Note: Descriptions are shown in the official language in which they were submitted.
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a y
METHOD AND APPARATUS FOR GRINDING A ROTATING
ROLLER WITH AN ELASTIC STEADY
The invention relates to a method and an apparatus for grinding the exterior
circumference of a rotating roller, held at its ends, with a rotating grinding
wheel, whereby the length of the roller is a multiple of the width of the
grinding wheel.
In many large-scale and industrial production processes, long narrow rollers
are required that rotate during operation, sometimes must be driven, and
often must be heated or cooled from inside. Such rollers can for instance
have a length of approximately 1000 mm and a diameter of 85 mm. In
addition the rollers are frequently tube-shaped with a low wall thickness that
can be less than.' 1 mm. High stresses are placed on the surface quality of
these rollers and on their dimensional stability. Grinding such rollers to
final
dimensions and the required surface quality therefore present great
challenges to one skilled in the art.
One known disadvantageous aspect when grinding the exterior of rollers is
that they bend outward laterally when the grinding wheel acts on their
circumferential surface. This can lead to a situation in which the finished
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roller deviates from the cylindrical shape. In addition, the roller begins
self-
starting transverse vibrations, so-called regenerative chattering. The result
of this regenerative chattering is chatter marks on the circumferential
surface of the roller, which can cause reduced surface quality and thereby
render the resultant roller unusable for many applications.
In order to prevent rollers from bending outward during grinding, it is
known to support the roller at its exterior circumference with one or a
plurality of steadies or rests. The steadies or rests comprise steel supports
that support the blank. However, supporting the rotating roller on the
steadies or rests comprising steel frequently leads to tracks, which can also
cause reduced surface quality that cannot be tolerated. Known operating
measures for eliminating regenerative chattering slow the grinding process.
One type of method mentioned in the foregoing known from commercial
practice is that the roller is first rough-ground in the plunging method using
a grinding wheel comprising corundum. For this, the roller is processed to a
rough-ground dimension such that there are a plurality of successive plunges
with the grinding wheel until the entire length of the roller has been rough-
ground to this dimension. Subsequently this same grinding wheel is dressed
and then fine- or finish-grinding is performed. Finish-grinding is done using
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longitudinal grinding, whereby the rotating grinding wheel and the rotating
roller are moved relative to one another in the longitudinal direction of the
roller on its exterior circumference. When the length of the roller is for
instance 1,000 mm, grinding wheels with a width of for instance 100 mm are
used. The disadvantage of this known method is that the grinding wheels
comprising corundum must be dressed. This can even become necessary
during a single finish-grinding process. Overall, the known grinding method
is very tedious.
Known from DE 16 27 998 Al is a follower rest for supporting cylindrical
workpieces in a grinding machine that forms a hydrostatic semi-bearing.
The rotating workpiece to be ground thus rests on a film of liquid that must
be continuously replenished. An uninterrupted stream of liquid is fed to the
hydrostatic semi-bearing for this purpose. The liquid can be a coolant that is
always necessary when grinding. This known rest was used to achieve the
goal of effectively supporting the workpiece, protecting its surface, and
achieving a low-friction bearing, so that the rest does not need to be changed
too often. Damping vibrations and avoiding chatter marks were not
objectives with the known rests and therefore are also to a large extent
unattainable with them. In addition, since the semi-bearing comprises metal,
operation of the hydrostatic semi-bearing must be constantly and carefully
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monitored, because if the liquid film breaks down, then metal is on metal,
which can
damage the workpiece.
The object of some embodiments of the invention is therefore to create a
method of
the type cited in the foregoing that makes it possible to use CBN grinding
wheels and
that also enables substantially reduced processing times while still leading
to rollers
that have higher dimensional stability and surface quality.
According to an aspect of the invention, there is provided method for
grinding, with a
rotating grinding wheel, an exterior circumference of a rotating cylindrical
roller, held
at ends thereof, length of said roller being greater than width of said
grinding wheel,
comprising: during grinding, positioning at least one deformable, cushioned
body
against, and conforming to a portion of the exterior circumference of the
roller
opposite a portion of the exterior circumference of the roller contacted by
the grinding
wheel, the cushioned body being comprised of an elastic solid material or an
elastic
exterior skin filled with an elastic pressure medium.
