U.S. patent application number 09/812491 was filed with the patent office on 2001-08-02 for method for forming a short-radius bend in flanged sheet metal member.
This patent application is currently assigned to Simpson Strong-Tie Company, Inc.. Invention is credited to Leek, William F..
Application Number | 20010010167 09/812491 |
Document ID | / |
Family ID | 23014498 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010167 |
Kind Code |
A1 |
Leek, William F. |
August 2, 2001 |
Method for forming a short-radius bend in flanged sheet metal
member
Abstract
One or more closed perimeter openings are formed in the
compression area of a flange of a member that is to be bent
transversely to the flange. The member is bent along a transverse
bend line, and the flanges are bent inwardly on themselves. The
bending of the member along the transverse bend line is done with a
great force, and because portions of the side flanges are supported
on their distal and proximal side, the material of the side flanges
in the compression area plasticizes and flows into the closed
perimeter opening, causing them to deform. Because the closed
perimeter opening or openings are present, the side flanges are
compressed in a more controlled manner, reducing cracking,
wrinkling and thinning during the bending of the member along the
transverse bend line.
Inventors: |
Leek, William F.; (Carmel,
CA) |
Correspondence
Address: |
JAMES R. CYPHER
405 14TH STREET
SUITE 1607
OAKLAND
CA
94612
|
Assignee: |
Simpson Strong-Tie Company,
Inc.
|
Family ID: |
23014498 |
Appl. No.: |
09/812491 |
Filed: |
March 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09812491 |
Mar 19, 2001 |
|
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|
09266416 |
Mar 10, 1999 |
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Current U.S.
Class: |
72/379.2 |
Current CPC
Class: |
E04B 1/2608 20130101;
B21D 53/74 20130101; B21D 11/10 20130101; B21D 5/0209 20130101 |
Class at
Publication: |
72/379.2 |
International
Class: |
B21D 031/00 |
Claims
I claim:
1. A method for shaping a piece of bendable sheet material having a
distal side and a proximal side and first and second ends,
comprising: a. forming a closed perimeter opening in said piece,
said closed perimeter opening having a first shape; b. bending said
piece along a flange bend line so that said piece adopts a first
intermediate position, said flange bend line dividing said piece
into a flange that contains said closed perimeter opening and a web
to the other side of said flange bend line, said flange having
distal and proximal sides, a top disposed away from said flange
bend line and a bottom coincident with said flange bend line; and
c. bending said web along a transverse bend line that divides said
web into a seat and a back and said flange into a seat flange and a
back flange, so that said piece adopts a second position, said
transverse bend line lying near said closed perimeter opening,
while bending said web along said transverse bend line
simultaneously supporting portions of said distal and proximal
sides of said flange such that said seat flange and said back
flange are swung inwardly on each other, such that portions of said
seat flange and said back flange near said ends of said part are
bent out of line and lie at an angle to each other, said bending
being carried out with a force sufficient to create compression
forces in portions of said flange near said transverse bend line,
causing portions of said flange to plasticize and flow into said
closed perimeter opening in said flange, such that said closed
perimeter of said opening is deformed by said material flow and
said opening adopts a second smaller shape than said first
shape.
2. The method of claim 1, further comprising: a. forming an
additional closed perimeter opening in said piece with a first
shape, said additional closed perimeter opening being located in
said flange near said transverse bend line, said first and
additional closed perimeter openings lying substantially similar
distances from where said transverse bend line and said flange bend
line intersect; and b. said additional closed perimeter opening
also being deformed by said material flow, such that said
additional closed perimeter opening adopts a second smaller shape
than said first shape when said bending along said transverse bend
line occurs.
3. The method of claim 1, wherein: said operation of forming said
closed perimeter opening in said flange occurs after said flange
has been formed by bending said piece along said flange bend
line.
4. The method of claim 1, further comprising: a. forming a second
closed perimeter opening in said piece simultaneously with said
closed perimeter opening, said second closed perimeter opening
having a first shape; b. bending said piece along a second flange
bend line that has a portion substantially parallel to said flange
bend line simultaneously with said bending along said flange bend
line, said second flange bend line dividing said piece into a
second flange that contains said second closed perimeter opening
and said web to the other side of said second flange bend line,
said second flange having distal and proximal sides, a top disposed
away from said second flange bend line and a bottom coincident with
said second flange bend line, and wherein when said piece is bent
along said transverse bend line that divides said web into said
seat and said back and said flange into said seat flange and said
back flange, said transverse bend lines also divides said second
flange into a second seat flange and a second back flange, and said
transverse bend line lies near said second closed perimeter
opening; and c. while bending said web along said transverse bend
line simultaneously supporting portions of said distal and proximal
sides of said second flange such that said second seat flange and
said second back flange are swung inwardly on each other, such that
portions of said second seat flange and said second back flange
near said ends of said part are bent out of line and lie at an
angle to each other, said bending occurring with a force sufficient
to create compression forces in portions of said second flange near
said transverse bend line, causing portions of said second flange
to plasticize and flow into said second closed perimeter opening in
said second flange, such that said closed perimeter of said second
opening is deformed by said material flow and said second closed
perimeter opening adopts a second smaller shape than said first
shape.
5. The method of claim 1, wherein: said closed perimeter opening
lies on said transverse bend line.
6. The method of claim 1, wherein: said closed perimeter opening
lies closer to said flange bend line than to said top of said
flange.
7. The method of claim 1, wherein: a. said sheet material has a
given thickness; and b. said closed perimeter opening and said top
of said flange are separated from each other by a space wider than
said thickness of said sheet material.
8. The method of claim 1, wherein: a. portions of said flange near
said bottom of said flange are curved by said bending of said
flange along said flange bend line; and b. said closed perimeter
opening lies adjacent to said curved portion of said flange.
9. The method of claim 1, wherein: said bends occurring along said
flange bend line and said transverse bend line are tight-radius, 90
degree bends.
