BACKGROUND OF THE INVENTION
[0001] The present invention relates to a prefabricated structure for outward and inward
environment and, more specifically, it relates to a modular step unit for making modular
ladders.
[0002] The invention further relates to a prefabricated self-supporting ladder including
a plurality of modular units of the above indicated type.
[0003] The mentioned prefabricated ladders are provided for use in public and private environments,
and they can be of a right plan type, a curved, ellipsoidal, ovoidal and mixed plan
type.
[0004] A lot of prior self-supporting ladders comprise a plurality of prefabricated metal
elements of different shapes which are assembled to one another partially in an assembling
shop, partially on the installing field, by removable coupling or connecting elements,
such as screws, bolts, to allow them to be easily shipped and assembled-disassembled
in very short times.
[0005] Such a construction also allows to reduce to a minimum the number of standardized
components, thereby also reducing the managing and storing costs for the makers thereof.
[0006] Several examples of the above mentioned prefabricated or pre-made ladders are disclosed
in the CH Patent No. 554,998, Belgian Patent No. 872,495, as well as in the German
Patent Application No. 3,505,688 and French Patents Nos. 893,503, 604,662, 2,065,332,
2,597,909, GB Patent No. 151,487, U.S. Patent No. 4,355,700, European Patent No. 0,060,014
and Italian Patent Application No. MI96A 000410.
[0007] A drawback of prior commercially available prefabricated ladders is that said ladders
are excessively resilient because they are formed by individual metal sheet elements
which are mutually coupled by coupling screws or nails. Thus, these prior constructions
would be subjected to excessive oscillations and vibrations making said construction
unstable and unsafe, and, accordingly, uncomfortable in use. Moreover, the mentioned
highly resilient nature would reduce the structural strength thereof, with the requirement
of adding stabilizing middle elements.
[0008] A further drawback of prior prefabricated ladder constructions is that in these prior
ladders it is not possible to precisely adjust the rise or height of the ladder steps,
and, accordingly, of the overall step, mainly on the installing field and, for providing
such a fine adjustment, prior ladder constructions usually comprise a lot of specially
designed additional elements with a consequent increasing of the assembling time and
cost.
[0009] Yet another drawback of prior ladder constructions is that their component elements
have an outer contour which is rather complex, said elements being frequently made
by laser cutting sheet metal members.
[0010] Yet a further drawback of prior ladder constructions is that they have a comparatively
intricate configuration, with a lot of gaps and exposed to view connecting screw elements.
SUMMARY OF THE INVENTION
[0011] Accordingly, the aim of the present invention is to overcome or at least alleviate
the above mentioned drawbacks, by providing a modular step unit and a prefabricated
ladder construction having a highly rigid structure, and which can be simply and quickly
assembled and installed, while providing a very good aesthetic aspect.
[0012] Within the scope of the above mentioned aim, a main object of the present invention
is to provide such a step modular allowing to reduce the oscillations and vibrations
affecting prior ladder constructions, while enlarging the net distance of the ladder
bearing elements, and eliminating the requirements of providing middle supporting
elements.
[0013] Yet another object of the present invention is to provide a modular step unit allowing
to easily and quickly adjust the heights of the individual ladder steps.
[0014] Yet another object of the present invention is to provide a modular step unit which
is very simple construction-wise.
[0015] According to one aspect of the present invention, the above mentioned aim and objects,
as well as yet other objects, which will become more apparent hereinafter, are achieved
by a modular step unit, specifically designed for self-supporting metal ladders, comprising
a pair of side supporting constructions, which support a flat step element. Connecting
means are moreover provided for connecting each unit to an adjoining unit in order
to define a self-supporting ladder ramp, said ladder ramp being characterized in that
each supporting construction comprises at least a substantially vertical inner element
arranged between and rigidly coupled to at least a pair of outer substantially horizontal
elements; at least an inner element being adapted to be coupled to at least a pair
of outer elements pertaining to an adjoining modular unit by a height adjustable coupling
device in order to provide a variable height ladder ramp.
