U.S. patent application number 10/887212 was filed with the patent office on 2005-09-22 for method and apparatus for making metallic, non-rotationally symmetric rings.
This patent application is currently assigned to MANNESMANNROHREN-WERKE AG. Invention is credited to Forster, Wilfried, Stephan, Roland.
Application Number | 20050204556 10/887212 |
Document ID | / |
Family ID | 33395068 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050204556 |
Kind Code |
A1 |
Stephan, Roland ; et
al. |
September 22, 2005 |
Method and apparatus for making metallic, non-rotationally
symmetric rings
Abstract
In a method of making a metallic, non-rotationally symmetric
ring with substantially constant wall thickness about its
circumference, in particular a cam ring, from a circular ring, a
circular ring is mechanically machined on both inner and outer
sides with an edge-shortening form element and then intermittently
fed by a transport belt to an area between two continuously closing
and opening die members. The transport belt is hereby positioned
with its upper strand below the die members. After closing the die
members, the circular ring is shaped through cold forming to a
non-rotationally symmetric shape whereby the die members continue
to maintain the closed position momentarily before being opened for
removal of the non-rotationally symmetric ring from the area
between the die members.
Inventors: |
Stephan, Roland; (Riesa,
DE) ; Forster, Wilfried; (Groditz, DE) |
Correspondence
Address: |
HENRY M FEIEREISEN, LLC
350 FIFTH AVENUE
SUITE 4714
NEW YORK
NY
10118
US
|
Assignee: |
MANNESMANNROHREN-WERKE AG
Mulheim
DE
|
Family ID: |
33395068 |
Appl. No.: |
10/887212 |
Filed: |
July 8, 2004 |
Current U.S.
Class: |
29/888.01 ;
29/888.1 |
Current CPC
Class: |
Y10T 29/49231 20150115;
B21D 53/16 20130101; Y10T 29/49293 20150115 |
Class at
Publication: |
029/888.01 ;
029/888.1 |
International
Class: |
B21K 003/00; B21K
001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2003 |
DE |
103 32 069.5 |
Claims
What is claimed is:
1. A method of making a metallic, non-rotationally symmetric ring
with substantially constant wall thickness about its circumference,
in particular a cam ring, comprising the steps of: mechanically
machining both sides of a circular ring to provide on the inside
and outside edge-shortening form elements; feeding the circular
ring incrementally to an area between two continuously closing and
opening die members; closing the die members for cold forming the
circular ring into the shape of a non-rotationally symmetric ring;
maintaining the die members in closed position for an additional
short time; and opening the die members for removal of the
non-rotationally symmetric ring from the area between the die
members.
2. The method of claim 1, wherein the circular ring is cold-formed
in horizontal disposition.
3. The method of claim 1, and further comprising the step of
continuously lubricating an inner contour surface of each of the
die members.
4. The method of claim 1, wherein the edge-shortening form element
is a radius.
5. The method of claim 1, wherein the edge-shortening form element
is a bevel.
6. Apparatus for making a metallic, non-rotationally symmetric ring
with substantially constant wall thickness about its circumference,
in particular a cam ring, from a circular ring, comprising: a frame
bed; a forming tool supported by the frame bed and having an inner
contour which approximates a finished contour of a non-rotationally
symmetric ring, said forming tool including two die members
constructed in the form of two flat disks in opposite disposition
and movable back and forth; an endless transport belt arranged in
an area between the die members and so operated as to move in a
production clock cycle and to move transversely to the die members,
said transport belt having an upper strand extending in immediate
proximity underneath the die members.
7. The apparatus of claim 6, wherein the upper strand has a top
side spaced from an underside of the die members at a distance
which is at least 0.05 mm.
8. The apparatus of claim 6, and further comprising a machining
device for shortening an inside edge and an outside edge of a
circular blank before the circular ring is placed between the die
members for shaping the circular blank into the non-rotationally
symmetric ring.
9. The apparatus of claim 8, wherein the machining device is
constructed to radius the inside and the outside edges.
10. The apparatus of claim 8, wherein the machining device is
constructed to bevel the inside and the outside edges.
11. The apparatus of claim 8, wherein the inside and the outside
edges are shortened by up to one millimeter.
