The present invention relates to a cross member for
fast-fit prefabricated scaffolding.
More specifically, the present invention relates to
a cross member for "LAYHER" type fast-fit prefabricated
scaffolding or similar.
As is known, "LAYHER" type fast-fit prefabricated
scaffolding comprises a number of vertical members and
horizontal cross members, which can be erected quickly
and dismantled easily.
More specifically, the vertical members each
comprise a cylindrical tubular member of appropriate
length; and a number of anchoring disks or plates
appropriately spaced along the whole length of the
tubular member. And each anchoring plate has a central
through hole, by which it fits rigidly to the body of the
cylindrical tubular member; and a number of radial
through slits spaced angularly about the whole body of
the plate.
Each horizontal cross member comprises a cylindrical
tubular member of appropriate length; and two end
attachments fixed rigidly to the two ends of the tubular
member.
Each of the two end attachments comprises a
transverse groove or slot extending, perpendicular to the
central longitudinal plane of the horizontal cross
member, from the end of the end attachment, and which is
engaged by a portion of the anchoring plate of the
vertical member; and a diametrical through hole extending
through the body of the end attachment, parallel to the
central longitudinal plane of the horizontal cross
member, so as to intersect the transverse slot.
The diametrical through hole is engaged by a key,
shim, or wedge sized to also fit through one of the
radial through slits, in the anchoring plate, aligned
with the hole, so as to fasten the end attachment rigidly
to the anchoring plate.
At present, the end attachments of the horizontal
cross members are simply cast in one piece separately
from the tubular member, and are then driven into the two
ends of the tubular member to form an interference fit.
Horizontal cross members produced in this way are
obviously much more expensive to manufacture than those
of conventional scaffolding, and so account for the big
difference in the purchase cost of "LAYHER" type fast-fit
prefabricated scaffolding as compared with conventional
types.
It is an object of the present invention to provide
a cross member for "LAYHER" type fast-fit prefabricated
scaffolding or similar, which is much cheaper to produce
than similar currently marketed cross members.
According to the present invention, there is
provided a cross member for "LAYHER" type fast-fit
prefabricated scaffolding or similar, comprising a
tubular member of predetermined length and two end
attachments located at the two ends of the tubular member
and designed to fit onto the anchoring plates of the
vertical members of said "LAYHER" type fast-fit
prefabricated scaffolding or similar; said cross member
being characterized in that at least one of said two end
attachments is formed in one piece with the tubular
member.
The present invention also relates to a new method
of producing cross members for "LAYHER" type fast-fit
prefabricated scaffolding or similar.
According to the present invention, there is
provided a method of producing cross members for "LAYHER"
type fast-fit prefabricated scaffolding or similar, each
comprising a tubular member of predetermined length and
two end attachments located at the two ends of said
tubular member; at least one of said two end attachments
being formed in one piece with said tubular member and
the method of producing being characterized by comprising
the steps of:
- permanently deforming an end portion of said
tubular member, so that the end portion assumes an ogival
shape with a substantially wedge-shaped profile; and
- appropriately cutting the wall of the ogival-shaped
end portion, so as to form a transverse groove or
slot extending inwards of said end portion of the tubular
member and perpendicular to a first central longitudinal
plane of the tubular member; and two longitudinal through
slits formed in the wall of the end portion of the
tubular member aligned with each other on opposite sides
of said transverse slot.
A non-limiting embodiment of the present invention
will be described by way of example with reference to the
accompanying drawings, in which:
Figure 1 shows a view in perspective of a
scaffolding cross member in accordance with the teachings
of the present invention; Figure 2 shows a plan view of an end portion of the
Figure 1 scaffolding cross member; Figure 3 shows a side view of the Figure 2 end
portion of the scaffolding cross member sectioned along
line III-III; Figure 4 shows a schematic plan view of part of a
fast-fit prefabricated scaffold comprising the
scaffolding cross member in Figures 1, 2 and 3; Figure 5 shows a side view of the Figure 4
prefabricated scaffold sectioned along line V-V; Figure 6 shows, schematically, the various steps in
a method of producing fast-fit prefabricated scaffolding
cross members in accordance with the teachings of the
present invention.
With reference to Figures 1 to 5, number 1 indicates
as a whole a cross member, for "LAYHER" type fast-fit
prefabricated scaffolding or similar, designed to fit
onto vertical members 2, each of which comprises a
cylindrical tubular member 3 of appropriate length, and a
number of anchoring disks or plates 4 appropriately
spaced along the whole length of tubular member 3.
