U.S. patent application number 10/435310 was filed with the patent office on 2004-11-11 for method for producing strip-shaped input stock, especially from metal, which is profiled in subsequent sections, and corresponding device.
Invention is credited to Bauder, Hans Jorg.
Application Number | 20040221635 10/435310 |
Document ID | / |
Family ID | 33555873 |
Filed Date | 2004-11-11 |
United States Patent
Application |
20040221635 |
Kind Code |
A1 |
Bauder, Hans Jorg |
November 11, 2004 |
Method for producing strip-shaped input stock, especially from
metal, which is profiled in subsequent sections, and corresponding
device
Abstract
A method is described for producing strip-shaped input stock,
especially from metal, which is profiled in subsequent sections
either on one side or on both sides, by rolling a metal strip in
one or more rolling steps. The method is characterized by carrying
out the following steps: (a) tensioning the metal strip (16), (b)
positioning the metal strip (16) in a rolling gap (13) that is
defined by a roller (12) and a movable plate (67) relative the
roller (12), and (c) positioning the plate (67) relative the roller
(12). Steps (b) and (c) are successively or simultaneously carried
out or are carried out in a timewise overlapping manner or in a
successive inverse order, and step (c) can also be carried out
before step (a).
Inventors: |
Bauder, Hans Jorg;
(Muhlacker, DE) |
Correspondence
Address: |
Peter L. Berger, Esq.
Levisohn, Lerner, Berger & Langsam, LLP
Suite 2500
757 Third Avenue
New York
NY
10017
US
|
Family ID: |
33555873 |
Appl. No.: |
10/435310 |
Filed: |
May 9, 2003 |
Current U.S.
Class: |
72/192 |
Current CPC
Class: |
B21B 37/54 20130101;
B21C 37/02 20130101; B21B 1/32 20130101; B21B 1/42 20130101; B21B
13/00 20130101; B21B 31/24 20130101; B21H 8/00 20130101 |
Class at
Publication: |
072/192 |
International
Class: |
B21B 021/00 |
Claims
1. Method for producing strip-like input stock from metal, which is
profiled in subsequent sections on one or both sides, by rolling a
metal strip in one or more rolling steps, comprising the following
process steps: (a) Tensioning the metal strip (16); (b) positioning
the metal strip (16) in a rolling gap (13), which is defined by a
roller (12) and a movable plate (67), relative to the roller (12);
(c) positioning the plate (67) relative to the roller (12); steps
(b) and (c) being carried out either successively or simultaneously
or in timely overlapping fashion or in a successive inverse order,
or step (c) being carried out before step (a); (d) grooving the
metal strip (16) with the roller (12) by reducing the distance of
the shell surface of the roller (12) to the metal strip (16), the
metal strip (16) being maintained steady or being moved only slowly
at least during the beginning phase of the grooving step, and the
roller (12) being rotated not at all or only very slowly so that
the metal strip (16) remains under tensile stress in the rolling
gap (13); (e) rolling a section of the metal strip (16) in the
rolling gap (13) by rotating the roller (12) and moving the plate
(67) in a rectilinear manner in synchronism with the rotation of
the roller (12); and (f) releasing the metal strip (16) by opening
the rolling gap (13); steps (b) to (f) being repeated for every
section to be profiled of the metal strip (16).
2. The method as defined in claim 1, characterised in that the
metal strip (16) is profiled on one side only.
3. The method as defined in claim 1, characterised in that the
metal strip (16) is at first profiled on one side only and is then
turned over so that its profiled side faces the plate (67), and
that the metal strip (16) is then profiled on its other side.
4. The method as defined in claim 3, characterised in that
following profiling of the one side of the metal strip (16) the
plate (67) is exchanged against another plate provided with a
profile complementary to the profile previously rolled into the
metal strip (16).
5. The method as defined in any of the preceding claims,
characterised in that a flat plate (67) is used if the metal strip
(16) is profiled only on one side or initially only on one
side.
6. The method as defined in any of the preceding claims,
characterised in that recesses (80) with closed borders are formed
in the metal strip (16), for which purpose the plate (67) used is
one provided with bumps (81) complementary to the recesses
(80).
7. The method as defined in claim 6, characterised in that a
moderate reduction of the overall thickness of the metal strip (16)
is effected by having the roller (12), arranged opposite the plate
(67), acting on the metal strip (16) at the same time the recesses
(80) are formed.
8. The method as defined in claim 7, characterised in that the
moderate reduction in thickness of the metal strip (16) is equal to
approximately 10% of its previous thickness.
9. The method as defined in claim 6, 7 or 8, characterised in that
the recesses (80) are formed in several steps and that the
steepness of the circumferential wall of the recesses (80)
increases from one step to the next.
10. The method as defined in any of the preceding claims,
characterised in that the tensile stress in the metal strip (16) is
kept constant during the grooving and the rolling phases.
11. The method as defined in any of the preceding claims,
characterised in that when several rolling steps are carried out
for profiling the metal strip (16) in the respective sections, the
process steps (b) to (e) are repeated, for which purpose the metal
strip (16) is recalled after opening the rolling gap (13), and the
recalled section of the metal strip (16) is rolled once again in
the rolling gap (13) under the action of the same roller (12).
12. The method as defined in any of the preceding claims,
characterised in that the metal strip (16) is not rolled during the
recalling phase.
13. The method as defined in any of claims 1 to 11, characterised
in that the metal strip (16) is rolled also during the recalling
phase.
14. The method as defined in any of the preceding claims,
characterised in that plate (67) is floatingly supported.
15. The method as defined in any of the preceding claims,
characterised in that the roller (12) defines the rolling gap (13)
from above, and that the plate (67) is arranged in horizontal
position and is supported by a back-up roller (15).
16. The method as defined in any of the preceding claims,
characterised in that the plate (67) is supported on both sides of
the rolling gap (13).
17. The method as defined in claim 15 or claim 16, characterised in
that the plate (67) is supported on both sides of the rolling gap
(13) by rolling elements.
18. The method as defined in any of the preceding claims,
characterised in that the surface of the plate (67), facing the
roller (12), is configured to be flat.
19. The method as defined in any of the preceding claims,
characterised in that the plate (67) is moved during the rolling
process by being entrained by the driven roller (12) and/or the
metal strip (16).
20. The method as defined in any of claims 13 to 17, characterised
in that the plate (67) is moved by its back-up roller (15), which
is driven for that purpose.
21. The method as defined in any of the preceding claims,
characterised in that the metal strip (16) is recalled by a length
shorter than the circumference of the roller (12).
22. The method as defined in any of the preceding claims,
characterised in that the metal strip (16) is simultaneously
equalised by the rolling process.
23. The method as defined in any of the preceding claims,
characterised in that using the roller (12) a profile is rolled,
into the sections of the metal strip (16), the profile extending
over the full width of the metal strip (16), so that the metal
strip (16) exhibits a thickness that varies over its length.
24. The method as defined in claim 23, characterised in that a
periodically recurring profile is rolled into the metal strip
(16).
25. The method as defined in any of the preceding claims,
characterised in that the roller (12), the plate (67) and the metal
strip (16) are accelerated and braked, resp., in synchronism and to
the same degree during the rolling steps.
26. The method as defined in any of the preceding claims,
characterised in that for producing strip-shaped input stock with a
selected profile, which recurs in successive sections of the input
stock, the sections to be profiled of the metal strip (16) are
guided through the rolling gap (13) in steps of predetermined
lengths, and the height of the rolling gap (13) is reduced from one
rolling step to the next until the desired depth of the selected
profile of the input stock is obtained in the respective sections
of the metal strip (16).
27. The method as defined in any of the preceding claims in
combination with claim 14, characterised in that in the first
rolling step the metal strip (16) is only reduced in thickness, but
is not yet profiled.
28. The method as defined in claim 27, characterised in that the
metal strip (16) is equalised in the first rolling step.
29. The method as defined in claim 27 or claim 28, characterised in
that the reducing rolling step is followed by one or more profiling
rolling steps in one and the same rolling gap (13).
30. The method as defined in claim 27, 28 or 29, characterised in
that the length (L2) of the reducing rolling step, during which the
metal strip may also be equalised, is longer than the length (L1)
of the next following profiling rolling step, taking into account
the elongation of the reduced section occurring in the next
following profiling step.
31. The method as defined in any of claims 27 to 30, characterised
in that following the reducing rolling step the metal strip (16) is
recalled by a length shorter than the length (L2) of the reducing
rolling step and longer than the length (L1) of the next following
profiling rolling step to be performed on the same section of the
metal strip (16).
32. The method as defined in any of the preceding claims in
combination with claim 14, characterised in that it is performed in
a roll stand (2), in which the surface of the roller (12) includes
a profiled section (35, 40) having a contour which together with
the plate (67) defines the rolling gap (13).
33. The method as defined in any of the preceding claims,
characterised in that the roller (12) has a cylindrical shell which
is preferably subdivided into segments of equal or different
diameter.
34. The method as defined in any of claims 1 to 32 in combination
with claim 19, characterised in that prior to rolling a profile the
metal strip (16) is initially equalised in the rolling gap (13),
with moderate reduction of its thickness, between the roller (12)
and the plate (67) in steps having a length (L2) not shorter than
the length (L1) of the first profiling rolling step, and is then
recalled by a step at least equal to the length (L1) of the first
profiling rolling step and maximally equal to the second length
(L2), whereafter the profile is rolled into the recalled section of
the metal strip (16), and that for equalising the metal strip (16)
the shell of the roller (12) has a cylindrical circumferential
section (36) separate from those one or more profiled
circumferential sections (35, 40) that exhibit a non-cylindrical
contour.
35. The method as defined in any of the preceding claims,
characterised in that during rolling of the metal strip (16) the
roller (12) of the roll stand (2) is displaced for varying the
height of the rolling gap (13).
36. The method as defined in claim 35, characterised in that the
roller (12) is displaced by a servo drive (32, 34, 44).
37. The method as defined in claim 36, characterised in that one or
two electric motors (34) or one or two short hydraulic cylinders
are used for the servo drive.
38. The method as defined in any of claims 35 to 37, characterised
in that the displacement of the roller (12) is effected with the
aid of a program-controlled drive (32, 33, 34, 44), the profile to
be produced in the respective rolling step being stored in a
programmable control unit (43) as control curve for the drive (32,
33, 34, 44) effecting the displacement of the roller (12).
39. The method as defined in any of claims 35 to 38, characterised
in that the roller (2) has a notch (45), which is parallel to the
axis of the roller (2).
40. The method as defined in any of the preceding claims,
characterised in that the roller (12) is driven in synchronism with
the feeding motion of the metal strip (16).
