sector or a circular segment with a center angle of less
than 180 is in contact with the profile 2. In contrast
to a centered orientation of the axis of rotation 6
directed toward the profile 2, a concave grinding surface
5 of the grinding body 4 can be implemented in the radial
direction relative to the axis of rotation 6. This
concave shape 8 can be already introduced into the
grinding body 4 in the production process, which in use
is optimally adapted to the profile 2, so that the
occurring wear cannot lead to an undesired shape
deviation.
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It should be emphasized that, due to this offset or
eccentric positioning and the orientation inclined at the
angle a, p of the axis of rotation 6 of the grinding body
4, not only is an optimal concave shape obtained for the
first time but also the width b, B of the surface portion
to be machined by the grinding body 4 and running in the
cross sectional plane of the profile 2 is substantially
larger than is possible by the tools known from the prior
art and the resulting facets. Rather, it has been already
shown that an optimal surface machining of the profile 2
according to the invention requires no more than two
grinding bodies 4 arranged one behind the other in the
feed direction, and in some cases even only a single
grinding body 4 is required, as indicated in figure 1 in
combination with figure 7.
In practice, the grinding surface 5 engages sufficiently
far around the convex surface portion 9 between the
running surface 3 and an inner side surface 10, which
defines the profile 2 medially, that it permits a
machining quality regarding dimensional accuracy and
shape accuracy which was previously unachievable.
Each of the grinding bodies 4 is arranged on a support
11 which, to compensate for wear, permits an axial
delivery of the grinding body 4 parallel to the axis of
rotation 6 relative to the profile 2 and also an
adjustment of desired inclination angle a, p which is
optimal for the respective conditions of use.
The support 11 in turn is movable by means of a guide 12
in a translatory manner relative thereto in a plane
parallel to the cross-sectional plane of the profile 2
or in the transverse plane to the feed direction of the
device 1. As a result, during operation it is possible
to maintain a constant position of the grinding body 4
which is always optimal relative to the profile 2, even
when the device as a mobile rail-bound vehicle is in turn
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subjected to a movement relative to the profile 2, as is
the case in principle with cornering. In such cases, the
support 11 is moved to the side, wherein two supports 11
arranged in a common transverse plane are kinematically
coupled together for the common adjustment of the
respective grinding body 4, and thereby carry out a
common movement.
The control of this lateral medial movement or lateral
movement of the supports 11 is achieved by the support
11 being connected to at least one contact element 13,
which can be applied non-positively against the profile
2, the support 11 being automatically aligned thereby
with the grinding body 4 in the transverse plane relative
to the profile 2 and relative to the device 1. To this
end, the contact element 13, which is provided as a slide
with a sliding surface, can be applied against the side
surface 10 of the profile 2, while for detecting the
height a further contact element 14 which is designed as
a roller is supported from above against the running
surface 3 so that the two contact elements 13, 14 together
form a reference for the alignment of the grinding body
4, and the support 11 is automatically aligned relative
to the profile 2 and relative to the device 1 due to an
adjustable pretensioning force F in the transverse plane.
As shown by way of indication in figure 8, a plurality
of, for example also different, grinding bodies 4 with
differently inclined axes of rotation 6 can be arranged
one behind the other on one respective support 11 in the
feed direction of the device 1, wherein the axes of
rotation 6 of the grinding bodies 4 enclose an acute
angle p. The grinding bodies 4 permit the machining of
different surface portions 9 of the convex or planar
surface as parallel tracks.
According to the invention, a superimposed reversing
movement of the grinding body 4, which can be driven in
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a rotationally movable or oscillating manner about its
axis of rotation 6, with its grinding surface 5 can be
implemented when grinding the profile 2. The support 11
of the grinding body 4 is designed to be movable in a
reversing translatory manner for introducing a
superimposed movement during the rotating or oscillating
movement of the grinding body 4 parallel to the central
longitudinal plane 7 of the profile 2. Due to this
translatory movement of the grinding body 4 superimposed
on the rotational movement, the grinding body repeatedly
reaches each surface portion of the profile 2 even when
the vehicle bearing the device follows the path of the
profile 2 at its own usual speed. As a result, a rail
portion is not only reached once by the grinding surface
5 of the grinding body 4 but can be passed over repeatedly
thereby so that very good surface qualities can be
produced. The axes of rotation 6, which are inclined at
the angle p to one another, ensure that the removed
material is transported out of the grinding gap and
cannot accumulate therein. Due to the efficient machining
and the high level of material removed, the rotational
speed can be reduced and flying sparks can also be reduced
thereby, in addition to the wear, while at the same time
the relative speed is increased between the surface of
the profile 2 and the grinding body 4.
Since the translatory movement of the support 11 between
its reversal points follows a sinusoidal speed curve, and
is additionally superimposed by the intrinsic movement
of the vehicle, the rotation preferably can also be
controlled such that the rotational speed of the grinding
body 4 is increased in the region of the reversal points
of the reversing movement. In particular, the rotational
speed of the rotating movement is reciprocally adapted
to the translatory movement. Since the translatory
movement is also superimposed by the intrinsic movement
of the vehicle along the profile 2, the translatory speed
is added with the movement in the direction of travel and
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the translatory speed is subtracted with the movement
counter to the direction of travel, so that the
rotational speed of the grinding body 4 is also adjusted
as a function of the leading or trailing phase.
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List of reference signs
1 Device
2 Profile
3 Running surface
4 Grinding body
5 Grinding surface
6 Axis of rotation
7 Central longitudinal plane
8 Shape
9 Surface portions
10 Side surface
11 Support
12 Guide
13 Contact element
14 Contact element
b, B Width
a, p, p Angle
F Pre-tensioning force
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