12. The apparatus of claim 6, wherein the transport belt is
provided in midsection with vertical engagement pins which are
spaced apart in length direction of the transport belt.
13. The apparatus of claim 6, wherein the die members have end
surfaces in confronting relationship, each said end surface
provided with two centering elements.
14. The apparatus of claim 13, wherein the centering elements of
one die member are configured with a triangular pointed end, and
the centering elements of the other die member are configured with
a complementary recess.
15. The apparatus of claim 6, and further comprising a press
arranged downstream of the forming tool and having an upper die and
a lower die.
16. The apparatus of claim 15, wherein the forming tool and the
press are integrated in a common shaping unit.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of German Patent
Application, Serial No. 103 32 069.5, filed Jul. 8, 2003, pursuant
to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates, in general, to a method and
apparatus for making metallic, non-rotationally symmetric
rings.
[0003] German Pat. No. DE 101 34 776 A1 describes a method for
making metallic, non-rotationally symmetric rings with a constant
wall thickness about their circumference. Hereby, circular ring
blanks of equal width are severed from a hot-rolled pipe and
mechanically machined on all sides. The non-rotationally symmetric
shape is produced by cold forming carried out in a forming tool
having two die members and configured with an inner contour which
approximates the final contour of the non-rotationally symmetric
ring.
[0004] It would be desirable and advantageous to provide an
improved method and apparatus for making metallic, non-rotationally
symmetric rings to obviate prior art shortcomings and to provide a
cold-forming operation which is easy to implement and carried out
at a high cycle rate.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the present invention, a method
of making a metallic, non-rotationally symmetric ring with
substantially constant wall thickness about its circumference, in
particular a cam ring, includes the steps of mechanically machining
both sides of a circular ring to provide on the inside and outside
edge-shortening form elements, feeding the circular ring
incrementally to an area between two continuously closing and
opening die members, closing the die members for cold forming the
circular ring into the shape of a non-rotationally symmetric ring,
maintaining the die members in closed position for an additional
short time, and opening the die members for removal of the
non-rotationally symmetric ring from the area between the die
members.
[0006] The present invention resolves prior art problems by
providing the circular ring during preceding mechanically machining
of the circular ring, on the inside and outside with
edge-shortening forming elements, such as radii and/or bevels, and
continuing to hold the shaped ring for a short time between the
closed die members before being ejected. This mode of operation
results in a simple method that can be carried out at a high cycle
rate. As is generally known, metallic bodies that are subjected to
a cold forming process exhibit a tendency to swell elastically
after the forming tool is opened. By maintaining the die members in
closed position for a short time longer, any shift in the crystal
structure during cold forming is able to "settle" so that the
previously encountered swelling effect is neutralized and the
finished contour of the non-rotationally symmetric ring can be
produced within narrow tolerances.
[0007] According to another feature of the present invention, the
circular ring may be cold formed in horizontal disposition. This
facilitates feeding of the circular ring, on the one hand, and
positioning of the circular ring during cold forming, on the other
hand.
[0008] According to another feature of the present invention, at
least the inner contour surface of each of the die members is
continuously lubricated. In this way, friction between the inner
contour surfaces of the die members and the narrow outer surface
area of the circular ring is decreased.
[0009] According to another aspect of the present invention, an
apparatus for making a metallic, non-rotationally symmetric ring
with substantially constant wall thickness about its circumference,
in particular a cam ring, from a circular ring, includes a frame
bed, a forming tool supported by the frame bed and having an inner
contour which approximates a finished contour of a non-rotationally
symmetric ring, wherein the forming tool includes two die members
constructed in the form of two flat disks in opposite disposition
and movable back and forth, and an endless transport belt arranged
in an area between the die members and so operated as to move in a
production clock cycle and to move transversely to the die members,
with the transport belt having an upper strand extending in
immediate proximity underneath the die members.
[0010] In order to prevent damage to the transport belt as the die
members oscillate, the upper strand of the transport belt has a top
side which is spaced from the underside of the die members at a
distance which is at least 0.05 mm. The following fact is hereby
exploited: Cold forming of the circular ring leads in the region of
greatest deformation, which is generally the region of greatest
deviation from the original circular shape, to minor material
accumulation in the respective edge zone of both end surfaces. To
minimize this effect, the circular ring is provided during the
preceding mechanical machining process on both sides, on the inside
and the outside, with edge-shortening form elements, such as radii
and/or bevels. The extent of edge shortening depends hereby on the
size of the cross sectional area and can amount to one millimeter.
