The invention relates to a fastener box according to the preamble of claim 1 .

The invention relates also to a method according to the preamble of claim 9 for providing a fastener box with an attachment element.

The invention further relates to a method for mounting a fastener box on the end face of a concrete element.

For the purpose of connecting precast concrete building elements or sections thereof to each other, the mold systems employed in the fabrication of con- crete elements are fitted with fastener boxes which will be located at the end walls of fabricated concrete elements, after concrete casting. Inside each fastener box is a wire rope loop which can be extracted from the box after concrete casting. This is followed by fastening concrete elements or sections thereof to each other with these wire rope loops. The part of a casting mold in a mold system, which has the fastener box connected thereto, is most commonly made of steel.

There are various ways of connecting fastener boxes to a concrete element casting mold, depending, among other things, on a material of the fastener boxes and the mold. One method, applied specifically for fastener boxes of sheet metal and casting mold parts of steel, comprises connecting the box to a part of the casting mold with separate magnetic closure or attachment elements, but use is also made of e.g. mechanical attachment elements such as screws or nails. Inside each fastener box is a wire rope loop, which extends outward of the fastener box such that its free end is directed away from a base of the box, being thereby confined within the cast concrete element or a section thereof as the fastener box in turn has its mouth, which has been closed with an attachment or closure element, directed away from the cast concrete element. When two concrete elements or sections thereof are connected by the end walls thereof to each other, it is the attachment or closure elements used for the mutual attachment of fastener boxes and mold parts which are released first and this is followed by connecting opposite concrete elements to each other by means of fasteners, such as wire rope loops, housed in the fastener boxes. Regarding how fastener boxes of the foregoing type, connected to concrete casting molds, are mounted to casting molds, a currently existing problem is that, in case the fastener boxes are connected to a frame of the box magnetically, for example by means of plate type closure or attachment elements, the mouth thereof is not always tight in all conditions, whereby, during concrete casting, some concrete may find its way inside the box, thus precluding in a worst case scenario the use of a wire rope housed in the box.

On the other hand, if the fastener box is made of a non-magnetizable material, and it is connected to a mold for example with a mechanical joint or a clamping joint, it is possible that opening the mouth of an attachment element for taking out the wire rope loop becomes problematic after the casting of a concrete element.

It is an object of the invention to eliminate the drawbacks appearing in the prior art. Accordingly, the invention has an objective of providing a fastener box, which is of the above-described type, appropriate for the mutual attachment of precast concrete elements or sections thereof, and connectable particularly to a magnetizable casting mold, and on whose mouth can be mounted a readily removable, tightly mouth-closing attachment element.

The foregoing objective is attained with a fastener box attachment element ac- cording to claim 1 .

More specifically, the invention relates to a fastener box attachment element, said fastener box comprising an upward open frame which is provided with a fastener loop, especially a wire rope loop, and comprises a base encircled by end and side walls whose respective upper edges make up a top edge of the box, whereby a first portion of said fastener loop, especially the wire rope loop, is located in an interior of the fastener box and a second portion of the fastener loop, especially the wire rope loop, is located outside the fastener box, and a plate type attachment element fitted on top of said frame for connecting the fastener box to a casting mold. Hence, - the at least two opposite upper edges of the end and/or side wall, which make up the top edge of the fastener box, are folded inward,

- the fastener box attachment element is generally plate-shaped and manufactured from a magnetizable material and set in contact with a bottom surface of the upper edge of the inward-folded end and/or side walls of the fastener box's top edge, such that the inward-folded upper edges of the box, especially the inward-folded side edges, have a material thickness which is equal to a protrusion of magnets from a top surface of the box attachment element, whereby the top surface of permanent magnets embedded in said attachment element has its plane extending also by way of the top surface of all said inward-folded upper edges of the fastener box for fixing the attachment element and the fastener box to a surface of the casting mold to be placed on the plane of a top surface of the upper edge of the frame, especially a top surface of the inward- folded upper edges of the end walls and/or side walls of the frame, by means of a magnetic flux which travels at least in said attachment element and in the casting mold.

What the invention is based on is that the attachment element to be placed against the surface of a magnetizable casting mold has its edges fitted under- neath a portion of the fastener box's inward-folded upper edge. When the attachment element connects magnetically to the surface of a casting mold, the inward-folded edge of the fastener box prevents concrete casting from entering inside the fastener box.