According to another aspect of the invention, there is provided apparatus for
grinding
exterior circumference of a rotating cylindrical roller held at ends thereof,
comprising:
a rotating grinding wheel, length of said roller being greater than width of
said grinding
wheel, tension and drive members for chucking the roller at end faces of the
roller and
for rotationally driving the roller, a first grinding spindle, a first
grinding wheel
rotationally driven by the first grinding spindle, means for driving the
grinding wheel in
a direction transverse to a longitudinal axis of the roller so that the
grinding wheel is
positionable against the roller, means for driving at least one of the roller
and the
grinding wheel for relative displacement thereof in directions parallel to the
length of
the roller, at least one deformable, cushioned body comprising an elastic
solid
material or an elastic exterior skin filled with an elastic pressure medium,
and means
for positioning said at least one cushioned body against and conforming to a
first
portion of the exterior circumference of the roller opposite a second portion
of the
exterior circumference of the roller contacted by the grinding wheel.
In that the cushioned body is positioned in the circumferential region
opposite the
grinding wheel against the roller to be ground, the transverse vibrations of
the roller
and even to an extent the vibrations deriving from the grinding wheel are
successfully
damped. The regenerative chattering does not occur, and thus there are no
longer
any feared chatter marks. That is, in contrast to the rests or supports
comprising
steel, the cushioned body does not lead to any tracks that result in reduced
surface
quality and are
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immediately recognizable to one skilled in the art. Prescribing the
circumferential region opposite the grinding wheel means that the cushioned
body is to be positioned approximately radially opposite the grinding wheel
on the other side of the roller. However, this prescription should not be
interpreted to be strict in geometric terms, because it is possible to
successfully reduce vibrations even when the location at which the cushioned
body is positioned against the roller differs radially and axially relative
from the grinding wheel in a certain area. The inventive method makes
possible a substantial reduction in the grinding process, which can be up to a
50 percent reduction compared to the known method. Using the cushioned
body is successful in both plunge-cut grinding and in longitudinal grinding.
However, it is preferred to perform the inventive method as longitudinal
grinding, whereby the rotating grinding wheel 13 and the rotating roller 6
are moved relative to one another in the longitudinal direction of the roller
6
against its exterior circumference. For this, the roller, which is borne in
centers and driven to rotate by means of these or using a carrier, can be
passed on a grinding table against.the rotating grinding wheel. However, the
reverse arrangement is also conceivable. The continuously running
longitudinal grinding works better in an automated procedure than plunge-
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cut grinding, which must be done in steps; in addition, there is no problem
with tracks at the transition points.
Using the inventive method, the disadvantageous occurrence of vibrations is
successfully suppressed such that it is possible to process by means of CBN
grinding wheels. One embodiment of the
inventive method is comprised in that the roller 6 is rough-ground and
finish-ground successively in a single instance of chucking, each with a
ceramic-bound CBN grinding wheel 12,13 and the cushioned body 6 is
used at least during re-grinding.
The following embodiments of the inventive method are
related to how the cushioned body -- hereinafter collectively referred to as
flexible cushion -- is positioned against the roller and moved in relation to
it.
Thus, it is provided, in some embodiments, that the cushion 15 is positioned
elastically
flexible against the roller 6. In the simplest case, this can occur using a
linear
guide with a positioning set spring, the. tension of which is adjustable.
In some embodiments, however, it is positioned using a pressure medium, but
electronically controlled positioning using electromotors is also conceivable.
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There are broad options for applications and the positioning force with
which the flexible cushion 15 is positioned against the roller 6 is adjustable
and can even equal a value of 0 prior to the beginning of the grinding
process. Positioning of the at least one flexible cushion occurs because the
roller bends outward in the direction of cushion under the influence of the
processing forces of the grinding wheel.
In terms of operations technology, pneumatically positioning the flexible
cushion 15 against the roller 6 results in particularly good control of the
positioning force.