The provided form elements on the outside are used to produce the
required distance between die members and transport belt such that
the die members engage the outer surface area of the circular ring
on the transport belt, whereby the engagement begins only by the
distance of the edge shortening from the disposition of the
circular ring on the transport belt. As a consequence, a direct
contact with the die members is not required for the shaping
process during cold forming in the edge area of the mechanically
machined ring.
[0011] According to another feature of the present invention, the
transport belt may be provided in midsection with vertical
engagement pins, which are spaced apart in length direction of the
transport belt, for supply of the circular rings. Typically, the
forming tool is preceded by an apparatus for singling circular
rings before supply to the forming tool. The singling apparatus
normally includes hereby an open-topped drum which rotates slowly
and is provided on the inside with a screw and a deflector. At the
singling position, the circular ring slides onto the transport belt
via a cage having an outlet above the respective engagement pin.
Stopper pins moving cyclically make sure that only a single ring is
positioned at the end of the cage outlet for subsequent timed
placement of the ring on the transport belt upon the engagement pin
in surrounding relationship thereto. The incremental movement of
the transport belt results in a supply of the circular ring to the
forming tool. After conclusion of the cold forming process and
opening of the die members, the engagement pin engages the
non-rotationally symmetric ring and ejects the ring in the area of
the belt-reversing roller from the transport belt.
[0012] According to another feature of the present invention, the
die members have end surfaces in confronting relationship, with
each end surface provided with two centering elements. In this way,
it is ensured that the die members are precisely positioned in
relation to one another. Suitably, the centering elements of one
die member may be configured with a triangular pointed end, and the
centering elements of the other die member may be configured with a
complementary recess. The legs of the pointed ends and the legs of
the recesses assume hereby the centering function.
[0013] According to another feature of the present invention, a
press may be arranged downstream of the forming tool and have an
upper die and a lower die. Through provision of the press, the
presence of material accumulations, as described above, can be
further decreased. The non-rotationally symmetric ring can hereby
be placed flatly between the dies and then compressed. Suitably,
the forming tool and the press may be integrated in a common
shaping unit. As an alternative to the provision of a press for
minimizing the presence of material accumulations, it is, of
course, also conceivable to simply grind away the material
accumulations, partially or entirely, after conclusion of the final
heat treatment of the rings.
BRIEF DESCRIPTION OF THE DRAWING
[0014] 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:
[0015] FIG. 1 is a longitudinal section of an apparatus for making
metallic, non-rotationally symmetric rings in accordance with the
present invention;
[0016] FIG. 2 is a plan view of the apparatus of FIG. 1;
[0017] FIG. 3 is a sectional view, on an enlarged scale, of the
apparatus, taken along the line III-III in FIG. 2;
[0018] FIG. 4 is a detailed view, on an enlarged scale, of an area
marked X in FIG. 3; depicting the die members in open position;
[0019] FIG. 5 is a sectional view of the area X, depicting the die
members in closed position; and
[0020] FIG. 6 is a front view of a produced cam ring.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] 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.
[0022] Turning now to the drawing, and in particular to FIG. 1,
there is shown a longitudinal section of an apparatus for making
metallic, non-rotationally symmetric rings in accordance with the
present invention. The apparatus includes a forming tool, generally
designated by reference numeral 20 and having an inner contour
which approximates a finished contour of a non-rotationally
symmetric ring to be made. As shown in FIG. 2, which is a plan view
of the apparatus, the forming tool 20 has a frame bed (not shown)
and two die members 1, 2 which are supported by the frame bed and
move cyclically to and fro, as indicated by double arrow 3. It will
be appreciated by persons skilled in the art that the forming tool
20 must contain much mechanical apparatus which does not appear in
the foregoing Figures, e.g. a drive for moving the die members.
However, this apparatus, like much other necessary apparatus, is
not part of the invention, and has been omitted from the Figures
for the sake of simplicity.
