[0001] The present invention relates to a fastening device for attaching sandwich construction
units to a support structure, said construction units comprising a core element of
a thermally insulating material and surface sheets on its two major surfaces, said
surface sheets being attached to the core element by means of a bonding agent on the
opposite major surfaces of the core element, each of said surface sheets having at
least one of its edges provided with a tongue and its respective opposite edge with
a groove, and said construction units being mountable to a wall in such a way that
said tongues and grooves of adjacent construction units are placed against each other
for providing a tongue-and-groove joint between the construction units, said device
comprising a plate-like fastening member, which extends in a longitudinal direction
of the construction unit and is arranged on the construction unit's one narrow side
provided with tongue-and-groove edges and which in its lateral direction extends over
some of the width of said narrow side, said fastening member being shaped in its outer
edge portion appropriately for engaging under the outer surface sheet's tongue edge,
said fastening member being formed with at least one recess for passing a construction
unit fastening element therethrough to a support structure.
[0002] The fastening of a sandwich construction unit provided with a core element of some
heat insulating material is generally performed by means of various fastening elements,
which are designed to fit in a clamping joint of the units for cooperation with a
tongue-and-groove design of the unit's surface sheet. The objective with these has
been to conceal the fasteners as effectively as possible and to fit the same in a
joint so as not to generate cold bridges or otherwise compromise the joint's tightness,
such as by being placed discontinuously between the mating surfaces of a tongue-and-groove
joint. One design of this type is described in the present Applicant's European patent
No. 0839239, in which a fastening member engages under a tongue-and-groove edge and
said fastening member is provided with a recess, through which a fastening element,
such as a retention screw, can be passed to support structures.
[0003] It is an aim of the present invention to provide an improved fastening device for
attaching sandwich construction units to frame structures by ensuring the transfer
of attachment forces to the outer surface without subjecting the latter to local strains
or deformations. In order to accomplish this objective, a fastening device of the
invention is characterized in that the device further comprises a clamping member,
which extends in a longitudinal direction of the construction unit and which is attachable
to the fastening member, and which clamping member is shaped in its outer edge to
be substantially complementary to the shape of the outer surface of the outer surface
sheet's tongue edge, and which clamping member is engageable for a clamping attachment
with said tongue edge for securing the fastening member to the outer surface sheet.
[0004] The invention will now be described in more detail with reference to the accompanying
drawings, in which:
- Fig. 1
- shows schematically in an axonometric view a fastening member for a fastening device
of the invention,
- Fig. 2
- shows the fastening member of fig. 1 together with a clamping member connectable thereto,
and
- Fig. 3
- shows the use of a fastening device of the invention in a joint between two adjacent
panels.
[0005] As shown in fig. 3, a sandwich construction unit 1 comprises a core element 4 of
some insulating material, preferably mineral wool, and a facade-forming outer surface
sheet 2, as well as an inner surface sheet 3 set against support structures. The surface
sheet of a lower unit has its top edge provided with a tongue 5 and the respective
bottom edge of an upper unit is provided with a matching groove 6, whereby, in the
process of mounting the units, the tongues and grooves will be interlocked for holding
the units steady relative to each other. In view of resisting forces generated by
wind loads and thermal expansions, the units must be fastened to support structures,
typically with retention screws. In fig. 3, represented by reference numeral 13 is
a narrow side of the construction unit, which remains between the lower unit's 1 tongue
edges 5 and which is fitted with a fastening device of the invention in such a way
that, in the process of mounting the units, the fastening device becomes hidden in
a joint area between units. In this context, the terms lower and upper panel, as well
as bottom edge and top edge, are only used in reference to the relative position of
construction units depicted in fig. 3. In addition to a horizontal position, the units
can be installed also in a vertical position or in an inclined position.
[0006] According to figs. 1-3, the inventive fastening device for sandwich construction
units comprises a plate-like fastening member 7 positioned on the unit's 1 narrow
side 13. The fastening member extends over some of the construction unit's 1 length,
and in its lateral direction it extends over some of the width of said narrow side
13, thus, avoiding the formation of cold bridges through a joint area. The fastening
member has a length which is preferably within the range of 200-500 mm, but it can
be shorter or longer as necessary. The fastening member 7 has its outer edge 8 shaped
appropriately for engaging under the outer surface sheet's 2 tongue 5. The fastening
member is formed with one or more recesses 9 for passing a construction unit fastening
element 12 therethrough to a support structure. In this example, the fastening element
12 comprises a screw which is passed through a fastening hole 10 in the recess portion
9 to support structures (not shown). The number of fastening elements can be one or
more at each recess portion. The fastening member is further provided with a plurality
of engagement slots 11 successive in its lengthwise direction. The engagement slots
can also be arranged in more than one row and can also have a shape other than the
depicted rectangle, e.g. circular or oval.