10. A method of making a substantially channel-shaped joist hanger
from a piece of sheet material, comprising: a. providing closed
perimeter openings in said piece, each of said closed perimeter
openings having a first shape; b. bending said piece into a
substantially channel-shaped, first intermediate position, having a
central web and first and second flanges, by bending said piece
along first and second flange bend lines, each said flange having a
distal and a proximal side, a top disposed away from said flange
bend line and a bottom coincident with said flange bend line, with
at least one closed perimeter opening occurring in each of said
flanges; c. bending said web along a transverse bend line that
divides said web into a seat and a back and said flanges into seat
flanges and back flanges, so that said piece adopts a second
position, said transverse bend line lying near said closed
perimeter openings, while bending said web along said transverse
bend line simultaneously supporting portions of said distal and
proximal sides of said flanges such that said seat flanges and said
back flanges are swung inwardly on each other, such that portions
of said corresponding seat flanges and said back flanges near said
ends of said part are bent out of line and lie at an angle to each
other, said bending occurring with a force sufficient to create
compression forces in portions of said flanges near said transverse
bend line, causing portions of said flanges to plasticize and flow
into said closed perimeter openings in said flanges, deforming and
reducing said first shape of said closed perimeter openings such
that each of said closed perimeter openings adopts a second
shape.
11. A connector, comprising: a. a back; b. a seat connected to said
back along a transverse bend line; c. a first continuous corner
flange connected to said back and said seat along a first flange
bend line, said continuous corner flange having a seat flange
portion and a back flange portion, said seat flange and back flange
portions lying substantially in a single plane and disposed at
angles to each other such that said continuous corner flange
appears bent; and d. at least one closed perimeter opening in said
continuous corner flange near said transverse bend line, said
closed perimeter opening being partially shaped by punching and
partially by material flow in said seat flange and back flange
portions resulting from inwardly bending said continuous corner
flange on itself by bending said back and seat towards each other
along said transverse bend line.
12. The connector of claim 11, further comprising: a. a second
continuous corner flange connected to said back and said seat along
a second flange bend line, said second continuous corner flange
having a seat flange portion and a back flange portion, said seat
flange and back flange portions of said second flange lying
substantially in a single plane and disposed at angles to each
other such that said second continuous corner flange appears bent;
b. a second closed perimeter opening in said second flange near
said transverse bend line, said second closed perimeter opening
being partially shaped by punching and partially by material flow
of said seat flange and back flange portions resulting from
inwardly bending said second continuous corner flange on itself by
bending said back and seat towards each other along said transverse
bend line.
13. The connector of claim 12, further comprising: a top flange
connected to said back along a top flange bend line, said top
flange being disposed away from said back member in a direction
opposite to said seat flange.
14. The connector of claim 13, further comprising: embossed dimples
in said first and second continuous corner flanges to better hold a
joist in said connector.
15. The connector of claim 13, further comprising: longitudinal
embossments that start in said top flange, extend through said top
flange bend line and end in said back flange to stiffen said
connector.
16. The connector of claim 12, wherein: said first and second
flange bend lines have curved portions.
Description
BACKGROUND
[0001] The present invention relates to a process of manufacture
and the product made therefrom. It relates to shaping sheet metal
blanks, particularly to operations in which a sheet metal member
having a continuous flange is folded along a bend line transverse
to the flange, creating a continuous corner flange. As an example,
the present invention is useful in forming a joist hanger having a
seat member, a back member connected thereto, and parallel
continuous corner flanges also connecting the two members.
[0002] When a sheet metal member having one or more flanges is bent
transversely to the flange or flanges such that the flanges are
swung inwardly on themselves, surplus material in the flanges along
and near the bend develops. This excess material wants to fold over
itself or crimp.
[0003] The problems caused by excess material are particularly
acute in forming and wiping dies, operating at high frequencies.
For example, if the tolerances in the press are such that the
flange is closely contained between the punch and the die of the
press, then this surplus material in the flange can fold over
itself and tear, having no where into which to flow or bend. This
condition is also known as wrinkling. In such presses, the material
can also become caught, causing other portions of the sheet metal
member to stretch.
[0004] Wrinkling is unsightly and is often perceived as a weak spot
in the part. Stretching can also create undesirable indentations in
the corner of the flange. Both wrinkling and stretching are not
easily controlled between parts, such that there is a lack of
uniformity between the parts. The present invention seeks to create
a part, having a continuous corner flange that is smooth and lacks
any visible wrinkles, crimps, puckering in the portions of the
flange that have been compressed, and any deleterious stretching in
the portions of the part near the compressed areas of the flange.
The process creates more uniform parts.
[0005] The difficulties caused by the surplus material that
develops can also prematurely age the press. It is known in the
prior art that excess material that develops between components of
a die can cause "technical difficulties"which affects the operation
of the press. See U.S. Pat. No. 1,343,647, granted to R. S. Smith
in 1920 at page 1, line 37.
[0006] There are a number of ways of avoiding the difficulties
associated with forming a continuous corner flange on a high-speed
wiping or forming die. For example, if the transverse bend is made
with a large radius, the compressed area is reduced, and tearing is
less likely. Further, reducing the height of the flange or flanges
also reduces the portions of the flanges to be compressed, reducing
the likelihood that tearing will occur.
[0007] However, it is often desirable to form a continuous corner
flange in a part having a tight-radius, 90-degree bend with
relatively high side flanges. For example, the inventor, using the
present method can consistently form a tight-radius, 90-degree bend
with a {fraction (9/16)}" high continuous corner flange without
wrinkling, and with only minimal stretching the material in both 12
gauge and 18 gauge material. The height of the side flange is
measured away from the transverse bend line and from the back along
the proximal side of the flange to the top of the flange. With
regard to stretching of the material, the inventor tested parts
formed in a v-shaped forming die with openings in their side
flanges and without openings in their side flanges. The inventor
found that with an 18 gauge part with no openings in the side
flanges, the material in the very corner of the part where the
transverse bend line meets the flange bend line the part was
thinned by 0.08". In comparison, the inventors noticed less
thinning in the same part formed with a {fraction (1/8)}" diameter
opening located on the transverse bend line in the side flange, the
opening being adjacent the edge of the curved portion in the flange
that results from the transverse and flange bends. The material
thinned only 0.04" in the very corner. Thinning was similarly less
in side-by-side comparisons of a parts formed with 12 gauge
material.
