U.S. patent application number 10/953859 was filed with the patent office on 2005-05-19 for rolling tool and roller for rolling, particularly deep rolling, a work piece.
This patent application is currently assigned to ECOROLL AG Werkzeugtechnik. Invention is credited to Ostertag, Alfred, Rottger, Karsten.
Application Number | 20050107230 10/953859 |
Document ID | / |
Family ID | 34577294 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050107230 |
Kind Code |
A1 |
Ostertag, Alfred ; et
al. |
May 19, 2005 |
Rolling tool and roller for rolling, particularly deep rolling, a
work piece
Abstract
Previously known mechanical deep rolling tools share the feature
that their rollers not only roll over the work piece but also over
a counter roller on the tool side. This allows the deep rolling
roller to swing to the side; but the roller material becomes
fatigued relatively quickly. To achieve longer life, a rolling tool
is suggested in which a working periphery is located in a work
piece contact area spatially separated from a bearing contact area
of the roller. A rolling tool with a hydraulically supported
forming roller and a roller suitable therefor are also
suggested.
Inventors: |
Ostertag, Alfred; (Celle,
DE) ; Rottger, Karsten; (Celle, DE) |
Correspondence
Address: |
HENRY M FEIEREISEN, LLC
350 FIFTH AVENUE
SUITE 4714
NEW YORK
NY
10118
US
|
Assignee: |
ECOROLL AG Werkzeugtechnik
Celle
DE
|
Family ID: |
34577294 |
Appl. No.: |
10/953859 |
Filed: |
September 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10953859 |
Sep 29, 2004 |
|
|
|
PCT/DE04/01860 |
Aug 20, 2004 |
|
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60506749 |
Sep 29, 2003 |
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Current U.S.
Class: |
492/1 ;
72/236 |
Current CPC
Class: |
B21H 7/185 20130101;
B24B 39/003 20130101; B23P 9/02 20130101 |
Class at
Publication: |
492/001 ;
072/236 |
International
Class: |
B21B 027/02; B21B
027/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2003 |
DE |
103 40 267.5 |
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims and includes equivalents
of the elements recited therein:
1. A rolling tool, comprising a roller for rolling, particularly
for deep rolling, a work piece, said roller, while rolling, running
along the work piece with a working periphery, wherein the working
periphery is located in a work piece contact area of the roller
that is separated from a bearing contact area.
2. The rolling tool of claim 1, wherein the bearing contact area is
arranged on both sides of the work piece contact area.
3. The rolling tool of claim 1, wherein the roller has a circular
arc shaped contour in the bearing contact area.
4. The rolling tool of claim 1, wherein the bearing contact area
has a bearing contour of a continuous arc on both sides of the work
piece contact area, wherein a centre point of the continuous arc is
in a plane of the work piece contact area.
5. The rolling tool of claim 4, wherein tangents with the work
piece contact area and the bearing contact area are perpendicular
to a line from there to the centre point of the circle.
6. The rolling tool of claim 1, wherein the roller has a barrel
shape in the bearing contact area.
7. The rolling tool of claim 1, further comprising a mechanical
bearing on a tool side to accommodate the roller.
8. The rolling tool of claim 1, wherein the roller has a spherical
shape in the bearing contact area.
9. The rolling tool of claim 1, further comprising a hydraulic
bearing on the tool side to accommodate the roller.
10. The rolling tool of claim 9, wherein the hydraulic bearing is a
hydrostatic bearing.
11. The rolling tool of claim 1, further comprising a pivoting
bearing area on the roller to maintain a constant bearing surface
when the roller is shifted.
12. The rolling tool of claim 1, further comprising two hydraulic
supply lines to a bearing of the roller on a tool side.
13. A rolling tool, comprising a hydraulically supported roller for
rolling, particularly deep rolling a work piece, wherein the roller
is supported spherically and having an aspherical
configuration.
14. The rolling tool of claim 13, wherein the roller is partly
spherical.
15. The rolling tool of claim 1, further comprising two hydraulic
supply lines to a bearing of the roller on a tool side.
16. A rolling tool, comprising a roller for rolling, particularly
deep rolling a work piece, wherein the roller is a forming roller
with a hydraulic bearing.
17. The rolling tool of claim 16, further comprising two hydraulic
supply lines to a bearing of the roller on a tool side.