For the purpose of fitting an attachment element with sufficient tightness and firmness underneath the inward-folded upper edge of a box, the magnetic flux of magnets included in the cover, i.e. in this attachment element, must travel by way of the casting mold's surface. This is achieved in the invention in such a way that the top surface of magnets protruding from a top surface of the attachment element extends to the surface of a casting mold set in a position coplanar with a top surface of the inward-folded upper edge while the attachment element has its top surface in contact with a bottom surface of the fastener box's inward-folded upper edges. The major benefit attained this way is that in terms of its material the box can have its actual frame made for example of acid resistant steel or plastic which becomes magnetized only poorly or not at all.

In one preferred embodiment of the invention, the fastener box is manufactured from a magnetizable material and the magnetic flux interconnecting the attachment element and the casting mold travels also by way of the inward- folded upper edges of the fastener box's end or side walls. In one embodiment of the invention, the inward-folded upper edges of the end or side walls have been deflected to a 90-degree angle with respect to the respective end or side walls.

In one preferred embodiment of the invention, the permanent magnets have the magnetic field thereof adapted to travel at least in the material of the attachment element as well as the casting mold so as to keep, during the casting of a concrete element, the attachment element's top surface underneath the box's inward-folded upper edges, especially inward-folded side edges, and in contact with a bottom surface of said side edges, such that the orientation of a lengthwise center line of the attachment element and a lengthwise center line of the fastener box's frame remains unchanged during the casting of a concrete element.

If, for example, there are two magnets embedded in a box attachment element, these will be located at the attachment element's longitudinal end walls. On the other hand, if there are for example four magnets embedded in a box attachment element, these will be located at regular intervals, concentrically with a lengthwise center line of the attachment element.

The invention relates also to a method for providing a fastener box with an attachment element, said method comprising at the following steps of - grasping the attachment element with a handle of the attachment element and fitting the attachment element's side walls underneath the fastener box's inward-folded end or side edges by tilting a plane of the attachment element relative to a plane of the base

- bringing the attachment element's side walls to contact with a bottom surface of the frame's inward-folded upper edge, especially with bottom surfaces of the frame's inward-folded side edges, by changing an inclination angle of the attachment element and by moving the attachment element upward or away as seen from a base of the box.

In a preferred embodiment of the method according to the invention, the at- tachment element is placed in an interior of the box and the side walls of the attachment element are fitted underneath the inward-folded side edges of an open box by tilting the plate type attachment element by means of a handle to an inclined position relative to a plane of the base, - a plane of the plate type attachment element is rotated to become approximately co-directional with a plane of the base and the side walls of the attachment element are brought to contact with the bottom surfaces of the inward- folded side edges. The invention relates also to a method for mounting a fastener box according to claim 1 on the end wall of a concrete element, wherein

- the fastener box is mounted on a concrete element in such a way that a box attachment element is left in flushness with the surface of an element to be fabricated and the portion of a fastener loop (51 ), especially a wire rope loop, emerging from an interior of the box, is left inside the element,

- the box attachment element is removed from a frame of the box,

- the portion of a fastener loop, especially a wire rope loop, present inside the box, is deflected outward of the box so as to extend away as seen from a base of the box. The invention and benefits attainable thereby will now be described in even more detail with reference to the accompanying figures.

Figs. 1 A and 1 B show in perspective views, as seen from slightly difference viewing angles, one fastener box provided with a fastener and an attachment element. Fig. 1 C shows, in a side view, another fastener box which is provided with an attachment element of the invention.

Fig. 1 D shows the fastener box of fig. 1 C without an attachment element.

Fig. 2 shows the fastener box of figs. 1 A-1 B without an attachment element.

Figs. 3A and 3B show, in perspective views, a fastener box attachment ele- ment.

Figs. 4A-4D illustrate fitting of an attachment element to a fastener box.

Fig. 5A shows schematically an attachment element in a longitudinal section view. Fig. 5B shows a fastener box in a cross-section view looking directly at an end wall.

Next will be reviewed main structures of the invention visible in the figures and which aspect of the invention is intended to be illustrated with each figure. Figs. 1 A and 1 B show from slightly different viewing angles a fastener box 1 , which is provided with a wire rope loop 5 and an attachment element 4 and whose side walls 33 are provided with an indentation such that the box tapers vigorously towards a mouth 32. The fastener box shown in figs. 1 C and 1 D differs from that of figs. 1 A and 1 B primarily in the sense that the side walls 33 therein are straight.