Another aspect of the inventive method is to perform in accordance with one
additional embodiment in that at least one flexible cushion is positioned
during grinding at a location that remains the same in the longitudinal
extension of the roller. If, for example, the roller is borne between centers
and the grinding wheel is passed at the exterior circumference of the roller
in
its longitudinal direction, the flexible cushion will in some embodiments be
arranged
largely in the axial center of the roller because this is where the strongest
transverse vibrations occur.
Even better adapted vibration damping occurs in that the at least one flexible
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cushion 15 and the roller 6 are moved relative to one another parallel to the
longitudinal direction of the roller 6 during the grinding process. If the
flexible cushion 15 is moved radially opposite the grinding wheel 13 with this
relative to the roller 6, the cushion is always situated opposite the grinding
wheel and thus at the location where the vibrations are excited. In this
manner a particularly effective abatement in the vibrations can be achieved.
The further developments cited in the following relate to the embodiment of
the cushion and to the associated addition of a lubricant/coolant to the
region
in which the flexible cushion is positioned against the roller.
It is thus provided that for example the flexible cushion 15, 23, 26, 34
conforms to the cylindrical contour of the roller 6 when positioned against
it.
This conforming can occur particularly in some embodiments in that a pressure
medium, in particular a gas, acts on the exterior skin of the cushion 23, 26,
34
positioned against the roller 6 to be ground. In this manner the cushion is
inflated like a balloon that gently conforms to an obstacle.
Because of the friction that occurs between the exterior skin of the cushion
and the roller, it is provided that a liquid or gaseous lubricant is fed to
the location at which the flexible cushion 23, 26, 34 is positioned against
the
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roller 6. The method associated with this is particularly easy to construct in
that the lubricant is formed by the pressure medium of the cushion 34 and
fed to the location through apertures 35 that are situated in the exterior
skin
of the cushion 34 facing the roller 6.
Additional embodiments relate to how the inventive grinding method is
controlled in detail.
Thus, a certain longitudinal contour of the roller can be attained during
grinding in that the flexible cushion is adjusted transverse to the roller
such
that the roller bends outward during the grinding process and due to the
grinding in its final state the roller has a longitudinal contour with a
slightly
concave or convex curve. During the grinding the roller takes on a certain
bending without transverse vibrations occurring. When the flexible cushion
is a certain distance from the exterior circumference of the roller while the
roller is at rest, the roller will bend outward under the influence of the
grinding wheel until it comes into contact with the cushion. However, it is
also possible to set a pre-tension, whereby the roller is then pre-curved in
the
direction of the grinding wheel. When the grinding process is appropriately
controlled, the result is rollers with an axial longitudinal contour that is
curved concavely or convexly in the desired manner.
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If the grinding wheel migrates in the axial direction relative to the roller
to be
ground, the resultant transverse vibrations also change depending on the axial
region of the roller in which the grinding wheel is situated. Therefore, for
fine-
tuning the grinding process it is provided that the positioning force of the
at least
one flexible cushion is changed during the grinding process and/or is adjusted
to
different values for a plurality of cushions 39, 40, 41. The change in the
positioning force will occur depending on the axial region of the roller on
which the
grinding wheel and/or the cushion are acting at that moment. The required
values
can be determined quickly using calculations or practical trials.
Some embodiments of the invention also relates to an apparatus for external
grinding of rollers, in particular for performing some embodiments of the
inventive
method as described above. An aspect of the invention is provided with an
apparatus for external grinding of rollers 6, in particular for performing the
method
as described above, with tension and drive members for chucking the roller 6
at its
end faces and for rotationally driving the roller 6 with at least one grinding
spindle
11, driving a grinding wheel 13, that can be driven in a direction running
transverse to the longitudinal axis of the roller 6 so that the grinding wheel
13 can
be positioned against the roller 6, with drives for mutual longitudinal
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displacement of roller 6 and grinding wheel 13, and with at least one device
14 that is situated in a circumferential region of the roller 6 opposite the
grinding wheel 13, through which device a cushioned body 15, 23, 26, 34, 39,
40, 41 made of an elastic solid material or an elastic exterior skin filled
with
an elastic pressure medium can likewise be positioned transverse to the
longitudinal direction of the roller 6 against its circumference.