More specifically, each anchoring plate 4 comprises
a central through hole, by which it fits rigidly onto the
outer surface of the body of cylindrical tubular member
3, coaxially with the longitudinal axis A of tubular
member 3; and a number of radial through slits 5
angularly spaced on the body of the plate.
With reference to Figures 1, 2 and 3, scaffolding
cross member 1 comprises a tubular member 6 of
appropriate length and preferably, though not
necessarily, circular or oval cross section; and two end
attachments 7 at the two ends of tubular member 6.
More specifically, the two end attachments 7 are
designed to fit, by means of keys, to anchoring plates 4
of vertical members 2, and, unlike known scaffolding
cross members, are formed in one piece with tubular
member 6, and so define the two end portions 6a of
tubular member 6.
More specifically, to form each of the two end
attachments 7 of scaffolding cross member 1, a
corresponding end portion 6a of tubular member 6 is
worked mechanically to permanently deform the wall of
tubular member 6, and is subsequently cold cut to obtain
a finished form compatible with use with "LAYHER" type
fast-fit prefabricated scaffolding or similar.
With particular reference to Figures 1, 2 and 3,
following mechanical working as referred to above, each
end attachment 7 is defined by an end portion 6a, of
tubular member 6, which has been cold formed to a hollow
ogival shape with a substantially wedge-shaped profile
extending along a first central longitudinal plane P1 of
tubular member 6.
More specifically, the ogival end portion 6a of
tubular member 6 is symmetrical with respect to central
longitudinal plane P1, and is bounded laterally by two
substantially flat major lateral surfaces 7a facing each
other on opposite sides of central longitudinal plane P1
and sloping to form an angle α of less than 90°.
In the example shown, end portion 6a of tubular
member 6 also comprises two substantially flat minor
lateral surfaces 7b parallel to and facing each other on
opposite sides of a second central longitudinal plane P2,
perpendicular to central longitudinal plane P1, of
tubular member 6.
In other words, the two major lateral surfaces 7a
converge with each other and are perpendicular to central
longitudinal plane P2, and the two minor lateral surfaces
7b are perpendicular to central longitudinal plane P1 and
substantially parallel to central longitudinal plane P2.
In the example shown, end attachment 7, i.e. the
cold formed end portion 6a of tubular member 6,
terminates with a front surface 7c, which is
perpendicular to the longitudinal axis of tubular member
6 defined by the intersection of central longitudinal
planes P1 and P2, and is shaped to rest against the outer
surface of tubular member 3 of vertical member 2. In the
example shown, front surface 7c is substantially
cylindrical with substantially the same radius of
curvature as tubular member 3 of vertical members 2.
It should be pointed out, however, that front
surface 7c of end attachment 7 may even be substantially
flat.
Again with reference to Figures 1, 2 and 3, end
attachment 7, i.e. the cold formed end portion 6a of
tubular member 6, also comprises a transverse groove or
slot 8, which extends inwards of the attachment, from the
axial end, i.e. front surface 7c, of the attachment, is
perpendicular to central longitudinal plane P1 of tubular
member 6, and is coplanar or at any rate parallel to the
second central longitudinal plane P2 of tubular member 6.
With reference to Figures 4 and 5, transverse slot 8
is sized to be engaged by a portion of anchoring plate 4
of vertical member 2, and end attachment 7 also comprises
two longitudinal through slits 9, preferably though not
necessarily with a rectangular cross section, which are
formed in the wall of end portion 6a of tubular member 6,
on opposite sides of central longitudinal plane P2 of
tubular member 6, and therefore on opposite sides of
transverse slot 8, and each at a respective minor lateral
surface 7b of end attachment 7.
More specifically, with reference to Figure 5, the
two through slits 9 are formed in the lateral wall of
tubular member 6 so as to be aligned with each other
along central longitudinal plane P1, and are engaged by a
substantially trapezoidal key, shim, or wedge 10 sized to
also engage the radial through slit 5, in anchoring plate
4, aligned with the two through slits 9, so as to fasten
end attachment 7 rigidly to anchoring plate 4.
Operation of scaffolding cross member 1 is easily
deducible from the foregoing description with no further
explanation required.
As for the method of producing scaffolding cross
members 1, this will be described assuming a tubular
member 6 of desired length is already available, and for
the sake of simplicity, with reference to the formation
of one end attachment 7 on tubular member 6 of
scaffolding cross member 1.
