Method for passing web tail from one paper machine section to another and apparatus therefor and construction thereof

Abstract

The invention relates to a method and apparatus for passing a web tail being threaded from one paper machine section to another by way of guiding the tail with the help of an air jet from a transfer plate. An essential feature of the invention is to employ a construction rising from the surface of the transfer plate to a height with the shape of a linear ramp or a droplet for guiding the web tail in its travel direction thereby minimizing the contact area between the web tail and the transfer plate.

1 . A method for passing a web tail being threaded from one section to another by way of guiding the tail with the help of an air jet from a transfer plate, wherein a structure rising from the surface of the transfer plate to a height with the shape of a linear ramp or a droplet guides the web tail in its travel direction thereby minimizing the contact area between the web tail and the transfer plate. 
     
     
         2 . The method of  claim 1 , wherein, from one or more air exit openings of a frog eye structure arising seamlessly from transfer plate surface, the air flow is directed essentially parallel to the web tail travel direction, whereby simultaneously is created an advantageous level of vacuum at 5-300 Pa between the web tail and transfer plate so that with the help of the vacuum the web tail is kept in the immediate vicinity of surface of the transfer plate, most advantageously at a distance of about 0-5 mm. 
     
     
         3 . The method of  claim 1 , wherein onto the transfer plate are formed a plurality of frog eyes suited to create a maximally high air flow released from air exit openings serving to transfer the web tail forward, whereby the height of frog eye is 0.3-10 mm, most advantageously 3-6 mm, with a width of 2-10 mm, most advantageously 3-8 mm and, in the web tail travel direction over transfer plate, a length of 2-150 mm, most advantageously 10-50 mm, whereby the frog eye has an essentially droplet-like shape wherein the angle of its slanting surface in respect to surface of transfer plate is 10-170 deg., most advantageously 45-135 deg. 
     
     
         4 . The method of  claim 3 , wherein as seen from above the transfer plate, the air flow exits from frog eye essentially directly onto surface of transfer plate, either parallel thereto or inclined to transfer plate and the web tail travel direction by −60-+60 deg., most advantageously by −45-+45 deg. 
     
     
         5 . The method of  claim 1 , wherein the frog eyes are located on surface of the transfer plate interspaced apart from each other by 5-150 mm laterally and by 10-300 mm longitudinally either in an equispaced, unsymmetrical and/or dispersed fashion in the xy-directions at a distance of 30-100 min from each other, either over the entire area or only a given partial area of one or a plurality of transfer plates. 
     
     
         6 . The method of  claim 1 , wherein from the air exit openings the air flow is directed essentially parallel to the web tail travel direction so that the frog eyes are formed either essentially flush with the level of surface of the transfer plate or just above the same or, alternatively, a portion of the frog eye structure extends below the surface of transfer plate. 
     
     
         7 . The method of  claim 1 , wherein the air flow is directed out from one or a plurality of air exit openings of the frog eye so that one or more of the openings are formed either flush with the level of surface of the transfer plate or above the same or alternatively and/or below the surface of transfer plate. 
     
     
         8 . The method of  claim 1 , wherein, in order to improve the direction of the air flow parallel to the surface of the transfer plate, into the frog eye are formed openings from two directions, i.e., from below and from above of the transfer plate so that one opening situated above surface is aligned either parallel to the transfer plate or at an angle of −10-+10 deg. to the plate, most advantageously −5-+5 deg., while as seen from below of the transfer plate the other opening is inclined by 10-170 deg. to the plane of the transfer plate, most advantageously by 45-135 deg., whereafter the air flow path is continued as a duct through the frog eye ending as an air exit opening on the surface of the transfer plate. 
     
     
         9 . An apparatus for passing a web tail being threaded from one paper machine section to another by way of guiding the tail with the help of an air jet from a transfer plate, wherein having a structure adapted thereto rising from the surface of the transfer plate to a height with the shape of a linear ramp or a droplet, said structure guiding the web tail in its travel direction thereby minimizing the contact area between the web tail and the transfer plate. 
     
     
         10 . The apparatus of  claim 9 , wherein having onto the surface of transfer plate seamlessly rising from said surface adapted a frog eye structure incorporating one or more air exit openings, wherefrom an air flow is directed essentially parallel to the web tail travel direction, whereby simultaneously is created an advantageous level of vacuum at 5-300 Pa between the web tail and transfer plate so that with the help of the vacuum the web tail is kept in the immediate vicinity of surface of the transfer plate, most advantageously at a distance of about 0-5 mm. 
     
     
         11 . The apparatus of  claim 9 , wherein having onto the transfer plate formed a plurality of frog eyes suited to create a maximally high air flow released from air exit openings serving to transfer the web tail forward, whereby the height of frog eye is 0.3-10 mm, most advantageously 3-6 mm with a width of 2-10 mm, most advantageously 3-8 mm and, in the web tail travel direction over transfer plate, a length of 2-150 mm, most advantageously 10-50 mm, whereby the frog eye has a droplet-like shape wherein the angle of its slanting surface in respect to surface of transfer plate is 10-170 deg., most advantageously 45-135 deg. 
     