The device for positioning the cushioned body (of the flexible cushion) can
for instance be present on the machine bed or on a grinding table that also
carries the roller to be ground. It can be positioned mechanically,
electrically, or by a pressure medium.
The following embodiments are related to how the positioning force can be
applied advantageously and usefully in terms of structure and level. Thus,
for controlling a high-grade grinding process it is essential that a control
arrangement is present for setting the positioning force with which the
flexible cushion 15 is positioned against the circumference of the roller 6 to
be ground..
If a plurality of flexible cushions 39, 40, 41 are arranged along the roller 6
to
be ground, in some embodiments, the positioning force of each cushion 39,
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40, 41 can be adjusted individually and independent of the other cushions.
Particularly good control options result when the device for positioning the
flexible cushion 15 includes a double-acting pneumatic sliding cylinder 17 at
the piston rod 19 of which the cushion 15 is attached. If there are a
plurality
of flexible cushions 39, 40, 41 arranged along the roller 6 to be ground, each
pneumatic sliding cylinder is allocated a discrete pressure regulator 44, 45,
46. In this manner perfect pneumatic control is ensured with which the
vibrations are successfully damped at a plurality of locations on the axial
extension of the roller.
Particular attention should be paid to the design of the cushion. A
solution is for the flexible cushion 15 to be formed by a body made of an
elastic solid material. A high-quality plastic foam with closed cells and
having or provided with an abrasion-resistant surface can accomplish this
task well. It will to a certain extent conform to the exterior contour of the
roller and in this manner successfully dampen the vibrations.
in some embodiments, the flexible cushion 23 is
formed by a hollow body made of an elastic exterior skin in which a pressure
medium is located. This pressure medium can be a gas, in some embodiments,
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compressed air. A hollow body that is under pressure is particularly well-
suited for conforming to the exterior contour of the roller, whereby the
effect
can even be controlled in that the internal pressure is optimally set as a
function of the grinding process to be performed.
Precisely because such cushions conform well to be exterior contour of the
roller, significant friction occurs between the flexible cushion and the
roller.
In order to reduce this friction, it is necessary for a lubricant/coolant to
be
fed to the location. For this purpose in accordance with one
embodiment,feed lines are provided that open in the region of the location
where the flexible cushion is positioned against the roller through which a
lubricant is fed to this location. The grinding emulsions, synthetic coolant
lubricants, and grinding oils conventionally used in abrasive engineering are
appropriate as lubricants. However, compressed air can also be used. If the
feed lines conducting the lubricant pass through the flexible cushion directly
to the location where the cushion is positioned against the roller, the
lubricant is located at precisely the location where it can have its greatest
effect. In the case of a liquid lubricant, a film forms between the roller and
the flexible cushion, just as in aqua-planing in an automobile tire, and is
particularly effective. If lubrication is performed with compressed air, an
air
cushion can form, as is known from air cushion vehicles. It must be stressed
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that the lubricant film or the air cushion effectively reduces friction losses
during grinding without this reducing the effectiveness of the vibration
damping.
One particularly effective solution in terms of design is that the feed lines
that pass through the flexible cushion 26 and forward lubricant are
embodied as tubes 30 that are integral with the elastic external skin of the
cushion 26, whereby the lubricant and the pressure medium are separated
from one another.
However, if the pressure medium of the cushion is itself used as coolant, it
is
particularly simple in terms of design that the elastic exterior skin of the
flexible cushion 34 is provided at its positioning surface facing the roller 6
to
be ground with a plurality of apertures through which the pressure medium
passes to the positioning location to form the cooling and lubricating film at
this location. Thus, in this embodiment pressure medium must pass
continuously from the flexible cushion outward to the positioning location. It
is necessary to feed the pressure medium continuously, and this can be done
with no problem using pressure regulators. This solution can be even further
perfected in that the pneumatic control of the sliding cylinder, at the piston
rod of which the flexible cushion is situated, is included in the process.
