There are numerous ways of laying-out boxes and numerous ways of
folding them up. The MAGNABEND is ideally suited to forming
boxes, especially complex ones, because of the versatility of using
short clampbars to form folds relatively unhindered by previous folds.
Plain Boxes
- Make the first two bends using the long clampbar as
for
normal bending.
- Select one or more of the shorter clampbars and
position
as
shown. (It is not necessary to make up the exact length as
the bend will carry over gaps of at least 20 mm between the clampbars.)
For bends up to 70 mm long, just select the largest clamp piece that
will fit.
For longer lengths it may be necessary to use
several clamp pieces. Just select the longest clampbar that
will fit in, then the longest that will fit in the remaining gap, and
possibly a third one, thus making up the required length.
For repetitive bending the clamp pieces may be plugged together to make
a single unit with the required length. Alternatively, if the
boxes have shallow sides and you have available a slotted clampbar,
then it may be quicker to make the boxes in the same manner as shallow
trays.
Lipped
boxes
Lipped boxes can be made using the standard set of short clampbars
provided one of the dimensions is greater than the width of the
clampbar (98 mm).
1. Using the full-length clampbar, form the length wise folds
1, 2, 3,
&4.
2. Select a short clampbar (or possibly two or three plugged
together)
with a length at least a lip-width shorter than the width of the box
(so that it may later be removed). Form folds 5, 6, 7
& 8.
While forming the folds 6 & 7, be
careful to guide the corner tabs either inside or outside the sides of
the box, as desired.
Boxes with
separate ends
A box made with separate ends has several advantages:
- it saves material especially if the
box has deep sides,
- it does not require corner notching,
- all cutting-out can be done with a
guillotine,
- all folding can be done with a plain
full-length clampbar;
and some drawbacks:
- more folds must be formed,
- more corners must be joined, and
- more metal edges and fasteners show on
the finished box.
Making this kind of box is straight forward and the
full-length clampbar can be used for all folds.
- Prepare the blanks as shown below.
- First form the four folds in the main workpiece.
- Next, form the 4 flanges on each end piece.
For each of these folds, insert the narrow flange of the end piece
under the clampbar.
- Join the box together.
Flanged
boxes with plain corners
Plain cornered boxes with outside flanges are easy to make if the
length and width are greater than the clampbar width of 98 mm.
Forming boxes with outside flanges is related to making TOP-HAT
SECTIONS (described in a later section)
- Prepare the blank.
- Using the full-length clampbar, form folds 1, 2, 3
& 4.
- Insert the flange under the clampbar to form fold 5,
and then fold 6.
- Using appropriate short clampbars, complete folds 7
& 8.
Flanged Box
with Corner Tabs
When making an outside flanged box with corner tabs and without using
separate end pieces, it is important to form the folds in the correct
sequence.
- Prepare the blank with corner tabs arranged as shown.
- At one end of the full-length clampbar, form all tab
folds "A" to 90. It is best to do this by inserting the tab
under the clampbar.
- At the same end of the full-length clampbar, form
folds "B" to 45° only. Do this by inserting the side of the
box, rather than the bottom of the box, under the clampbar.
- At the other end of the full-length clampbar, form
the flange folds "C" to 90°.
- Using appropriate short clampbars, complete folds "B"
to 90.
- Join the corners.
Remember that for deep boxes it may be better to make the box with
separate end pieces.
FORMING
TRAYS USING THE SLOTTED CLAMPBAR
The Slotted Clampbar, when supplied, is ideal for making shallow trays
and pans quickly and accurately.
The advantages of the slotted clampbar over the set of short clampbars
for making trays are that the bending edge is automatically aligned to
the rest of the machine, and the clampbar automatically lifts to
facilitate the insertion or removal of the workpiece.
Never-the-less, the short clampbars can be used to form trays of
unlimited depth, and of course, are better for making complex shapes.
In use, the slots are equivalent to gaps left between the fingers of a
conventional box & pan folding machine. The width of
the slots is such that any two slots will fit trays over a size range
of 10 mm, and the number and locations of the slots are such that for
all sizes of tray, there can always be found two slots that will fit
it. (The shortest and longest tray sizes the slotted clampbar
will accommodate are listed under SPECIFICATIONS.)