[0008] There are prior art methods of forming similar shapes in
light gauge sheet metal; however, they suffer from various
drawbacks. For example, forming a short-radius, 90-degree bend with
a continuous corner flange could be accomplished in a draw-action
die. However, draw-action dies are relatively slow compared to
forming or wiping dies. Also draw action dies require excess
material around the part to hold the part while it is being
stretched. This excess material usually needs to be cut off the
part once the drawing operation is complete, adding an extra step
to the process.
[0009] A number of other patented prior art processes form a
transverse bend in a sheet metal part having corner flanges,
however, these methods remove most or all of the material from the
side flanges that is likely to be compressed. This avoids the
problem of having the excess material of the flanges near the
transverse bend crimp or wrinkle on itself; however, the flange is
substantially weakened by the removal of most or all of the
material near the transverse bend. See U.S. Pat. No. 1,925,804,
granted to William C. Hiering on Sep. 5, 1933, and U.S. Pat. No.
5,203,069, granted to Kurt Hennig on Apr. 20, 1992.
[0010] The present inventive method for laterally bending an
elongated sheet metal member having one or more side flanges treats
the above problems, preventing tearing or undue stretching of the
metal of and around the flanges without removing excessive amounts
of material from the flanges near the transverse bend, or using a
slower draw method, or reducing the height of the flanges or
reducing the sharpness of the transverse bend.
[0011] The method of the present invention is particularly suited
for forming certain types of sheet metal joist hangers. Sheet metal
joist hangers are widely used in wood frame construction to attach
joists to carrying members. The method of the present invention has
particular relevance for forming light gauge hangers having an
upright back with parallel opposed side flanges extending
therefrom, and a flanged horizontal seat extending outwardly from
the back in the same direction as the flanges to form a bearing
area for a joist. See U.S. Pat. No. 4,802,786 granted to James G.
Yauger and John M. Rushton on Feb. 7, 1989 for an example of such a
hanger. U.S. Pat. No. 3,633,950, granted to Tyrell T. Gilb on Jan.
11, 1972 is also exemplary.
[0012] The particular joist hangers described in the two
above-identified patents are used in the panelized roofing
industry, where large roofs are normal, requiring the use of
hundreds of such hangers at a time. Currently, many industrial
buildings are designed with panelized roofs, creating a high demand
for such hangers. The present invention provides an economic method
for forming the critical transverse bend in such hangers between
the back member and the seat.
SUMMARY OF THE PRESENT INVENTION
[0013] It is an object of the present invention to form a bend in a
sheet metal member having one or more flanges, the bend being
transverse to the flange or flanges, without causing a wrinkling or
buckling of the material of the flanges in the compressed
areas.
[0014] It is a further object of the present invention to form a
transverse, short-radius bend in an elongated sheet metal member
having one or more flanges, creating continuous corner flanges free
from wrinkles or puckering.
[0015] It is a further object of the present invention to form a
transverse, tight-radius bend in an elongated sheet metal member
having one or more flanges that are relatively high, creating
wrinkle-free, continuous corner flanges.
[0016] It is a further object of the present invention to form a
bent sheet metal member having a tall side flange with minimal
deformities such that the connection of the flange across the bend
line is substantial.
[0017] It is a further object of the present invention to form a
folded sheet metal member having a tall side flange on a high-speed
forming die.
[0018] These objects are accomplished by providing one or more
openings in the portions of the areas of the flanges that are bent
inwardly and would otherwise buckle or fold on themselves if the
openings were not there. The openings allow for the controlled flow
of material of the compressed side flanges during the formation of
the critical transverse bend. Controlling the flow of the material
into the openings prevents wrinkling of the material of the flanges
and wear on the press.
[0019] According to the present invention, one or more closed
perimeter openings are formed in the compression areas of the
flanges. The flanges are bent inwardly on themselves during the
bending of the web portion of the part along the transverse bend
line. Because of the force at which the inward bending occurs, and
because portions of the side flanges are supported on their distal
and proximal side, the material of the side flanges in the
compression area plasticizes and flows into the closed perimeter
opening, causing them to deform. Because the closed perimeter
opening or openings are present, the side flanges are compressed in
a more controlled manner, reducing cracking, wrinkling and thinning
during the final bending of the web of the part.
[0020] This method is particularly useful for shaping metal members
as light as 18 gauge. It has also been used on sheet material as
thick as 12 gauge.
[0021] The method of the present invention improves upon existing
methods by forming the short-radius, 90-degree bend in flanged
metal member without wrinkling. As it is the wrinkling of the metal
that prematurely ages the die components, use of the method of the
present invention allows the manufacturer to go longer before the
die components have to be replaced.
[0022] The present invention is particularly useful for
manufacturing a flanged joist hanger having an upright back member
and a seat member formed out of the back member by a sharp-radius
bend. The blank is provided with two or more openings. These
openings are formed in the flanges at or near the transverse bend
line where the seat will be formed from the back member.
Preferably, the openings formed in the blank are separated by the
width of the web plus additional material on either side of the
web, and are separated from what will be the edges of the flanges.
In the preferred method of the present invention, the flanges are
then formed, and finally the transverse bend at or near the
openings.