41. The method as defined in any of the preceding claims in
combination with claim 18, characterised in that a relieved portion
(37, 38, 39) is provided in the shell surface of the roller (12)
between the circumferential sections (35, 38, 40) which are active
during the rolling process, which relieved portion extends over a
circumferential angle sufficient to ensure that the circumferential
section (35, 36, 40), which is active during the rolling process,
will groove the metal strip (16) only after the metal strip (16)
has been released by the circumferential section active during the
preceding rolling step.
42. The method as defined in any of the preceding claims,
characterised in that the metal strip (16) to be rolled is uncoiled
from a first coiler (5) and the rolled metal strip (16) is wound up
on a second coiler (6), and that the rotary speed of the roller
(12) and the circumferential speed of the coilers (5, 6) are
matched, especially during the phase when the roller (12) grooves
the metal strip (16).
43. The method as defined in any of the preceding claims,
characterised in that grooving by the roller (12) is effected at
reduced rotary speed of the roller (12) and, correspondingly, at
reduced feeding speed of the metal strip (16), and that the
movements are then accelerated.
44. The method as defined in any of claims 1 to 40, characterised
in that the metal strip (16) is recalled by means of a first
gripper mechanism (52).
45. The method as defined in claim 44, characterised in that by
means of the first gripper mechanism (52) the metal strip (16) is
also advanced for rolling.
46. The method as defined in claim 43 or claim 44, characterised in
that the metal strip (16) is pulled during the rolling process with
the aid of a second gripper mechanism (53) which engages that
section of the metal strip (16) that leaves the rolling gap
(13).
47. The method as defined in any of the preceding claims,
characterised in that a tensile stress is continuously maintained
in the metal strip (16) during rolling and also during recalling of
the strip.
48. The method as defined in any of the preceding claims,
characterised in that a tensile stress is continuously maintained
in the metal strip (16) during the grooving of the metal strip (16)
by the roller (12).
49. The method as defined in any of the preceding claims
characterised in that the width of the metal strip (16) is so
selected to allow two or more of the objects, which are intended to
be punched out from the input stock formed by the rolling process,
can be punched out one beside the other across the width of the
metal strip (16).
50. The method according to any of the preceding claims as applied
to strips consisting of a plastic material and to strips consisting
of a compound material based on a plastic material or including a
plastic material as substantial component.
51. Device for producing strip-shaped input stock, especially from
metal, by rolling a strip (16), especially for performing the
method defined in claim 1 or claim 46, having a roll stand (2) in
which a roller (12) defines a rolling gap (13), and having
recalling means (5, 52) for the strip (16) arranged on the intake
side of the rolling gap (13), characterised in that a drive motor
(7, 54), especially a servomotor, is provided for the recalling
means (5, 52), which drive motor permits the strip (16) to be
recalled in steps of a predeterminable length, and that the rolling
gap (13) is additionally defined by a plate (67) that faces the
roller (12) and can be linearly displaced, and can be driven in
synchronism with the roller (12) and/or with the strip (16) in the
predetermined direction of movement of the strip (16) in the
rolling gap (13), and can also be driven and recalled independently
of the strip (16).
52. The device as defined in claim 51, characterised in that the
plate (67) is arranged below the roller (12).
53. The device as defined in claim 51 or claim 52, characterised in
that the height of the rolling gap (13) is variable.
54. The device as defined in claim 51 for producing strip-shaped
input stock, having a selected profile which recurs in successive
sections of the input stock, characterised in that the roller (12)
and/or the plate (67) can be displaced during the rolling operation
in upward and downward direction in the roll stand (2) in
controlled fashion, namely by a distance determined by the selected
profile and in response to the feeding motion of the strip
(16).
55. The device as defined in any of the preceding claims 51 to 54,
characterised in that the roller (12) has a cylindrical shell
surface.
56. The device as defined in claim 53 for producing strip-shaped
input stock, having a profile which recurs in successive sections
of the input stock characterised in that the shell surface of the
roller (12) has two or more separate circumferential sections (35,
36, 40), that follow each other in the circumferential direction
and that do not all exhibit the same contour.
57. The device as defined in any of claims 51 to 56, wherein the
recalling means for the strip (16) is a first coiler (5).
58. The device as defined in any of claims 51 to 56, wherein the
recalling means for the strip (16) is a first gripper mechanism
(52).
59. The device as defined in any of claims 51 to 58, wherein a
pulling device (6, 53) for the strip-shaped input stock is provided
on a discharge side of the rolling gap (13).
60. The device as defined in claim 59, wherein the pulling device
is a second coiler (6) intended to wind up the strip-shaped input
stock.
61. The device as defined in claim 59, wherein the pulling device
is a second gripper mechanism (53).
62. The device as defined in claim 56, wherein the roller (12) has
a cylindrical circumferential section (36).
63. The device as defined in any of claims 51 to 62, wherein the
roll stand (2) is designed as an equalising rolling mill.
64. The device as defined in any of claims 51 to 63, wherein the
drive motor (7, 52) for the recalling device (5, 52) provided on
the intake side of the rolling gap (13) is an electric
servomotor.
65. The device as defined in any of claims 51 to 64, wherein the
pulling device (6, 53) provided on the discharge side of the
rolling gap (13) is driven by an electric servomotor (8, 55).
66. The device as defined in any of the preceding claims,
characterised in that a roller coupled to an incremental rotary
transducer, which can be rotated by the strip (16) running over it,
is associated to the recalling device (5, 52) and/or the pulling
device (6, 53).
67. The device as defined in any of claims 51 to 66, wherein the
roller (12) and the plate (67), respectively, are engaged on their
sides facing away from the rolling gap (13) by a back-up roller
(14, 15), respectively, whose roller necks (25) preferably can be
prestressed in their roller neck bearings (26) in order to reduce
their bearing play.
68. The device as defined in any of claims 51 to 67, wherein the
roller (12) is driven intermittently so that during the advance
motion of the strip (16) it is driven in synchronism with the
pulling device (6, 53) provided on the discharge side of the
rolling gap (13), whereas when the recalling device (5, 52)
provided on the intake side of the rolling gap (13) is driven in
reverse direction for the purpose of maintaining the strip tension
and for recalling the strip (16), it is temporarily stopped and/or
repositioned by rotating it in forward or in reverse direction.
69. The device as defined in any of claims 51 to 68, wherein the
circumferential speed of the roller (12) and the speed of the
pulling device (6, 53), and preferably also the speed of the
recalling device (5, 52) can be controlled at desire.
70. The device as defined in claim 53 or claim 54, wherein one or
more servo drives (32, 33, 34, 44) are provided for displacing the
roller (12).
71. The device as defined in claim 70, wherein each of the servo
drives (32, 33, 34, 44) comprises an electric motor (34) or one or
two short hydraulic cylinders.
72. The device as defined in claim 65, wherein an electronic
control unit (43) is provided in which the displacement of the
roller (12) required for an envisaged profile is stored as curve,
preferably digitally, and wherein the servomotors (7, 8; 54, 55) of
the recalling device (5, 52) and the pulling device (6, 53), a
servomotor (42) for rotation of the roller (12) and one or more
setting drives (32, 33, 34) with an incremental rotary transducer
(44) for the roller (12) are connected with that control unit (13),
and wherein preferably a servomotor is also provided for the
back-up roller (15) that may be provided for the plate (67).
73. The device as defined in any of claims 51 to 72, wherein the
sense of rotation of the roller (12) and of the coilers (5, 6) can
be reversed for rolling in both directions.
74. The device as defined in any of claims 51 to 73, wherein the
roller (12) has a notch (45) parallel to its axis.
Description
[0001] The invention relates to a method for producing strip-shaped
input stock, especially from metal, which is profiled in subsequent
sections, and a corresponding device.
[0002] DE 195 04 711 C2 describes a method for producing
strip-shaped input stock from metal using rollers of a roll stand
that define a rolling gap in which a metal strip is rolled in two
or more than two rolling steps. The operation of the method is such
that a metal strip is rolled repeatedly, being continuously guided
from its beginning to its end through a roll stand, the working
direction of which is then reversed so that thereafter the metal
strip is run through the roll stand once again over its full
length, but now in reverse direction.
[0003] From DE-PS 104 875 it has been known to profile strip-shaped
or plate-shaped workpieces in a single step, for the production of
tubes. A similar method is disclosed by DE 197 04 300 A1 for the
production of profiled blanks, especially of car body sheets.
[0004] A reciprocating rolling method for the production of thin
strips from thick input stock is described in DE-PS 638 195. In the
case of this method, the input stock is shaped step by step with a
high degree of deformation, being passed through the rolling gap in
reverse direction to the usual rolling direction.
[0005] From U.S. Pat. No. 1,106,172 it has been known to convert
profiles continuously to a strip using an arrangement of three roll
stands arranged one behind the other.
[0006] DE 199 38 966 C1 shows a way of producing strip-shaped input
stock, which is profiled in subsequent sections, economically and
with a uniform, high surface quality. To this end, the metal strip
is rolled always between the same two rollers, in two or more
sections each shorter than the circumference of the rollers, for
which purpose the metal strip is recalled between every two
successive rolling steps, and the recalled section of the metal
strip is rolled once again.
[0007] For carrying out that method, DE 199 38 966 C1 discloses a
roll stand which has a first coiler for the metal strip to be
rolled arranged on the intake end of the rolling gap, and a second
coiler for winding up the strip-like input stock arranged on the
discharge end of the rolling gap, the coiler arranged on the intake
end of the rolling gap being provided with a drive motor,
especially a servomotor, for recalling the metal strip by steps of
a predetermined length. The length of the steps by which the metal
strip is recalled may be adapted to the particular needs by an
electronic drive control, especially in programme-controlled
fashion. Such a programme control also permits the intermittent
drive of the rollers, including forward rotation, stoppage and, if
necessary, reverse rotation, to be optimally adapted to the
particular rolling task.
[0008] Now, it has been found that when grooving the metal strip by
the profiled roller it may happen that the semi-finished product
obtained does not exhibit the intended shape and the desired
accuracy on its side facing away from the profiled roller. This is
true especially when rolling metal strips that are profiled in
sections on one side only while the other side should remain flat,
but does not actually remain flat with the desired precision.
[0009] Now, it is the object of the present invention to open up a
way of producing a strip-shaped semi-finished product, which is to
be profiled in sections by a rolling process, so that the desired
shape can be realised with higher accuracy on its side facing away
from the profiled roller. Especially in the case of a strip-like
semi-finished product, which is to be profiled in sections on one
of its sides only, the other side is to be kept flat with higher
precision.