The fastener box 1 comprises an upward open frame 3, including a base 31 which is encircled by end and side walls 34, 33. The end and side walls 34, 33 have respective upper edges 32b, 32a thereof making up a top edge 32 for the box 1 , which is at the same time an upward open mouth of the box 1 . In figs. 1 A, 1 B and 1 C, the box 1 has its mouth 32 further closed with an attachment element 4 which is placed, as visible in figs. 4A-4D, underneath inward-folded upper edges 32; 32a', 32a" of side walls 33; 33', 33" of the mouth 32. Hence, the plate type attachment element 4, which is co-directional with a plane of the base 31 , attaches magnetically to a casting mold 7 supported on a top surface of the upper edges 32a of said side walls 33 (cf. fig, 5B). The fastener box 1 is provided with a wire rope loop 5 of which is visible in figs. 1 A-1 D a portion 5; 51 thereof left outside the fastener box 1 . The wire rope 1 is brought into an interior of the box by way of its base 31 .

Figs. 1 D and 2 show the box 1 without the attachment element 4. As seen from these figures, what is left of the wire rope loop 5 in an interior S of the box is the portion 51 resting against the box's base 31 .

A more detailed structure of the plate type attachment element 4 can be seen from figs. 3A-3B, as well as from fig. 5A showing the attachment element in section. The box attachment element 4 is plate-shaped and manufactured from a magnetizable material such as iron. In an embodiment of the invention visualized in the figures, the box attachment element 4 has embedded therein two magnets 4b; 4b', 4b", which are located at lengthwise end walls of the attachment ele- ment. As can be seen from fig. 5A, the magnets 4b; 4b', 4b" attach to a collective mounting 4c, which traces along a bottom surface 41 of the attachment element 4 and which is for example a flat bar. In another embodiment of the invention, the plate type box attachment element 4 has embedded therein four magnets 4b which are located at regular intervals, concentrically with a lengthwise center line P3 of the attachment element. A protrusion K3 of the permanent magnets from a top surface 40 of the attachment element 4 is arranged to equal a material thickness K1 of the box's inward-folded side edges 32a; 32a', 32a", i.e. the distance between bottom and top surfaces 32aala, 32ayla of the box's side edges 32a.

The attachment element 4 has a width L1 which matches a distance S1 between the box's side walls 33; 33' and 33; 33" in an upper part of the side walls 33, the bottom surface 32aala of the upper edge 32a of said side walls being contacted by the edge of the side wall 33 of the attachment element 4. On the other hand, the attachment element 4 has a length which is approximately equal to the length of the box, i.e. the distance between the box's opposite end walls 34; 34' and 34; 34". Because the width L1 of the attachment element 4 is equal to the distance S1 between the side walls 33; 33' and 33; 33" in an upper part of said side walls, the placement of a side wall edge of the attachment element 4 underneath said inward-folded upper edges 32a; 32a', 32a" of the side walls 33 of the frame 3 prevents effectively the entrance of concrete casting into the interior S of the box 1 as long as the contact between the attachment element 4 and the box's inward-folded side edges 32a is sufficiently solid. In order to ensure a solid contact between the attachment element 4 and the inward-folded upper edges 32a of the side walls of the fastener box's frame 3 and in order to block the access of concrete casting into the box's interior S, the protrusion K3 of magnets from the top surface 40 of the box attachment element 4 is arranged to equal a material thickness K2 of said inward-folded side edges 32a of the fastener box 1 .

Mounting of the attachment element 4 on the mouth 32 of the frame can be seen in more detail from cross-section view 5B of the box.

An edge zone limited to the opposite side walls 43; 43', 43" of the top surface 40 of the attachment element 4 is pushed to a position underneath each in- ward-folded side edge 32a, 32a' and 32; 32a" of the top edge 32 of the box's frame. The resulting condition is illustrated in the cross-section view 5B of the box: by way of a top surface 4b1 of the permanent magnet, the top surface 32ayla of the box's side edge, and a surface of the casting mold 7 extends a horizontal plane T2, by way of the bottom surface 32aala of the side edge 32 of the box's frame and the top surface 40 of the attachment element 4 extends a horizontal plane T1 , and by way of the attachment element's bottom surface 41 extends a horizontal plane T3.

This signifies that the plane T2 of the top surface 4b1 of permanent magnets 4b embedded in the attachment element 4 extends by way of both the surface of the casting mold 7 and the top surfaces 32ayla of the inward-folded upper edges (side edges) 32a, 32a', 32a" of the fastener box's frame 3 as the zone limited to the side walls of the attachment element's top surface 40 is brought to contact with the bottom surface 32aala of said inward-folded upper edges 32a; 32a', 32a" of the side walls 33.