[0023] Use of the method of the present invention to form a
channel-shaped, light-gauge joist hanger on a high-speed
progressive press also reduces the work that needs to be performed
on the part. Use of the inventive method allows the press to be
operated at a lower tonnage than with traditional methods that wipe
the channel-shaped part to create the critical transverse bend. The
inventor found that it took 750 pounds per square inch less
pressure to form tight-radius, 90 degree bend in a 12 gauge
channel-shaped member having openings in the side flanges in the
compression zone in a v-shaped forming press, over a channel-shaped
member having no such openings. It only took pressure of 2750
pounds per square inch to form a 12 gauge member according to the
present invention with closed perimeter openings in the
flanges.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a top plan view of a blank from which a joist
hanger can be formed according to the method of the present
invention. The blank is shown as already being cut from a coil of
sheet metal and with any openings, notches and embossments already
formed therein. As is well-known in the art, the blank would not be
completely cut from the coil if the part were to be formed on a
progressive press as is the preferred method for the present
invention.
[0025] FIG. 2 is a top plan view of the same part of FIG. 1 after
side flanges have been formed in the part.
[0026] FIG. 3 is a top plan view of the same part of FIG. 1 after
the final bends have been made. A top flange has been formed by
means common in the art and a seat member has been formed according
to the method of the present invention. The closed perimeter
openings in the side flanges along the transverse bend line have
been narrowed to slits due to the flow of plasticized metal during
the forming of the final transverse bend.
[0027] FIG. 4 is an end view of the blank of FIG. 1 taken along
view line 4-4 of FIG. 1.
[0028] FIG. 5 is an end view of the part of FIG. 2 taken along view
line 5-5 of FIG. 2.
[0029] FIG. 6 is an end view of the finished part of FIG. 3 taken
along view line 6-6 of FIG. 3.
[0030] FIG. 7 is a side view of the part of FIG. 1 taken along view
line 7-7 of FIG. 1.
[0031] FIG. 8 is a side view of the part of FIG. 2 taken along view
line 8-8 of FIG. 2.
[0032] FIG. 9A is a side view of the finished part of FIG. 3 taken
along view line 9A-9A.
[0033] FIG. 9b is cross-section of the finished part of FIG. 3
taken along section line 9B-9B.
[0034] FIG. 10 is side view of a press used to form a transverse
bend according to the present invention in a sheet metal part. The
part created will be the finished joist hanger shown in FIG. 3. The
part is shown resting on the upper surfaces of the die, and the
punch is shown in the raised position prior to its downward
stroke.
[0035] FIG. 11 is a sectional, side view of the same press of FIG.
10 taken along view line 11-11 of FIG. 12. The view shows the punch
at the bottom of its stroke having formed the transverse bend
according to the present invention in the part.
[0036] FIG. 12 is a sectional view of the press shown in FIGS. 10
and 11 taken along section line 12-12 of FIG. 11. The finished part
is shown in cross-section as well.
[0037] FIG. 13A is a perspective view of the finished joist hanger
of FIG. 3 formed according to the present invention.
[0038] FIG. 13B is a perspective view of the finished joist hanger
of FIG. 16 formed according to the method of the present invention.
The joist hanger of FIG. 13B differs from FIG. 13A only in that it
is formed with a plurality of openings near the transverse bend for
allowing the plasticized metal of the flanges in the compressed
areas to flow freely during the forming of the transverse bend.
[0039] FIG. 14 is a top plan view of another blank from which a
joist hanger can be formed according to the method of the present
invention. The blank is shown as already being cut from a coil of
sheet metal and with any openings, notches and embossments already
formed therein. In this blank for a joist hanger two openings are
formed in each side flange. The openings in each flange straddle
the transverse bend line.
[0040] FIG. 15 is a side view of the same part of FIG. 14 after
side flanges have been formed in the part.
[0041] FIG. 16 is a side view of the same part of FIG. 14 after the
final bends have been made. A top flange has been formed by means
common in the art and a seat member has been formed according to
the method of the present invention.
[0042] FIG. 17 is a top plan view of a sheet metal blank. This
blank is provided with a bend line to form a single side flange and
another bend line for making a transverse bend in the part. The
bend lines are shown in phantom. Since the part formed from the
blank will have only one side flange, only one opening is formed in
the part to accommodate the flow of plasticized metal, during the
formation of the transverse bend.
[0043] FIG. 18 is a sectional side view of a press used to form the
transverse bend according to the present invention in a sheet metal
part having only a single side flange. The movable upper punch is
shown nearing the completion of its stroke. The sheet metal part is
disposed between the moving punch and the stationary die. The
transverse bend in the part has been partially formed. The opening
in the compression area of the side flange has already narrowed to
an oval due to the flow of plasticized metal. The lower die is
shown with a knock-out plate or lifter that holds the part as the
punch moves through its downward stroke.
[0044] FIG. 19 is a sectional side view of the die of FIG. 18. The
upper movable punch is shown having completed its downward stroke.
The part is shown with the transverse bend having been completely
formed.
[0045] FIG. 20 is a sectional view of the press of FIG. 18 taken
along section line 19-19.
[0046] FIG. 21 is top plan view of punch die for making the
transverse bend in a part according to the present invention. The
punch die shown is particularly useful for forming the part on a
progressive press.
[0047] FIG. 22 is a side view of a station in a progressive press
used to form the transverse bend according to he present invention
in a sheet metal part. The station shown is actually the last
station in a progressive press. At this station, both the final
transverse bend is formed in the part and the part is cut from
sheet metal coil. The station is shown with the punch press and
cutter press at the top of their stroke and the part having just
been inserted into the station. Portions of the punch press and
punch die are shown in phantom lines to illustrate the station
better.
[0048] FIG. 23 is a similar view to FIG. 22 of the last station in
a progressive press where the part is cut from the coil and the
transverse bend is formed. The station is shown with the punch
press and cutter press beginning their downward stroke. The part is
shown pinched between the ejector pin and the lifter.
[0049] FIG. 24 is a similar view to FIG. 22 of the last station in
a progressive press where the part is cut from the coil and the
transverse bend is formed. The station is shown with the punch
press and cutter press well into their downward stroke. The punch
press has made contact with the part. The ejector pin is now
completely encapsulated in the punch press, and the cutter press
has cut the part from the coil.