[0010] This object is achieved by the method having the features
defined in Claim 1. A device especially suited for carrying out the
method according to the invention is the subject-matter of Claim
51. Advantageous further developments of the invention are the
subject-matter of the sub-claims.
[0011] According to the invention, for producing strip-shaped input
stock, a metal strip is rolled in a rolling gap defined by a roller
and a plate. The rolling process is carried out in one or more
rolling steps with the aid of the following process steps:
[0012] (a) Tensioning the metal strip;
[0013] (b) positioning the metal strip in a rolling gap, which is
defined by a roller and a movable plate, relative to the
roller;
[0014] (c) positioning the plate relative to the roller;
[0015] steps (b) and (c) being carried out either successively or
simultaneously or in timely overlapping fashion, or step (c) being
carried out before step (a);
[0016] (d) grooving the metal strip with the roller by reducing the
distance of the peripheral surface of the roller to the metal
strip, the metal strip being maintained steady or being moved only
slowly at least during the beginning phase of the grooving step,
and the roller being rotated not at all or only very slowly so that
the metal strip remains under tensile stress in the rolling
gap;
[0017] (e) rolling a section of the metal strip in the rolling gap
by rotating the roller and moving the plate in synchronism in a
rectilinear manner; and
[0018] (f) releasing the metal strip by opening the rolling
gap;
[0019] steps (b) to (f) being repeated for every section of the
metal strip to be profiled.
[0020] The term "metal strip" as used herein also includes strips
which instead of consisting entirely of metal, include non-metallic
components, such as oxidic, carbidic or ceramic components, or a
metalloid, such as graphite. Strips made of compound materials such
as silver graphite or silver metal oxide, especially materials
based on silver tin oxide containing up to 20% by weight of
non-metallic components, may serve as examples. Strips made of such
materials are used as semi-finished products for the production of
electric contacts.
[0021] If in order to achieve higher reductions per pass and/or
smaller dimensional deviations, the respective metal strip section
to be profiled is rolled in more than one passes, then steps (b) to
(f) are repeated after the first pass, for which purpose the metal
strip is recalled, after the rolling gap has been opened in step
(f), and the recalled strip section is rolled once again in the
rolling gap under the action of the same roller. The tensile stress
in the strip is conveniently kept constant at a predetermined value
during the whole process. This results in higher positioning
accuracy of the metal strip in the rolling gap and in improved
dimensional accuracy.
[0022] In order to achieve an especially high degree of accuracy
and repeatability, the roller is positioned in a predetermined
reference position prior to each rolling cycle or to each rolling
step, in order to prevent positional errors from summing up.
Positioning the rollers in a reference position is effected most
conveniently by reversing the roller, and may take place before
step (b), after step (b) or after step (c). Simultaneously with the
adjustment of the starting angle of the roller, a preliminary
adjustment of the size of the roller gap is preferably carried
out.
[0023] According to the invention, the metal strip is formed in the
rolling gap between a roller and a plate that coacts with the
latter. If the rolling gap is to be profiled on one side only, then
the plate exhibits a flat shape in the area in which it is in
contact with the metal strip during the forming operation. During
rolling of a section of the metal strip, the plate is moved
linearly in synchronism with the roller with which it cooperates.
For recalling the metal strip, it is not absolutely necessary that
the plate be moved in synchronism with the roller and/or the metal
strip, unless the metal strip is to be rolled also during the
recalling motion, which may be the case in one embodiment of the
method according to the invention.
[0024] When the metal strip is to be profiled on both sides then,
according to the method according to the invention, one initially
profiles one side whereafter the metal strip is turned over so that
its profiled side faces the plate, and then the other side is
profiled, it being especially preferred--depending on the shape of
the profile to be produced--that the plate be exchanged against
another plate which is profiled, on the side facing the metal
strip, in a manner complementary to the profile already rolled so
that the profiled side of the metal strip can be optimally
supported during profiling of the other side. One thereby obtains
the desired profiles with an especially high degree of accuracy.
For profiling the meal strip on both sides, one conveniently
profiles at first one side of the strip over its full length,
whereafter the strip is turned over and profiled on its other side
in a further pass in one or more rolling steps. If necessary, the
profiling roller is exchanged for that purpose. Instead of
exchanging the plate, it may be more favourable--especially if the
metal strip is to be profiled on the second side in places that
overlie recesses, which have been rolled before into the first side
of the strip--to use a profiled back-up roller of the biggest
possible diameter as support for the metal strip when the latter is
to be profiled on the second side.
[0025] If the plate is exchanged, or if a back-up roller with an
especially big diameter is used instead, the register line of the
rolled strip should, conveniently, be placed a little above the
profile projecting from the plate or the back-up roller. This
provides the advantage that stretching of the metal strip during
its transport will be excluded and any vertical adjustment of the
plate or instead the back-up roller, with the especially big
diameter, can be avoided. Otherwise, such vertical adjustment would
be necessary when the segment of the back-up roller supporting the
metal strip, or the profile of the plate supporting the profiled
metal strip, must be returned to its initial position for the next
rolling pass to be carried out.
[0026] It has been found that the method according to the invention
permits the production of strips that are profiled in sections,
preferably on one side only, so that irregularities on one side of
the strip, produced by the action of the roller upon the other side
of the strip, are clearly reduced or even fully avoided, compared
with the previous process.
[0027] During the rolling process, the plate serves as back-up for
the roller acting on the metal strip, also known as working roller.
It absorbs the rolling forces and transmits them conveniently to
the frame of the roll stand, which also supports the working roller
and any back-up rollers conveniently provided. Preferably, the
plate is supported in floating fashion which allows easy and
low-friction motion combined with reliable transmission of
forces.
[0028] Conveniently, the arrangement is selected in such a way that
the roller defines the roll gap from above and that the plate
extends horizontally below the roller and is supported by a back-up
roller seated in the roll stand in the usual way. In that case, the
rolling forces can be transmitted by the plate to the back-up
roller and from the latter, in the usual way, to the frame of the
roll stand. In order to guarantee the horizontal alignment of the
plate, the latter should be additionally supported beside the
back-up roller, preferably on both sides of the roll gap; the
carrying capacity of those supporting means may be smaller than
that of the back-up roller, the later being arranged directly below
the working roller that coacts with the plate.
[0029] A floating arrangement of the plate is achieved with
advantage if the plate is supported by rolling elements. The
rolling elements may consist of rolls forming a field, conveniently
on both sides of the roll gap, that supports the plate at a
plurality of points or lines which may be distributed over the
entire width and length of the plate. The rolling elements may be
driven or may be free-running, instead of being driven. Especially
preferred as rolling elements are balls seated in free-running
fashion, on which the bottom surface of the plate is supported.
[0030] The plate may be directly driven, for example by means of a
spur gear ring, shrunk onto the back-up roller arranged below the
plate and transmitting its momentum to the plate via a toothed rod
mounted on the plate. This ensures exact positioning of the plate
in any phase of its movement, i.e. during the positioning, rolling
and recalling phases. Further, there is also the possibility to
drive the plate by means of a hydraulic piston-and-cylinder unit or
by means of a screw, driven by an electric motor, especially a
low-friction and precise recirculating ball screw. Preferably,
however, the plate is driven during the rolling process not
directly, but indirectly, being entrained by the driving motion of
the working roller and/or the metal strip. A locking effect
sufficient for this purpose is produced by the rolling pressure
acting between the working roll and the plate.
[0031] Preferably, for entraining the plate, its back-up roller
arranged below the plate is likewise driven.
[0032] An important advantage of the invention lies in the fact
that it can be transferred to other applications. One such
application relates to the production of metal strips with grooves,
which instead of extending in longitudinal direction from the
beginning to the end of the strip, extend crosswise over the full
width of the metal strip, from one longitudinal edge to the other
longitudinal edge of the strip, and which reoccur at intervals in
the metal strip. Such grooved metal strips can be split, before
being used for the production of parts, such as contact springs or
commutator segments for electric motors, especially for
servomotors. Modern servomotors are getting ever quicker and ever
more precise. This places increasing demands on the accuracy to
gauge of the commutator segments of such motors. The accuracy to
gauge of the groove width should be better than 0.02 mm. If such a
groove is to be produced in a metal strip by rolling, one or more
passes will be necessary.
[0033] Conventionally, the grooves are produced in a metal strip by
milling, but the surface quality achieved in this way is not very
high. Milling grooves, which extend crosswise over the metal strip,
is difficult. One has also tried to produce grooved, strip-shaped
input stock by rolling a longitudinally extending groove into a
metal strip by several rolling passes. As a result of this process,
lateral lands, delimiting the groove, remain in the metal strips on
both sides of the groove. Given the fact that the metal strip is
elongated in the area of the groove by a certain dimension, due to
the displacement of material during the rolling process, but is not
so elongated in the area of the lateral lands, the lateral lands
must be correspondingly stretched in compensation, for example by
the use of coilers that develop a correspondingly high tensile
force. But even if the lateral lands are stretched, it is not
possible to roll grooves the depth of which exceeds approximately
10% of the thickness of the metal strip. Moreover, the method is
laborious and does not lead to the desired accuracy because the
metal strip suffers a certain draught in each pass, with the result
that the groove gets wider from one pass to the next, with
increasing variation. The ways of proceeding described in DE-PS 104
875 and DE 197 04 300 A1 also do not permit high degrees of
accuracy to gauge.
[0034] On the other hand, the method of rolling strips step by step
and in sections according to the invention allows, generally,
profiled metal strips which have the profile extending over the
entire width of the metal strip to be rolled with both a high
degree of accuracy to gauge and high surface quality, and this
especially when the described multi-pass rolling method according
to the invention is improved in such a way that, instead of rolling
the metal strip in one step, each of its sections to be profiled is
rolled in several steps, for which purpose the metal strip is
recalled at the end of one rolling step and the section, which has
been rolled before, is rolled once again. Especially high degrees
of accuracy can be achieved when, instead of being rolled in the
one direction and recalled in the reverse direction, the metal
strip is rolled in both directions, i.e. also during the recalling
step.
[0035] A particular advantage of the invention lies in the fact
that it is now possible, with the aid of the invention, to roll
profiles into strips which cannot be produced by cutting processes,
for example by milling, namely grooves that extend crosswise to the
longitudinal direction of the metal strip and that are provided
with edges which, instead of extending along a straight line from
one edge to the other edge of the metal strip, open in the
longitudinal direction of the metal strip to form pockets or niches
whose edges then extend along a straight or curved line. Such
grooves, opening into pockets or niches, can be rolled in any case
by the method according to the invention if the pockets or niches
do not widen the groove to such an extent as to create problems
with the resulting displacement of material from the pockets or
niches to be formed. Even grooves that extend along a curved or an
oblique line can be rolled into a metal strip using the
intermittent rolling process according to the invention.
