U.S. patent number 3,838,590 [Application Number 05/340,874] was granted by the patent office on 1974-10-01 for method and apparatus for forming undercut corrugations in sheet metal.
Invention is credited to Edsger Wybe Van Dijk.
United States Patent |
3,838,590 |
Van Dijk |
October 1, 1974 |
METHOD AND APPARATUS FOR FORMING UNDERCUT CORRUGATIONS IN SHEET
METAL
Abstract
A metal sheet or band is clamped betweed spaced pairs of clamps,
movable toward and away from each other, at points spaced apart a
distance equal to the width of the sheet required to define an
undercut corrugation to be formed. A forming die having an enlarged
head, such as a circular cross-section head, and a narrow neck,
such as a rectangular neck, extending from the head, is movable
perpendicularly to the plane of the sheet centrally between the
pairs of clamps to engage and deform the sheet while the pairs of
clamps are moved toward each other to wrap the sheet closely around
the head and neck of the die to form the undercut corrugation. A
second die may be provided to move in opposition to the first die
to press the metal sheet against the top of the head of the first
die. After formation of the undercut corrugation, the pairs of
closed clamps are retracted relative to each other to provide
clearance for retraction of the die head through the narrow
undercut portion of the formed corrugation. The clamps may then be
released, or they may be brought toward each other until they are
spaced apart a distance equal to the thickness of the narrow part
of the undercut corrugation. Stops may be provided to limit the
movement of the clamps relative to each other.
Inventors: |
Van Dijk; Edsger Wybe (Utrecht,
NL) |
Family
ID: |
26644745 |
Appl.
No.: |
05/340,874 |
Filed: |
March 13, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
72/307; 72/381;
72/379.6; 72/403 |
Current CPC
Class: |
B21D
13/10 (20130101); B21D 13/02 (20130101) |
Current International
Class: |
B21D
13/00 (20060101); B21D 13/10 (20060101); B21D
13/02 (20060101); B21d 013/10 () |
Field of
Search: |
;72/381,383,401,403,306,308,309,307,296,301,305,316,318,379,385,389 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
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177,308 |
|
Jan 1954 |
|
OE |
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79,261 |
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Feb 1932 |
|
SW |
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Primary Examiner: Lanham; C. W.
Assistant Examiner: Keenan; M. J.
Attorney, Agent or Firm: Blum, Moscovitz, Friedman &
Kaplan
Claims
What is claimed is:
1. A method of forming a series of undercut corrugations in a metal
sheet or band comprising the steps of clamping a sheet between
spaced pairs of clamps, movable toward and away from each other, at
points spaced apart a distance equal to the width of the sheet
defining the undercut corrugation to be formed; moving a forming
die, having an enlarged head and a narrow neck, perpendicular to
the plane of the sheet centrally between the pairs of clamps to
engage and deform the sheet while moving the pairs of clamps toward
each other to wrap the sheet around the head and neck of the die to
form the undercut corrugation; and thereafter opening the undercut
corrugation an amount sufficient to provide clearance for
retraction of the die head through the undercut portion of the
formed undercut corrugation.
2. A method of forming a series of undercut corrugations in a metal
sheet or band, as claimed in claim 1, in which, when the metal
sheet or band is springy, opening of the undercut corrugation is
effected by retraction of the forming die.
3. A method of forming a series of undercut corrugations in a metal
sheet or band, as claimed in claim 1, in which opening of the
undercut corrugation is effected by withdrawing the pairs of closed
clamps a distance sufficient to provide clearance for retraction of
the die head through the undercut portion of the formed undercut
corrugation.
4. A method of forming a series of undercut corrugations in a metal
sheet or band, as claimed in claim 3, including, following such
withdrawal of said clamps, advancing the clamps toward each other
to restore the undercut corrugation to its initial shape.
5. A method of forming a series of undercut corrugations in a metal
sheet or band, as claimed in claim 1, including applying a
counterdie against the sheet wrapped around the head of the forming
die.
6. A corrugating station for forming a series of undercut
corrugations in a sheet metal or band, comprising in combination,
means for intermittently moving said sheet metal or band in a first
direction into a position to be corrugated, a forming die having an
enlarged continuous cross-sectioned head terminating in a narrow
neck, said narrow neck being mounted for movement perpendicular to
the plane of said sheet, a counter die movable in opposition to and
alignment with said forming die and having a surface
cross-sectioned to mate with said forming die when said surface is
moved in contact with said sheet portion wrapped around said
forming die by the perpendicular movement of said forming die into
engagement with said sheet, and spaced pairs of clamps on each side
of said forming die, said clamp pairs being adapted to be moved
toward said forming die to form said corrugation and away from said
forming die after said corrugation is formed, and means for moving
one of said clamps of said clamp pair downstream of the direction
of intermittent movement of said sheet metal and on the same side
of the sheet metal as said counter die, and said counter die, away
from said sheet after said clamp pairs have been moved away from
said counter die prior to the intermittent movement of said
sheet.