Between the casting mold 7 and the attachment element 4 develops consequently a magnetic attraction by means of the magnets 4b of the attachment element 4. The resulting magnetic attraction connects the attachment element tightly also to the bottom surface 32aala of the fastener box's inward-folded upper edges 32a, 32a', 32a". When examining a resulting magnetic flux, it can be noticed that the magnetic flux travels by way of the permanent magnets 4b embedded in the attachment element 4 as well as the surface of the casting mold 7 present in flushness with the permanent magnets. In case the fastener box 1 consists of magnetizable metal, such as sheet metal, the magnetic flux may travel also by way of the inward-folded edges 32a of the frame's top edge 32.

Hence, said magnetic flux connects at least the attachment element 4 and the casting mold to each other and pulls the part, which has been pushed underneath the frame's upper edges 32 (here: side edges 32a), from the top surface 40 of the side walls 33 of the attachment element's 4 frame tightly to the attachment with the bottom surface 32aala of the inward-folded edges 32a of the frame's top edge. Consequently, the attachment element has its top surface 40 as well as the frame 3 has the bottom surface 32aala of its side edge 32a lying on the same (horizontal) plane T1 . With figs. 4A-4D there is further illustrated how the attachment element 4 is fitted to the top edge 32 of the upward opening fastener box 2.

As shown in figs. 4A-4D, the process of providing the fastener box 2 with the attachment element 4 is as follows: - the attachment element 4 is grasped with the attachment element's handle 6 by threading the end of the handle 6 into the attachment element's central opening 4a,

- the attachment element 4 is fitted in the box's interior S in such a way that the side walls 43; 43', 43" of the attachment element are brought underneath the inward-folded side edges 32a; 32' and 32; 32" of the open fastener box 2 by tilting the plane of the plate type attachment element 4 relative to the plane of the base 31 by means of the handle 6,

- the side walls 43; 43', 43" of the attachment element 4 are brought to contact with the bottom surfaces 32aala of the frame's inward-folded side edges 32a; 32a' and 32; 32a" by changing the angle between the plane of the attachment element 4 and the plane of the base 31 and by moving the attachment element 4 away as seen from the base 31 of the box.

Thereby, a part of the top surface 40 of the attachment element 4 can be brought underneath the box's inward-folded side edges 32a and to contact with the bottom surface 32aala thereof. Hence, the attachment element 4 has its lengthwise center line P2 and the box has the lengthwise center line P3 of its frame lying concentrically. Since the attachment element 4 has a length which is equal to the length of the box's mouth, i.e. the distance between the box's end walls 34; 34' and 34; 34" in an upper part of said walls, the box 1 will be tightly closed by the attachment element 4.

What has been illustrated above by means of the figures are just a few embodiments of the invention and it is obvious for a skilled artisan that the invention lends itself to being implemented in many other ways within the scope of an inventive concept defined in the claims. Thus, the number of permanent mag- nets embedded in the attachment element can be other than what has been presented above. The box is often manufactured entirely from a magnetizable material such as sheet metal.

A protruding distance of the magnets 4b1 from the surface 40 of the attachment element 4 can be adjusted with separate adjustment blocks that can be placed under the magnets.

List of reference numerals

1 Fastener box equipped with a fastener 2 Box without an attachment element 3 Frame of the box 31 Base of the box

31 a Base opening for a wire rope

32 Top edge of the box, mouth

32a; 32a', 32a Side edge, inward-folded upper edge

32b; 32b', 32b End edge

32ayla Top surface of the side edge

32aala Bottom surface of the side edge

33 Side wall of the box

331 Upper part of the side wall 332 Lower part of the side wall 34 End wall of the box 4 Attachment element for the box

40 Top surface of the attachment element 41 Bottom surface of the attachment element

43; 43', 43" Side wall of the attachment element

44; 44', 44" End wall of the attachment element

4a Opening in the attachment element 4b; 4b', 4b" Magnet in the attachment element

4b1 Top surface of the magnet

4c Magnet mounting, flat bar

4d; 4d', 4d" Opening for magnet in the attachment element

5 Fastener loop 51 Portion of fastener loop outside the box

52 Portion of fastener loop inside the box

6 Attachment element handle

7 Casting mold

K1 Material thickness of the inward-folded upper edge K2 Material thickness of the attachment element

K3 Protrusion of magnet from the attachment element's top surface

L1 Width of the attachment element

P1 Crosswise center line of the attachment element P2 Lengthwise center line of the attachment element

P3 Lengthwise center line of the box

T1 Plane of the attachment element's top surface, bottom surface of the side edge T2 Plane of the magnets' top surface, plane of the side edge's top surface

T3 Plane of the attachment element's bottom surface

S Interior of the box

S1 Width of the box in an upper part of the side walls

S2 Width of the box in a lower part of the side walls