U.S. patent application number 09/833853 was filed with the patent office on 2002-10-17 for process of bending laminated metal sheet.
Invention is credited to Krutz, Keith J., McKinney, John L..
Application Number | 20020148273 09/833853 |
Document ID | / |
Family ID | 25265444 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020148273 |
Kind Code |
A1 |
McKinney, John L. ; et
al. |
October 17, 2002 |
Process of bending laminated metal sheet
Abstract
This invention improves on the process of bending in a
conventional progressive stamping press a flat laminated metal
sheet around a corner edge of a die block to form a generally
straight piece-part corner, and comprises the steps of forming
extended concavely rounded depressions in the opposite sheet faces
at the sheet locations of the intended corner, then locating and
clamping the sheet with the depressed regions aligned along a die
block corner, and then mechanically bending the sheet with said
depressed sheet regions aligned over the die block corner edge. The
sheet depressions can be aligned essentially opposite one another,
being rounded concavely and of a high width-to-depth ratio and of a
depth to reduce the sheet to between 80-30% of its original
thickness. The sheet depressions might occur at one stamping press
station by opposing press tools each having a convex rounded
working edge elongated along the length of the intended corner,
with the blank bending occurring at a subsequent stamping press
station.
Inventors: |
McKinney, John L.;
(Arlington Hts., IL) ; Krutz, Keith J.; (Des
Plaines, IL) |
Correspondence
Address: |
CHARLES F. LIND & ASSOCIATES
ATTORNEYS AT LAW
SUITE 300
120 W. EASTMAN
ARLINGTON HEIGHTS
IL
60004-5950
US
|
Family ID: |
25265444 |
Appl. No.: |
09/833853 |
Filed: |
April 12, 2001 |
Current U.S.
Class: |
72/379.2 |
Current CPC
Class: |
B21D 5/00 20130101; B21D
35/00 20130101 |
Class at
Publication: |
72/379.2 |
International
Class: |
B21D 031/00 |
Claims
What is claimed is:
1. A method of folding, with a conventional stamping press, a
generally flat laminated metal sheet about a corner to form a
three-dimensional piece, the combination comprising the steps of:
locating the sheet at a first press station, and striking a press
tool having a convexly rounded working edge elongated substantially
along the entire length of the intended piece corner against a
sheet face at the location of said intended piece corner, for
forming an elongated concavely rounded depressed region therein and
thereby reducing the sheet thickness between adjacent main and fold
sheet portions; locating the sheet at a second press station to
have the main sheet portion supported on a press block with the
depressed region aligned adjacent a press block corner and the fold
sheet portions cantilevered beyond the press block corner to an
adjacent clearance space; and holding the main sheet portion
against the press block while moving a folding tool against the
fold sheet portion for bending said sheet about the press block
corner at the depressed region.
2. A method of folding a laminated metal sheet according to claim
1, further wherein opposed striking press tools are used for
forming concavely rounded depressed regions in the opposite sheet
faces at essentially opposite locations proximate said intended
piece corner operable for reducing the sheet thickness between the
adjacent main and fold sheet portions.
3. A method of folding a laminated metal sheet according to claim
2, further wherein each depressed region is of a generally uniform
curvature having a radius sized between the same as and up to
several times the sheet thickness.
4. A method of folding a laminated metal sheet according to claim
2, further comprising each depressed region having a depth between
10-35% of the original blank thickness, leaving the thinnest part
of the sheet at the intended corner between 80-30% of the original
sheet thickness.
5. A method of folding a laminated metal sheet according to claim
2, further wherein each depressed region has a high width-to-depth
ratio, the width being at least twice and up to many times the
depth.
6. A method of folding a laminated metal sheet according to claim
4, further wherein each depressed region is of a generally uniform
curvature having a radius sized between the same as and up to
several times the sheet thickness.
7. A method of folding a laminated metal sheet according to claim
6, further wherein each depressed region has a high width-to-depth
ratio, the width being at least twice and up to many times the
depth.