[0050] FIG. 25 is a similar view to FIG. 22 of the last station in
a progressive press where the part is cut from the coil and the
transverse bend is formed. The station is shown with the punch
press and cutter press at the bottom of their downward stroke. The
part has been bent along the transverse bend line, adopting its
final shape.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
[0051] With reference to FIG. 1, the method of the present
invention is performed on a piece 1 of bendable sheet material
having a distal side 2, a proximal side 3 and first and second ends
4 and 5. In the first step of the process, a closed perimeter
opening 6 is formed in the piece 1. The closed perimeter 6 opening
has a first shape.
[0052] Next the piece 1 is bent along a flange bend line 7 so that
the piece 1 adopts a first intermediate position. See FIG. 2. The
flange bend line 7 divides the piece 1 into a flange 8 that
contains the closed perimeter opening 6 and a web 9 to the other
side of said flange bend line 7. The flange 8 has distal and
proximal sides 10 and 11 corresponding to the distal and proximal
sides 2 and 3 of the piece 1. The flange 8 also has a top 12
disposed away from the flange bend line 7 and a bottom 13
coincident with the flange bend line 7.
[0053] To complete the inventive method, the web 9 is bent along a
transverse bend line 14 that divides the web 9 into a back 15 and a
seat 16 and the flange 8 into a back flange 17 and a seat flange
18, so that said piece adopts a second position. See FIGS. 3, 11
and 12. The transverse bend line 14 lies near the closed perimeter
opening 6. While bending the web 9 along the transverse bend line
14, portions of the distal and proximal sides 10 and 11 of the
flange 7 are supported such that the seat flange 18 and the back
flange 17 are swung inwardly on each other, such that portions of
the seat flange 18 and the back flange 17 near the ends 4 and 5 of
the part are bent out of line and lie at an angle to each other.
The bending of the web 9 along the transverse bend line 14 is
carried out with a force sufficient to create compression forces in
portions of the flange 8 near the transverse bend line 14, causing
portions of the flange 8 to plasticize and flow into the closed
perimeter opening 6 in the flange 8, such that the closed perimeter
of the opening 6 is deformed by the material flow and the opening 6
adopts a second smaller shape than the first shape.
[0054] As shown in FIG. 1, the preferred first shape of the closed
perimeter opening 6 is a circle having a diameter of {fraction
(1/8)}". Such an opening 6 is preferred for forming continuous
corner flanges in both 12 gauge and 18 gauge metal. Other shapes
are possible, but a circle is preferred. The closed perimeter
opening 6 can be made with a first shape that is a polygon.
However, the sharp angles in a polygon are more likely to be the
point where a tear begins during failure of the part when a load is
placed on the part. Thus, shaping the closed perimeter opening 6 as
a continuously curving member is preferred.
[0055] The closed perimeter opening 6 is preferably formed in the
compression area caused by the inward swinging of the back flange
and seat flange portions 17 and 18, just above or adjacent to any
curved portions in the side flange 8 due to bending the part along
the flange bend line 7 or the transverse bend line 14.
[0056] As it is the bending of the side flange 8 along the
transverse bend line 14 that creates compression areas in the side
flange 8 where the metal wants to accumulate due to material flow,
the closed perimeter opening 6, according to the present invention
must be located in the compression area such that it is transected
by the transverse bend line 14 or must be located near the
transverse bend line 14, such that plastic flow will deform the
opening 6. In the preferred embodiment, the closed perimeter
opening 6 in the compression area is bisected by the transverse
bend line 14.
[0057] In the preferred embodiment the closed perimeter opening 6
is also located closer to the web 9 or the flange bend line 7,
rather than to the top 12 of the flange 8. This makes for a
stronger flange 8.
[0058] When only one closed perimeter opening 6 is used, ideally it
will be spaced away from both the top 12 of the flange 8 and the
flange bend line 7 by continuous material zones 19 and 20. See FIG.
1. The continuous material zones 19 and 20 consist of areas made up
of lines running substantially perpendicular to the flange bend
line 7 between the closed perimeter opening 6 and the top 12 and
bottom 13 of the flange 8 in the first intermediate position.
[0059] The flange bend line 7 could be a tangent of the closed
perimeter opening 6, but this is not preferred.
[0060] The continuous material zone 19 above the closed perimeter
opening 6 can also be described in the following manner: it has an
upper limit defined by the top 12 of the flange 8, a lower limit
defined by the top edge of the closed perimeter opening 6 and
boundaries on either side defined by lines orthogonal to the flange
bend line 7 and tangent to the closed perimeter opening 6 at the
outermost opposed points of the perimeter of the closed perimeter
opening 6 along the flange bend line 7 when the part is in the
first intermediate position. The lower continuous material zone is
defined similarly, except with reference to bottom 13 of the flange
8.
[0061] This upper continuous material zone 19 has a width defined
as the distance between the top 12 of the flange 7 and the closest
point on the perimeter of the closed perimeter opening 6 to the top
12 of the flange 8. Ideally this width is greater than the
thickness of the material from which the piece 1 is made.
[0062] In the preferred embodiment, a majority of the material of
the flange 8 lies in a first plane after the piece 1 has adopted
its first intermediate position, and after the piece 1 has been
shaped into its second position, the majority of the material of
the flange 8 still lies in that first plane. See FIGS. 2 and
13a.
[0063] Even if the majority of the material of the flange 8 does
not lie in a first plane, under the present invention, the back
flange 17 will lie at a selected angle or orientation to the back
15 and the seat flange 18 will lie at a selected angle or
orientation to the seat 16, and the back and seat flanges 17 and 18
will retaining those orientation to the back 15 and seat 16
throughout the process of forming the transverse bend.
[0064] In this preferred case where the substantial portion of the
flange 8 lies in a single plane, that plane is at 90 degrees to the
web 9, such that the back flange 17 is 90 degrees to the back 15
and the seat flange 18 is 90 degrees to the seat 16.
[0065] Since in the preferred form, all bends are made with
tight-radius bends, the substantial majority of the flange 8 when
viewed in cross section near the transverse bend line 14 will be
planar and only the portion near the flange bend line 7 will be
curved. See FIGS. 5, 6 and 12.
