The invention relates to a device and a method for lif¬ ting building elements or corresponding plate-like mem- bers, which members are at least partially comprised of a core portion of a resilient material as well as of a pla¬ te-like surface layer covering this core portion on both side surfaces, which surface layer on at least one ele¬ ment edge is bent into a part of the thickness of the core portion.

A building element, to whose lifting the inventive device is applicable, may be comprised e.g. of a resilient core portion made of e.g mineral wool fiber, each flat surface of which is coated with a metal sheet glued onto the sur¬ face of the wool plate. The treatment of such building elements has to be gentle for preventing the damaging of the plates, and clamp jaw type lifting devices known per se cannot be applied to lifting these plates. Different gripping elements have been developed for lifting said inherently light plates, which are fixed to the flat sur¬ faces of the elements by suction pads.

In spite of the relative lightness of the plates to be lifted, the number of the suction pads has to be fairly large for ensuring a sufficient lifting safety and for taking into account the effect of factors possibly dis¬ turbing the fixing of the suction pads. Furthermore, these gripping elements of lifting devices require a suf- ficient free space at least in the area of one surface of the plate for fixing the gripping member to the flat sur¬ face of the plate to be lifted.

Said drawbacks may be eliminated by means of the inven- tive device and method, which make the gripping on the plate edge possible, in a certain embodiment even hori¬ zontally in a space essentially required by the plate thickness.

The essential characteristics of the device are described in the enclosed patent claim 1. The essential character¬ istics of the method are in turn described in the en- closed patent claim 11.

The invention is illustrated by means of the accompanying drawing, wherein

Fig. 1 shows an element to be lifted, on whose upper edge is placed an inventive device in the initial fixing step;

Fig. 2 shows the element to be lifted from the same di¬ rection, when the inventive device is fixed to the lift- ing position;

Fig. 3 shows the element from the direction of the flat surface, when the lifting device is fixed to the upper edge in the lifting position; and

Fig. 4 shows an inventive application for lifting roof elements.

A plate-like building element, which is of a type that may be lifted by means of the inventive device, is com¬ prised of a core portion 8, whose thickness forms an es¬ sential part of the element thickness, as well as of a plate 9, 9 ' covering the core portion on both sides. The core portion 8 may be made e.g. of a mineral wool mat having a suitable strength, which is coated with a metal sheet.

The upper edge of the wall element of Fig. 1-3 is design¬ ed for achieving a joint structure such that each cover plate 9, 9 ' extends by some distance above the core por¬ tion 8 and is bent towards the core portion for forming a bead extending along the length of the element. The bead

structures extend by some distance towards the center part of the element, but leave an essential part of the upper edge of the core portion 8 free. In the embodiment shown, each bead forms a tongue 10 in the longitudinal direction of the plate, and a matching groove shape cor¬ responds to this tongue on the lower edge of the next element.

In the roof element of Fig. 4, the joining edge is de- signed to deviate from the wall elements. A plate cover 9 forming the lower surface of the element is extended, corresponding to the wall elements, partly on top of the core portion 8, but the edge of a plate cover 9 ' forming the upper surface is in turn bent outwards for forming a water seam between two element plates to be placed adjac¬ ent to each other. Also a tongue and groove structure 10 ' of the lower surface deviates from the tongue and groove structure of the lifting edge of the wall element and corresponds in fact better to the tongue and groove structure of the lower edge of the wall element, which tongue and groove structure has a longitudinal groove.

First of all, the inventive lifting device is comprised of a beam 1 forming a frame. The width of this beam in the lifting device, which is intended for lifting wall elements, preferably corresponds to the thickness of the wall element. In contrast, the width of the frame piece intended for lifting roof elements is not critical. In a device intended for lifting wall elements, the frame beam 1 may in turn have an optional length, but in a device intended for lifting roof elements, the length of the frame beam is defined by the thickness of the element to be lifted. On the frame beam 1 is mounted at least one gripping unit, which is comprised of a shaft or a corres- ponding member 2, which is preferably placed in a boring made in the middle of the width of the frame beam 1. The shaft 1 is in the boring provided with a movement clear-

ance such that the shaft may be both turned and moved in its longitudinal direction relative to the frame beam 1.