8. A method of folding a laminated metal sheet according to claim
2, further wherein each depressed region is of a generally uniform
curvature having a radius sized between the same as and up to
several times the sheet thickness, and each depressed region having
a depth between 10-35% of the original blank thickness, leaving the
thinnest part of the sheet at the intended corner between 80-30% of
the original sheet thickness.
9. A method of folding a laminated metal sheet according to claim
2, further comprising each depressed region having a depth between
10-35% of the original blank thickness, leaving the thinnest part
of the sheet at the intended corner between 80-30% of the original
sheet thickness, and each depressed region having a high
width-to-depth ratio, the width being at least twice and up to many
times the depth.
10. A method of folding a laminated metal sheet according to claim
2, further wherein each depressed region being of a generally
uniform curvature having a radius sized between the same as and up
to several times the sheet thickness, and each depressed region
having a high width-to-depth ratio, the width being at least twice
and up to many times the depth.
11. A method of folding, with a conventional stamping press, a
generally flat laminated metal sheet about a corner to form a
three-dimensional piece, the combination comprising the steps of:
forming opposed elongated concavely rounded depressed regions in
opposite sheet faces substantially along the entire length of and
at the sheet location of the intended piece corner and between
adjacent main and fold sheet portions; supporting the main sheet
portion on a press block with the depressed region aligned adjacent
a press block corner and holding it there, and moving a fording
tool against the fold sheet portion cantilevered beyond the press
block corner to an adjacent clearance space for bending said sheet
about the press block corner at the depressed region.
12. A method of folding a laminated metal sheet according to claim
11, further comprising each depressed region being of a generally
uniform curvature having a radius sized between the same as and up
to several times the sheet thickness, each depressed region having
a depth between 10-35% of the original sheet thickness, leaving the
thinnest part of the sheet at the intended corner between 80-30% of
the original sheet thickness, and each depressed region having a
high width-to-depth ratio, the width being at least twice and up to
many times the depth.
Description
BACKGROUND OF THE INVENTION
[0001] It has long been common to enclose physical components, such
as electrical or electronics controls, mechanical pumps, valving,
cooling fans and powering electric motors, or the Like, in a formed
sheet metal housing having rigidity and strength for protecting the
enclosed components. Use of conventional progressive stamping
presses has been a favored manner of fabricating three-dimensional
metal parts including housings, particularly when a great number of
pieces are to be made, as a continuous web or blank of material can
be used in making up all or a major portion of the part, for
reducing inventory and the time and effort of assembling different
parts. Progressive fabricating operations will be performed at
sequential stamping stations, such as for shaping ribs, bosses,
etc. on the blank surfaces, and/or for cutting, shearing or
piercing through the blank for yielding needed holes or the overall
blank shape, and/or for folding the blank to a general three
dimensional part shape, and ultimately for shearing the folded and
shaped piece from the blank. Each stamping station will thus have
specifically configured but otherwise generally conventional
punch/die assemblies that cooperate to achieve the above noted and
possibly other fabricating procedures.
[0002] Specifically, a typical stamping press might have a base and
ram powered to move toward and away from one another, with
cooperating die and punch assemblies being respectively carried
thereon at each stamping station and cooperating pin-bushing
structures providing accurate reciprocating stamping strikes. A
stripper plate is also carried by the ram guided to move in a
direction substantially parallel to the punches, and being spring
bias to a position with the punches essentially retracted behind
the stripper plate remotely of the die assembly and die assembly
blocks thereon. With the base and ram fully separated, the web or
blank can be moved with clearance between the adjacent stripper
plate and die blocks, being indexed with equal advances and stopped
with the same blank portions in registry with the spaced stamping
stations. To provide registry, pilot holes pierced in the stopped
blank at a first stamping station receive pilot pins at each
successive stamping station. The advancing web could be elevated
slightly above the die blocks by spring biased lifters engaging the
web side edges. Upon the ram-base closing, the stripper plate
engages the web and holds it under the spring forces against the
die blocks face, while subsequent continued ram-base closure
protrudes the punches through stripper plate openings to effect a
punch hit against the blank and die blocks. Bottoming blocks
between each cooperating set of adjacent punch and die assemblies
limit the punch-die block penetration. The reverse ram-base
movement separates the punches from the die assemblies, spring
lifters separate the blank from the die blocks, and the rising
spring biased stripper plate strips the punches from the blank. Any
blank portions severed during the stamping procedure, including
both scrap and stamped piece-parts, can pass to an underlying
collection bin or take-away conveyor for later recovery.