7. A corrugating station as claimed in claim 6 and including outer
stops for limiting the movement of said clamp pairs away from each
other after said corrugation has been formed and intermediate stops
selectively positioned in the path of said clamp pairs being
displaced away from each other to limit the retracting movement of
said clamps to a distance sufficient to provide an opening of the
formed corrugation and thereby allow said forming die to be removed
from said corrugation through the undercut portion of the formed
under cut corrugation.
Description
FIELD AND BACKGROUND OF THE INVENTION
The invention is directed to the manufacturing or forming of
undercut corrugations in a metal sheet or band and, more
particularly, to a novel and improved method of and apparatus for
effecting such formation.
In a known apparatus for forming undercut corrugations in a metal
sheet or band, two pairs of clamps are arranged in a frame to be
movable horizontally relative to each other while clamping
therebetween a piece of sheet metal. At the same time, as the
clamps are moved toward each other, a forming die, positioned
between the pairs of clamps and beneath the sheet material, is
moved upwardly, with the motions of the clamps and of the forming
die being coordinated in such a way that the sheet is folded
against the forming die without shifting relative to the die. Such
an apparatus is disclosed, for example, in Netherlands Pat. No.
132,181. In the known apparatus, the forming die is then retracted
to its original position while the clamps remain stationary, after
which the clamps, with the corrugation between them, are moved
further toward each other.
With the known procedure, it is indeed possible to form a manifold
of several undercut corrugations. However, if the material to be
corrugated is not entirely homogeneous, either in thickness or in
its mechanical properties, exactly the same corrugation is not
always obtained, and identical corrugations are often required.
SUMMARY OF THE INVENTION
The objective of the invention is, on the one hand, to enlarge or
expand the range of possible undercut corrugations which can be
formed and, on the other hand, to decrease the dependence of
reproducible results on the homogenity of the material. In
accordance with the invention, the forming part of the forming die
is made in such a way that, by folding of the sheet material
against the forming die, an undercut corrugation is formed. With
springy material, the undercut corrugation may be released by
loosening the clamps, moving them outward a slight distance from
their middle position, and then retracting the forming die
forcibly, whereby the deformation of the formed corrugation, caused
by the passing of the widest part of the forming die through the
narrowest part of the corrugation, is compensated by springback of
the force of the opened corrugation.
In accordance with the invention, the forming die may also be
withdrawn from the corrugation by maintaining the clamps closed and
moving them sufficiently far apart that the forming die may be
pulled back freely through the resultant opened corrugation. The
undercut corrugation, already shaped, is thereby partly unfolded.
From experiments, however, it has been determined that the
deformation by the original formation has been such, in many cases,
that in moving the clamps together again, while clamping the sheet,
the original corrugation is restored. Although it is not always
necessary, a suitable counterdie beam, as known from the art, may
be used.
An object of the invention is to provide a novel method of forming
a series of undercut corrugations in sheet metal.
Another object of the invention is to provide an improved apparatus
for forming a series of undercut corrugations in sheet metal.
A further object of the invention is to provide such a method and
apparatus operable to form identical corrugations in sheet metal
and independent of whether or not the material is completely
homogeneous either in thickness or in mechanical properties.
Still other objects and advantages of the invention will in part be
obvious and will in part be apparent from the specification.
The invention accordingly comprises the several steps and the
relation of one or more of such steps with respect to each of the
others, and the apparatus embodying features of construction,
combinations of elements and arrangement of parts which are adapted
to effect such steps, all as exemplified in the following detailed
disclosure, and the scope of the invention will be indicated in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, reference is had to
the following description taken in connection with the accompanying
drawings in which:
FIG. 1 is a somewhat schematic perspective view of apparatus
embodying the invention; and
FIGS. 2 through 10 are somewhat schematic vertical sectional views
along the line 2--2 of FIG. 1 and illustrating the different phases
of a working cycle.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 1, the metal sheet to be corrugated is
indicated at 15, with the corrugation to be formed being indicated,
as in FIG. 10, at 30. The apparatus includes clamps 12, 12 and 13,
13 which are arranged to be moved substantially horizontally toward
and away from each other. Motions of clamps 12 and 13 away from
each other, or away from the center of the apparatus, are limited
by adjustable stops 16 and 16', it being noted that the stops 16'
are substantially longer than the stops 16. Stops 18 limit movement
of clamps 12 and 13 toward each other, and are adapted to the
ultimately required corrugation. Stops 18 may be omitted if the
required corrugation requires that, in the last folding operation,
as shown in FIGS. 6 and 7, the clamps 12 and 13 are moved as close
to each other as possible. Adjustable stops 17 are provided and, in
the phase of the apparatus shown in FIGS. 1 and 2, are positioned
directly beneath clamps 12 and 13.
