The present invention relates to an elastic tentering mat for a hide tentering apparatus, said mat being in the form of an endless mat loop and having at least two layers of rubber attached to each other by vulcanizat¬ ion (hot or cold vulcanization) .

A continuous-action tentering apparatus employing this type of tentering mat is disclosed in the Applicant's earlier published application WO 85/03309. A hide to be tentered resists strongly the elongation of tenter¬ ing mats within the area where the hide is compressed between the tentering mats. A result of this is that, beyond this mentioned area, i.e. within the marginal area of mats, a mat will be subjected to quite sub¬ stantial elongations resulting in a hazard of tenter¬ ing mat edges ripping off.

An object of the invention is to provide a tentering mat capable of eliminating this rip-off hazard of mat edge portions. In order to achieve this objective, a tentering mat of the invention is characterized in that between the layers of rubber are placed crimped or other¬ wise winding fibres for preventing elongation of said tentering mat after a certain stretch and that, in add¬ ition to said fibre layer, the mat is provided with longitudinal straight fibres or filaments for preventing elongation of the mat in its lengthwise direction.

The fibres allowing a limited stretch or elongation may form a network in which the directions of fibres are so distributed that said elongation limiting action is ac¬ hieved in all directions in the plane of a mat.

In order to achieve the objectives of the invention, a layer, of fibres having said limited elasticity need not necessarily extend across the entire width of a mat as its duty is to prevent disproportional elongation of sections beyond the hide to be tentered as compared to a section or area covered by the hide to be tentered. However, this would restrict the disposition of hides and the minimum hide size that can be tentered by means of the apparatus, so in the most preferred embodiment, said layer of fibres extends over the entire area of a tentering mat.

In an optimum case, a stretch allowed by the layer of fibres is substantially equal to the maximum stretch of a hide in question.

A layer of fibres can be made of single or multithread crimped or creped filaments. For example, a net braid¬ ing woven from creped polyamide thread can be consider¬ ed. It is obvious, however, that the fibres employed can be any synthetic or natural fibres having high tensile strength.

For using such a tentering mat in a continuous-action tentering apparatus as disclosed in publication WO 85/03309, the mat must include, in addition to a layer of fibres allowing a limited elongation, straight longitudinal fibres or filaments for preventing elongation of the mat in its lengthwise direction, i.e. in the direction of an endlessly continuing mat loop.

The invention will now be illustrated further with re¬ ference made to the accompanying drawing in which

fig. 1 shows a portion of a tentering mat of the invent¬ ion as a section taken along line I-I in fig. 2 and

fig. 2 is a cross-section of a corresponding mat port- -ion with the sectional lines of the upper rubber layer 1 being omitted for the sake of clarity.

In this example case, there is shown a portion of an endless mat loop, with the lengthwise direction of an endlessly continuing loop indicated by an arrow A. The longitudinal center axis of said mat loop is indicated by a dot-dash line B. The mat is made of two rubber layers 1 and 2, attached to each other by vulcanization. Vulcanization can be hot vulcanization or cold vulcani¬ zation with the help of adhesives. Between rubber lay¬ ers 1 and 2 is placed a layer 3, comprising crimped, creped or otherwise winding fibres and characterized by its ability to prevent elongation of a ready-made mat after a certain stretch. The fibre layer 3 is prefer¬ ably designed as net braiding for obtaining a firm en¬ gagement of rubber layers 1 and 2 through net eyelets. What is essential, however, is that as a result of crimping, creping or other zifzagging the eyelet fila¬ ments stretch over a certain distance before they begin to limit elongation of the rubber mat. This stretch is preferably selected to be equal to the maximum stretch of hides. A suitable material is e.g. creped poly- amide filament. It is clear that all synthetic or natural fibres having sufficient tensile strength can be used.

When the directions of the filaments in net braiding 3 are chose diagonally as shown in fig. 1, the mat elon¬ gation and elongation limiting action is obtained in all directions of the plane of said mat. In addition to that, the lengthwise (direction A) elongation of the mat loop of such continuous-action apparatus must be prevented completely for securing operation of the

apparatus on a principle shown in publication WO 85/ 03309. - In order to achieve this, within one rubber layer 1 there is fitted one or several layers of long¬ itudinal (direction A) straight fibres or filaments 4 for preventing lengthwise elongation of the mat. Filament layers 4 can also be placed in rubber layer 1 by making this rubber layer from several rubber layers vulcanized together.