[0036] According to a particular embodiment of the invention it is
now possible to provide a metal strip with recesses with a border
closed all around, and to simultaneously preserve a flat surface
area on the opposite side of the metal strip, in the area of the
recess so formed. The contour of such a recess may be square,
rectangular, oval, circular, or may follow any other closed line.
The edge of the recess may consist of a peripheral wall extending
perpendicularly or nearly perpendicularly relative to the plate, or
of a peripheral wall extending obliquely relative to the plate and
opening from the bottom of the recess toward the outside.
Alternatively, however, the edge may gradually merge with the
bottom of the recess, as is the case with a flat depression.
Recesses of that kind have been produced heretofore in strips by a
punching process, for example by deep drawing, in which case a
bulging area is formed on the opposite surface of the metal strip
which is then removed by milling in order to restore the flatness
of the strip surface. The procedure used so far is connected with
the following disadvantages:
[0037] Insufficient flatness of the strip surface and of the bottom
of the punched recess;
[0038] variation of the strip thickness in the area of the bottom
of the recesses, in the order of one or a few tenths of a
millimeter;
[0039] irregular roughness of the strip surface in the area of
bulging portions that have been removed by milling;
[0040] strips profiled in this way can be reproduced only with
tolerances in the order of some tenths of a millimeter, the quality
being even deteriorated if more than one recesses formed are
distributed over the width of the metal strip. In addition the
known process is uneconomical as the recesses are formed by two
separate processes, in terms of time and place, namely the process
of punching the recess and the process of removing the resulting
bulging portions by milling.
[0041] Compared with that situation, forming a profiled metal strip
with recesses, which are surrounded by a closed border, using a
rolling method according to the invention provides the essential
advantage that the recesses need not be produced using separate
process steps, in terms of time and place, but can be produced in
the roll gap between a roller and a plate simultaneously. This can
be achieved by the use of a plate with bumps that are pressed into
one side of the metal strip during the rolling process, thereby
displacing a corresponding quantity of the metal toward the
opposite side of the metal strip, where it is rolled flat by the
roller so that the flatness of the strip surface opposite the
respective recess is preserved.
[0042] The dimensional accuracy and the flatness of the surfaces
that can be achieved according to the invention are better by the
power of ten, compared with the conventional method.
[0043] The method according to the invention is particularly
advantageous for rolling recesses into a metal strip, if the
material that has been displaced by the recess-forming process is
rolled flat by the same rolling process on the opposite side, and
if simultaneously the overall thickness of the metal strip is
moderately reduced, preferably in an order of magnitude of 10% of
its thickness. It is then possible to achieve an especially high
degree of accuracy.
[0044] Recesses can be formed most easily if they have the shape of
flat depressions or are provided with a peripheral wall inclined in
such a way that the recess opens from its bottom toward the
outside. If a recess with a steeper, especially a vertical
peripheral wall is to be formed, it may be of advantage if this
process is carried out in two or more than two steps and if in a
first step a recess with an inclined peripheral wall, for example a
wall inclined at an angle of 45.degree., is formed and thereafter
the inclination of the peripheral wall is increased in a second
step, for example to nearly 90.degree..
[0045] The continuous multi-pass rolling process according to the
invention is especially advantageous for the production of such
profiled strips. The plate arranged opposite the driven roller can
be recalled for this purpose again and again for repeated rolling.
In order to prevent scratching of the metal strip during its
passage through the rolling gap, and to prevent the back-up roller
arranged below the plate from being dislocated, the register line
of the metal strip is preferably placed a little above the profile
that projects upwardly from the plate and which is to be pressed
into the metal strip during the rolling process.
[0046] The invention is particularly well-suited for rolling a
regularly recurring profile intermittently into a metal strip; such
a metal strip can then be split to produce mutually identical mass
parts, such as commutator segments or contact springs for electric
purposes, with a high degree of accuracy. Splitting the strip is
conveniently effected by stamping. The method according to the
invention can be used with advantage also for plated strips and for
strips to be plated where the sheets to be applied by plating lie
at different levels after the rolling process according to the
invention. It is not possible with known roll-plating methods to
produce profiled strips with recessed plating by rolling the strip
in lengthwise direction since in the case of higher degrees of
deformation, especially in the case of a deformation of more than
50%, the resulting displacement of material will become a serious
problem.
[0047] Using the discontinuous multi-pass rolling process according
to the invention, it is now possible to produce the strip-like
input stock with especially high and uniform surface quality and
with very low thickness tolerances, or to produce input stock with
the quality known from the prior art in greater lengths than was
heretofore possible, without having to exchange the rollers. There
have already been achieved thickness tolerances of .+-.1 .mu.m,
repetitive accuracy values of .+-.2 .mu.m, peak-to-value heights of
only R.sub.1=0.18 .mu.m and centre line average heights (CLA) of
only R.sub.a=0.022 .mu.m (DIN 4762).
[0048] In order to permit at least two rolling steps to be carried
out on one section of the metal strip with the method according to
the invention, the circumference of the rollers should be equal to
at least twice the length of the recalled sections, and the
recalled section should be a little longer than the dimension of
the workpieces to be stamped from the semi-finished product,
measured in the longitudinal direction of the strip-shaped
semi-finished product, in order to allow for the unavoidable
stamping waste. If the metal strip is rolled not only in one
direction, but alternately in the one and the other direction, then
one may chose to roll the metal strip several times in forward and
reverse direction between the same segments of the roller and of
the plate and to perform the last rolling step between one
circumferential segment of the roller and one section of the plate
which had been previously employed for a smaller number of rolling
steps and which, therefore, still have a better surface quality so
that they will give the metal strip a surface with equally optimum
quality in the last rolling step.
[0049] If sections of the metal strip are rolled alternately in one
and the other direction, one additionally achieves a more
favourable material structure than would be obtained if the metal
strip were rolled always in one and the same direction. This gets
even more important the more the thickness of the metal strip is
reduced by the rolling process, because in the latter case material
crowding caused by the rollers is also increased. Another advantage
lies in the fact that the favourable effect on the material
structure, when rolling individual sections by a reciprocating
process, is greater than when conventionally rolling a metal strip
alternately in the one and the other direction over its full
length.
[0050] The number of rolling steps to be performed on one and the
same section of the metal strip is adapted to the desired reduction
per pass and the desired surface quality of the input stock to be
produced.
[0051] The accuracy and surface quality allowed by the method
according to the invention are better than the accuracy and surface
quality achievable by milling, and also better than achievable by
the conventional method, where a longitudinally extending groove is
produced in the metal strip by rolling over the full length which,
due to the non-uniform elongation occurring in this case, is
possible only up to reductions per pass of maximally 10%.
[0052] The intermittent operation of the method according to the
invention contributes essentially to the accuracy to gauge of the
profile of profiled metal strips. Due to the intermittent
operation, each pass begins from the stopped condition of the metal
strip, the roller and the plate, or with a speed so low that any
tensile stress prevailing in the metal strip can be preserved as
the roller cuts into the metal strip. In the initial phase of each
pass, therefore, the elongation of the metal strip resulting from
the engagement of the rollers in the metal strip does not begin
abruptly, as is the case with continuous profile rolling methods,
but sets in so smoothly that a constant tensile stress, which is
important for the accuracy to gauge of the profile, is maintained
in the metal strip, for example by suitably controlling the drive
of the coilers which serve to maintain the tensile stress. To this
end, the rollers and the metal strip are accelerated and braked
during the rolling process uniformly and synchronously.
Conveniently, a constant tensile stress is maintained in the metal
strip during cutting-in of the roller and most conveniently also
during the rolling process.
[0053] If a profile is to be rolled into a metal strip by sections,
the roller may comprise a cylindrical shell, which may be
subdivided into segments with identical or different diameters, or
a profiled shell. A cylindrical shell enables a profile to be
rolled into the metal strip by varying the height of the rolling
gap during the rolling process, especially by corresponding
relocation of the roller.
[0054] The accuracy to gauge and the surface quality will be the
better the shorter the rolling passes are. Advantageously, the
rolling passes are selected to be shorter than half the diameter of
the rollers. In this case, the profile extends over only part of
the circumference of the roller. The remaining part of the shell
surface of the roller may be made cylindrical; it is then possible
to use the cylindrical section of the roller surface in a first
rolling pass for equalising, instead of profiling, the respective
section of the metal strip in order to improve the accuracy to
gauge of the rolled strip.
[0055] One application, for which the invention was realised with
advantage, for producing strip-like input stock from metal, which
is profiled in regularly recurring sections, relates to pens for
fountain-pens.
[0056] Pens for fountain-pens have a thickness varying over their
length. Typically, pens have a thickness of 0.2 mm in the rear
region, with their thickness rising toward their point, where the
pen finally reaches a thickness of maximally 0.6 mm. It is known to
produce pens by rolling a metal strip by sections, i.e. by steps,
the length of which corresponds to the length of the pens to be
produced, so as to provide it initially with a corresponding
longitudinal profile, which extends over the full width of the
metal strip. This profiled metal strip serves as input stock from
which the pens are then stamped out and thereafter formed to give
them the desired bent shape.
[0057] To produce the profiled input stock it has been known to
give the upper roller of the two rollers, which define the rolling
gap and which are supported in a roll stand, an empirically
determined contour in the circumferential direction, complementary
to the intended thickness profile of the pens. Outside that
complementary contour, the spacing of the outer surface of the
roller from its axis is selected to ensure that there will be no
engagement with the metal strip in the rolling gap in that area. At
the beginning of the circumferential segment, which exhibits the
complementary contour, the roller comes to cut into the metal
strip, entraining it thereafter for the time of one rolling step,
namely so long as it is in engagement with the metal strip, whereby
the metal strip is both advanced and profiled. During this process,
the metal strip is drawn off the first coiler, and the profiled
metal strip exiting the rolling gap is wound up by a second coiler.
The motion of the metal strip being effected by the two rollers, a
certain loop formation will necessarily occur between the rollers
and the second, namely the winding-up coiler, which makes it
necessary, according to the prior art, to provide a strip loop with
a loop-tensioning device that balances out the intermittent strip
transport by the rollers and the continuous winding-up action of
the second coiler. This is connected with some apparatus input,
which is a disadvantage.
[0058] Pens produced in the known manner exhibit undesirable
variations in thickness.