The undercut corrugation is arranged to be formed by a lower die,
generally indicated at 20, including, in the illustrated example, a
circular cross-section head 21 and a narrow neck 22, neck 22 being
received in a groove 24 in a die support 23, so that lower die 20
is interchangeable when different shaped undercut corrugations are
to be formed. An upper die 25 is provided, in the particular
example shown in the drawings, to cooperate with lower die 20, and
includes a die part 26, having a concave lower edge, inserted into
a groove 28 in a die support 27, so that die part 26 is also
interchangeable with other die parts. Such interchangeability
allows the use of various shapes of dies in the respective die
holders 23 and 27 in accordance with the particular shape of the
undercut corrugation to be formed in metal sheet 15.
In the phase of the operation indicated in FIGS. 1 and 2, metal
sheet 15 has been clamped by the pairs of clamps 12 and 13 while
the latter are in engagement with the outer limit stops 16 and 16'
respectively. Clamps 12 and 13 maintain sheet 15 pressed while the
clamps are moved toward each other. During such mvoement, forming
die 20 is moved upwardly to engage and deform sheet 15 by wrapping
of the sheet metal around the head 21 and pressing of the sheet
metal against the neck 22, of die 20. At the same time, if
counterdie 25 is provided, it presses against the sheet metal
engaged with the upper portion of head 21. The parts thus obtain
the state shown in FIG. 3.
At this time, stops 17, 17 initially positioned under clamps 12 and
13 move upwardly to limit the retraction motion of clamps 12 and
13, the parts now occupying the position shown in FIG. 4. Clamps 12
and 13 are then retracted until they engage the stops 17, as shown
in FIG. 5. Due to this retraction of the closed clamps 12 and 13,
the sheet material hitherto folded around forming die 20 is
partially unfolded, also as shown in FIG. 5. The adjustment of
stops 17 must be such that, when clamps 12 and 13 engage these
stops, the head 21 of forming die 20 can be retracted vertically
through the resultant opening in the undercut corrugation 30.
When forming die 20 has been retracted, the parts have the position
as shown in FIG. 6. The formed, and afterwards partly unfolded
sheet material 15, has been deformed permanently by the first
forming action in such a way that, when clamps 12 and 13 are again
moved toward each other, as shown in FIG. 7, the undercut
corrugation assumes its originally formed shape. Such inward
movement of clamps 12 and 13 toward each other is limited by the
stops 18.
The shaped corrugation 30 must now be freed. For this purpose, the
upper clamps 12 and 13, of the respective pairs of clamps, are
displaced a slight distance upwardly, carrying with them the
counterdie 25. Stops 17, at the same time, are returned to their
retracted position. It is also possible to lower the lower clamps
12 and 13, of the respective clamp pairs, a small amount.
After this operation, clamps 12 and 13 are retracted horizontally
to their outer limiting position in which they engage the stops 16
and 16', respectively, and are aligned over the stops 17. At the
same time, the upper clamp 13 is raised a sufficient amount, as
shown in FIG. 9, so that the shaped corrugation 30 can be shifted
to the right beneath the upper die 13. Sheet material 15 is moved
to the right through the distance required or performed by the
usual feeding apparatus, which has not been shown, so that the
parts attain the position shown in FIG. 10.
With the parts having the position shown in FIG. 10, the cycle is
repeated by engaging clamps 12 and 13 with the sheet 15 and
operating the dies 20 and 25 to form a new corrugation, with the
initial step being the same as illustrated in FIGS. 1 and 2.
In the illustrated embodiment of the invention, the counterdie 25
is used. Very often this is not necessary, and it is not really
necessary in the illustrated embodiment. For example, if the
forming part or head 21 of forming die 20 is designed with an
elliptical cross-section having the longer axis extending
horizontally, the same ultimate corrugation would be obtained.
As a matter of practice, many constructional variations are
possible with respect to the schematically illustrated embodiment.
All of them have in common that the forming part or head of the
forming die has, under its widest part, a narrower part or neck 22
whereby, upon folding of the sheet material around the head, there
is shaped at all times an undercut corrugation.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in carrying out the
above method and in the construction set forth without departing
from the spirit or scope of the invention, it is intended that all
matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
* * * * *