[0016] According to the invention, a prefabricated self-supporting ladder comprises a series
of modular units as above indicated, wherein each modular unit comprises a pair of
side supporting constructions supporting a flat step, characterized in that each construction
comprises at least a substantially vertical inner element arranged between and rigidly
coupled to at least a pair of substantially horizontal outer elements; at least an
inner element being coupled to at least a pair of outer elements pertaining to an
adjoining modular unit by a height adjustable coupling device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further characteristics and advantages of the invention will become more apparent
hereinafter from the following detailed disclosure of some preferred, though not exclusive,
embodiments of a step unit and a prefabricated ladder construction, which will be
disclosed as a merely indicative and not limitative example with reference to the
accompanying drawings, where:
Figure 1 is a perspective view of a modular step unit according to the present invention;
Figure 2 is a further perspective view illustrating a portion of a straight self-supporting
ladder construction formed by a plurality of modular step units;
Figure 3 is a side view illustrating a ladder construction of the type shown in Figure
1;
Figure 4 is a further side view illustrating a variation of the ladder of Figure 3
provided with a parapet or guard element;
Figure 5 is a further side view, on an enlarged scale, illustrating a detail of the
ladder construction shown in Figure 4;
Figure 6 is a perspective view of a sub-assembly of the modular step unit shown in
Figure 1;
Figure 7 is a further perspective view of another sub-assembly of the modular step
unit shown in Figure 1;
Figure 8 is a front view illustrating a modular step unit according to the present
invention, as partially cross-sectioned according to a vertical plane;
Figure 9 is a schematic side view illustrating a step unit according to the invention,
with a component of the first size;
Figure 10 is a view analogous to Figure 9 illustrating the same component of a second
size;
Figure 11 is a view analogous to Figure 10 illustrating the same component of a third
size;
Figure 12 is a perspective view of a detail of an adjustable connecting or coupling
device included in the modular unit of Figure 1;
Figure 13 illustrates a front view of the detail of Figure 12;
Figure 14 is a cross-sectional view illustrating the detail of Figure 11, as cross-sectioned
according to the section plane XIV-XIV;
Figure 15 is a perspective view illustrating a further detail of an adjustable coupling
or connecting device of the modular unit shown in Figure 1, in a first operating position
thereof;
Figure 16 is a front view illustrating the detail of Figure 15;
Figure 17 illustrates a cross-sectional view of the detail of Figure 13 substantially
taken along the section plane XVII-XVII;
Figure 18 illustrates a cross-sectional view, on an enlarged scale, of a detail of
the adjustable coupling or connecting device of the preceding figures, as cross-sectioned
according to a vertical plane;
Figure 19 illustrates a perspective view of the detail of Figure 15, according to
a different use embodiment;
Figure 20 illustrates a further perspective view of a modified embodiment of a modular
step unit for a helical ladder construction, as seen from the inside;
Figure 21 illustrates a further perspective view of the unit shown in Figure 20, as
seen from the outside;
Figure 22 illustrates a further perspective view of a helical or coil ladder construction
made by assembling a plurality of modular units shown in Figures 20 and 21 as seen
from the inside;
Figure 23 illustrates a perspective view of the ladder construction of Figure 22,
as seen from the outside;
Figure 24 illustrates a side view of a ladder step, according to the present invention,
including a specifically designed insert, for allowing the height of the ladder step
to be vertically adjusted;
Figure 25 is a front view illustrating a vertical modular unit;
Figure 26 is a side cross-sectioned view illustrating the same vertical modular unit
as shown in Figure 25;
Figure 27 illustrates an enlarged detail of the vertical modular unit, in which inserts
for adjusting the height of the step can be engaged;
Figures 28 and 29 are respectively a front view and a cross-sectioned side view illustrating
the mentioned inserts for adjusting the height of the ladder steps;
Figure 30 is a side perspective view illustrating a step modular unit;
Figure 31 is a schematic side view illustrating a ladder step, with a component of
a first size, and provided with an insert including a middle hole for allowing a middle
height adjusting of a ladder step;
Figure 32 illustrates an enlarged detail of a vertical modular unit and of an insert
provided with a middle hole;
Figure 33 illustrates an insert provided with a middle hole;
Figure 34 is a cross-sectioned and orthogonal side view illustrating the same insert
as shown in Figure 33;
Figures 35 and 36 are respective side views illustrating a ladder step including a
recess for housing therein an insert for adjusting the height of the ladder step and
being provided with an anchoring downwardly directed hole; and
Figures 37 and 38 are respectively a cross-sectioned front and side view illustrating
the mentioned insert provided with said downward directed hole.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] With reference to the above mentioned figures, a self-supporting ladder construction
according to the present invention, which has been generally indicated by the reference
number 1, comprises a plurality of modular step units, each indicated by the reference
number 2, which are mutually coupled so as to provide a continuous type of construction.