[0059] In contrast, the present invention discloses a way of
producing profiled strip-like input stock, for example for pens,
with higher accuracy. This is achieved, to a considerable extent,
due to the large-surface, flat support for the metal strip,
combined with the condition that the roller initially cuts into the
static metal strip while still in non-rotating condition. For the
cutting-in operation, the roller is shifted toward the plate, with
the latter still in its static condition. Another advantageous
contribution lies in the fact that the tension of the strip can be
maintained throughout all phases of the rolling process. This is
different with the known process because in that case the rollers
rotate continuously at constant speed so that the cutting-in action
of the roller and, thus, feeding of the strip, set in and end
abruptly. It is not possible with the known method to maintain a
constant tensile force in the metal strip during the profiling
operation, which would be an advantage for uniform and
high-precision rolling results.
[0060] The metal strip is rolled in one step, or if higher demands
are placed on its accuracy or in the case of greater reductions per
pass in several rolling steps, until the intended depth of the
desired profile of the input stock is reached. If more than one
rolling steps are carried out, the metal strip is recalled between
every two successive rolling steps, and the recalled section of the
metal strip is rolled once again between the roller and the plate.
There is, however, also the possibility to roll the respective
strip section a second time during the recalling phase. Only when
the desired profile has been achieved in a section of the metal
strip to be profiled by one or more rolling passes and, if
necessary, after one or more recalling steps, is the next strip
section fed into the rolling gap, exactly positioned in its
longitudinal direction and then processed in the rolling gap, for
profiling that next section of the metal strip.
[0061] However, it would likewise be possible to proceed in such a
way that following the first rolling pass on a first strip section
a similar first rolling pass is performed on the next following
strip section, if necessary after having restored the initial
position of the rollers, for example by reverse rotation of the
roller and, if necessary, reverse movement of the plate, and that
the strip is then recalled by two steps, whereafter the second
rolling pass is carried out first on the first strip section and
then on the second strip section.
[0062] This improvement of the invention, which relates to the
production of profiled input stock, offers essential
advantages:
[0063] By producing the profile of the metal strip not in one, but
rather in two or more rolling passes, a higher accuracy to gauge is
achieved than was heretofore possible, which is of significance, in
the case of writing pens, especially in the area which later forms
the shank.
[0064] Since the desired profile is formed in one section of the
metal strip not by one, but by two or more rolling passes, it is
possible to profile even harder metal strips, including springy
strips.
[0065] The fact that the profile of the metal strip can be produced
in more than one rolling passes opens up the possibility to carry
out different rolling processes, such as equalising, pre-profiling,
plating, pattern rolling and mirror-finishing in succession and in
different sequence on the same section of the strip.
[0066] This opens up applications of the invention that go beyond
the field of writing pens and that cover a plurality of profiled
parts that are formed from a strip-like semi-finished product and
can be separated from the strip by punching. Such applications
comprise, for example, electric conductive structures, such as
contact springs, commutator segments for electric motors, further
leadframes and chain links for watch straps and for bracelets.
[0067] Due to the possibility to carry out the profiling operation
by several rolling steps, the most diverse profiles can be
produced.
[0068] The versatility of the invention is increased by the fact
that the metal strip need not be profiled in each rolling pass, but
may also be simply and uniformly reduced in thickness in a first
rolling step, for which purpose the two rollers must have at least
one cylindrical segment, if they are not anyway cylindrical.
[0069] The progress realised by the invention is achieved with a
minimum of apparatus input. Starting out from a roll stand known
per se, one essentially only has to substitute a plate for one
roller and to modify the operating procedure that leads to the
desired profile. If the roller is profiled in the circumferential
direction, then it is conveniently modified in such a way as to
give it successive segments of different contours in the
circumferential direction, which segments are separated one from
the other, especially by relieved sections, and in combination with
the preferred step of recalling the metal strip permit one and the
same section of the metal strip to be repeatedly rolled.
[0070] There is also the possibility to make the roller cylindrical
and to achieve the variation in height of the rolling gap, required
for the profiling operation, during rolling by displacing the
roller and/or the plate, preferably the roller, which preferably is
located above the plate, in the roll stand. This may be done, for
example, with the aid of an electric motor driving screws, which
act on the roller to be displaced and which are coupled to an
incremental rotary transducer which permits recurring adjustments,
and by means of which the electric motor can be controlled.
Further, it is also possible to displace the roller and/or the
plate hydraulically by locating a hydraulically operated cylinder
in each frame, in the head or the lower traverse. The two hydraulic
cylinders are integrated in the hydraulically operated
roll-adjusting system and are driven by a positioning system
comprising a power monitoring system. The positioning system may be
equipped with pilot valves as servo components and with
displacement sensors and pressure transducers as actual-value
sensors. It is thus possible to drive the roller along almost any
predefined curve, depending on the profile to be rolled. Compared
with the use of an electronically controlled electric drive, a
hydraulic servo drive provides the advantage of being quicker and
more precise.
[0071] Such a servo drive for the displacement of the roller and/or
the plate, serving as its back-up element, permits a profile to be
rolled into the metal strip in one or more steps, even with a
cylindrical roller. The selection of the diameter of the roller,
and the way in which the roller is to be displaced relative to the
plate, in response to the strip transport, depends on the desired
profile. A corresponding control curve for the drive, derived from
the profile to be rolled and intended to displace the roller
relative to the plate, may be stored as a control curve in a
programmable electronic control unit. By storing a plurality of
control curves, it is possible according to the invention to work a
corresponding number of profiles in metal strips with a single roll
stand and without any exchange of the roller. Moreover, it is also
possible to make use of the displacement of the roller during the
rolling process in a roll stand having one profiled roller. This
combination of two different possibilities of varying the height of
the rolling gap during the rolling process, namely by the use of a
profiled roller in combination with the displacement of the roller
relative to the plate, further increases the versatility of the
roll stand in the production of strips that are profiled by
sections.
[0072] If a cylindrical roller is employed, it is of advantage if
the roller is provided with a notch parallel to its axis, in order
to have a reference for the angular position of the roller.
[0073] Exact positioning of the respective roller section relative
to the metal strip can be effected with the aid of a regulating
system controlling the angle of rotation of the roller.
[0074] In connection with the recalling step for the metal strip,
the recalling device, for example a first coiler from which the
metal strip is unwound, is of particular importance because it must
be capable of reproducing with sufficient accuracy the length of
the step by which the metal strip is recalled. To this end, that
first coiler, conveniently also the second coiler that pulls the
metal strip, is provided with a servomotor comprising an
incremental rotary transducer which allows the desired step length
to be precisely defined, both for the unwinding and for the coiling
process. The step length can be defined with even greater precision
if the coilers are provided with strip transfer rollers coupled
with an incremental rotary transducer that serves as an
actual-value sensor in the strip-position regulating system.
[0075] The width of the metal strip may be selected to permit a
single profiled part, for example a single profiled writing pen, to
be punched out from each of the successively arranged strip
sections. The economy of the process, and of the roll stand
operating according to the invention, can easily be multiplied if
broader strips are profiled, which are wide enough to permit two or
more writing pens or similarly profiled objects, lying one beside
the other, to be formed from each profiled section of the input
stock.
[0076] A particularly advantageous improvement of the invention is
defined in claim 22. According to that improvement of the
invention, the metal strip is equalised before the profile is
rolled. The term equalising is understood to mean that the metal
strip is rolled in a roll stand with highly constant rolling gap,
whereby any variations in thickness of the metal strip are reduced.
Roll stands using two working rollers for equalising purposes are
known from DE 25 41 402 C2, to which reference is made for further
details. In the case of a roll stand suited for purposes of the
invention, a highly constant rolling gap is achieved by the fact
that pre-stress forces, acting vertically to the roller axes in a
sense away from the material being rolled, are exerted on the roll
necks, that extend outwardly beyond the roll neck bearings, by two
back-up rolls, which support the plate from below and the other
working roller from above, respectively, which pre-stress forces
may be oriented perpendicularly and may, preferably, act along a
line of action that passes through the incoming metal strip and
deviates from the plane of the roller axis by the rolling angle.
This reduces the working play of the rollers in the roll neck
bearings.
[0077] According to the invention it is, however, not necessary for
equalisation purposes to have the roll stand, which serves to
profile the metal strip, preceded by an additional roll stand
serving the equalisation process. Rather, the equalising and the
profiling processes are carried out in one and the same roll stand,
for which purpose the metal strip is moved through the rolling gap
in the feeding direction not only during the working steps that
serve the profiling operation. Instead, the metal strip is first
equalised with an only moderate reduction in thickness by steps
which--considering the elongation of the equalised section
occurring during the subsequent profiling operation--are at least
as long as the step for the profiling operation. Thereafter, the
strip is recalled by a step of a length at least equal to the
length required for the profiling operation and maximally equal to
the length by which it has been advanced during the equalisation
process, whereafter the profile is rolled into the recalled section
of the metal strip. In a roll stand comprising a profiled working
roller, where one circumferential segment has the contour adapted
to the desired variation in thickness of, for example, a writing
pen to be produced from the metal strip, the roller is additionally
provided for this purpose with a cylindrical circumferential
segment separate from the circumferential segment that is provided
with the contour (claim 25). The cylindrical circumferential
segment serves to carry out the equalising step. The length of the
cylindrical circumferential segment is selected, depending on its
function and giving due consideration to the elongation of the
metal strip occurring during the rolling process, to ensure that
the equalised section of the metal strip will at least have the
length of the writing pen, or preferably a somewhat greater length,
so that the beginning and/or the end of the profiling step can
occur at a certain distance from the beginning and the end of the
equalised section.
[0078] Advantageously, the roll stand serving the profiling
operation is, therefore, simultaneously designed as equalising roll
stand and is equipped with a strip feeding system by which the
strip is moved by steps in forward and backward direction.
[0079] The improvement of the invention defined in claim 28 and
claim 34 offers essential advantages:
[0080] The variation in thickness by .+-.20 .mu.m in the input
stock and, thus, in the workpieces, for example writing pens, to be
produced can be reduced to less than .+-.2 .mu.m, for example .+-.1
.mu.m, in a particular pen, especially in the area of the pen that
later serves as shank.
[0081] The reproducibility of the thickness profile from one pen to
the next can be improved to less than .+-.4 .mu.m, for example
.+-.2 .mu.m.
[0082] These are accuracy values that could not be reached
heretofore in the production of pens by rolling. Corresponding
accuracy values can be reached also with strip-like input stock for
other profiled products than pens.