18. A roller for rolling, particularly for deep rolling a work
piece, said roller having an essentially disc-shaped work piece
contact element arranged symmetrically about a rolling axis, and
bearing elements arranged lengthwise relative to the axis of the
roller and rotationally symmetrically about the same axis.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of prior filed copending
PCT International application no. PCT/DE2004/001860, filed Aug. 20,
2004, which designated the United States and on which priority is
claimed under 35 U.S.C. .sctn.120, the disclosure of which is
hereby incorporated by reference, and which claims the priority of
German Patent Application, Serial No. 103 40 267.5, filed Aug. 29,
2003, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is
incorporated herein by reference.
[0002] This application also claims the benefit of prior filed U.S.
provisional Application No. 60/506,749, filed Sep. 29, 2003,
pursuant to 35 U.S.C. 119(e), the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a rolling tool and a roller
for rolling, particularly for deep rolling, a work piece.
[0004] Nothing in the following discussion of the state of the art
is to be construed as an admission of prior art.
[0005] The task of designing components that can withstand
especially heavy loads is encountered regularly in countless
mechanical engineering applications. Indications of premature wear
and the associated unexpected failures occur particularly often
with dynamically stressed components. The reason for this is often
to be found in cracks that begin on the surface of the work piece,
particularly on the micronotches or geometric fissures that exist
there.
[0006] When used for dynamically stressed components, deep rolling
significantly increases fatigue strength. Rolling the work piece
causes the edge layer to be deformed. The rolling force used in
this process is selected such that the edge layer is rendered
plastic during rolling. This is essentially associated with three
advantages:
[0007] Firstly, residual internal stresses are created in the edge
layer of the component skin, which are also suitable for
counteracting tensile stresses that occur otherwise in the edge
layer. Secondly, greater resistances are achieved locally with cold
forming. Finally, the surface is smoothed microscopically, so that
the micronotches, which may lead to cracks are largely
eliminated.
[0008] In view of these process-related advantages, of the many
mechanical surface treatment processes possible, deep rolling
assumes a particular importance. Deep rolling is normally used in
the cut-in or the though feed rolling processes. In cut-in
processing, profile rollers are used that are specially adjusted to
the radius of a fillet to be compacted. They are set up at an angle
so that the resulting rolling force is directed at the zone in
which the highest material fatigue is to be expected. The deep
rolling rollers are suspended in pendulum manner such that the
inclination of the rollers may be adjusted automatically to the
actual local angle of the surface when they are set against the
fillet. In this way, working tolerances are compensated, while
assuring the desired distribution of compression stresses in the
fillet. This is exceptionally important for assuring the
effectiveness of the process.
[0009] The process usually extends over several revolutions of the
work piece. The rolling force is gradually increased over a given
number of revolutions, then kept constant, and finally reduced
again over a further predetermined number of revolutions. The soft
engagement/disengagement of the roller avoids sharp stress
increases and the additional notching effects that necessarily
accompany such.
[0010] While the infeed process is suitable only for narrowly
defined areas, preferably for fillets with radii smaller than 4 mm,
the throughfeed process is provided for processing larger
surfaces.
[0011] In conventional use, no special machinery is required for
rolling; instead, the rolling tool may simply be integrated in the
existing machine, for example a lathe.
[0012] When deep rolling, the tools are loaded with very high
rolling forces. During the rolling process, the roller is pressed
against the work piece to be compacted with a defined force and is
moved relative thereto. In order to transfer the rolling force to
the roller and, at the same time ensure a certain pendulum
capability of the roller, the working periphery of the roller runs
along the work piece on the work piece side and along a counter
roller on the tool side. The pendulum motion is essential for an
even distribution of stress in the radius.
[0013] In operation, the roller is thus necessarily rolled twice
per revolution. This causes the material to fatigue relatively
quickly, particularly given the very high deep rolling forces
applied. A low-wearing arrangement is known from European Patent EP
0 353 376 A1. Here, a rolling tool is suggested in which the
support is assured hydrostatically. However, the rolling body in
this case is spherical and this neat solution does not lend itself
to use with form rollers because the sealing edge along a roller
contour is much more complex than the sealing edge along a
spherical body. With hydrostatically supported rollers, the seal
gap would vary so much, even with small--inevitable--pendulum
motions, that the essential hydrostatic pressure could not be
assured. Moreover, even minor surface damage in the work area of
the roller would cause defects in the gap seal.
[0014] Similar or species-related rolling tools are also known from
German Patents DE 43 09 176 C2 and DE 33 90 141 C2, and from U.S.