[0003] To reduce the needed power of the stamping press in having
the punches pass through and/or deform the web material, the
punches at the different stamping stations might be set at
different heights to sequentially strike the blank.
[0004] When press folding a blank, the fold panel first will be die
cut to have its perimeter free, while it yet will be coplanar with
and cantilevered away from the main panel. The region where the
blank is to be folded will be positioned to overlie a die block
corner exteriorly shaped the same as the intended interior blank
corner and fold panel angle, with clearance space underlying the
fold panel. The main panel will be clamped between the stripper
plate and die blocks, and a punch shaped generally the same as the
fold panel, in the stamping stroke will engage the fold panel and
force it around the die block corner and into the clearance space
and possibly against the side of the die block. A punch lip can
engage the blank corner exterior, between the main and fold panels,
for improved corner retention at the folded angle.
[0005] While some advantages of conventional metal housings have
been noted, a realized negative is that such housings will transmit
or even amplify the noises of the housed components, or might even
vibrate and create its own noises. This noise transmission aspect
of course holds true for other sheet metal parts, so the invention
to be disclosed herein might be advantageously applied for the
stamping fabrication of them.
[0006] A modified form of sheet material, known as laminated metal,
has been found most suited for reducing the transmission of noise
or vibrations. This laminated metal is comprised basically by two
metal sheets that sandwich and are held separated but relative to
one another by a bonding elastic or vicoelastic material. One form
of such laminated metal is sold under the trademark QUITE STEEL by
MSC Laminates and Composites, Inc. of Elk Grove, Ill. The theory of
providing reduced sound transmission is that the vibrational energy
is converted into heat energy by the shear deformation of the
vicoelastic core.
[0007] While the laminated metal housing and/or piece part made
therefrom will effectively reduce noise or vibration transmission,
the shaping or bending of the laminated metal, from a flat piece,
to the desired three dimensional housing or any other intended part
shape, by a conventional sheet metal stamping or progressive die
press has been unexpectedly difficult, unreliable or even
unacceptable. For example, bending the thin cross-section laminate
material (of steel or possibly other metals) into a
three-dimensional piece, has tended to shift the metal sheets
relative to one another and along the sandwiched bonding elastic or
vicoelastic material. Such sheet shifting could raise cosmetic
concerns at visible misaligned sheet edges, and/or could create
functional tolerance problems of location and/or size of holes, for
example, due to misaligned sheet edges at the holes previously
punched through the sheets. Further, sheet separation has been
experienced at the edges, and/or internal stresses created in the
laminated sheets on both sides of the formed corner has bowed or
otherwise distorted the panels from being planar, as intended. The
offshoot is potential customer rejection of the formed housing or
component piece-part.
SUMMARY AND OBJECTS OF THE INVENTION
[0008] This invention relates to the process of shaping or bending
a laminated metal web or blank, by means of a conventional
progressive stamping press or folding technique that bends the flat
blank or sheet over and around a corner edge of a supporting block
or the like to form a generally straight corner.
[0009] An object of the invention is to improve the conventional
stamping techniques or process to avoid misalignment of the exposed
bent sheet edges and/or separation of the sheet laminates from the
sandwiched adhesive therebetween and/or residual bowing of intended
planar flat sheet portions or panels adjacent the formed corner or
between adjacent formed corners.
[0010] A basic feature of the improved process of bending a
laminated metal sheet, includes deforming the laminated metal to
reduce the sheet thickness along the extended location of the
intended corner, and thereafter mechanically bending the laminated
metal sheet at said reduced sheet thickness location according to
conventional press and/or sheet bending techniques.