To fold up
a shallow tray:
- Fold-up the first two opposite sides and the corner
tabs using the slotted clampbar but ignoring the presence of the
slots. These slots will not have any discernible effect on
the finished folds.
- Now select two slots between which to fold-up the
remaining two sides. This is actually very easy and
surprisingly quick. Just line-up the left side of the partly
made tray with the leftmost slot and see if there is a slot for the
right side to push into; if not, slide the tray along till
the left side is at the next slot and try again. Typically,
it takes about 4 such tries to find two suitable slots.
- Finally, with the edge of the tray under the clampbar
and between the two chosen slots, fold up the remaining
sides. The previously formed sides go into the selected slots
as the final folds are completed.
With tray lengths that are nearly as long as the clampbar it
may be necessary to use one end of the clampbar in lieu of a slot.
Top-Hat
Profiles
The Top-Hat profile is so-named because its shape resembles a top-hat
of the kind that was worn by English gentlemen in past
centuries:
Top-hat profiles have numerous uses; common ones being
stiffening ribs,
roof purlins and
fence posts.
Top-hats can have square sides, as shown below on the left, or tapered
sides as shown on the right:
A square-sided top hat is easy to make on a Magnabend provided that the
width is more than the width of the clampbar (98mm for
the standard clampbar or 50mm for the (optional) narrow
clampbar).
A top hat with tapered sides can be made much narrower and in fact its
width is not determined by the width of the clampbar at all.
An advantage of tapered top-hats is that they can be lapped over each
other and joined to make
longer sections.
Also, this style of top-hat can nest together thus making a
very compact bundle to facilitate
transport.
How
to make top-hats:
Square-sided top-hats can be made as shown below:
- If the profile is more than 98mm wide then the
standard clampbar can be used.
- For profiles
between
50mm and 98
mm wide (or wider) the Narrow Clampbar can be used.
- A very narrow top-hat can be made using an auxiliary
square bar as shown below on the right.
When using these techniques the machine will not have its
full bending
thickness capacity and thus sheetmetal up to about 1mm thick only can
be used.
Also, when using a square bar as auxiliary tooling it will not be
possible to overbend the sheetmetal to allow for springback and thus
some compromise may be necessary.
Tapered top-hats:
If the top hat can be tapered then it can be formed without any special
tooling and the thickness can be up to the full capacity of the machine
(1.6mm for top-hats over 30mm deep or 1.2mm for top-hats between 15mm
and 30mm deep).
The amount of taper needed depends on the width of the top-hat.
Wider top-hats can have steeper sides as shown below.
For a symetrical top-hat all 4 bends should be made to the
same angle.
Height of Top-Hat:
There is no upper limit to the height that a top-hat can be made but
there is a lower limit and that is set by the thickness of the
bending beam.
- With the Extension Bar removed the bending beam
thickness is 15mm
(left drawing). The thickness capacity will be about 1.2mm and the
minimum height of a top-hat will be 15mm.
- With the Extension Bar fitted the effective bending
beam width is 30mm
(right drawing). The thickness capacity will be about 1.6mm and the
minimum height of a top-hat will be 30mm.
Making very close Reverse Bends:
Sometimes it can be very important to be able to make reverse bends
closer together than the theoretical minimum set by the thickness of
the bending beam (15mm).
The following technique will achieve this although the bends may be a
little rounded:
- Remove the extension bar from the bending beam. (You
need it as narrow as possible).
- Make the first bend to about 60 degrees and then
reposition the workpiece as shown in FIG
1.
- Next make the second bend to 90 degrees as shown in FIG 2.
- Now turn the workpiece around and position it in the
Magnabend as shown in FIG 3.
- Lastly complete that bend to 90 degrees as shown in FIG 4.
This sequence should be able to achieve reverse bends down to about
8mm apart.
Even closer reverse bends can be achieved by by bending thru smaller
angles and applying more successive stages.
- For instance make bend 1 to only 40 degrees, then
bend 2 to say 45 degrees.
- Then increase bend 1 to say 70 degrees, and bend 2 to
say 70 degrees also.
- Keep repeating until the desired result is achieved.
It is easily possible to achieve reverse bends down to only
5mm apart or even
less.
Also, if it is acceptable to have a sloping offset like this:
rather than
this:
then
fewer bending operations will be needed.
Using the Slotted Clampbar:
See this page:
The_Slotted_Clampbar.html
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last updated: April 2018 |