[0066] While it is preferred that only one closed perimeter opening
6 be formed in the side flange 8 near the transverse bend line 14,
a plurality of openings can be formed in the side flange 8 near the
transverse bend line 14. See FIGS. 13B through 16. For example, an
additional closed perimeter opening 21 can also be made in the
piece 1'. Preferably, the additional closed perimeter opening 21
also has the same first shape. The additional closed perimeter
opening 21 is located in the flange 8 near the transverse bend line
14. The first and additional closed perimeter openings 6 and 21 lie
substantially similar distances from where the transverse bend line
14 and the flange bend line 7 intersect.
[0067] The additional closed perimeter opening 21 is also located
close enough to the transverse bend line 14 such that the
additional closed perimeter 21 opening is also deformed by material
flow. The additional closed perimeter opening 21 will also take on
a second smaller shape than its first shape, after the bending
along the transverse bend line 14 has taken place.
[0068] When two closed perimeter openings 6 and 21 are formed in a
single flange 8, preferably the two closed perimeter openings 6 and
21 are spaced along the flange bend line 7 equal distances from the
transverse bend line 14, and equal heights above the flange bend
line 7.
[0069] As mentioned above, preferably the first and additional
closed perimeter openings 6 and 21 are formed with the same first
shape. However, in embodiments where more than one closed perimeter
opening 6 is formed, said closed perimeter openings do not need to
be formed with the same first shape. Further, since the material
flow cannot be perfectly controlled, the second, finished shape
adopted by the closed perimeter openings will not be the same among
the openings even if they are formed with the same first shape.
Although, the preferred first shape has been selected such that
material flow almost completely closes or fills-in the closed
perimeter opening such that the second shapes adopted by the closed
perimeter openings are similar.
[0070] While it is preferred that the closed perimeter opening 6 be
formed in the sheet material blank before any bends are made in the
material, the operation of forming the closed perimeter opening 6
in the flange 8 can occur after the flange 8 has been formed by
bending the piece along the flange bend line 7.
[0071] Additional steps can be added to the preferred method
described above to create a part 1 having two side flanges 8 and
108 formed according to the present invention. See FIG. 1. First, a
second closed perimeter opening 106 is formed in the piece 1
simultaneously with the closed perimeter opening 6 by piercing the
part 1. The second closed perimeter opening 106 is formed with a
first shape. Next, the piece 1 is bent along a second flange bend
line 107 that has a portion substantially parallel to the flange
bend line 7 simultaneously with the bending along the flange bend
line 7. As with the first flange bend line 7, the second flange
bend line 107 divides the piece into a second flange 108 that
contains the second closed perimeter opening 106 and the web 9 to
the other side of the second flange bend line 107. The second
flange 108 also has distal and proximal sides 110 and 111, a top
112 disposed away from the second flange bend line 107 and a bottom
113 coincident with the second flange bend line 107. As with the
first flange 7, when the piece 1 is bent along the transverse bend
line 14 that divides the web 9 into a seat 16 and a back 15 and the
flange 8 into a seat flange 18 and a back flange 17, the transverse
bend line 14 also divides the second flange 107 into a second seat
flange 118 and a second back flange 117. The transverse bend line
14 also lies near the second closed perimeter opening 106.
[0072] When the piece 1 is bent along the transverse bend line 14,
portions of the distal and proximal sides 110 and 111 of the second
flange 108 are simultaneously supported such that the second seat
flange 118 and the second back flange 117 are swung inwardly on
each other, such that portions of the second seat flange 118 and
the second back flange 117 near the ends 4 and 5 of the part 1 are
bent out of line and lie at an angle to each other. The bending of
the piece 1 along the transverse bend line 14 occurs with a force
sufficient to create compression forces in portions of the second
flange 108 near the transverse bend line 14, causing portions of
the second flange 108 to plasticize and flow into the second closed
perimeter opening 106 in the second flange 108, such that the
closed perimeter of the second opening 106 is deformed by the
material flow and the second closed perimeter opening 106 adopts a
second smaller shape than the first shape.
[0073] Also in the preferred embodiment, the bends occurring along
the flange bend lines 7 and 107 and the transverse bend line 14 are
tight-radius, 90 degree bends, having a radius equal to the
thickness of the material. This radius is measured as the distance
from the axis about which the bend is formed and the proximal side
2 of the piece 1. See FIG. 9b.
[0074] Although it is not preferred the second flange 108 can be
formed with a second closed perimeter opening 106 and an additional
closed perimeter opening 121.
[0075] The following description relates the process of forming a
fold or transverse bend in a channel-shaped member to create a
primarily "L-shaped" channel member that can be used as the joist
receiving portion of a hanger 201.
[0076] It will be understood by those skilled in the art, that the
same process with slight adaptations can be used to create a sheet
metal member 202 having a base or web 9 portion and only one side
flange disposed at an angle thereto. Those of ordinary skill in the
art will also recognize that the inventive method is equally
applicable to innumerable other articles having bends transverse to
continuous corner flanges. It is also to be noted that all the
bends formed according to the preferred method are tight-radius, 90
degree bends; however, it is not essential to the invention that
the side flanges 8 and 108 be disposed normal to the web member 9
for purposes of the invention, nor is essential that the transverse
bend itself create two members disposed orthogonally to each other.
Further, the transverse bend line 14 need not be normal to the
flange bend lines 7 and 107.
[0077] The preferred method of forming a light-gauge,
channel-shaped hanger 201 with a tight-radius transverse bend on a
high-speed progressive press according to the present invention
consists of the following steps.
[0078] To initiate the process, the leading edge of a coil of sheet
metal is fed into a progressive press. Progressive presses are
well-known in the art for forming light-gauge sheet metal members
having multiple bends. For forming a joist hanger 201 according to
the preferred method of the present invention, the press has a
plurality of stations, and the coil is fed incrementally into the
press. At each station successive operations are performed on the
coil, until the finished hanger 201 is ejected from the final
station. The following steps can be performed with a 100 ton press
to make a channel-shaped joist hanger 201 from 18 gauge galvanized
sheet metal. The progressive press is ideally run at approximately
100 strokes per minute.
