Basic structure and covering

Abstract

A basic structure for a covering, in particular a press felt for a machine for producing a fiber web, includes a first ply having first MD yarns and first CD yarns, and a second ply having second MD yarns and second CD yarns. The first ply is disposed above the second ply. The first CD yarns have a smaller diameter than the second CD yarns, and the yarn density of the first CD yarns is greater than the yarn density of the second CD yarns.

1 . A basic structure for a covering or a press felt for a machine for producing a fiber web, the basic structure comprising:
 a first ply having first MD yarns and first CD yarns;   a second ply having second MD yarns and second CD yarns;   said first ply being disposed above said second ply;   said first ply and said second ply not being interwoven;   at least one of said first ply or said second ply including or being formed of a flat-woven fabric;   said first CD yarns having a smaller diameter than said second CD yarns; and   said first CD yarns having a greater yarn density than said second CD yarns.   
     
     
         2 . The basic structure according to  claim 1 , wherein said diameter of said first CD yarns is a maximum of 90% of said diameter of said second CD yarns. 
     
     
         3 . The basic structure according to  claim 1 , wherein said yarn density of said first CD yarns is at least 3% higher than said yarn density of said second CD yarns. 
     
     
         4 . The basic structure according to  claim 1 , wherein said yarn density of said first CD yarns is at least 10% higher than said yarn density of said second CD yarns. 
     
     
         5 . The basic structure according to  claim 1 , wherein said yarn density of said first CD yarns is 15% higher than said yarn density of said second CD yarns. 
     
     
         6 . The basic structure according to  claim 1 , which further comprises no further plies above said first ply. 
     
     
         7 . The basic structure according to  claim 1 , which further comprises no further plies below said second ply. 
     
     
         8 . The basic structure according to  claim 1 , wherein at least one of:
 all of said first CD yarns are identical, or   all of said second CD yarns are identical.   
     
     
         9 . The basic structure according to  claim 1 , wherein at least one of:
 said first CD yarns are formed of different yarns, or   said second CD yarns are formed of different yarns.   
     
     
         10 . The basic structure according to  claim 9 , wherein both filaments and twists are used as at least one of said first CD yarns, or said second CD yarns. 
     
     
         11 . The basic structure according to  claim 10 , wherein at least one of said first ply or said second ply has a ratio of twists to monofilaments selected from the group consisting of 3:1, 2:1; 3:2, 1:1, 2:3, 1:2 and 1:3. 
     
     
         12 . The basic structure according to  claim 1 , wherein said first ply and said second ply have the same MD yarns or at least MD yarns with substantially the same yarn cross-section. 
     
     
         13 . The basic structure according to  claim 1 , wherein said MD yarns of at least one of said first ply or said second ply have a diameter of between 0.24 mm and 0.6 mm. 
     
     
         14 . The basic structure according to  claim 1 , wherein said MD yarns of at least one of said first ply or said second ply have a diameter of between 0.3 mm and 0.5 mm. 
     
     
         15 . A covering or a press felt for a machine for producing a fiber web, the covering or press felt comprising the basic structure according to  claim 1 .