     
         12 . The apparatus of  claim 11 , wherein having, as seen from above the transfer plate, the air flow exiting from frog eye is essentially directed onto surface of transfer plate, either parallel thereto or inclined to transfer plate and the web tail travel direction by −60-+60 deg., most advantageously by −45-+45 deg. 
     
     
         13 . The apparatus of  claim 9 , wherein having the frog eyes located on surface of the transfer plate interspaced apart from each other by 5-150 mm laterally and by 10-100 mm longitudinally either in an equispaced, unsymmetrical and/or dispersed fashion in the xy-directions at a distance of 30-100 mm from each other, either over the entire area or only a partial area of one or a plurality of transfer plates. 
     
     
         14 . The apparatus of  claim 9 , wherein having the air flow released from the air exit openings directed essential parallel to the web tail travel direction so that the frog eyes are formed either essentially flush with the level of surface of the transfer plate or just above the same or alternatively and/or below the surface of transfer plate. 
     
     
         15 . The apparatus of  claim 9 , wherein having the air flow directed out from one or a plurality of air exit openings of the frog eye so that one or more of the openings are formed either flush with the level of surface of the transfer plate or above the same or, alternatively, a portion of the frog eye structure extends below the surface of transfer plate. 
     
     
         16 . The apparatus of  claim 9 , wherein having into the frog eye formed openings from two directions, i.e., from below and from above of the transfer plate so that one opening on the surface is aligned either parallel to the transfer plate or at an angle of −10-+10 deg., most advantageously −5-+5 deg., while as seen from below of the transfer plate the other opening is inclined by 10-170 deg. to the plane of the transfer plate, most advantageously by 45-135 deg., whereafter the air flow is continued as a duct through the frog eye ending as an air exit opening on the surface of the transfer plate. 
     
     
         17 . A construction of a transfer plate for passing a web tail being threaded from one paper machine section to another by way of guiding the tail with the help of an air jet from a transfer plate, wherein having a guiding construction adapted thereto rising from the surface of the transfer plate to a height with the shape of a linear ramp or a droplet, said construction guiding the web tail in its travel direction thereby minimizing the contact area between the web tail and the transfer plate. 
     
     
         18 . The construction of  claim 17 , wherein having onto the surface of transfer plate seamlessly rising from said surface adapted a frog eye construction incorporating one or more air exit openings, wherefrom an air flow is directed essentially parallel to the web tail travel direction, whereby simultaneously is created an advantageous level of vacuum at 5-300 Pa between the web tail and transfer plate so that with the help of the vacuum the web tail is kept in the immediate vicinity of surface of the transfer plate, most advantageously at a distance of about 0-5 mm. 
     
     
         19 . The construction of  claim 17 , wherein having onto the transfer plate formed a plurality of frog eye constructions suited to create a maximally high air flow released from air exit openings serving to transfer the web tail forward, whereby the height of frog eye is 0.3-10 mm, most advantageously 3-6 mm with a width of 2-10 mm, most advantageously 3-8 mm and, in the web tail travel direction over transfer plate, a length of 2-150 mm, most advantageously 10-50 mm, whereby the frog eye has a droplet-like shape wherein the angle of its slanting surface in respect to surface of transfer plate is 10-170 deg., most advantageously 45-135 deg. 
     
     
         20 . The construction of  claim 19 , wherein having, as seen from above the transfer plate, the air flow exiting from frog eye construction is essentially directed onto surface of transfer plate, either parallel thereto or inclined to transfer plate and the web tail travel direction by −60-+60 deg., most advantageously by −45-+45 deg. 
     
     
         21 . The construction of  claim 17 , wherein having the frog eye constructions located on surface of the transfer plate interspaced apart from each other by 5-150 mm laterally and by 10-300 mm longitudinally either in an equispaced, unsymmetrical and/or dispersed fashion in the xy-directions at a distance of 30-100 mm from each other, either over the entire area or only a given partial area of one or a plurality of transfer plates. 
     
     
         22 . The construction of  claim 17 , wherein having the air flow released from the air exit openings directed essential parallel to the web tail travel direction so that the frog eye constructions are formed either essentially flush with the level of surface of the transfer plate or just above the same or, alternatively, a portion of the frog eye structure extends below the surface of transfer plate. 
     
     
         23 . The construction of  claim 17 , wherein having the air flow directed out from one or a plurality of air exit openings of the frog eye construction so that one or more of the openings are formed either flush with the level of surface of the transfer plate or above the same or alternatively and/or below the surface of transfer plate. 
     
     
         24 . The construction of  claim 17 , wherein having into the frog eye construction formed openings from two directions, i.e., from below and from above of the transfer plate so that one opening on the surface is aligned either parallel to the transfer plate or at an angle of −10-+10 deg., most advantageously −5-+5 deg., while as seen from below of the transfer plate the other opening is inclined by 10-170 deg. to the plane of the transfer plate, most advantageously by 45-135 deg., whereafter the air flow is continued as a duct through the frog eye ending as an air exit opening on the surface of the transfer plate.