[0023] Disposed below the forming tool 20 and moving transversely
to the die members 1, 2 is an endless transport belt 4 which is
looped about belt-reversing rollers 5, 6 at the end zones of the
transport belt 4 and moves in a direction indicated by arrow 10. On
its topside, the transport belt 4 is provided approximately in
midsection thereof with a plurality of engagement pins 7 which are
spaced apart in length direction of the transport belt 4.
[0024] Arranged at the right hand side of FIG. 1 is a feed unit 8,
shown only schematically, to place single ring blanks 9 on the
transport belt 4. The ring blanks 9 are mechanically machined on
all sides and have a circular configuration.
[0025] Shaping of the ring blanks 9 through a cold forming process
in the forming tool 20 to produce, for example, a cam ring 11, as
shown in FIG. 6, is as follows: The ring blanks 9 are delivered
intermittently by the feed unit 8 to the transport belt 4 in such a
manner that an engagement pin 7 enters the opening of the ring
blank 9 at the singling position at the end of the feed unit 8 to
advance the ring blank 9. As the transport belt 4 advances, the
respective ring blank 9 is moved by the engagement pin 7 into the
area between the die members 1, 2 which move cyclically to and fro
between open and closed positions.
[0026] FIG. 2 shows the disposition of a ring blank 9 upstream of
the forming tool 20 and the disposition of a ring blank 9 in the
area between the open die members 1, 2 of the forming tool 20. At
this point, die members 1, 2 close and shape the circular ring
blank 9 into the non-rotationally symmetric cam ring 11 through
cold forming. Before the die members 1, 2 open again, the shaped
cam ring 11 is held in the constrained position, as the closed
position of the die members 1, 2 is maintained for a short time
longer, to thereby control elastic swelling.
[0027] After opening the die members 1, 2, the cam ring 11 is
advanced incrementally by the transport belt 4 until being dropped
into a container 12 at the end of the transport belt 4.
[0028] Turning now to FIGS. 3, 4 and 5, there are shown details of
the apparatus to illustrate the absence of a contact between the
advancing transport belt 4 and the oscillating die members 1, 2. As
the ring blank 9 to be shaped rests flatly on the top surface of
the transport belt 4, the underside of the oscillating die members
1, 2 moves at a distance 13 to the topside of the upper strand of
the transport belt 4 above the transport belt 4. The distance of
the upper strand of the transport belt 4 to the underside of the
die members 1, 2 is at least 0.05 mm. This requires, as shown in
FIG. 5, that the ring blank 9 is provided on both sides, on the
inside and the outside, with edge-shortening form elements 14, such
as radii and/or bevels. As a consequence, the die members 1, 2 bear
only against the outer surface area of the ring blank 9, and the
required distance 13 between the top surface of the transport belt
4 and the underside of the die members 2 is maintained. In other
words, the form elements 14 are provided in the edge areas most
likely to experience material accumulation during the cold forming
process so that material can be displaced into the free space as a
result of the form elements 14 and is prevented from migrating into
the area between the die members 1,2 and the transport belt 4. The
extent of edge shortening depends hereby on the size of the cross
sectional area and can amount to one millimeter.
[0029] The cam ring 11, produced in this way, is shown in FIG. 6,
with those regions that may encounter material accumulation being
marked by reference numeral 15. Material accumulation may occur in
particular in those regions that undergo the greatest deformation
from round to substantially straight. The extent of possible
material accumulation is dependent on the flow behavior of the
material, on the degree of deformation, and on the material
thickness. The present of material accumulation can be minimized
through subsequent cold pressing between two flat dies of a press
or may be eliminated altogether by mechanical machining, such as
grinding. When providing a press, the press and the shaping tool
are integrated in a common shaping unit.
[0030] Although not shown in detail in the drawing, the die members
1, 2 are provided at their confronting end surfaces with a
complementary centering mechanism. An example of such a centering
mechanism includes the provision of two centering pin extending out
from the end surface of one of the die members 1, 2 for engagement
in complementary recesses in the end surface of the other one of
the die members 1, 2. Suitably, the centering pins have a
triangular pointed end for engagement in the complementarily
configured recesses.
[0031] 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.
[0032] 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:
* * * * *