[0011] A more detailed feature of this invention is to deform the
laminated metal web or blank by depressing its opposite faces at
locations essentially opposite one another, to reduce the sheet
thickness greatest at what should be the center of the anticipated
corner to be formed. This might be done at one press station with
the web or blank generally planar by opposed press tools, each
having a convex or rounded working edge elongated along the length
of the intended corner, striking against the opposite sheet
faces.
[0012] A suitable forming press tool might have a convex protrusion
having a curvature radius between being approximately equal to and
several times the original sheet thickness; and each face might be
depressed between possibly 10-35% of the original sheet thickness,
leaving the thinnest part of the web possibly between 80-30% of the
original sheet thickness. The convex shape of the cooperating tools
and the extent of the concave deformations provide that the
greatest sheet depression occurs across opposed arcuate curvatures,
although minor bulges might occur above the face of the blank
immediately adjacent the ends of each depressed region, and further
seem to confine all blank bending in these regions and virtually
eliminates laminate sheet sliding or shifting in the blank regions
laterally adjacent the depressions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above objects, advantages and features of the invention
will be more completely understood and appreciated upon reviewing
the following specification, the accompanying drawings being a part
thereof, wherein;
[0014] FIG. 1 is a sectional view of a typical laminated metal
sheet (or blank), with opposed crease regions or impressions formed
therein;
[0015] FIG. 2 is a sectional view of punch or tool components for
forming the crease regions in the FIG. 1 metal sheet;
[0016] FIG. 3 is a plan view of a flat blank illustrating the
crease regions needed to form the piece-part of FIG. 4;
[0017] FIG. 4 is a perspective view of the piece-part formed from
the blank of FIG. 3, practicing the invention; and
[0018] FIGS. 5 and 6 are cross sectional views of successive
typical blank folding stations, showing cooperating punch and die
components as used in folding the blank of FIG. 3.
DESCRIPTION AND EXPLANATION OF THIS INVENTION
[0019] FIG. 1 shows a sectional view of a piece 10 of laminated
metal, being comprised of two metal sheets 12, 14 that sandwich and
are held separated but relative to one another by a core 16 of a
bonding elastic or vicoelastic material. The figure also shows
typical crease regions or depressions 18, 20 formed in the opposite
faces 18F, 20F of the laminated metal piece, according to the
teachings of this invention.
[0020] More specifically, FIG. 3 shows in plan view a blank 22
which might be folded to three-dimensional piece-part 24
illustrated in FIG. 4. The piece part 24 has main panel 26, and
opposed side panels 28, 30 (30 being shown only in FIG. 4), and
side panel 32 folded 90 degrees from the main panel across corners
29, 31, 33 respectively; and further has flange panel 34 folded 90
degrees from the side panel 32 across corner 35.
[0021] The invention provides that prior to bending the fold panels
28, 30, 32, 34 relative to its adjacent hinged panel, crease
regions or depressions 18, 20 will be formed in the opposite faces
18F, 20F of the laminated metal blank 22 along what will be the
respective corner 29, 31, 33, 35 between the panels, as indicated
by the dotted depression lines 29D, 31D, 33D, 35D in FIG. 3. The
depressions 18, 20 can be made at any stamping station prior to
bending the defined panels; as typically the miscellaneous holes or
openings 40 will be punched in the blank 22 before panel
folding.
[0022] Even after the crease regions or depressions 18, 20 have
been formed at the 29D, 31D, 33D, 35D locations, the blank 22 will
be substantially flat and each panel will yet be integral and
coplanar with the adjacent panel(s) across each crease region or
depression where each corner will be folded. Further though, the
fold panel will be die cut to have free perimeter edges spaced from
the anticipated fold regions and corners.
[0023] In forming the crease regions or depressions 18, 20,
opposing punch and die components 40, 42 (FIG. 2) will be provided
at one press stamping station "A" prior any subsequent blank
bending stamping station(s) "B" (FIG. 5) and "C" (FIG. 6). Each
punch and die component 40, 42 can be shaped as a protrusion 44
extended substantially along the entire intended corner length and
terminating across a rounded converging end. As illustrated, the
protrusion end might be curved convex and even of uniform curvature
radius, which might be sized between being the same as and up to
several times the sheet thickness. The punch and die components 40,
42 can be mounted to essentially oppose one another, and be moved
toward one another without touching, operable to create the shallow
depressions or concave valleys 18, 20 (FIG. 1) in the opposite
blank faces at locations or regions essentially opposite one
another.