Pat. No. 4,821,388 and U.S. Pat. No. 3,945,098.
[0015] It would therefore be desirable and advantageous to provide
an improved rolling tool to obviate prior art shortcomings and to
cause little wear for a roller.
SUMMARY OF THE INVENTION
[0016] According to one aspect of the present invention, a rolling
tool includes a roller for rolling, particularly deep rolling, a
work piece, the working periphery of the roller running rotatingly
along the work piece when the working periphery is located in a
work piece contact area of the roller that is separated from the
bearing contact area.
[0017] The working periphery is understood to mean the narrow or
wider strip along the outer periphery of the roller that transfers
the rolling forces to the area of the work piece for compaction
during rolling. In microscopic terms, in cases of doubt this is
will be two or more strips; macroscopically, this is usually a
rotationally symmetrical strip from less than 1 mm to about 8 mm
wide that encircles the roller. Although only a small part of the
roller's working periphery is in contact with the work piece at any
given time, the roller is moved so that it rolls over the area to
be compacted. This is effected by applying a constant pressure to
either the work piece or the tool so that the two are pressed
against one another. Normally in such cases, the working periphery
is exactly rotationally symmetrical, so that a constant radial
force is transferred from the roller to the work piece during
rotation.
[0018] The term "areas", refers primarily to the surface of the
roller, that is to say particularly the bearing contact area and
the work piece contact area. As soon as the rolling force is
applied to the roller via the surface of the roller in the bearing
contact area and then transferred as deep rolling force from the
roller via that part of its surface which is in contact with the
work piece, and as long as these loaded surface sections on the
roller do not overlap, the reduced load on the rolling material
according to the invention is present. For design reasons, this is
achieved most simply if the bearing contact area and the work piece
contact area are offset with respect to one another, that is to say
that the two contact areas do not overlap when the bearing contact
area and the and the work piece contact are projected onto the axis
of rotation of the roller.
[0019] This creates a configuration in which the roller is
supported in a bearing area that is does not include the working
periphery. As a result the degree of wear caused directly to the
roller is minor.
[0020] The solution for reducing wear according to the invention is
suitable for mechanically supported and hydrostatically supported
rollers.
[0021] In a preferred embodiment of the rolling tool according to
the invention, the bearing contact area is arranged on both sides
of the work piece contact area. With a bearing arrangement of such
kind, relatively small bearing forces are needed. Whereas with a
single-sided bearing cantilever moments would have to be removed
via a clamped support, in this way essentially simple compressive
forces may be transferred between the bearing and the roller. It is
particularly advantageous to ensure that the bearing is
symmetrical.
[0022] The bearing may advantageously have a circular arc shaped
contour in the bearing contact area. This is understood to mean
that in a cross-section through the bearing surface the
delimitation of the roller is arced in shape and with this shape
preferably lies flush on the bearing. The cross-section through the
bearing surface is preferably selected such that the plane of the
cross-section is perpendicular to a plane of the working periphery
and/or the plane of the bearing contact surface and parallel to the
primary direction of pressure of the tool (see the intersecting
plane chosen in FIG. 1 of the drawing). Upon rotation about the
roller's axis of rotation, the arc segment forms a rotational
solid, wherein the distance between the roller's axis of rotation
and the arc segment does not have to be the radius of the circle
arc. Simply providing it with a circle arc-shaped contour results
in a particularly low-wearing, planar bearing. It may also be
sufficient if the roller is furnished with such a circular point
contour on only one side of the work piece contact area.
[0023] However, it is particularly suggested that the bearing
contact area be provided with a bearing contour of a continuous arc
in a circular arc shape on both sides of the work piece contact
area, the centre point of the continuous arc being in the plane of
the work piece contact area. In such a configuration, the roller
lies on top of two bearing surfaces on the support; in a
cross-section through the bearing however, the bearing surfaces are
shown to be shaped such that an arc may be drawn through both
bearing surfaces. The bearing surfaces are symmetrical about the
centre of the roller, the centre point of the arc passing through
the two bearing surfaces thus lies on an imaginary plane of the
work piece contact area or the working periphery. The plane is
normal with the axis of rotation of the roller.
[0024] In this configuration the roller may be pivoted at least to
some degree, thus it may skew the angle of the working plane while
the working periphery is rotating without the need to change the
roller's bearing surface on the bearing.