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For performing the two-stage grinding process mentioned in method claim 3
with positioning of the flexible cushions 6 against the roller or, at least
during
re-grinding, in terms of the apparatus design it is, in some embodiments,
provided
that a grinding headstock 8 is provided with two grinding spindles 10, 11
that can be selectively brought into the work position and of which the first
carries a ceramic-bound CBN grinding wheel 12 for rough-grinding and
the second carries a ceramic-bound CBN grinding wheel 13 for finish-
grinding, whereby an automatic coupling is provided through which the at
least one device for positioning the flexible cushion 15 against the wheel 6
to
be ground is activated when the second grinding wheel 11 is brought into the
work position. In this manner the inventive apparatus is prepared for
automating, which is highly desirable on production lines in modern mass
production.
The invention will be explained in greater detail using exemplary
embodiments that are illustrated in the figures.
Figure 1 illustrates an apparatus for performing the inventive method,
whereby the rough-grinding phase is depicted;
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Figure 2 depicts the apparatus in accordance with Figure 1 in the finish-
grinding phase;
Figure 3 is an enlarged view corresponding to direction A-A in accordance
with
Figure 2 and illustrates details of the flexible cushion cooperating with the
roller to be ground.
The subject of Figure 4 is another design of the flexible cushion.
Figure 5 illustrates the feed of a lubricant in the region of the flexible
cushion.
Figure 6 illustrates a flexible cushion, the pressure medium of which is also
a
lubricant.
Figure 7 contains a scheme that illustrates the control of a plurality of
devices
for positioning elastic cushions against the various axially distanced
locations
of the roller.
Figure 1 illustrates in a schematic representation a conventional circular
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grinding machine for external grinding of cylindrical parts. In a view from
above a machine bed 1 can be seen on which are located a workpiece
headstock 2 and a tailstock 3. Workpiece headstock 2 and tailstock 3 are
mutually adjustable in the axial direction so that the roller 6 to be ground
can be chucked and driven to rotation by means of the centers 4 and 5
located on them. However, the roller can also be driven by carriers that are
conventional in the art and are therefore not shown separately here. The
workpiece headstock 2 and the tailstock 3 are located on a grinding table 7
that can be moved as a whole in the Z direction.
Furthermore, located on the machine bed 1 is a grinding headstock 8 that is
adjustable about a vertical pivot axis 9. The grinding headstock carries a
first grinding spindle 10 and a second grinding spindle 11. Of these, the
first
grinding spindle 10 carries the first grinding wheel 12 that rough-grinds or
rough-cuts, while the second grinding spindle 11 carries a second grinding
wheel 13 intended for finish-grinding or finish-cutting.
By pivoting about the vertical pivot axis 9, the grinding headstock 8 moves in
the direction of the arrow B so that the grinding wheel 12 (Figure 1) or the
second grinding wheel 13 (Figure 2) can be selectively brought into the
working position. In addition, the entire grinding headstock 8 can be driven
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in the X direction numerically controlled, whereupon the grinding wheel
currently in the working position comes to be positioned against the roller 6
to be ground in a controlled manner.
As can be seen, the axial length of the roller 6 to be ground is a multiple of
the grinding wheel width so that for grinding using so-called longitudinal
grinding the grinding wheel and the roller to be ground must be moved past
one another in the axial direction. For this, the roller 6 located on the
grinding slide can be moved past the grinding wheel. However, the reverse
arrangement is also possible in that the roller to be ground is fixed in the
axial direction, while the grinding headstock is moved past it.
Labeled 14 is a device for vibration damping; it can be used to position a
flexible cushion 15 against the roller in a controlled manner. Figure 1
illustrates the device 14 in its non-working position; the flexible cushion 14
is
situated at a distance from the surface of the roller to be ground. In
contrast,
in the illustration in accordance with Figure 2 the flexible cushion 15 is
positioned against the roller. It is situated opposite the grinding wheel 13
in
the radial direction. If the grinding wheel acts on the roller 6, it will bend
outward laterally and have a tendency for transverse vibrations, especially if
the length/diameter ratio is greater than that illustrated in the drawing.