[0079] The width of the coil varies depending upon the size and
number of hanger blanks or pieces 1 which will be having identical
operations performed on them at a particular point in the press. In
the preferred method for forming a light gauge, joist hanger 201
suitable for panelized roof construction, the coil is wide enough
to accommodate two blanks or parts traveling through the press
side-by-side.
[0080] The coil is fed incrementally into the press. At the first
pair of stations in the progressive press, pilot holes 22, notches
and any openings in the part are formed. The pilot holes 22 are the
largest circular openings in the back member 15 shown in FIG. 1.
They are used only for tooling and guide the coil through the
progressive punch press. It is in this first pair of piercing
stations, that the closed perimeter openings 6 and 106 unique to
this invention are formed in what will be the continuous curved
side flanges 8 and 108 of the hanger 201.
[0081] Next the blank is partially cut from the coil, but not
completely. A portion of the part, between where the first and
second side flanges 8 and 108 end and what will become the top
flange 23 begins remains connected to the parts before it and
behind it in the coil. See FIG. 1. This allows the blank or part 1
to continue to be pushed through the progressive press. Also, as
mentioned above, there are two parts 1 traveling through the press
side-by-side, and at this point the two are still connected.
[0082] At the next pair of stations, the embossments 24 for
strengthening the top flange 23 are formed.
[0083] At the next pair of stations dimples 25 and 125 are formed
in what will be the side flanges 8 and 108.
[0084] At the next pair of stations, portions of the outer margins
of the blank are bent up normal to the web portion 9 to form a
channel-shaped portion consisting of a base or web 9 portion with
opposed side flanges 8 and 108.
[0085] At the next station, the two parts 1 traveling side by side
are separated by a lance, and the part is stamped with any
necessary indicia, labeling or instructions.
[0086] Next, the top flanges 23 in each part 1 are bent down by a
wiping punch known in the art.
[0087] Finally, the part that will become the joist hanger 201 is
moved into the final station. See FIGS. 21 through 25. At this
station, it is first cut from the coil and then bent along the
transverse bend line 14 by a male forming punch press 301 and a
mating female forming punch die 302. The male forming punch press
301 is driven downwards and bends the part 1 along the transverse
bend line 14.
[0088] The cut is made by a cutter press 401 located on the upper
movable platen 303 and a stationary punch press 402 located on the
bottom platen 304. The bottom edge 403 of the cutter press 401 lies
just below the lowest point of the punch press 301. This distance
is preferably the thickness of the coil. This allows the cutter
press 401 to cut the part 1 from the coil in combination with the
cutter die 402 before the punch press 301 begins to form the
transverse bend in the part 1.
[0089] In the last station, generally the clearance between the
sides 305 of the punch press 301 and the inner side walls 306 of
the lower punch die is substantially equal to the thickness of the
coil to give support to the side flanges 8 and 108. Other portions
305a of the sides 305 of the punch press 301 can be scalloped to
accommodate portions of the side flanges 8 and 108 which are not
substantially in the same plane. See FIG. 11.
[0090] The punch die 302 has a recessed portion or matrix cavity
307 and inner side walls 306 that support distal side portions 10
and 110 of the first and second flanges 8 and 108. The inner side
walls 306 are substantially vertical, but the bottom of the cavity
307 tapers from two directions at angles of 45 degrees. In the
preferred embodiment used on a progressive press, the lower punch
die 302 is made up of a plurality of parts. The lower punch die 302
has a rectangular containment die portion 308 containing two
angular die members 309. Each angular die member 309 has a slanted
face 310 sloping toward the center of the rectangular containment
die portion 308. These slanted faces 310 are disposed at 90 degrees
to each other. Located between the angular die members 309 is a
moveable lifter 311. The lifter 311 sits on a spring 312 which can
be a mechanical spring or a gas spring. In the preferred
progressive press it is a nitrogen gas spring.
[0091] The upper moveable portion of the press for this station,
the punch press 301, is formed with an ejector pin 313 that engages
the part 1 before the punch press 301 reaches it.
[0092] The ejector pin 313 is moved by a spring 314 as well, which
can be a mechanical spring or a nitrogen spring. The springs 314
and 312 for the ejector pin 313 and the lifter 311 are chosen such
that the ejector pin 313 cannot substantially move the lifter 311.
The lifter 311 of the punch die 302 engages the part 1 before the
part 1 reaches it. The ejector pin 313 and the lifter 311 support
the part 1 during the cutting operation that occurs higher up on
the downward stroke. The lifter 311 is also used in the progressive
press to eject the hanger 201 from the lower die 302 after the
transverse bend has been formed.
[0093] After the piece is cut from the coil, the punch press 301
continues to descend, engages the part 1 at the rounded tip 315 of
the punch press 301 and forces the material of the part 1 to deform
around its tip 315 and into the recessed portion 307 of the lower
punch die 302. The round tip 315 has a radius of one material
thickness. The punch press 315 has angular sides 316 disposed at 90
degrees to each other.
[0094] During the forming operation in the last station, along the
flanges 8 and 108 in the area surrounding the transverse bend line
14 the metal will be in compression due to the inwardly swinging
movement of the flanges 8 and 108 on opposite sides of the bend
that will be formed. Because of the force at which the punch press
301 forces the part 1 downward, plastic deformation of the metal of
the flanges 8 and 108 near the transverse bend line 14 will occur.
In the prior art wiping operations, the plasticized metal would
fold on itself, or buckle, which could lead to tearing and
wrinkling. The inventor has noticed from observing hangers made
according to the conventional process, that as the pieces of the
die press wear with use, tearing of the metal becomes more of a
problem. The tearing of the metal in the flanges of the part causes
mechanical deformities in the die and punch, which in turn lead to
larger wrinkles and tears in the press and so on. But in the
present invention, because of the presence of the closed perimeter
openings 6 and 106 in the compression area of the flanges 8 and
108, the plasticized metal is allowed to flow unhindered into the
openings 6 and 106, such that it need not fold on itself causing
wrinkles, bulges, crimps or tears. That is to say, the closed
perimeter openings 6 and 106 provide areas into which the metal of
the side flange 8 and 108 can flow without bunching up onto
itself.