[0025] If in such a configuration not only tangents with the
roller, but also a tangent in the work piece contact area
perpendicular to a line from there to the centre point of the
circle described are in the work piece contact area, a rolling
force that is applied to the roller via the working periphery does
not produce an undesired distortion of the roller.
[0026] As a special form of bearing with circle arc-shaped contour,
it is suggested that the roller have a barrel shape in the bearing
contact area. A barrel is characterized in that its curved surface
is the rotational solid of a circle arc segment, but that the
centre point of the circle arc does not lie on the axis of rotation
of the curved surface, which in the case of a roller is the
roller's axis of rotation. It is even advantageous if the centre
point of the circle defining the contour of the barrel-shaped
bearing contact surface is located in the plane of the working
periphery but outside of the roller. This is also associated with
the situation in which the radius of the circle defining the barrel
shape is a certain amount larger than the radius of the working
periphery. In this arrangement, the roller is supported securely
under static conditions. A bearing of this type is even suitable
for infeed deep rolling operations with cylindrical work pieces or
with large-radius contours.
[0027] A barrel-shaped roller in the bearing contact area may be
accessed particularly by a mechanical bearing on the tool side,
preferably via support rollers such as roller bearings,
particularly ball bearings, needle bearings and cylinder roller
bearings.
[0028] In a particularly preferred arrangement, the roller may have
a spherical shape in the bearing contact area. In this case, the
centre point of a circle defining the circle arc-shaped bearing
surfaces is coincident with the roller's axis of rotation. When
rotated about the roller's axis of rotation, the bearing surface
yields a strip between each of two lines of longitude on the sphere
shape. Suitable spherical shapes are for instance spherical caps or
spherical segments that are adjoined laterally to the work piece
contact area.
[0029] A roller with a spherical bearing of such shape is
advantageous in that it may be pivoted absolutely neutrally and
economically in terms of space.
[0030] The spherical shape even renders this roller accessible to a
hydraulic, particularly hydrostatic bearing on the tool side to
accommodate the roller. This enables the rolling force to be kept
extremely constant, thereby assuring high quality and
reproducibility of the rolling operation. Support is finally
assured with the geometrically relatively simple form of a sphere
and is thus independent of the conformation in the work piece
contact area.
[0031] The roller may thus pivot particularly easily on a locally
present angle of a fillet. In order to ensure that the forces,
particularly the hydrostatic forces, are kept constant during such
a pivoting operation, it is suggested to provide a pivot bearing
area on the roller to preserve the bearing surface when the roller
is pivoted. This may particularly be a circle arc contour on the
roller that extends beyond the limits of the bearing surface on the
tool side. When the roller is pivoted outwards, the roller's
bearing support shifts automatically relative to the bearing on the
tool side. As a result, the bearing on the tool side then forces at
least a part of the original contact surface downwards. If the
geometry of the original bearing area is continued in the manner
suggested beside the original bearing surface, the bearing surfaces
and the force and stress ratios remain constant in the bearing of
the roller.
[0032] It should be noted that a hydraulic, particularly
hydrostatic bearing on the tool side to accommodate the forming
roller--particularly in conjunction with a pivot bearing area on
the roller--is also advantageous and inventive independently of the
features of the present invention that are described in the
preceding.
[0033] As part of the underlying inventive step, the object
presented also suggests a solution for a rolling tool having a
hydraulically supported roller for rolling, particularly deep
rolling a work piece if the roller is supported on a spherical, but
even aspherical, and particularly partially spherical bearing. This
directly provides the advantages described, in that a hydraulic
bearing with the associated simple controllability of the
compressive force may be achieved via the geometrically adjustable
spherical bearing, and at the same time the working periphery may
be varied from this shape, and in particular modified to match the
fillet to be processed.
[0034] Accordingly, a particular aspect of the invention consists
in that the prior art is enhanced by a rolling tool having a
hydraulically supported forming roller for rolling a work
piece.
[0035] For all hydraulic bearings on two sections of a bearing
contact area separated by a work piece contact area, it is further
suggested that two hydraulic supply lines be provided on the tool
side. This particularly has the advantage that the hydraulic
bearing pressure on each side of the work piece contact area is
assured independently of the other side.
[0036] It should be noted that a roller for rolling, particularly
deep rolling a work piece, wherein the roller includes an
essentially disc-shaped work piece contact element arranged
symmetrically about a roller axis is also advantageous and
inventive per se if it is distinguished by bearing elements that
are arranged longitudinally relative to the roller axis and
rotationally symmetrically about the same axis. In this form it is
directly germane to the application according to the invention.