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Tube shaped rollers with low material strength are also particularly
susceptible to this type of vibration. Since the flexible cushion 15 is now
positioned against the roller with moderate adjustable pressure, the
transverse vibrations are damped and suppressed so that the "regenerative
chattering" feared by those skilled in the art does not occur. This also
prevents the chatter marks that betray roller surface quality in the ground
roller.
In the illustrations in accordance with Figures 1 and 2, the device 14 is
situated precisely opposite the grinding wheels 12 or 13. However, if the
roller 6 to be ground is caused by means of the grinding table 7 to pass the
grinding wheel in the axial direction, the position of the device 14 also
changes relative to that of the grinding wheel. It is therefore advantageous
when a plurality of devices with different flexible cushions is provided
across
the axial extension of the roller 6 to be ground as Figure 7 illustrates in
greater detail.
However, it is also conceivable to arrange the device 14 on the machine bed
so that it always remains precisely opposite the grinding wheel that is in the
working position. Finally, a solution is also conceivable in which only one
device 14 is provided, but it is moved axially with the grinding spindle
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opposite the roller to be ground so that the mutual allocation of grinding
wheel and device 14 is retained in every case.
Figures 1 and 2 also illustrate a method particularly preferred in accordance
with the invention in which the rough-grinding is performed by means of a
ceramic-bound CBN grinding wheel and the device 14 for damping the
vibrations does not operate. However, if the grinding wheel 13 is brought
into the working position for finish-grinding, this is automatically coupled
to
activation of the device 14 as illustrated in Figure 2. Thus, transverse
vibrations are effectively suppressed during finish-grinding or finish-cutting
so that optimum surface qualities are obtained despite a short processing
time.
Figure 3 illustrates the view A-A in accordance with Figure 2 in an enlarged
representation. It explains a device for vibration damping that is actuated
pneumatically. For thus, a base 16 is provided that can be attached directly
to the machine bed 1 or to the grinding table 7. The base 16 carries a
pneumatic dual-acting sliding cylinder 17 in which a piston 18 can be acted
upon from two sides. The piston 18 carries a piston rod 19 on which a
fastening plate 20 is situated. The flexible cushion 15 is glued or vulcanized
to the fastening plate 20. The cushion can comprise a rubber-like material or
a plastic with closed hollow cells that is thus particularly flexible and
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conformable. What is critical is that although the exterior surface of the
flexible cushion 15 is elastic, it is still resistive and resistant to wear.
21 and
22 are compressed air lines through which the sliding cylinder is controlled.
It can thus press the flexible cushion 15 against the roller 6 with precisely
adjustable force. As can be seen, the roller 6, which in this case is a hollow
roller, is acted upon on both sides between the grinding wheel 13 and the
flexible cushion 15. The roller will thus yield slightly under the positioning
force of the grinding wheel 13, whereby however transverse vibrations that
occur are suppressed by the damping effect of the flexible cushion 15.
The starting position of the flexible cushion 15 is also adjustable prior to
the
beginning of the grinding process. For instance, the positioning force can be
zero at the beginning so that the roller 6 is not pressed into the flexible
cushion 15 until it is acted upon by the grinding wheel 13.
Figure 4 illustrates a device 14 for damping vibrations in which the flexible
cushion 23 is embodied as a hollow body with an elastic exterior skin,
comparable to tires on automobiles. Compressed air for instance can be
introduced into the interior of the flexible cushion 23 with a feed line 24,
whereby different elasticity properties can be attained. However, it is also
conceivable to fill the flexible cushion with a fluid when elastic yielding of
the
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fluid is ensured. It can also be filled with a gel.
The other embodiments of the device 14 correspond to those in accordance
with Figure 4; in particular here as well the positioning of the flexible
cushion 23 against the roller 6 must occur with a particular device such as
for instance a sliding cylinder.
Figure 5 also explains a flexible cushion 26, filled with a pressure medium,
that here is situated on a fastening plate 25 and joined thereto. The
fastening
plate 25 is connected to a feed line 27 for the pressure medium, for which
compressed air is primarily used. The pressure medium is introduced into
the hollow space of the flexible cushion 26 via an internal channel 28 located
in the attaching plate 25. Passing through the flexible cushion 26 are tubes
30 that are integral with the exterior skin of the cushion 26, but that do not
communicate with the interior space of the cushion 26. The tubes 30 are
connected to a channel system 29 that is located in the attaching plates 25
and through which a coolant/lubricant is applied by means of the tubes 30
directly to the surface of the flexible cushion 26 that is against the roller
6.
