The invention relates to a device for clamping a reinforcing steel mat comprising a number of parallel transverse rods and a number of parallel longitudinal rods arranged at right angles to the transverse rods.

Reinforcing steel mats are used to reinforce concrete. Such mats are used particularly in the pouring of floors. The mats are first arranged inside a formwork and connected to each other to form an iron network. Concrete is then poured into the formwork, wherein the reinforcing steel mats are cast into the concrete. After curing the iron network imparts to the concrete the desired tensile strength, and thereby a desired load-bearing capacity of the floor.

Reinforcing steel mats are normally delivered in stacks to the construction site. The reinforcing steel mats are then taken one by one from the stack and lifted to the desired location.

Occupational health and safety legislation stipulates that this lifting take place by means of a lifting device. For this purpose a mat is lifted and displaced to the location where the mat has to be laid by means of a quadruple chain sling, a chain with four loose outer ends to which a hook is attached. A frequent occurrence is that under the weight of the reinforcing steel mat the hook becomes stuck and must then be prised loose by hand. In addition, a reinforcing steel mat will sag when it is lifted using a quadruple chain sling. This happens because in a quadruple chain sling the hooks are pulled toward each other as a result of the weight. Owing to this sagging a mat is then difficult to position, with the result that the mat must then often be adjusted by hand.

It is further also the case that floors are poured only once a building has been made wind-tight and watertight. Use can then only be made of small lifting devices to lift the reinforcing steel mats. Here too the positioning of the mats is difficult.

Known from the prior art, such as for instance EP 1650155, are only devices with which a stack of mats can be lifted. Such devices are too heavy and too large to easily handle a single reinforcing steel mat.

It is now an object of the invention to reduce or even obviate the above stated drawbacks.

This object is achieved with a device according to the preamble, the device comprising:

- a rigid lifting frame with means for attaching to a lifting device;

- at least two elongate, parallel flexible elements, wherein each flexible element is suspended movably from the lifting frame; and

- coupling means arranged on the flexible elements for coupling to a reinforcing steel mat.

Through the use of a rigid lifting frame the forces of a quadruple chain sling as used in the prior art can be distributed uniformly over a mat without the mat sagging in unnecessary manner .

In addition, the elongate flexible elements ensure that the coupling means can be easily coupled to a single mat. Reinforcing steel mats can easily curve to some extent. The flexible elements can easily follow this curving of the mats so that the coupling means can easily be coupled to one of the transverse rods or longitudinal rods of the mat .

In a preferred embodiment of the device according to the invention the flexible elements are suspended from the lifting frame with chains and/or cables. The flexibility of the flexible elements is hereby not affected when the device is lowered onto a mat. As soon as the device is lifted together with a reinforcing steel mat and the weight is suspended from the chains and/or cables, the rigid lifting frame ensures that there is little sagging of the mat.

In another embodiment of the device according to the invention the flexible element is a strip of iron. The thickness of the strip of iron is preferably of the same order as the thickness of the longitudinal rods and transverse rods of the reinforcing steel mat. This ensures that the strip of iron can easily follow the curves in the reinforcing steel mat. It is not necessary here for the flexible element to be considerably more flexible than the mat, which could possibly even result in adverse consequences for handling of the device.

In another embodiment of the device according to the invention the flexibility of the flexible elements is of an order similar to the flexibility of the reinforcing steel mats to be clamped.

In a preferred embodiment of the device the coupling means comprise a number of hooks. The hooks are preferably arranged parallel to and at a distance from the elongate flexible element such that between the flexible element and the hook a channel is formed into which a rod of the reinforcing steel mat can be placed.

The hooks are arranged at a mutual distance such that this distance corresponds to a multiple of the mesh width of the reinforcing steel mats. The mesh width is usually 10 or 15 centimetres. By then placing the hooks at a distance of a multiple of 30 centimetres, mats having a mesh width of 10 centimetres as well as a mesh width of 15 centimetres can be lifted by the device.