[0024] Each depression or valley 18, 20 might be of generally
uniform concave curvature, although they need not be at the same
curvature; but preferably each will be much wider than its depth.
This provides that the greatest reduction of sheet thickness would
be near or at the middle of each valley near or at the center of
the intended corner. Further, each depression face will blend then
along a concave curve to near its opposite ends, where it might
traverse across non-controlled small convex bulges before blending
with the planar faces 18F, 20F of the laminated metal blank. The
high width-to-depth ratio of the defined depression regions or
valleys, with the greatest blank depression being between adjacent
regions of lesser depressions, seems to confine virtually all panel
bending at the intended corner and within the depressed regions;
effectively then for substantially eliminating lateral sliding of
the laminate sheets 12, 14 relative to one another beyond the
depressions.
[0025] By way of example, a laminated metal blank 10 having a 0.042
inch thickness, formed of two steel sheets 12, 14 each of 0.020
inch thickness and a 0.002 inch resilient core 16, might be
deformed by similar 3 mm tool components 40, 42 having a 0.060 inch
radius convexly curved die. Further, each blank face might be
depressed approximately between 10-35% of the original blank
thickness, leaving the thinnest part of the web or blank possibly
between 80-30% of the original blank thickness, or possibly between
0.015-0.035 inch thickness. With such tooling and depression
formations, the width of each created concave valley might be at
least twice and up to many times the valley depth.
[0026] The laminated metal blank 10, as so prepared with the
extended depressed regions 18, 20 lying across the blank where the
corner folds are to be made, can thereafter be indexed to a
subsequent press station "B" (FIG. 5) or "C" (FIG. 6), where the
depressed fold regions will be lined up substantially at die block
corner edges (50 in FIG. 5, or 60 in FIG. 6) of supporting press
die blocks 52, 62 respectively. When so positioned, holding blocks
(52, 53 in FIG. 5 and 62, 63 in FIG. 6) opposing the main blank
panel (26, 32 in FIG. 5, and 26 only in FIG. 6) can effectively
clamp the blank in the press, and the fold panel (34 in FIG. 5 and
32 in FIG. 6) will be integral and coplanar therewith across the
depression region and cantilevered to underlie (FIG. 5) or overlie
(FIG. 6) adjacent clearance space (55 in FIG. 5 and 65 in FIG. 6).
The press folding punch (56 in FIG. 5 and 66 in FIG. 6) might then
be moved relative to and against the cantilevered fold panel for
bending it around the die block corner edge and into the adjacent
clearance space and possibly against the side face of the die
block. The die block corner edge might be slightly rounded convexly
and the punch might have a rounded Lip (58 in FIG. 5 and 68 in FIG.
6), operable to engage the opposite blank faces to help set the
size, shape and angle of the intended corner to the required
specifications.
[0027] The above noted stamping press fixtures and techniques can
be standard or conventional, except for the inventive tooling and
step of first preforming the blank to be folded with the corner
depressions and then appropriately aligning such depressions at the
die block corner edge, before actually bending the blank.
[0028] It should be noted that the above added preforming steps
have unexpectedly improved bending results in that post-formation
visual examinations of all formed corners made with this process
reveal that the panels adjacent the corner remain flat and planar,
and the exposed laminate edges of the fold panels remote from the
formed corner were yet sharp and square; indicating virtually no
lateral shifting of the different metal sheets occurred during the
otherwise conventional stamping formation of the bent corners.
[0029] The process is not limited to only laminate metals of steel,
as metal laminates can be made of other metals; and the metal
sheets need not be of the same thickness.
[0030] While only a single embodiment is illustrated, changes
thereto or modifications therefrom can be made by a person skilled
in the art. Consequently, the scope of the invention is to be
limited only by the following claims.
* * * * *