With reference to Figure 6, scaffolding cross member
1 is formed from a tubular member 6, by permanently
deforming an end portion 6a of tubular member 6, so that
the end portion assumes a hollow ogival shape with a
substantially wedge-shaped profile, and then
appropriately cutting the wall of end portion 6a to form
transverse slot 8 and the two longitudinal through slits
9.
More specifically, scaffolding cross member 1 is
formed from a tubular member 6 of predetermined length,
by bending two lateral portions 6b of end portion 6a of
tubular member 6, located on opposite sides of central
longitudinal plane P1, towards each other and towards
central longitudinal plane P1.
Once the two lateral portions 6b are bent, the
method of producing scaffolding cross members 1 comprises
pinching end portion 6a of tubular member 6 on opposite
sides of central longitudinal plane P1 to superimpose the
two lateral portions 6b and form two arc-shaped cusps 6c
on opposite sides of second central longitudinal plane
P2.
Once the two arc-shaped cusps 6c are formed, the
method of producing scaffolding cross members 1 comprises
bending the two arc-shaped cusps 6c towards each other
and onto the two lateral portions 6b, and then pinching
the deformed end portion 6a of tubular member 6 on
opposite sides of central longitudinal plane P2, so that
end portion 6a assumes an ogival shape with a
substantially wedge-shaped profile extending along first
central longitudinal plane P1 of tubular member 6, and
with four substantially flat lateral surfaces facing one
another in pairs.
More specifically, the method of producing
scaffolding cross members 1 comprises pinching end
portion 6a of tubular member 6 on opposite sides of
central longitudinal plane P2, so that end portion 6a
assumes a substantially wedge shape comprising two
substantially flat major lateral surfaces perpendicular
to central longitudinal plane P2 and on opposite sides of
central longitudinal plane P1, and two substantially flat
minor lateral surfaces perpendicular to central
longitudinal plane P1 and on opposite sides of central
longitudinal plane P2.
The major lateral surfaces define the two major
lateral surfaces 7a of end attachment 7, and the two
minor lateral surfaces define the two minor lateral
surfaces 7b of end attachment 7.
Once permanent deformation of end portion 6a of
tubular member 6 is completed, the method of producing
scaffolding cross members 1 comprises cutting the wall of
end portion 6a of tubular member 6 on opposite sides of
central longitudinal plane P2 and at the two minor
lateral surfaces of end portion 6a, i.e. at the two minor
lateral surfaces 7b of end attachment 7, to form two
preferably though not necessarily rectangular
longitudinal through slits 9 engageable by key, shim, or
wedge 10.
Depending on construction requirements, the flap or
scrap produced by cutting the wall of tubular member 6 to
form through slits 9 may either be removed completely or
folded inside tubular member 6 and pinched against the
two lateral portions 6b of the wall of tubular member 6
(see Figure 5).
Simultaneously with the formation of through slits
9, the method of producing scaffolding cross members 1
also comprises pinching the two lateral portions 6b, the
two arc-shaped cusps 6c, and possibly also the two flaps
or scraps produced by forming through slits 9, so as to
compact the whole and smooth the front surface of end
portion 6a defining front surface 7c of end attachment 7.
Once through slits 9 are completed, the method of
producing scaffolding cross members 1 comprises forming
transverse groove or slot 8 parallel to central
longitudinal plane P2 of tubular member 6. This can be
done by cold blanking or more simply using a rotary disk
cutter capable of cutting the deformed wall of tubular
member 6, while remaining coplanar with or at any rate
parallel to central longitudinal plane P2 of tubular
member 6.
Scaffolding cross member 1 as described and
illustrated herein has numerous, obvious advantages.
Firstly, the cross member so formed is much cheaper to
produce than known types, thus making "LAYHER" type fast-fit
prefabricated scaffolding economically competitive
with conventional scaffolding.
Secondly, the method of producing scaffolding cross
members 1 can be implemented easily using multipurpose
dies designed to perform the various permanent
deformation and cutting operations of the two ends of
tubular member 6 fully automatically.
Clearly, changes may be made to scaffolding cross
member 1 and to the method of producing it, without,
however, departing from the scope of the present
invention.
For example, tubular member 6 for producing
scaffolding cross member 1 may have a rectangular,
square, trapezoidal, or generally polygonal cross
section.