BRIEF DESCRIPTION OF THE DRAWING
[0037] Other features and advantages of the present invention will
be more readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
[0038] FIG. 1 is a cross-section of a tool head having a roller
cradle and a roller cradled on a hydrostatic bearing;
[0039] FIG. 2 is a diagram of a roller having a barrel-shaped
bearing element in a central position;
[0040] FIG. 3 is the roller of FIG. 2 in an outwardly pivoted
position;
[0041] FIG. 4 is a diagram of a roller having a spherical bearing
element in a central position;
[0042] FIG. 5 is the roller of FIG. 4 in an outwardly pivoted
position;
[0043] FIG. 6 shows a cross-section of a part of a deep rolling
tool having a roller cradle and two deep rolling rollers supported
therein by hydrostatic means;
[0044] FIG. 7 shows the roller cradle of FIG. 6, in which a deep
rolling roller has been removed and the sealing geometry for roller
in empty chamber thereof is shown diagrammatically;
[0045] FIG. 8 shows a view below empty roller chamber, taken along
line VIII-VIII in FIG. 7,
[0046] FIG. 9 shows a cross-section of a variant for a tool
according to the invention with two hollow cantilevered rollers
and
[0047] FIGS. 10, 11, 12 show a tool or the rollers thereof
according to the prior art for deep rolling crankshaft splines.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0048] Throughout all the Figures, same or corresponding elements
are generally indicated by same reference numerals. These depicted
embodiments are to be understood as illustrative of the invention
and not as limiting in any way. It should also be understood that
the drawings are not necessarily to scale and that the embodiments
are sometimes illustrated by graphic symbols, phantom lines,
diagrammatic representations and fragmentary views. In certain
instances, details which are not necessary for an understanding of
the present invention or which render other details difficult to
perceive may have been omitted.
[0049] Rolling tool 1 in FIG. 1 essentially includes a roller
cradle 2 and a roller 3. Roller 3 is supported by hydraulic
bearings in roller cradle 2. For this, two hydraulic bearing
pockets 4, 5 are used, which are supplied with a liquid during
operation via a hydraulic feed system 6 in roller cradle 2. The
liquid is forced on the tool side via a feed chamber 7 into roller
cradle 2; pressure is also controlled here, since hydraulic feed
system 6 is made up of interconnected pipes.
[0050] Roller 3 includes a rolling member 8 and two spherical
bearing elements 9, 10, which have the form of spherical caps and
are arranged on either side of disc-shaped rolling member 8. Roller
3 may be produced as a single unit or may incorporate the rolling
member and the spherical caps as three separate parts.
[0051] When in operation, bearing area 11 (shown shaded on one side
only of roller 3, but also present symmetrically on the other side)
of roller 3 rests on a fluid pressure cushion in pockets 4 and 5.
Rolling forces that are exerted on a work piece 13 along a pressure
direction 12 are transferred from bearing contact surface 11 and
roller cradle 2 to a connection 7 on the tool side by the pressure
cushion in pockets 4, 5. Thus the rolling pressure between tool 1
and work piece 13 may be kept extremely constant.
[0052] A pivot assembly 14 is provided in roller cradle 2 on both
sides of disc-shaped rolling member 8, so that rolling member 8
with a working periphery 15 may be pivoted outwards into a fillet
17 located outside of a central position 16. In this context,
bearing members 9, 10 rotate in pockets 4, 5 until the roller
reaches its outwardly pivoted position in fillet 17. The angular
momentum applied by roller 3 to counteract this torsion of its axis
of rotation is normally negligible compared with the high pivoting
forces generated by the high rolling force.
[0053] Working periphery 15 is formed by the strip-shaped area that
is connected with fillet 17 of work piece 13 when roller 3 rolls
along the length thereof. In the embodiment shown, the work piece
contact area is rather narrower--relative to an axis of rotation 18
of roller 3--than disc-shaped rolling member 8. Bearing contact
area 11 is arranged symmetrically on both sides of the work piece
contact area and at a certain distance from the rolling member.
Extended pivot bearing areas 19, 20 and the spherical shape thereof
attached to bearing contact area 11 serve to alter a bearing
surface 21 (shown on one side only of roller 3) and thus not the
size of the bearing contact area. To this extent, the ratio of
forces is also unaffected.