[0083] The great progress in accuracy is achieved with a minimum of
apparatus input. Starting out from a roll stand known per se the
profiling roll of the latter must under certain circumstances be
modified insofar as it must be provided with a suitable cylindrical
segment, a working roll has to be exchanged against a plate, and
the roll necks of the two rollers must be pre-stressed with a view
to reducing the bearing play, for example in one of the ways
disclosed in DE-25 41 402 C2. In addition, means are required that
allow the metal strip to be not only advanced by steps, but also
recalled by steps, the steps having approximately a length equal to
the length of the equalising steps. As has been mentioned before,
this can be achieved simply by providing the first coiler, from
which the metal strip to be profiled is unwound, with an electric
motor that can be controlled with sufficient accuracy in steps of
the desired length and can be reversed in the sense of rotation.
This is realised, preferably, with the aid of a servomotor
comprising an incremental rotary transducer that allows the desired
step length to be exactly predetermined both for the coiling and
for the uncoiling process, with the aid of two servo controls with
force transducers, provided on guide pulleys for the metal strip,
acting as actual-value sensors for coilers that uncoil and wind up
the metal strip, respectively, and that create the tensile force in
the metal strip, or are, alternatively, controlled with respect to
their position by an electronic control system. The actual-value
sensors consist, conveniently, of two incremental rotary
transducers positioned on the two guide pulleys of the coilers. One
servomotor is normally connected to a gearing arranged downstream.
Whenever the term servomotor is used hereinafter, it is supposed
that the servomotors are normally connected to a gearing arranged
downstream.
[0084] Preferably, the second coiler, intended to coil up the
profiled metal strip, is also provided with such a servomotor.
[0085] This has the additional advantage that a defined tensile
force, which acts toward the achievement of a uniform input stock
with little variation in thickness, can be exerted on the metal
strip, by the interaction of the servomotors in all phases of the
method of the invention, during the cutting-in operation, the
equalising step and also when profiling and recalling the metal
strip. The tensile force should be as uniform as possible and
should not drop below a certain basic tensile force which may be in
the order of, for example, 500 N for the production of pens. When
recalling the metal strip, the first coiler will, thus, pull the
strip with greater force, compared with the smaller coiling force
of the second coiler. By maintaining a basic tensile force in the
metal strip, that remains as uniform as possible in all working
phases of the metal strip, improved uniformity of the rolled input
stock is achieved and any off-centre running of the strip is
avoided, which means that the metal strip will not get
distorted.
[0086] Another advantage of driving the coilers by servomotors lies
in the fact that the strip-feeding motion and the drive of the two
rollers can be matched so precisely that, contrary to the prior
art, the rollers can be driven intermittently, instead of
continuously. Specifically, it is then possible to adjust the speed
at which the profiled rollers will cut into the metal strip so
perfectly to the feeding speed of the strip that no abrupt
acceleration of the metal strip will occur at the moment the roller
cuts in. Specifically, cutting into the metal strip by the profiled
roller may occur initially in stationary condition or at a lower
rate of strip feed and at low rotational speed of the roller,
whereafter the rate of feed and the rotational speed of the roller
may be increased. This is of particular advantage with respect to
the achievement of small dimensional tolerances.
[0087] Due to the fact that the metal strip is positioned in the
rolling gap relative to the roller by means of a strip-position
control system and that the roll is exactly re-positioned for each
rolling step by means of a rotary-angle control system, any
dimensional deviation in the profile distances will be kept within
the order of some hundredths of a millimeter, depending of the
particular profile.
[0088] Another advantage of using servomotors for driving the
coilers is seen in the fact that special strip-tensioning devices,
as required in prior-art devices, are no longer necessary.
[0089] A further advantage of using the servomotors for driving the
coilers lies in the fact that using a programmable electronic
control unit the strip feed can be adjusted very exactly to the
length and the position of the profiled strip sections and to the
rotation of the roller, preferably also to the vertical
displacement of the roller in order to vary the height of the
rolling gap, especially if the latter is defined by a cylindrical
roller shell or shell section, and to thereby produce a particular
profile.
[0090] Recalling the metal strip can be effected not only by a
coiler arranged on the intake end of the rolling gap, but also by a
recalling device designed as gripper feed mechanism. This
embodiment of the invention is especially well-suited for working
shorter or stiffer strips. When the recalling device is a gripper
feed device, it may be used additionally to advance the metal strip
and to feed it into the rolling gap.
[0091] The sequence control of the process, which combines the
control of the strip position, the rotary angle of the roll and the
position of the roll, is dependent on the recalling system.
[0092] Instead of using a coiler arranged on the discharge end of
the rolling gap, another gripper feed device may be used as pulling
device for the strip exiting the rolling gap during the rolling
process. This embodiment of the invention is likewise mainly suited
for working shorter or stiffer strips.
[0093] The quality of the strip-like input stock produced is
increased if a defined tension is maintained in the strip during
both, rolling and recalling, especially with the aid of a tensile
force control system with two servo controls and force transducers
on the guide pulleys as actual-value sensors for the coilers, that
favourable influence being the greater the thinner the metal strip
is. But it is of advantage also with thicker strips if the strip is
kept under tension and is exactly guided between the recalling
device and the pulling device by mutually matching the motion of
the two devices, and this both during the rolling and the recalling
steps.
[0094] The method according to the invention permits the optimum
strip tension to be maintained in all phases of a rolling step,
especially also in the critical phase when the profiled roller cuts
into the metal strip, because the particular nature of the
discontinuous multi-step rolling method according to the invention
has the effect that each rolling step starts out from the stopped
condition of the rollers, the plate and the metal strip so that the
engagement of the profiled roller in the metal strip occurs not
abruptly but rather so smoothly that the tensile force of the
strip-tensioning device, for example the coilers, can be controlled
to be maintained at a constant value optimally adapted to the
respective strip in the critical phase when the profiled roller
cuts into the metal strip and during the entire rolling step. For
this purpose, the coilers and the rollers are, advantageously,
accelerated and/or braked by their respective drive motors in
synchronism and to the same degree when accelerating and braking
the metal strip and the rollers.
[0095] The optimum pre-stress for removing the bearing play of the
rollers can be determined empirically for the respective
application and can then be kept constant for that application.
Preferably, the process is optimised by determining the elongation
of the roll stand occurring in the particular application during
the equalisation process, and compensating it by suitable
adjustment of the pre-stress.
[0096] The device, as defined in claim 51, for producing
strip-shaped input stock from metal by rolling a metal strip by the
method according to the invention comprises a roll stand in which a
roller and a plate, that can be moved linearly and that faces the
plate, define a rolling gap, and a recalling device for the metal
strip arranged on the intake side of the rolling gap, for which
device a drive motor, especially a servomotor, is provided with
permits the metal strip to be recalled in steps of pre-determinable
length, the plate being adapted for being driven, in synchronism
with the roller and/or with the metal strip, in the predetermined
direction of movement of the metal strip in the rolling gap, and
for being driven and recalled independently of the metal strip as
well. The possibility to move the plate in synchronism with the
roller and/or the metal strip guarantees that the metal strip will
not slip on the plate in the rolling gap as such during rolling of
the metal strip. Moreover, the metal strip can be driven and
recalled independently of the plate in order to permit the plate to
be recalled upon completion of a rolling pass in a selected section
of the metal strip, without however being forced to recall the
metal strip, so that a next section of the metal strip can be
rolled. The drive of the plate may be realised directly, but is
preferably realised indirectly in that the plate is entrained
during the rolling operation by the driven roller and by the driven
metal strip, preferably also by a driven back-up roller arranged
below the plate and supporting the plate. Likewise, the back-up
roller can recall the plate between two successive rolling steps,
for which purpose the frictional lock between the back-up roller
and the plate resting on it will be sufficient although, if
necessary, the friction force generated by the dead load of the
plate can be increased by pressure elements that additionally urge
the plate against the back-up roller. Such pressure elements may
consist, for example, of rollers that are pressed upon the plate by
pneumatic cylinders.
[0097] Profiled metal parts, which are obtained by splitting metal
strips and which are formed by sections in a single rolling pass of
the intermittent rolling process, are employed for example in the
automotive industry where they can be used to replace metal parts
that heretofore had to be produced laboriously by welding
processes.
[0098] The invention is suited not only for rolling strips from
metal in the sense in which the term "metal strip" is used in this
description, but also for rolling strips from plastic materials and
also for strips made from plastic-based compound materials, for
example a plastic material with metallic or mineral or ceramic
fillers, or metallised plastic strips as well as metal strips
coated with a plastic material.
[0099] Further features and advantages of the invention will become
apparent from the appended diagrammatic drawings showing certain
embodiments of the invention in which:
[0100] FIG. 1 shows a side view, sectioned in part, of a machine
according to the invention;
[0101] FIG. 2 shows a front view of the machine, sectioned in
part;
[0102] FIG. 3 shows a detail of the machine, namely the main part
of the roll stand of the machine, in an enlarged scale compared
with FIG. 1;
[0103] FIG. 3a shows the detail marked "X" in FIG. 3;
[0104] FIG. 4 shows a detail of the machine, namely the roll stand,
in an enlarged scale compared with FIG. 2;
[0105] FIG. 4a shows the detail marked "Y" in FIG. 4;
[0106] FIGS. 5-10 show a flow diagram of a first working method
that can be carried out with the machine;
[0107] FIGS. 11-16 show a flow diagram of a second working method
that can be carried out with the machine;
[0108] FIG. 17 shows a diagrammatic view of a method for carrying
out the invention using two cylindrical rollers;
[0109] FIG. 18 shows a modified machine according to the invention,
in a representation similar to FIG. 1;
[0110] FIG. 19 shows a metal strip that can be produced using the
invention, comprising grooves that widen to form rectangular
niches;
[0111] FIG. 20 shows a metal strip that can be produced using the
invention, comprising grooves that widen to form a curved niche;
and
[0112] FIG. 21 shows a metal strip that can be produced using the
invention, comprising grooves that widen to form rectangular
niches, and comprising recesses that are defined by a closed
border.
[0113] Parts corresponding one to the other are identified in the
examples by the same reference numerals.
[0114] The machine shown in FIGS. 1 and 2 comprises a machine bed 1
with a roll stand 2 erected in its middle and with one mounting
device 3 and 4, respectively, for a coiler 5 and 6, respectively,
mounted before and behind the roll stand, which coilers can be
driven by a drive motor 7, 8 designed as electric servomotor.
[0115] Seated in lateral mounting elements 9 of the roll stand is a
working roller 12, hereinafter simply referred to as roller, which
coacts with a flat plate 67, arranged below the roller, to define a
rolling gap 13. Supporting rollers 14 and 15, respectively, of
larger diameter than the roller 12 are mounted in mounting elements
10 and 10a, respectively, above the upper roller 12 and below the
plate 67. The mounting elements 9, 9a of the working roller 12 are
each arranged in a recessed portion of the mounting elements 10,
10a of the supporting rollers 14, 15.