At the other end of the shaft is placed a longitudinal, gripping claw 3 transverse relative to the longitudinal axis of the shaft. In a device intended for lifting wall elements, the gripping claw 3 is dimensioned by its width such that it may be placed in an intermediate space left by the beads of the surface plates 9 to be freely pressed against the upper edge of the core portion 8. The grip¬ ping claw 3 is by its length dimensioned such that it, when turned cross-wise relative to the longitudinal di¬ rection of the element, extends below at least one tongue and groove 10, preferably however such that it extends according to Fig. 1 and 2 below the bead of both tongue and grooves 10. In a device intended for lifting roof elements, the gripping claw 3 preferably protrudes only from one side from the shaft 2 and is dimensioned by its length such that the location of the shaft 2 is taken into account such it extends below the bead of the tongue and groove structure 10' of the lower surface of the el¬ ement.

In a device intended for lifting wall elements, the lower surface of the frame beam 1 is designed such that it fol¬ lows the upper surface of the element to be lifted, i.e. longitudinal receiving grooves of the frame beam have been formed for the tongue shapes 10. In a device intend¬ ed for lifting a roof element, these tongue and grooves are not needed, but instead, it is advisable to provide the end of the frame beam 1 containing the gripping claw 3 with a cam 1' extending to the side of the gripping claw of the frame beam 1, which cam 1' is dimensioned to fit into the groove of the tongue and groove 10' of the lower surface of the roof element.

In a device intended for lifting roof elements, at one

end of the frame beam 1 is mounted a special gripping member 11 for gripping a water seam 12 of the upper sur¬ face of the roof element. This gripping member 11 is formed into a hook-like member, which may be fixed to the frame beam 1 by means of a shaft 2 placed in a correspon¬ ding manner as the gripping claw 3 located at the other end of the frame beam. The gripping member 11 is dimen¬ sioned such that it may be hooked behind a flange edge 12" of the water seam, before the frame beam is mounted in the fixing position of the gripping claw 3 against the edge of the roof element. In place of a hook-like grip¬ ping member 11, the structure may also include a member of another type for gripping the element to be lifted, e.g. a suction pad gripping the plate 9 ' forming the sur- face layer.

When the lifting device is set into the lifting position, in the wall-element lifting device according to Fig. 1- 3, the gripping claw 3 is first turned in the direction of the frame beam 1 and the frame beam 1 is then placed on top of the upper edge of the element according to Fig.

1. After this, the sahft 2 extending through the frame beam and the gripping claw 3 at the end thereof are pressed against the upper surface of the resilient core layer 8 of the element. The resilient core layer somewhat springs, whereby the gripping claw 3 may be caused to press inside the element to such an extent that it may be turned into a position in the thickness direction of the element. In this position, the claws of the gripping mem- ber extend below the beads of the bent tongue and grooves 10 of the surface layers of the element according to Fig.

2. A lifting arm 5 is then turned into its position in the direction of the frame beam 1 and locked into this position into a locking member 6 fixed to the frame beam 1. This locking member preferably acts simultaneously with a lifting eye of the device.

A device intended for lifting the roof element is in turn placed cross-wise relative to the element to be lifted, whereby the above-mentioned hooking fixing of the grip¬ ping member 11 is first performed behind the flange 12'. After this, the cam 1" of the frame element is pressed into the tongue and groove of the element, the shaft 2 and the gripping claw 3 at the end thereof are pressed against the resilient core layer 8, in a manner corres¬ ponding to that described above, and the shaft 2 is turn- ed such that the gripping claw 3 positions below the bead of the tongue and groove structure 10' . In place of said turnable realization, also such a structure may be used in a device intended for lifting roof elements, in which structure the a part corresponding to the shaft 2 may be moved in a longitudinal gap of the frame beam in the longitudinal direction of the frame beam. In this case, the gripping claw 3 may be in a position according to Fig. 4 already at the time as the claw is pressed against the upper surface of the core portion 8. The claw is slided in this position under the tongue-and-groove bead and locked i the lifting position by means of members also shown in Fig. 4.