[0054] Advantageously and in keeping with the basic inventive
concept, the geometry of the working periphery or the work piece
contact area on the roller is determined by the geometry of the
work piece; at the same time, however, the roller bearing on the
tool side and thus also the force application is provided via a
bearing contact area that is separate therefrom. The bearing
contact area is made up of spherical caps or spherical zones on
both sides of the work piece contact area.
[0055] The centre point of the sphere is situated on central axis
16 and on axis of rotation 18. In this way, the roller may be
supported either hydrostatically or mechanically by means of a
counter roller. In any case, it is assured that the roller may be
pivoted outwards about the centre point of the sphere to lie flush
with an eccentrically positioned radius for rolling without causing
blockages or changes to the seal gap. Moreover, the functions of
support and force application are no longer impaired by damage to
the roller.
[0056] A tool variant that may also be used in the infeed process
includes an axial bearing on the tool side on both end faces of the
roller. This bearing may be provided either mechanically or via
ball, needle or cylindrical roller bearings. However, for the
conditions cited, it is advantageous if the axial bearing is also
of hydrostatic type. This applies particularly if the bearing for
the rollers is hydrostatic.
[0057] Roller 30 in FIG. 2 also includes a roughly disc-shaped
rolling member 31, which defines the maximum width of the work
piece contact area, and barrel-shaped bearing members 32, 33
arranged on either side on rolling member 31. In the cross-section
shown, a bearing contact surface 34 (indicated on only one side of
roller 31) is formed by a segment 35 of a circle arc about a first
centre point 36. Like the entire roller 30, the bearing members are
arranged rotationally symmetrically about an axis of rotation 37,
thereby creating a second centre point 38 in the cross-section
shown, about which the surface of bearing contact area 40 not
currently resting flush on a bearing 39 is drawn in an arc. Centre
points 36, 38 lie on a central axis 41, which is also situated in
the plane of the working periphery.
[0058] The bearing with the circle arc-shaped cross-section enables
roller 30 to pivot outwards about centre point 36 that is offset
from the bearing. Roller 30 in FIG. 3 has completed such a pivoting
motion. It has shifted with its barrel-shaped bearing members 32,
33 tangentially along bearing surfaces 42, 43 on the tool side, but
still rests on new bearing contact area 44 exactly as wide as
bearing contact area 40 of FIG. 2, unless it is shifted beyond a
swivel bearing range 45.
[0059] Since the common centre point of the barrel-shaped bearing
areas is located outside roller 31, the roller is supported
securely for static purposes. The bearing shown is thus suitable
even for infeed deep rolling operations with work pieces that are
cylindrical or have large radii. Mechanical force transfer bearings
are suitable for use as bearings on the tool side.
[0060] Roller 50 in FIG. 4 essentially includes a disc-shaped
roller 51 and two spherical caps 52, 53 for supporting roller 50.
Since a centre point 54 of spherical caps 52, 53 is located on an
axis of rotation 55 of roller 50, this may be moved easily about
centre point 54 through a pivot angle 56 (shown in FIG. 5) without
changing the bearing ratios. A bearing of such kind is suitable for
both mechanical and hydraulic force application. Even in the fully
pivoted position, as indicated in the roller 50 shown, a bearing
contact area 57, 58 remains entirely separate from a work piece
contact area 59.
[0061] The versatility of the invention is also shown by a deep
rolling roller, a deep rolling tool and a method for deep rolling a
surface fillet of a work piece.
[0062] A description of an exemplary application follows with
reference to FIGS. 6, 7, 8 and 9. FIG. 6 shows a cross-section of a
part of a deep rolling tool having a roller cradle 106 and two deep
rolling rollers 101, 124 supported therein by hydrostatic means.
FIG. 7 shows roller cradle 106 of FIG. 6, in which deep rolling
roller 124 has been removed and the sealing geometry for roller 124
in empty chamber 126 thereof is shown diagrammatically. FIG. 8
shows a view below empty roller chamber 126 along line VIII-VIII in
FIG. 7. FIG. 9 shows a cross-section of a variant for a tool
according to the invention with two hollow cantilevered rollers.
FIGS. 10, 11 and 12 show a tool or the rollers thereof according to
the prior art for deep rolling crankshaft splines.