[0095] In an alternate method of the present invention, a connector
202 with only one flange 8 is formed with a transverse bend
creating a continuous corner flange. See FIGS. 17 through 20.
[0096] As in the method descried previously, preferably, a
{fraction (1/8)}' diameter closed perimeter opening 6 is formed in
the portion of the blank 1" that will become the side flange 8. The
closed perimeter opening 6 is also located near the transverse bend
line 14. The closed perimeter opening 6 is also positioned so that
it will lie just above the curved portion in the side flange 8
which results from first bending the flange 8 along the flange bend
line 7 and then bending the entire part along the transverse bend
line 14.
[0097] After the closed perimeter opening 6 is formed, the flange 8
is formed by bending the part along the flange bend line 7.
Preferably, this bend has an inner radius of one part
thickness.
[0098] Finally, the part is bent along the transverse bend line 14.
Preferably, this bend also has an inner radius of one part
thickness.
[0099] The punch press 501 and punch die 502 for making connector
202 with only a single flange is similar to the punch press 301 and
302 punch die for making a part with first and second flanges 8 and
108, and the description of like parts with similar functions is
not repeated. Like parts are given like numbers, except they begin
with the numeral 5 instead of the numeral 3. The lower punch die
502 need only have one inner sidewall 506.
[0100] In this alternate method, the lower punch die 502 for making
the transverse bend is formed with a lifter 511 which is necessary
to serve as a clamping member. The lifter 511 holds the part
against the punch press 501, so that it moves with the punch press
501 and is not unduly stretched during the formation of the
transverse bend. Like the lifter 311 described for the part 1 with
two side flanges 8 and 108 formed in a progressive press the lifter
511 is actuated by a spring 512. The spring 512 can be a mechanical
spring or a pneumatic spring. The lower punch die 502 is similar to
the other lower punch die 302 described previously.
[0101] The preferred connector 201 formed according to the method
of the present invention has a back 15, a seat 16 connected to the
back along a transverse bend line 14, first and second continuous
corner flanges 8 and 108 and first and second closed perimeter
openings 6 and 106 in the first and second continuous corner
flanges 8 and 108.
[0102] The first continuous corner flange 8 of the preferred
connector 201 is connected to the back 15 and the seat 16 along a
first flange bend line 7. The first continuous corner flange 8 has
a seat flange portion 18 and a back flange portion 17. The seat
flange and back flange portions 18 and 17 lie substantially in a
single plane and are disposed at angles to each other such that the
continuous corner flange 8 appears bent. The first continuous
corner flange 8 also has at least one closed perimeter opening 6 on
the transverse bend line 14, the closed perimeter opening 6 being
partially shaped by punching and partially by material flow in the
seat flange and back flange portions 18 and 17 resulting from
inwardly bending the continuous corner flange 8 on itself by
bending the back 15 and seat 16 towards each other along the
transverse bend line 14.
[0103] The second continuous corner flange 108 is connected to the
back 15 and the seat 16 along a second flange bend line 107, the
second continuous corner flange 108 has a seat flange portion 118
and a back flange portion 117, the seat flange and back flange
portions 118 and 117 of the second flange lie 108 substantially in
a single plane and are disposed at angles to each other such that
the second continuous corner flange 108 appears bent. The second
closed perimeter opening 106 in the second flange 108 lies on the
transverse bend line 14. The second closed perimeter opening 106 is
partially shaped by punching and partially by material flow of the
seat flange and back flange portions 117 and 118 resulting from
inwardly bending the second continuous corner flange 108 on itself
by bending the back 15 and seat 16 towards each other along the
transverse bend line 14.
[0104] The preferred connector 201 formed according to the present
invention is a joist hanger used in panelized construction.
[0105] The preferred connector 201 formed according to the present
invention also has a top flange 23 connected to the back 15 along a
top flange bend line 28, the top flange 23 is disposed away from
the back member 15 in a direction opposite to the seat 16. The top
flange 23 is used to attach the connector 201 to a header or beam.
In the preferred connector 201, dimples 25 and 125 are embossed in
the first and second continuous corner flanges 8 and 108 to better
hold a joist in the connector 201. The joist held in the connector
201 is pinched by the dimples 25 and 125 and rests on the seat 16.
The connector 201 also has longitudinal embossments 24 that start
in the top flange 23 extend through the top flange bend line 28 and
end in the back 15 to stiffen the connector 201. Also the first and
second flange bend lines 7 and 107 have curved portions near the
top flange bend line 28. This causes the side flanges 8 and 108 to
spread outward as they near the top flange bend line 28. The
spreading flanges 8 and 108 make it easier to insert a joist into
the connector 201.
[0106] The preferred connector 201 formed according to the present
invention also has a pair of slotted openings 26 in the top flange
23 for receiving fasteners and a rectangular opening 27 in the back
15 for receiving an optional fastener. The corners of the part are
chamfered to lessen the risk of being cut by the part. See FIG.
1.
[0107] The preferred connector 201 is made from 18 gauge galvanized
G60 ASTM A653 LFQ sheet steel with a minimum yield strength of 33
ksi and an ultimate strength of 45 ksi. The closed perimeter
openings 6 and 106 are formed with a {fraction (1/8)}" diameter.
The side flanges 8 and 108 as measured from the distal side 2 of
the back 15 to the top 12 or 112 of the flange 8 or 108 at a point
well away from the transverse bend line 14 are approximately
{fraction (1/2)}" tall. The back is dimensioned to receive a
2.times.4 or 2.times.6. Both the seat 16 and top flange 23 extend
approximately 1" from the back 15.
* * * * *