[0116] A metal strip 16 to be worked runs from the coiler 5 over a
transfer roller 17 into the rolling gap 13, passes the latter and
reaches the second coiler 6, via a further transfer roller 18,
where the metal strip 16, having been worked in the roll stand 2,
is coiled up. Between the rolling gap 13 and the second transfer
roller 18, there is further provided a device 19 for exhausting
rolling oil, in which the metal strip is cleaned from rolling
oil.
[0117] The structure of the roll stand 2 is shown more fully in
FIGS. 3 and 4. There it can be seen that the roller 12, the
diameter of which is only 1/3 of the diameter of the supporting
rollers 14 and 15, is seated with its roll necks 20 and 21 in roll
neck bearings 22 designed as roller bearings. One roll neck 21 of
the roller 12 is extended beyond the respective roll neck bearing
22 and designed as part of a gimbal suspension 23, which allows the
roller 12 to be driven using a cardan shaft 24. An electric motor
41, driving the roller 12 in synchronism via the cardan shaft 24,
is shown in FIG. 2. It drives the roller 12 and the lower back-up
roller 15 via a branched gearing 48, although it is likewise
possible to have the roller 12 and the back-up roller 15 driven by
two separate motors.
[0118] The supporting rollers 14 and 15 have roll necks 25 seated
in roll neck bearings 26, designed as roller bearings, in the
lateral mounting elements 10 and 10a. The roll necks 25 are
extended beyond the roll neck bearings 26 and fitted in bushes 27,
the bushes of the lower supporting roller 14 being braced with the
machine bed 1, whereas the bushes 27 of the upper supporting roller
15 are braced with a crosshead 28 arranged above it. Bracing is
effected in each case using a threaded rod 29, projecting from the
bushing 27, on which a set of cup springs 30 is tensioned by a nut
31. This is shown only above the crosshead 28, but the arrangement
at the machine bed 1 is the same. The pre-stress so created reduces
the bearing play of the supporting rollers 14 and 15 and, thus, its
influence on the thickness deviations of the rolled metal strip,
compared with the intended thickness. The roller 12 and the back-up
rollers 14 and 15 thereby reach a degree of concentricity of .+-.1
.mu.m.
[0119] The plate 67 is supported not only by the lower back-up
roller 15, but additionally by two fields of ball-bearings 65, one
of such fields being arranged on the intake side of the rolling gap
13, the other field being arranged on the discharge side of the
rolling gap 13. Each of the ball-bearings consists of a cup 69,
firmly closed by a spherical cover 70. The cover 70 comprises a
central, circular opening, and a ball 71, arranged below the cover
and having a diameter larger than the diameter of the central hole,
projects with part of its surface through that hole. The ball 71 is
urged against the spherical cover by a spring 72 arranged in the
cup 69. The ball 71 is, thus, seated resiliently and besides in
freely moving fashion between the edge of the central opening in
the cover 70 and the spring 72. The ball-bearings 65 are arranged
in the two fields in such a way that their upper surfaces lie in a
common plane in which they support the bottom surface of the plate
67 resiliently and in easy-moving, i.e. low-friction fashion. The
ball-bearings are arranged in holders 66 that are mounted on the
roll stand 2 in a vertically adjustable way. The vertical position
of the ball-bearings 65 is adjusted to ensure that during rolling,
i.e. when the plate 67 is urged against the lower back-up roller
15, the plate urges the balls 71 in downward direction and slightly
away from the edge of the central opening in the cover 70.
[0120] The lower back-up roller 15 can be vertically adjusted with
the aid of adjusting means 73 using wedges, as indicated between
the two beds of the roll frame window and the two lower bearing
blocks of the lower back-up roller 15. Accordingly, the plate 67 is
likewise adjustable in vertical direction.
[0121] Mounted on the bottom surface of the plate 67, via cup
springs 84, are two mutually parallel toothed rods 82 which extend
in a direction indicated by the double arrow (FIG. 3), namely
the-rolling direction. The toothed rods 82 mesh with two ring gears
83, which are mounted laterally, especially by shrinking, on the
lower back-up roller 15. This permits the plate 67 to be driven
very precisely by the lower back-up roller 15, which in turn is
driven by the electric motor 41 (FIG. 2). The cup springs 84 act in
this connection to compensate any possible flattening of the
back-up roller 15 that may be caused by the rolling forces.
[0122] Alternatively, the plate 67 may not have a drive of its own,
but may be entrained, by a frictional locking effect, by the
synchronously driven roller 12, the metal strip 16 and the lower
back-up roller 15. If the plate 67 is to be recalled between two
rolling steps, this is effected by driving the lower back-up roller
15 in the corresponding direction, the necessary frictional locking
effect between the back-up roller 15 and the plate 67 being
generated in this case by the dead load of the plate 67. Should
that dead load be insufficient to achieve a reliable frictional
locking effect, then the plate 67 may be additionally urged against
the back-up roller 15 by rollers--not shown in the drawing--that
are urged against the upper surface of the plate 67 by pneumatic
cylinders.
[0123] The required pre-stress on the roll stand 2 is produced by
means of two screws 32 and 33, that press on the crosshead 28 and
the bearing shells 27 from above and that are each driven by a
separate electric motor 34 (see FIG. 1) arranged on top of the roll
stand 2. Both electric motors 34 are provided for this purpose with
a driving shaft 49, configured as pinion, whose teeth mate with a
gear 50. The two gears 50 are fixed against rotation on the one
screw 32 and on the other screw 33. The suitable pre-stress on the
roll stand is determined empirically, based on the elongation of
the roll stand in the particular application, and is adjusted so as
to compensate for the elongation. After that preliminary
adjustment, the machine according to the invention works as
follows:
[0124] The metal strip 16 to be worked is drawn off the first
coiler 5, passed through the rolling gap 13, pulled to the second
coiler 26 and fixed on the latter.
[0125] The plate 67 has a flat upper surface. The roller 12 has a
shell surface (FIG. 5) with a profiled circumferential segment 35
of a length L1, measured in the circumferential direction of the
roller 12, and a cylindrical circumferential segment 36 of a length
L2, measured in the circumferential direction of the roller 12, the
two segments being separated by two relieved portions 37 and 38.
The cylindrical circumferential segment 36 of the surface is spaced
the largest distance from the axis of the second roller 12, the
relieved portions 37 and 38 are spaced the smallest distance from
the axis of the second roller 12. The profiled circumferential
segment 35 of the surface has a contour the shape of which, viewed
in the circumferential direction, is matched to the longitudinal
development of the thickness of the workpiece, for example a
writing pen, finally produced from the metal strip 16.
[0126] In FIGS. 5 to 16, the plate 67, which supports the metal
strip 16 during the rolling process, is shown only in part.
[0127] Working the metal strip 16 commences by causing the
cylindrical circumferential segment 36 of the second roller 12 to
cut into the metal strip stretched between the two coilers 5 and 6,
and this smoothly with the metal strip 16 in static condition and
the roller 12 not rotating, or at best at a low feeding speed of
the metal strip 16 adapted to the circumferential speed of the
cylindrical circumferential segment 36. The cutting-in phase is
shown in FIG. 5, although not true to scale but with the metal
strip 16 shown in exaggerated thickness. The further FIGS. 6 to 16
also show exaggerated reductions per pass, produced by the rolling
process on the metal strip, in order to illustrate the rolling
process more clearly. The cylindrical circumferential segment 36
rolls on the metal strip 16, thereby reducing the latter's
thickness typically from 0.66 mm to 0.60 mm, while simultaneously
equalising the thickness. The end of the equalising step is shown
in FIG. 6. Now, the metal strip 16 gets out of engagement with the
cylindrical circumferential segment 36 of the roller 12, which
continues to rotate over an additional small angle until the
relieved portion 37 faces the metal strip 16. By reversing the two
drive motors 7 and 8, designed as servomotors, the metal strip 16
is now recalled, preferably with the roller 12 and the plate 67
stopped, by a length greater than L1 but smaller than L2, L2 being
the length over which the metal strip 16 had been equalised. The
length by which the metal strip 16 is recalled is selected in such
a way that in the next step (FIG. 7), when the movement of the
roller 12 and the feeding movement of the metal strip 16 are
re-started, the profiled circumferential segment 35 of the roller
12, with the contour adapted to the workpieces to be produced, will
smoothly cut into the equalised section of the metal strip 16
directly after its beginning (FIG. 7) or at a small distance, for
example 2 mm, behind it. With the relieved portion 37 facing the
metal strip 16, the screws 32 and 33 are rotated to lower the
roller 12 far enough to ensure that the desired cutting depth will
be reached with the profiled circumferential segment 35 of the
roller 12, which is the next to cut into the metal strip 16. As the
second roller 12 continues to rotate and the metal strip 16 is
correspondingly advanced by the second coiler 6, the profiled
circumferential segment 35 rolls the intended profile into the
equalised section of the metal strip 16, over its entire width
(FIGS. 7 and 8). FIG. 8 shows the final point of the profiling
step. It ends a small distance before the end of the equalised
section, at the latter's level. As the upper roller 12 continues to
rotate, its relieved portion 38 faces the metal strip 16. In this
phase, the upper roller 12 is returned to its upper position, by
rotating the screws 32 and 33, so as to adjust the height of the
rolling gap 13 as necessary for the following equalising step. The
position of the relieved portion 38 between the profiled
circumferential segment 35 and the cylindrical circumferential
segment 36 of the roller 12, and the action of positioning the
metal strip 16 in the rolling gap 13 by means of the servomotors 7
and 8 of the coilers 5 and 6, are matched in such a way that the
next time the cylindrical circumferential segment 36 cuts into the
material, this occurs at a small distance, approximately 2 mm,
behind the end of the previously equalised section of the metal
strip 16 (FIG. 9), whereby another equalising step is initiated, as
shown in FIGS. 9 and 10.
[0128] During the equalising, profiling and recalling processes,
the servomotors 8 and 9 ensure that the tensile stress in the metal
strip 16 is kept as uniform as possible.
[0129] If the higher degree of accuracy that can be achieved by the
equalising step is not of importance that step may be omitted, and
the respective sections of the metal strip may be processed by a
single rolling pass, namely the one by which the section is
profiled.
