Screening element of open-mesh fabric and methods for producing screens of open-mesh fabric

Abstract

A screening element ( 10 ) comprises an open-mesh fabric ( 11 ) made up of interwoven threads to form warp threads ( 12 ) and weft threads ( 13 ). A strip element ( 14 ) is held fast between, and is parallel to two warp threads. The strip element ( 14 ) is flexible along its length parallel to the warp threads and basically rigid in the plane of the fabric transversally to the warp threads. This strip element acts as a hooking connection for support elements ( 16, 17 ) of the screening element. The strip element is tensioned longitudinally at its ends and the fabric is transversally tensioned by means of transversal actions on the strip element itself.

What is claimed is:  
     
         1 . Screening element comprising open-mesh fabric made up of interwoven threads to constitute warp threads and weft threads, characterized in that a strip element is present between, and parallel to, two warp threads, held fast between the weft threads, flexible along its length parallel to the warp threads and basically rigid in the plane of the fabric transversally to the warp threads, the strip element acting as a hooking connection for elements supporting the screening element.  
     
     
         2 . Screening element according to  claim 1 , characterized in that said support elements comprise first elements destined to tension the fabric and acting on the strip element transversally to it and second elements destined to tension the strip element longitudinally.  
     
     
         3 . Screening element according to  claim 2 , characterized in that the second elements comprise elastically supple elements.  
     
     
         4 . Screening element according to  claim 3 , characterized in that the second elements comprise elastic expanders for tensioning the strip element at a value of at least about 30% of its breaking load.  
     
     
         5 . Screening element according to  claim 3 , characterized in that the second elements comprise elastic expanders for tensioning the strip element at a value of not exceeding about 50% of its breaking load.  
     
     
         6 . Screening element according to  claim 1 , characterized in that the strip element has a rectangular transversal section.  
     
     
         7 . Screening element according to  claim 2 , characterized in that the strip element has a ratio between the sides of between {fraction (1/10)} and {fraction (1/20)}.  
     
     
         8 . Screening element according to  claim 1 , characterized in that the strip element is made of an extruded thermoplastic material.  
     
     
         9 . Screening element according to  claim 1 , characterized in that the weft threads are in the form of a flattened band.  
     
     
         10 . Screening element according to  claim 9 , characterized in that the flattened bands are made of a plastic film material.  
     
     
         11 . Screening element according to  claim 9 , characterized in that the flattened bands have at least one reflecting side.  
     
     
         12 . Screening element according to  claim 1 , characterized in that the support elements comprise hook elements with an end that passes through the fabric from the side of the strip element opposite said edge of the fabric to hook onto said strip element on said side, the hook element having the opposite end suitable for being connected to a support of the screening element.  
     
     
         13 . Screening element according to  claim 12 , characterized in that the said opposite end of the hook element protrudes from the edge of the fabric and is in the form of a hook.  
     
     
         14 . Screening element according to  claim 12 , characterized in that the hook element has the first end with basically parallel arms to be positioned parallel and on the opposite sides of the strip element in the plane of the fabric.  
     
     
         15 . Screening element according to  claim 1 , characterized in that there are two strip elements, each one positioned near an opposite edge of the open-mesh fabric.  
     
     
         16 . Screening element according to  claim 1 , characterized in that the width of the strip element is basically near the distance between the two warp threads.  
     
     
         17 . Method for producing a screening element comprising the phases of producing open-mesh fabric made up of interwoven threads to constitute warp threads and weft threads, during the weaving inserting a strip element between the weft threads placed between, and parallel to, two warp threads, the strip element being flexible along its length parallel to the warp threads and basically rigid in the plane of the fabric transversally to the warp threads, the strip element acting as a hooking connection for elements supporting the screening element.  
     
     
         18 . Method for producing a screening with a screening element comprising an open-mesh fabric made up of interwoven threads to constitute warp threads and weft threads, a strip element being held fast between the weft threads, positioned between, and parallel to, two warp threads, the strip element being flexible along its length parallel to the warp threads and basically rigid in the plane of the fabric transversally to the warp threads, the strip element acting as a hooking connection for elements supporting the screening element, in which the strip element is tensioned at a value of at least about 30% of its breaking load and in which the fabric is tensioned by acting on the strip element transversally to it.