For this, the tubes 30 end in apertures 31 that are directly oriented to the
roller 6. As can be seen, the apertures 31 open at the surface of the roller 6
so that the coolant/lubricant travels precisely to the location at which it is
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most urgently needed.
P11 and P12 indicate pressure regulators that set the optimum operating
pressure for the media.
When the pressure medium located in the hollow flexible cushions can be
both coolant and lubricant, it is no longer necessary to have separate feed
lines for the pressure medium of the cushion and for the coolant/lubricant.
Figure 6 illustrates this advantageous design.
In accordance with it, a flexible cushion 34 is again glued or vulcanized to a
fastening plate 32, whereby a feed line 33 leads via a pressure regulator P21
into the interior of the flexible cushion 34. In this case the flexible
cushion is
provided at its end face that faces the roller 6 with a number of apertures
35.
Thus the pressure medium of the cushion exits through the apertures 35
continuously in the direction of the surface of the roller 6. In this case
pressure medium must be continuously fed into the flexible cushion 34 so
that the required pressure is maintained.
Figures 4 through 6 illustrate how well the inflatable cushions conform to the
contour of the roller. In the case of Figures 5 and 6 it is particularly
ensured
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that the coolant/lubricant forms a film between the flexible cushion and the
roller, comparable to the film of water during so-called aqua-planing or to an
air cushion vehicle like a hovercraft. The embodiment in accordance with
Figure 6 is particularly advantageous when an air cushion is used.
Figure 7 is a schematic illustration of how the devices for vibration damping
should be controlled when a plurality of these devices is provided along the
axial extension of the roller 6 to be ground. In the instance represented,
three devices 36, 37, 38 are provided, of which each positions a flexible
cushion 39, 40, 41 against the roller 6 to be ground. Positioning occurs
pneumatically, for which reason each of the devices 36, 37, 38 has a sliding
cylinder in accordance with Figure 3. As can be seen, the vibration
amplitudes in the center of the roller 6 chucked between the centers 4 and 5
will be greater than in the region of its exterior ends, which are situated
closer to the chucking locations. It is therefore useful to select the
positioning
force of the device 37 higher than that of the devices 36 and 38.
Correspondingly, a discrete pressure regulator 44, 45, 46 is provided in the
compressed air line P for each of the devices 36, 37, 38 so that the sliding
cylinder of each device can maintain the optimum pneumatic pressure for
vibration damping. In addition, the compressed air lines P and return line L
are embodied common for all devices.
24 TRANSLATION OF W02004-007145.DOC
CA 02491800 2005-01-06
F-8502 Identifier: Erwin JUNKER
25 TRANSLATION OF W02004-007145.DOC
CA 02491800 2005-01-06
F-8502 Identifier: Erwin JUNKER
1 Machine bed
2 Workpiece headstock
3 Tailstock
4 Center
Center
6 Roller
7 Grinding table
8 Grinding headstock
9 Pivot axis
First grinding spindle
11 Second grinding spindle
12 First grinding wheel
13 Second grinding wheel
14 Device for vibration damping
Flexible cushion
16 Base
17 Sliding cylinder
18 Piston
19 Piston rod
26 TRANSLATION OF W02004-007145.DOC
CA 02491800 2005-01-06
F-8502 Identifier: Erwin JUNKER
2021 Attaching plateCompressed air line
22 Compressed air line
23 Flexible cushion
24 Feed line
25 Attaching plate
26 Flexible cushion
27 Feed line
28 Internal channel
29 Channel system
30 Tube
31 Apertures
32 Attaching plate
33 Feed line
34 Flexible cushion
35 Apertures
36, 37, 38 Devices for vibration damping
39, 40,41 Flexible cushion
42, 43 Control line
44, 45, 46 Pressure regulator
27 TRANSLATION OF W02004-007145.DOC