In this embodiment the flexible elements can be laid on the mats and subsequently displaced parallel to the mat so that the transverse rods or longitudinal rods of the mat slide into the channel. The mat can then be lifted with the device.

In a further preferred embodiment the coupling means comprise a lock for holding a reinforcing steel mat on the device in the coupled situation. This prevents the mat sliding for instance out of the hooks during lifting.

The flexible element on which the lock is arranged is preferably suspended via the lock from the lifting frame such that the lock closes when the flexible elements are raised. As soon as the device is now lifted with a coupled reinforcing steel mat, the lifting force is transmitted via the lock and the lock is forced into the closed position, so preventing the lock accidentally being released. In yet another embodiment of the device according to the invention an operating lever is arranged on the lifting frame for operating the lock. Using the operating lever a driver of the device can easily uncouple the mat from the device as soon as the mat lies in position.

These and other features of the invention will be further elucidated with reference to the accompanying drawings.

Figure 1 shows a perspective view of an embodiment according to the invention.

Figure 2 shows a first detail of the embodiment of figure 1 in unlocked situation.

Figure 3 shows the detail of figure 2 in locked situation.

Figure 4 shows a second detail of the embodiment according to figure 1.

Figure 1 shows an embodiment of a device 1 according to the invention. Device 1 has a rigid lifting frame 2 which can be suspended with four eyes 3 from a quadruple chain sling 4.

Two elongate flexible elements 5, 6 are arranged under the rigid lifting frame 2. These flexible elements 5, 6 are for instance steel strips corresponding in terms of flexibility to the reinforcing steel mats to be clamped.

Flexible elements 5, 6 are suspended under the rigid lifting frame from chains 7. Owing to these chains 7 the flexible elements 5, 6 can follow the curve of a reinforcing steel mat and, when device 1 is raised, flexible elements 5, 6 will be pulled straight by the weight of the mat. The mat is hereby also straightened and can be positioned more easily.

Arranged under flexible elements 5, 6 are hooks 8 with which the elements 5, 6 can be coupled to a reinforcing steel mat. Securing hooks 9 are further arranged at the outer ends of elements 5, 6. These securing hooks 9 can be operated via coupling rods 10 and operating lever 11, which is connected pivotally to flexible elements 5, 6. Flexible elements 5, 6 are further held at a distance from and parallel to each other via connecting strips 12. These connecting strips 12 have a flexibility similar to that of elements 5, 6.

Arranged on the side opposite operating lever 11 is a handle 18 which is connected to flexible elements 5, 6 via profiles 19 and rods 20. Using this handle 18 and operating lever 11 the device 1 can be handled and operated easily by two persons.

Figure 2 shows the securing hook 9 in more detail. Securing hook 9 is arranged pivotally on flexible element 6. Chain 7 is attached to the rear side 13 of hook 9 so that during lifting the securing hook 9 is pulled closed. Coupling rod 10 is fixed to this same rear side 13 to enable manual operation of securing hook 9.

Device 1 is lowered onto a reinforcing steel mat 14, 15. This reinforcing steel mat has a number of parallel transverse rods 14 and a number of parallel longitudinal rods 15 arranged at right angles to transverse rods 14.

Hook 8 is attached via a spacer 16 to flexible element 6. Hook 8 is hereby at a distance from element 6, and hook 8 can be pushed round a transverse rod 14.

In figure 3 the securing hook 9 is drawn in locked position.

This prevents the transverse rods 14 sliding out of engagement with hooks 8. As soon as device 1 is raised, securing hook 9 is tightened further by the weight of reinforcing steel mat 14, 15, so that it cannot open by accident.

Figure 4 shows a side view of another hook 8. Hook 8 is attached via a spacer 16 and with a bolt 17 to flexible element 5. By selecting a correct thickness of spacer 16 it is possible to make allowance for the thickness of rods 14, 15 and to take into account the positioning of rods 14, 15 relative to device 1. If hooks 8 have to engage on longitudinal rods 15, it would then be necessary to make allowance for the thickness of the transverse rods 14 lying therebetween.