The fixing of the lifting device to the edge of the el- e ent to be lifted may be ensured by means of an addi¬ tional feature of the invention, according to which an hinged member 4 between the lifting arm 5 and the shaft 2 is formed into a clamping member by means of wedge sur¬ faces 4'. By means of these wedge surfaces, it is poss- ible to achieve for the shaft 2 a slight ascending move¬ ment, when the lifting arm 5 is turned into a horizontal position, which ascending movement is sufficient for tightening the gripping members, such as the tongue-and- groove bead and the water seam, of the element to be lifted between the frame beam and the gripping claw 3, correspondingly between the frame beam 1 and the gripping member 11.

The lifting device intended for lifting wall elements includes above-mentioned lifting pairs - a shaft 2, a gripping claw 2, an hinged member 4 and a lifting arm 5 - preferably in pairs in a manner shown in Fig. 3, in co¬ operation with the same locking member 6. By means of this arrangement, the lifting device may be made into a uniformly operating tool. However, other arrangements are naturally possible within the scope of the invention, such as only one lifting subunit per lifting device. The lifting device may be dimensioned also longer such that it comprises two or more lifting subpairs, which are lo¬ cated at a suitable distance from each other.

A device intended for lifting a roof element naturally comprises only parts shown in Fig. 4, whereby preferably several devices may be used for gripping elements to be lifted at points located at a distance from each other.

Deviating from the embodiments described above, in place of the beam-like frame 1 described to be uniform may also be used a frame structure of another type, such as a box structure made of plate or a structure made of plate by bending. Various framework-type frame structures are also possible.

In place of the shaft 2 mounted on the frame may be used a freely formed arm-like member extending through the thickness of the frame, which may be formed at its one such that it directly forms a gripping claw 3, and at its opposite end such that it directly forms a lifting arm 5 or a corresponding member, by means of which this arm member may be locked onto the frame. In contrast to what has been described above, the arm member 2 may be mounted on the frame 1 e.g. to be tilted relative to the frame, whereby in one tilting position the gripping claw 3 in the arm member 2 may be pushed under the cover layer bead

and in the other tilting position the gripping claw 3 locks the cover layer bead against the frame, in which position the arm member is locked onto the frame from its opposite end. The locking of the arm member 2 onto the frame may also be performed directly without using the lifting arm described, and in this case e.g. to a lifting eye 6 or to some other point of the frame.

In place of the above-mentioned turning and tilting move- ments of the shaft or the arm member 2 or togerher there¬ with, said part may also be slidable relative to the frame, e.g. in a groove extending through the frame. E.g. in the realization of Fig. 4, the gripping claw may then be pushed under the surface layer bead without the turn- ing movement of the shaft 2 and the gripping claw 3, whereby the gripping claw 3 may be designed ski-like for facilitating the pushing movement and for avoiding sur¬ face damage to the core layer.

As shown above, it is sufficient in many applications that the lifting device is provided with a structure formed by the gripping claw 3 or a corresponding arm sec¬ tion 2 for gripping only one surface layer bead. The op¬ posite end of the lifting device may be supported on the opposite side of an element edge in various ways, of which one alternative is shown in Fig. 4 as a hook-like gripping member 11. In place of the member 11 may be used also a gripping member of another type, e.g. a suction pad structure to be fixed to the surface layer 9'. If also the surface layer 9' is extended on top of the core portion 8, it may then be considered a gripping member to be first inserted under the surface layer bead, e.g. a hook or the like protruding from the frame 1 towards its one end, which member is first inserted under a bead formed of the surface layer 9 ' . After this, the opposite end of the frame is locked e.g. by means of a gripping claw 3 functioning according to Fig. 4 under the bead of

the opposite surface layer 9,