The invention relatestoa jointing device for fastening cross directional sheets, where the sheets are joined to each other through slots, the width of which corresponds to the wall thickness in such a way that the slot of both sheets fits the non-slotted part of the cross directional sheet. Such solution is already known, where slot is formed in each sheet for fastening the sheets ar¬ ranged perpendicularly to each other, the slot is some what wider than the thickness of the sheet and thus the two sheets canbe slided into each other along the slots. The shortcoming of this solution is that the joint is not stable and the two sheets may easily come apart.

Purpose of the invention is to produce such releasable joint between the two sheets which prevents their disengagement.

The problem is solved- according to the in¬ vention in that at least one widening is formed in the slot of one of the sheets joined to each other, and at least one hole is in the solid part of the other sheet, or the slot of both sheets is provided with at least o widening and the holes and/or the widenings are fittin to each other as to be suitable for receiving a joint¬ ing piece, preferably a ball or prism.

The material of the sheets is capable for plastic deformation or permanent deformation suitable at least on the part along the jointing piece and thus the part along the jointing piece of the sheets can be bent away from the jointing piece.

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Preferably a set of the widenings of the slot is arranged on both sheets, and a set of holes on the non-slotted part.

The widening at the end of the slot or at its intermediate part may be prepared in many forms, but simplest is the circular slot, i.e. the hole. The slots formed in the solid part of the sheet may also have different shapes, but since the circular slot formed in the solid part is the simplest, thus hereinafter the slot will be mentioned as hole.

A jointing piece is arranged at the meeting point of the widenings and holes, which is preferably a ball, prism, or cube, but could be any other optio¬ nal shape. The jointing piece may be inserted and re- moved by use of the flexibility of the sheets, thus by bending the part of the sheet along the widening or the hole and this way the jointing piece is inserte or removed. Such solution is also conceivable, where the jointing piece is sufficiently small to insert it without bending, and after insertion it swells or expands in another way, thus it fastens the sheets.

If a set of widenings is in the sheets and the jointing pieces are some kind of objects, e.g. tennis balls, then after insertion the tennis balls not only hold the two sheets together, but inversely the sheets are used as means of packing or for carry¬ ing the tennis balls.

The sheets may be flat, curved or bent. The invention is described in detail with the aid of the drawings showing the jointing device according to the invention given by way of example only.

Figure 1 is a perspective view of the first alterna¬ tive of the jointing device according to the invention in its engaged position.

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Figure 2 is a side view of one sheet of the solution according to Figure 1. Figure 3 is a side view of the other sheet of th,e so¬ lution according to Figure 1. Figure 4 is a perspective view of the jointing device according to the invention in engaged positi Figure 5 is a side view of one sheet of the solution according to Figure 4. Figure 6 is a side view of the other sheet of the solution according to Figure 4-

Figure 7 is a perspective view of a further alterna¬ tive of the jointing device according to the invention in engaged position. Figure 8 is a side view of one sheet of the solution according to Figure 7.

Figure 9 is a side view of the other sheet of the solution according to Figure 7. Figure 10 is a perspective view of a further alterna¬ tive of the jointing device according to th invention in engaged position.

Figure 11 is a side view of one sheet of the solution

.according to Figure 10. Figure ^" 12 is a side view of the other sheet of the solution according to Figure 10. Figure 13 is a further alternative of the jointing device according to the invention in engaged position. Figure 14 is a side view of the sheets of the solutin according to Figure 13» Figure 15 is a perspective view of a further alterna¬ tive of the jointing device according to the invention in engaged position. Figure lβ is a side view of one sheet of the solution according to Figure 15.

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Figure 17 is a side view of the other sheet of the solution according to Figure 15 _* Figure 18 is a perspective view ofa further alterna¬ tive of the jointing device according to the invention in engaged position.

Figure 19 is a side view of one sheet of the solution according to Figure 18. Figure 20 is a side view of the other sheet of the so¬ lution according to Figure 18. In case of the solution shown in Figures 1 to 3, a slot 4 extending to half width of the sheets is formed in a sheet 1 and 2. A circular widening 5a is on each end of the slot 4- The jointing piece 3 ^irL this solution is a ball 3a. In the solution shown in Figures 4 to 6, the slots 4 formed in the sheets1 and 2 extend similarly ^' to half width of the sheet. Widening 5a is formed in the slot 4 of the sheet 1, while a hole 6 is formed in a centreline above slot 4 of the sheet 2. Naturally the hole 6 is on the same level with the widening 5a in the other sheet 1. Here the jointing piece 3 is also a ball 3a.

In the solution shown in Figures 7 to 9, the sheets 1 and 2 are held together by two jointing pieces 3, in. this case too by balls 3a. Accordingly a slot 4 is formed in each sheet 1 and 2 and widening 5a is part of the slot. In addition a hole 6 is formed in the cen reline of each slot 4#

In the solution shown in Figures 10 to 12, th jointing piece 3 is a prism 3b. The slots 4 formed in the sheets 1 and 2 extend to half width of the sheets. The widening formed at the end of slots 4 is square shap corredponding to the prism 3b.

In the solution shown in Figures 13 to 14, th jointing piece 3 is again a ball 3a, but here a set of

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balls is used. Accordingly a long slot 4 is formed in the sheets 1 and 2, in which several widenings 5 and several holes 6 are formed in the centreline of the slots 4 _* 5 In the solution shown in Figures 15 to 17, the slots 4 formed in the sheets 1 and 2 are shorter than the half width of both slots 4. The jointing piece 3 is a ball 3a in this solution too.

In the solution shown in Figures 18 to 20, 10 the sheets 1 and 2 are bent to cylindrical shape. A widening 5a is formed in the slot 4 of.the sheet 1, while a hole 6 is formed in the centreline of the slot 4 of the other sheet 2, naturally on the same level with the widening 5a. 15 The sheets 1 and 2 are perpendicular to each other or at least cross directional in relation to each other in each solution and the widenings 5 or holes 6 covering each other surround the jointing piece 3 or other suitable body like a cage, thus it

20 can not fall out and the three pieces, i.e. sheets 1 and 2 and jointing piece 3 form a unit.

In order to insert the jointing piece, the part of the sheets along the jointing piece is bent as shown with dashed line in Figure 1. Best is the

25 solution where the bending is possible through the plastic deformation of the sheet, tha iø the sheet returns into its original position after the jointing piece is inserted. In order to remove the jointing piece, the part of the sheet along the jointing piece

30 is to be bent.Such solution is also conceivable, where the bending results in permanent deformation and af¬ ter insertion of the jointing piece or other holding body, the sheet is bent back by hand.

The jointing device according to the inven-

35 tion is used to advantage in building toys or other

detachable structures or packing materials, when the - jointing piece used for fastening of the sheets serves as packed or mass produced goods.

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