[0019] Each modular unit 2 comprises a pair of side supporting or bearing structures, indicated
by the reference number 3, which, at the end portions thereof support a respective
flat ladder step 43, possibly through one or more cross-members 4a.
[0020] According to the invention, each side supporting structure 3 is a "sandwich" type
of structure, including adjoining elements, and comprising at least an inner element
5, which substantially vertically extends between a pair of substantially horizontally
extending outer element pair 6.
[0021] Preferably, the inner elements 5 are provided in a number of two and are arranged
between the pair of outer elements 6. The elements 5, 6 are constituted by essentially
flat plates, formed from alloy steel (38NCD4) or stainless steel (AISI 316), having
a thickness from about 8 to 12 mm, which have been automatically cut, for example
by using a laser cutting apparatus.
[0022] Both the inner elements 5 and outer elements 6 have a very simple elongated plan
configuration, for example of approximatively rectangular shape, thereby allowing
very quick and precise cutting operations to be performed. In this connection it should
be also apparent that the cut elements could be also subjected to a plurality of surface
finishing treatments, for providing said elements with a desired aesthetic final aspect.
[0023] Advantageously, each outer element 6 is provided with a cross lug 7 extending from
a longitudinal end portion of a major side thereof, and facing downwardly, as the
element is in a full assembled condition.
[0024] The inner elements 5 and outer elements 6 of each structure 3 are rigidly coupled
by fixed coupling or connecting elements arranged at adjoining end portions thereof,
thereby their middle axes extend in substantially perpendicular directions and their
extension planes being substantially vertical.
[0025] To that end, the inner elements 5 are provided with a pair of terminal circular holes
8, cooperating with corresponding circular holes 9 of like diameters, formed at an
end of the outer elements 6. Preferably, the centers of the holes 8, 9 are arranged
on a segment which is slanted at about 45° with respect to the middle axes of the
elements 5, 6.
[0026] The fixed coupling elements 10 each comprise a cylindric pin 11, having a diameter
slightly less than that of the holes 8, provided with end threads, on which cylindric
or tapering head clamping screws 12, 13 are engaged, said clamping screws being provided
with respective flat face.
[0027] Advantageously, the outer elements 6 are provided with counter-shaped cylindric or
tapering seats or recesses for housing therein, in a not to the view exposed manner,
the corresponding heads or screws 12, 13, thereby their flat outer faces are flush
with the outer surfaces of the elements 6, to provide a continuous visual aspect and
overcoming any gaps as due to possible projecting screws.
[0028] Moreover, an anchoring bracket 15 for anchoring each cross-member 4a could be affixed
to a face of the outer elements 6 adjoining the ladder step 4.
[0029] Finally, between the two inner elements 5, and between each of said inner element
and an adjoining outer element 6, spacing washers 14 provided for holding the several
assembled elements at a set mutual distance. This distance, together with the several
adjoining elements, will operate to increase the inertial momentum of the assembled
construction 3, thereby providing the overall unit a high constructional stiffness.
[0030] This high constructional stiffness will provide the unit 2 and assembled ladder construction
with a very great resistance to oscillations and vibrations, much greater than in
prior ladder constructions, thereby providing a ladder construction which can be comfortably
used.
[0031] Moreover, it would allow to make ladder constructions having a greater net distance
between the ladder bearing or supporting elements, and will allow to overcome the
requirements of using middle supporting elements in order to spatially support the
ladder construction.