[0063] The objective in this exemplary application is to fixed roll
fillets on parts 130 subject to high dynamic loads. These may be
rotationally symmetrical parts 130 with a diameter 132 and a
shoulder 131. These be rotationally symmetrical components may be
delimited by a similar shoulder 133 on the opposite side. This
arrangement is found chiefly in crankshafts, wherein the diameter
132 may be a crank pin or a bearing pin.
[0064] The production tolerances applied for crankshafts mean that
shoulders 131, 133 may be located in axially offset positions 131',
131"; 133', 133". However, deep rolling can only be performed
optimally if roller radius 102 is in full surface contact with
fillet 102' of the work piece. Since dimensional deviations
occasionally occur in work pieces, the deep rolling rollers must be
capable of adjusting to the actual position of the shoulders every
time they are used.
[0065] Previous mechanical systems as shown in FIG. 10 operate with
deep rolling rollers 140, which are pressed against work piece
radii 144 by thrust rings 141. To achieve this, forces 142 are
applied to the rollers opposite the processing points. This
application of force generates strong Hertz compression in both the
thrust rings and the rollers. Together with the Hertz compression
at the processing points 144, which is also high, this loading
shortens the service life of the deep rolling rollers. The
mechanical arrangement also provides for a pivoting motion 143 to
compensate for production tolerances. However, this pivoting motion
takes place about the centre points of the radius 144.
[0066] Previous hydrostatic systems such as those shown in FIGS. 11
and 12 avoided stressing the rollers with the mechanical
application of force. However, the pivoting motion about centre of
rotation 150 necessary for this variant too cause the deep rolling
rollers to shift position in the roller cradle. This misalignment
caused profile distortions of almost 0.2 mm. This altered the gap
insulation to an unacceptable degree. This led to excessive leakage
and caused the system to function unreliably.
[0067] The use of a hydrostatic bearing for a deep rolling roller
and an automatic replenishment system in conjunction with such a
tool is known from European Patent EP 0 353 376 B1. An important
property of hydrostatic bearings is the gap insulation between the
roller and the roller cradle. According to this, during operation a
certain quantity of pressure fluid escapes constantly along sealing
line 113, 114, 115. This allows the deep rolling roller 101 to
rotate without contact and thus also without friction. The fluid
that escapes through the seal gap must be substantially less than
the maximum quantity that can be supplied by the force pump through
connector hole 127. If this is not the case, the fluid pressure in
pressure chamber 126 falls and rolling force F is reduced. This is
not acceptable. The following system 106' responds to an upward
movement 125 that enlarges the seal gap slightly when the position
of the roller cradle changes relative to the roller. If the
pressure in chamber 126 is too low, the roller cradle is lowered
slightly in direction 125' by the following system, so that the
circumferential seal gap is narrowed and the fluid pressure
increases again.
[0068] Even with an automatic following system and a hydraulic
bearing for a deep rolling roller, it has not been possible until
now to achieve optimum results for rolling grooves with varying
dimensions in a work piece using known methods. The present
invention is also represents a solution to the task underlying the
use that will now be described in detail, that of providing a tool
which is able to assure optimum surface treatment by economical
means.
[0069] The object according to this aspect of the invention is
solved with a deep rolling roller, a deep rolling tool and a method
for deep rolling as illustrated by the two embodiments in FIGS. 6
to 9 and the following description:
[0070] The deep rolling rollers according to the present invention
are capable of adapting to match the actual positions of the
shoulders at each use. For this purpose, the deep rolling rollers
according to FIG. 6 and FIG. 9 are mounted on the roller cradles in
such manner that they are able to be pivoted about centreline 104'.
Moreover, the deep rolling rollers are also rotatable about their
own centrelines 101'. Both movements may be performed
simultaneously. As the rolling process continues, a plastic
deformation takes place in the area of radius 102. Rolling force F
must remains constant throughout the entire process. This is
assured by the fact that the deep rolling rollers may be pivoted
further even during the process with rotation in an arced direction
125 about centreline 104'. In the case of crankshafts, it is
helpful to install a second, symmetrically arranged deep rolling
roller 124 to process both fillets at the same time. This
arrangement has the further advantage that horizontally acting
forces F act in opposing directions and thus cancel each other out.
Neither the work piece nor the tool is exposed to horizontal
forces. A setup of this kind is illustrated in FIG. 6.