[0130] The practical embodiment shown in FIGS. 11 to 16 differs
from the embodiment shown in FIGS. 5 to 10 in that the upper roller
12 acts on the metal strip 16 which is to be worked with three,
instead of two, circumferential segments 35, 36 and 40, separated
by relieved portions 37, 38 and 39. The roll stand 2 provided for
this purpose has the same structure as the one shown in FIGS. 1 to
4, with the proviso that the roller 12 illustrated in FIGS. 11 to
16 is used as roller 12, the profile of the roller 12 being
exaggerated in the drawing. Here again, the equalising step is not
absolutely necessary in that example.
[0131] The circumferential segment 36 is cylindrical, whereas the
two circumferential segments 35 and 40 have a non-cylindrical
profile. Similar to the example shown in FIGS. 5 to 10, the
cylindrical circumferential segment 36 has the largest spacing from
the axis of the roller 12 over its full length, which is of
advantage under the aspect that the cylindrical circumferential
segment, which serves to carry out the equalising step, must be
reground as necessary.
[0132] The working method illustrated in FIGS. 11 to 16 corresponds
to that illustrated in FIGS. 5 to 10, with the exception that
following the equalisation of the respective section of the metal
strip 16, the profiling step is carried out in two successive,
instead of one, rolling steps between which the metal strip is
recalled once more.
[0133] FIG. 11 shows, similar to FIG. 5, the moment when the
cylindrical circumferential segment 36 of the roller 12 cuts into
the metal strip 16. Similar to FIG. 6, FIG. 12 shows the end of the
equalising step. By continued rotation of the roller 12, the metal
strip 16 is brought out of engagement with the roller 12 and can be
recalled by the coiler 5. During that phase, the roller 12 is
lowered by means of the screws 32 and 33 in order to adjust the
height of the rolling gap 13 for the subsequent first profiling
pass, the beginning of which is illustrated in FIG. 13. FIG. 13
corresponds to FIG. 7 and shows the cutting-in phase for the first
non-cylindrical, profiled circumferential segment 35 of the roller
12. FIG. 14 corresponds to FIG. 8 and shows the end of the first
profiling step.
[0134] As the roller 12 continues to rotate, the metal strip 16 is
again brought out of engagement with the roller 12, and in this
phase, with the relieved portion 39 facing the metal strip 16, the
metal strip is recalled another time and the rolling gap is
adjusted, by operation of the screws 32 and 33, for the second
profiling step, the beginning of which is shown in FIG. 15 which
illustrates the cutting-in phase of the profiled circumferential
segment 40.
[0135] FIG. 16 shows the end of the second profiling step. By
further rotating the roller 12, the metal strip 16 is once more
disengaged and can be positioned for the equalising step in the
next following strip section, while the height of the rolling gap
13 is simultaneously, or subsequently, adjusted for the equalising
step. Thereafter, the sequence of the steps illustrated in FIGS. 11
to 16 is repeated. In order to achieve a high degree of
reproducibility of the rotary angle of the roller 12, it is most
convenient if the roller 12 is reversed to a predetermined starting
position (for example the 0.degree. position) at the end of every
process cycle, in order to prevent any inaccuracies from summing up
by continuous full revolutions of the roller 12.
[0136] This method of operation is especially well-suited for the
production of profiled sections in strips where the desired
reduction per pass cannot be reached, or can be reached only with
difficulty, with the desired accuracy in a single profiling
step.
[0137] The invention may be carried out also with more than two
profiling steps. In order to permit the required number of
circumferential segments participating in the rolling process to be
accommodated, the diameter of the roller 12 may be increased as
desired.
[0138] Further, there is the possibility to provide, either
additionally to or instead of an equalising step, a reducing step
by which the thickness of the metal strip 16 is initially uniformly
reduced in sections before these are profiled in a later rolling
step.
[0139] The invention finds its application not only in the
production of input stock for writing pens, but also in the
production of other input stock which is profiled, in a sequence of
regularly recurring sections, over the entire width of the metal
strip 16, for example for the production of a strip-like input
stock for the production of electric conductive structures, such as
contact springs or leadframes, or for the production of grooved
strips where the grooves, with or without pockets or niches, extend
crosswise to the longitudinal direction of the metal strip 16, in
parallel or not in parallel to the axis of the roller, and
continuously from one longitudinal edge to the other longitudinal
edge of the metal strip, for example for the production of
commutator segments, electric plug-in connectors or other electric
contact elements. Even sheet metal parts for the automotive
industry, which are stiffened by a corresponding profiling, can be
produced at low cost and with a high degree of precision. The
method according to the invention permits the production of any
profiled shape that can be produced by means of rollers, if
necessary profiled rollers.
[0140] FIG. 17. shows, in a schematic diagram, how the servomotors
7 and 8 of the two coilers 5 and 6, preferably also electric motors
41 and 42 designed as servomotors for driving the roller 12 and the
back-up roller 15, and the two electric motors 34, which preferably
also consist of servomotors with a gearing 34a connected
downstream, by which the roller 12 can be displaced using the
screws 33 and 32, are linked via a common electric control unit 43.
It is thus possible, by controlling the servomotors 7 and 8 in
response to a profile shape to be rolled into the metal strip 16,
which is input into the control unit 43 and, preferably, stored in
digital form, to control the feeding motion of the metal strip 16
during the rolling and recalling phases, to rotate, stop and, if
necessary, reverse the roller 12 and the back-up roller 15
correspondingly, and to displace the roller 12 by actuation of the
electric motors 34, in response to the feeding motion of the metal
strip 16 and the profile shape input to the control unit 43. To
this end, the actual positions are each fed back to the control
unit 43 by incremental rotary transducers. These rotary transducers
are integrated in the servomotors 7, 8, 41 and 42. In the drawing,
one incremental rotary transducer 44 is shown by way of example
between the screws 32 and 33 and two servomotors 34,
respectively.
[0141] FIG. 17 shows a cylindrical roller 12, which has a radial
notch 45 parallel to its axis in order to provide a reference for
its rotary position. If the roller 12 has a non-cylindrical
circumferential segment, as in the example previously discussed,
displacement of the roller 12 will not take place during the
rolling process, but can be carried out only between the individual
rolling steps, as necessary.
[0142] The curve according to which the roller 12 is displaced
cannot only be stored in the control unit in the form of suitable
software. Rather, a mechanical control using a cam running in
synchronism with the strip feed is, generally, likewise
possible.
[0143] The device illustrated in FIG. 17 also permits metal strips
with grooves that extend crosswise to their longitudinal direction,
or metal strips with another profile extending continuously over
the full width of the metal strip 16, to be produced if the roller
12 is provided with a corresponding profile extending in the
circumferential direction.
[0144] FIG. 18 shows an embodiment modified as compared with FIGS.
1 to 4. It differs from the embodiments illustrated in FIGS. 1 to 4
insofar as gripper feed mechanisms 52 and 53 are provided instead
of coilers 5 and 6. This embodiment is suited especially for
shorter or thicker metal strips 16 that cannot be coiled so
easily.
[0145] The gripper feed devices 52 and 53 comprise a carriage 56,
67 that can be approached to and withdrawn from the rolling gap 13
in horizontal direction, by means of a servomotor 54, 55. A
dovetail spring 58 is provided for this purpose on the bottom
surface of the carriage 56, 57, which spring engages a matching
dovetail groove 59, 60 formed in an element 61, 62 attached to the
roll stand 2. The engagement between the groove 59, 60 and the
spring 58 ensures perfect horizontal guidance for the carriages 56,
57. Other types of guides are also possible. Each carriage 56, 57
is equipped with a lower jaw 63 and an upper jaw 64, fixed rigidly
on the carriage, the distance of the upper jaw from the lower jaw
being variable, preferably by means of a pneumatic cylinder. The
metal strip 16 is passed, and clamped if necessary, between the two
jaws 63 and 64, which form a pair of grippers or a clamp. The
gripper feed mechanisms 52 and 53 can be actuated and displaced
individually, but also jointly in matched fashion. In the latter
case it is also possible, during both the rolling and the recalling
action, to maintain a defined tensile stress in the section of the
metal strip 16 that is tensioned between the two gripper feed
mechanisms 52 and 53.
[0146] The two gripper feed mechanisms 52 and 53 are arranged
adjacent the rolling gap 13, as shown in FIG. 18. The device 19 for
exhausting rolling oil is arranged at the discharge end of the
rolling gap 13, after the gripper feed mechanism 53 in the rolling
direction, followed by a thickness gauge 51 for picking up and
signalling the thickness of the rolled metal strip 16, either by
means of a probe or in no-contact fashion, so that suitable
controlling or regulating action can be taken to vary the height of
the roller 13 in a suitable manner if deviations from the desired
thickness should occur.
[0147] FIG. 19 shows a metal strip 16, which can be produced
according to the invention and which has been profiled on both
sides, with grooves 74 extending in crosswise direction in the
bottom surface of the metal strip 16 and grooves 75 and 76
extending in crosswise direction in the upper surface of the metal
strip 16, the grooves 74 in the bottom surface having been formed
in a first pass, the grooves 75 and 76 in the upper surface of the
metal strip 16 having been formed in a second pass, after the metal
strip has been turned over. That sequence of process steps is,
however, not compulsory. In the illustrated example, the grooves 74
are narrower than the overlying grooves 75, which alternate in the
upper surface of the metal strip 16 with the narrower grooves 76.
It is a particularity of that example that the wider grooves 75
open up to form rectangular niches 77 of a relatively small depth,
measured in the longitudinal direction 79 of the strip 16 so that
the displacement of material from the niches can be kept under
control.
[0148] The metal strip illustrated in FIG. 20, which can be
produced according to the invention, differs from the metal strip
illustrated in FIG. 19 in that niches 78 with curved borders have
been produced instead of rectangular niches 77.
[0149] The invention not only allows the production of metal strips
with grooves that open up to form rectangular or curved niches, as
shown in FIGS. 19 and 20, but also provides the possibility to
provide a metal strip 16 with recesses 80, arranged one behind
and/or one beside the other, which recesses are enclosed by a
closed border, for example of triangular, rectangular or circular
shape, as illustrated in FIG. 21. Other outline shapes are likewise
possible. In the example illustrated in FIG. 20, the recesses 80
are delimited by circumferential walls that extend at a right angle
or nearly a right angle relative to the plate 67. However, the
circumferential walls of the recesses 80 may also extend obliquely
to the plate 67, i.e. so that the recesses widen from their bottom
toward the upper surface of the metal strip 16.
[0150] Recesses 80 of that kind can be formed by moving the metal
strip 16 through the gap between the working roller 12 and a plate
67, which is provided on its upper surface with bumps 81 of a shape
complementary to the recesses 80, as shown diagrammatically in
FIGS. 3a and 4a.
* * * * *