[0032] According to the present invention, at least one of and preferably both the inner
elements 5 are coupled to a pair of outer elements 6 pertaining to a modular unit
2', 2'', 2''' ....2
n, by a coupling device which can be height adjusted in order to provide a variable
height or rise ladder ramp.
[0033] To that end, between each supporting structure 3 and an adjoining supporting structure
3', 3'', 3''' ...3
n a lot of height adjustable coupling devices, generally indicated by the reference
number 16, have been provided, in order to change the rise or height of the modular
unit 2 and, accordingly, of the overall ladder construction 1.
[0034] More specifically, said adjustable coupling or connecting devices, which have been
generally indicated by the reference number 15, comprise a support element or insert
17, made starting from a cylindric washer provided with milled portions or parallel
flat faces 18. Along the end circular edges thereof, the insert 17 is provided with
steps 19 defining coupling contours. The insert 17 is provided with a vertical symmetry
plane V and a horizontal symmetry plane C, with a central axis A. In the insert 17
a slotted hole 20 extending along the direction of the plane V is formed, said slotted
hole having a diameter slightly greater than the outer diameter of the pins 11. Moreover,
on the opposite faces of the insert 17 a plurality of tooth arrangements 21 are provided,
including symmetrical and parallel teeth, which are symmetrically arranged with respect
to the symmetry plane C.
[0035] Owing to the disclosed arrangement, the opposite faces of the insert 16 can be precisely
or snugly housed in two corresponding cavities 22 having a complementary configuration
formed at the bottom end portion of two adjoining elements 5, which cannot turn about
the axis A, owing to the provision of the two side milled portions 18.
[0036] Each insert 17 will be coupled to a small plate 23 arranged between each inner element
5 and an adjoining outer element 6. More specifically, each plate 23 has a plan shape
similar to that of the insert 17 and is provided with a central hole 24, having a
hole axis B, and a tooth arrangement 25 similar to that provided on the insert 17,
at a region thereof offset from the axis B.
[0037] By arranging the plates 23 at a position facing the insert 17, and engaging pin coupling
elements in the holes 20 and 24, the tooth arrangements 19, 25 can be mutually engaged
thereby locking said arrangements after having set their height mutual positions.
[0038] Owing to the symmetrical location of the tooth arrangements 21 on the insert 17 and
the eccentric or offset location of the tooth arrangements 25 on the plates 24, the
mutual position of this components can be displaced, with a maximum degree, either
upwardly or downwardly, by turning through 180° the plate 23 about its turning axis
B.
[0039] Advantageously, it would be possible to provide standardized outer elements 6 including
a plurality of lugs 7 having a different cross extension, corresponding to different
rise adjusting ranges.
[0040] As is schematically shown in Figures 9 to 11, the elements 6', 6'', 6''' would be
provided with respective lugs 7', 7'', 7''' having different heights D', D'', D''',
in order to provide different height adjusting ranges.
[0041] Moreover, on one of the outer elements 6 of each structure it would be possible to
support suitable supporting elements for corresponding uprights 26 of a parapet or
guard rail 27.
[0042] In order to provide a curved, elliptical or helical ladder constructions, as indicated
by 1c in Figures 22, 23, it should be necessary to use modular step units 2c which,
though conceptually similar to the preceding modular units, would be constituted by
inner 3i and outer 3e bearing structures of different configuration and length, supporting
at the end portions thereof ladder steps 4c having a substantially trapezoidal or
circular segment plan configuration.
[0043] Thus, while the inner elements 5c could be substantially like the preceding inner
elements, the outer elements 6c will have a different construction, both with respect
to the different extension of said elements 6c and due to the provision thereon of
bent portions along one or more vertical lines 28, 29.
[0044] From the preceding disclosure it should be apparent that the modular step unit and
self-supporting ladder construction according to the present invention fully achieve
the intended aim and objects.
[0045] In particular, it should be pointed out that a ladder construction having a great
resistance against oscillations and vibrations, owing to the sandwich provided construction
and the provision of several flat coupled elements, has been provided.