[0071] The following features of a hydrostatic deep rolling roller
101 with radii 102 or another profile corresponding to the work
piece contour are highlighted particularly in FIGS. 6 to 8:
[0072] At least one spherical delimiting surface 103 (rounded end
with radius 9)
[0073] Centreline 104 of the rounded end is located on centreline
104', centreline 104' forming the cylindrical axis of the convexity
on sealing surface 107. Sealing surface 107 seals chamber 126 along
the planar lateral surface 105 of roller 101 except for a hydraulic
escape gap.
[0074] Plan surface 105
[0075] Roller cradle 106 with seal gap 107, conformed cylindrically
aligned on centreline 104', provided with radius 108.
[0076] Cylindrical shape of sealing surface 110 with radius 109,
also aligned on centreline 104.
[0077] Recesses in the roller cradle furnished with radius zones
102', connecting sealing surfaces 110 and 107. Radius zones 102'
extend in an arc corresponding to centreline 111 at a distance from
radius 112 of centreline 104'.
[0078] Roller cradle and roller form a hydrostatic seal gap in the
area of contact lines 113, 114, 115.
[0079] Roller cradle connected with hydrostatic following system
106' as described in European Patent EP 0 353 376 and corresponding
national and international patents of this patent family.
[0080] When the tool is in the rest position, spring elements 126
pivot the deep rolling rollers back to a point so that the rollers
cannot collide with the work piece as the processing point
approaches or recedes.
[0081] Features of an alternative configuration (FIG. 9) are
largely similar to those of a hydrostatic roller as described
above, but with the following features:
[0082] Concave spherical surface 120, conformed with radius 121
relative to centre point 104.
[0083] Roller cradle 123 conformed with convex spherical or
approximately spherical surface 122, also with radius 121 relative
to centre point 104.
[0084] Particularly with reference to the concrete, second task
described, the following solutions are therefore also claimed as
falling within the scope of the present invention:
[0085] a) A deep rolling roller having a rolling area and two
lateral areas, wherein when the roller is in use the rolling area
is intended to run rotatingly along a work piece, wherein the deep
rolling roller is characterized in that it has an at least
approximately spherical shape in one lateral area and the opposing
lateral area is at least approximately flat.
[0086] b) A deep rolling roller having a rolling area and two
lateral areas, wherein when the roller is in use the rolling area
is intended to run rotatingly along a work piece, and which is
characterized in that the deep rolling roller is rotationally
symmetrical about a rolling axis, but at the same time has mirrored
symmetry with respect to all planes that are perpendicular to the
rolling axis.
[0087] c) A deep rolling roller having a rolling area and two
lateral areas, wherein when the roller is in use the rolling area
is intended to run rotatingly along a work piece, and which is
characterized by a similarly designed, at least approximately
spherical curvature of both lateral areas of the deep rolling
roller.
[0088] d) A hydrostatic deep rolling roller tool having a roller
particularly according to one of solutions (a), (b) or (c), wherein
the tool is equipped with a roller cradle with a chamber to
accommodate and guide the deep rolling roller, and which is
characterized in that the chamber has a roller aperture and/or an
cross-section aligned at least approximately parallel therewith,
and which extends lengthwise essentially between two radius zones,
a first delimitation having a convex curvature and the opposite
delimitation having a concave curvature or at least being
approximately straight.
[0089] e) A hydrostatic deep rolling roller tool having a roller
particularly according to one of solutions (a) to (c), wherein the
tool is equipped with a roller cradle having a chamber to
accommodate and guide the roller and which is characterized by a
convexity having an at least approximately cylindrical curved
surface shape on an outer wall of the chamber, wherein one opposing
sealing wall of the chamber is preferably conformed spherically,
wherein a centre point of the spherical shape is on an axis of the
cylinder. Alternatively, the outer sealing wall may also be
spherical in shape, in which case the centre points of both spheres
are superimposed on one another.
[0090] f) A method for deep rolling particularly a surface channel
of a work piece, preferably with a deep rolling roller according to
one of the solutions (a) to (c) and/or a tool according to one of
solutions (d) or (e), and which is characterized in that a deep
rolling roller is subjected to hydrostatic pressure between two
sealing walls in a roller cradle, which pressure exerts a deep
rolling force on the work piece with an escape through a seal gap
extending circumferentially around the roller, wherein the roller
shifts out of a chamber in a roller cradle due to the hydrostatic
load until equilibrium of the roller is established between fluid
loading and work piece, wherein the roller performs a pivoting
movement when moving out of the chamber on its path to the work
piece surface.
[0091] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit of the present
invention. The embodiments were chosen and described in order to
best explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
* * * * *