[0007] The fastening device comprises further a clamping member 14, having its inner edge
provided with locking tabs 16 intended for cooperation with the fastening member's
7 engagement slots 11. As for its outer edge 15, the clamping member 14 is shaped
to be substantially complementary to the shape of the outer surface of the outer surface
sheet's 2 tongue 5. The fastening device is preferably preassembled by inserting the
clamping member's tabs 16 in the fastening member's engagement slots 11 prior to fitting
the fastening device in place on the side 13 of a unit. In the process of installing
the fastening device, the clamping member is turned open, such that the fastening
member's outer edge 8 can be fitted under the tongue 5. This is followed by turning
the clamping member 14 on top of said tongue 5 for locking the clamping member, and
thus the fastening member 7, to the outer surface sheet 2, and then by screwing the
retention screws 12 securely into support structures through the holes 10. This way,
it is possible to prevent a sinking of the fastening member 7 inside the core element
4, caused by possible excessive tightening of the fastening element 12 and/or by various
external loads, such as e.g. wind loads and thermal stresses, and a weakening of the
attachment as a result thereof, which may happen when using solely the engagement
of a fastening member under the tongue edge 5 without a clamping member. The clamping
member 14 becomes firmly secured on top of the tongue 5 as the next unit is laid in
place for producing a tongue-and-groove joint.
[0008] The clamping member's 14 locking tabs 16 are preferably made hook-shaped in the cross-section
of the clamping member for an improved clamping engagement.
[0009] In the process of mounting construction units in place, a lower construction unit
is first secured in its position by means of the fastening device 7, 14 and the retention
screws 12, followed by laying the next construction unit on top of the lower one in
a tongue-and-groove joint resulting manner, the clamping member's shaped outer edge
15 becoming concealed within the tongue-and-groove joint. In order to reduce deformations
in the joint, it is possible, whenever necessary, that, prior to laying the upper
construction unit in place, an adhesive or bonding agent be applied within the space
between the top surface of the clamping member's 14 outer edge 15 and the inner surface
of the upper construction unit's groove 6.
[0010] The inventive fastening device can also be designed in such a manner that the clamping
member is attached to the fastening member by means of screws, rivets or in the like
manner, such that the tongue-and-groove edge becomes clamped between said members
of the fastening device. This solution is particularly suitable for fastening a single
tongue or groove (when a tongue-and-groove joint is not produced), such as, for example,
for fastening the top edge of the uppermost unit among construction units placed on
top of each other.
1. A fastening device for attaching sandwich construction units (1) to a support structure,
said construction units comprising a core element (4) of a thermally insulating material
and surface sheets (2, 3) on its two major surfaces, said surface sheets being attached
to the core element by means of a bonding agent on the opposite major surfaces of
the core element, each of said surface sheets having at least one of its edges provided
with a tongue (5) and its respective opposite edge with a groove (6), and said construction
units being mountable to a wall in such a way that said tongues and grooves (5, 6)
of adjacent construction units are placed against each other for providing a tongue-and-groove
joint between the construction units, said device comprising a plate-like fastening
member (7), which extends in a longitudinal direction of the construction unit and
is arranged on the construction unit's (1) one narrow side (13) provided with tongue-and-groove
edges and which in its lateral direction extends over some of the width of said narrow
side (13), said fastening member (7) being shaped in its outer edge portion appropriately
for engaging under the outer surface sheet's (2) tongue edge (5), said fastening member
being formed with at least one recess (9) for passing construction unit fastening
elements (12) therethrough to a support structure, characterized in that the device further comprises a clamping member (14), which extends in a longitudinal
direction of the construction unit (1) and which is attachable to the fastening member
(7), and which clamping member (14) is shaped in its outer edge (15) to be substantially
complementary to the shape of the outer surface of the outer surface sheet's (2) tongue
edge (5), and which clamping member (14) is engageable for a clamping attachment with
said tongue edge (5) for securing the fastening member (7) to the outer surface sheet
(2).
2. A fastening device as set forth in claim 1, characterized in that the fastening member (7) is further formed with engagement slots (11), and that the
clamping member (14) is at its innermost edge provided with locking tabs (16), which
are insertable in said engagement slots (11) of the fastening member (7).
3. A fastening device as set forth in claim 2, characterized in that the clamping member's (14) locking tabs (16) are made hook-shaped in the cross-section
of the clamping member.
4. A fastening device as set forth in any of claims 1-3, characterized in that a joint area between the mating surfaces of the clamping member's (14) edge portion
(15) and the adjacent construction unit's tongue-and-groove edge is applied with a
layer of adhesive prior to the engagement of construction units to each other with
a tongue-and-groove joint.