[0046] Moreover, it should be also pointed out that the height of the ladder construction
can be easily and quickly varied without affecting the geometrical configuration of
the prefabricated components.
[0047] While the modular unit and self-supporting ladder construction according to the invention
have been disclosed and illustrated with reference to the accompanying drawings, it
should be apparent that they would be susceptible to several modifications and variations
all of which will come within the inventive scope as claimed in the accompanying claims.
[0048] If ladder constructions of great width must be used, then it would be possible to
use more than two bearing structures 3, by adjoining each side bearing structure and
several middle bearing structures, coupled to the other side bearing structure, by
coupling cross-members 4a.
[0049] In this connection it should be apparent that the cross-member 4a, coupling the bearing
or supporting structures 3, can comprise either a plate-like or a tubular element.
[0050] Moreover, it should be pointed out that the modular unit according to the present
invention allows to easily made plate-like vertical modular units 5, in which suitable
slots 22 delimited by two vertical portions and two curved portions with a convexity
respectively facing upward and downward would be formed, thereby providing likewise
contoured insert 43 to be provided with corresponding holes at set levels, with respect
to the longitudinal extension of said inserts 43.
[0051] In particular, in the subject modular unit, the inserts 43 would be directly formed
by shearing or cutting operations on vertical plate-like modular units 5, which would
be provided with calibrated housing seats 22 for engaging therein the mentioned inserts
43.
[0052] Said inserts would be provided with a plurality of holes arranged at the center thereof,
or at a top and/or bottom position with respect to the longitudinal extension of said
inserts 43 thereby allowing to easily adjust the height of the individual ladder steps.
[0053] Finally, the mentioned inserts 43 could be easily engaged in the seats 22, which
would be provided with a corresponding configuration.
1. A modular step unit, specifically designed for metal self-supporting ladder constructions,
comprising a pair of side supporting structures (3, 3c) supporting a flat ladder step
(4, 4c), coupling means (16) for coupling each modular unit to an adjoining modular
unit for defining a self-supporting ladder ramp (1, 1c), characterized in that each
supporting structure (3, 3c) comprises at least a substantially vertical inner element
(5) arranged between and rigidly coupled to at least a pair of substantially horizontal
outer elements (6, 6c), at least an inner element (5) being adapted to be coupled
to at least a pair of outer elements (6, 6c) pertaining to an adjoining modular unit
(3, 3c) by a coupling device (16) which can be adjusted in height in order to provide
a variable height ladder ramp.
2. A modular unit according to Claim 1, characterized in that said inner and outer elements
(5, 6; 6c) comprise metal plates having a substantially constant thickness and a substantially
rectangular plan shape and being arranged on mutually spaced vertically extending
planes.
3. A modular unit according to Claim 2, characterized in that said substantially horizontal
outer elements (6, 6c) are provided, near a front corner of a ladder step, with a
downward directed lug (7) defining with a bottom edge thereof a vertical spacer for
an adjoining side structure.
4. A modular unit according to Claim 3, characterized in that each inner element (5)
is coupled to said outer elements at said cross lug (7) by fixed coupling elements
(11).
5. A modular unit according to Claim 4, characterized in that said unit comprises standardized
outer elements (6', 6'', 62''') having cross lugs (7', 7'') of different heights (D',
D'', D''') depending on the ladder step height range.
6. A modular unit according to Claim 2, characterized in that outer elements (6) are
substantially flat in order to provide straight ladder ramps, or bent (6c) along at
least a substantially vertical generatrix (28, 29) thereof to provide curved, mixed
or helical ladder ramps.
7. A modular unit according to Claim 4, characterized in that each adjustable coupling
device (16) comprises an insert (17) which can be engaged in a complementary shape
cavity (21) formed in each inner element (5).
8. A modular unit according to Claim 7, characterized in that said insert (17) is provided,
on respective faces thereof, with substantially horizontal tooth arrangements (21)
having a set pitch and a throughgoing hole (20) which is elongated in a substantially
vertical direction.
9. A modular unit according to Claim 8, characterized in that each adjustable coupling
device (16) comprises a pair of plates (23) arranged between at least an inner element
(5) and an adjoining outer element (6).
10. A modular unit according to Claim 9, characterized in that said plates (23) are provided
with tooth arrangements (25) identical to those (21) of said insert (17) for cooperating
therewith, and a central hole (25) of circular shape, having a diameter equal to the
minimum diameter of the elongated hole (20).
11. A modular unit according to Claim 10, characterized in that the tooth arrangement
(25) formed on each plate (23) is eccentrically arranged with respect to the axis
(B) of its hole (24) in order to allow a maximum height variation with respect to
the insert (17) by turning through 180° the plate (23) about the axis of the hole
(24) thereof.
12. A modular unit according to Claim 11, characterized in that each adjustable coupling
device (16), formed by an insert (17) and a pair of plates (23) is locked in a set
position by fixed coupling elements (10) passing through said throughgoing holes (20,
24) in order to clamp their respective facing tooth arrangements (21, 25) by height
adjusting their related positions.
13. A modular unit according to Claim 14, characterized in that said fixed coupling elements
(10) comprise a cylindric pin (11) having inner threaded end portions for engaging
therein respective locking screws (12, 13).
14. A modular unit according to Claim 13, characterized in that the head of the screws
(11,12) are engaged in complementary shape seats as formed on the outer faces of said
outer elements (6) thereby said screw head are flush with the latter.
15. A modular unit according to Claim 1, characterized in that each side supporting structure
(3) comprises a pair of inner elements (5) coupled to a pair of outer elements (6)
spacing washers (14) being arranged between each element and immediately adjoining
element.
16. A modular unit according to Claim 13, characterized in that said pair of inner elements
(5) is coupled to a pair of outer elements by a pair of coupling elements (9) arranged
along a line which is slanted at 45° with respect to a horizontal line.
17. A modular unit according to Claim 1, characterized in that at least one of said outer
elements (6) of each supporting structure (3) is provided with a support (15) for
one or more cross members (4a) for bearing thereon a ladder step (4) and an anchoring
bracket for anchoring upright elements (26) of a guard or parapet (27).
18. A prefabricated self supporting ladder construction comprising a plurality of modular
units (2, 2c) according to one or more of the preceding claims, wherein each modular
unit (2, 2c) comprises a pair of side supporting structures (3, 3c) supporting a flat
ladder step (4, 4c), characterized in that each supporting structure (3, 3c) comprises
at least a substantially vertical inner element (5) arranged between and rigidly coupled
to at least a pair of substantially horizontal outer elements (6, 6c), said inner
element (5) being coupled to at least a pair of outer elements (6, 6c) pertaining
to an adjoining modular unit by a height adjustable coupling device (16).
19. A modular unit according to one or more of the preceding claims, characterized in
that said modular unit comprises a plurality of plate-like vertical modules, in which
are formed a plurality of slots delimited by two vertical portions and two curved
portions, with a convexity respectively facing upward and downward, thereby providing
corresponding inserts of like shape including a plurality of throughgoing holes at
different levels or heights with respect to the longitudinal extension of said inserts.
20. A modular unit according to one or more of the preceding claims, characterized in
that said inserts with directly made by shearing or cutting operations on vertical
plate-like modules, said modules being provided with calibrated housing seats for
engaging therein said inserts.
21. A modular unit according to one or more of the preceding claims, characterized in
that said inserts are provided with a plurality of holes arranged at the center or
top or bottom thereof, with respect to the longitudinal extension of said inserts,
thereby allowing to adjust the height of the individual ladder steps, said inserts
being engaged in said seats which are provided with a corresponding configuration.
22. A modular unit according to one or more of the preceding claims, characterized in
that said cross member for coupling said supporting structures (3) comprises a plate-like
or tubular element.
23. A modular unit according to one or more of the preceding claims, characterized in
that, for making great width ladder constructions, said modular unit comprises a number
of supporting structures (3) greater than two, wherein each side supporting structure
adjoins one or more middle supporting structures, coupled to the other supporting
structure by said coupling cross-members (4a).