FR2656012A1 - Press for the manufacture of paper sheets with felts and rolls, wet and drying - Google Patents

Abstract

Press for the manufacture of paper sheets (10) with felts and rolls, wet and drying, comprising a wet part (1) followed by a dry part (2), the said wet part (1) comprising a wet felt (5) passing between two press rolls (3, 4) to remove the water from the sheet (10) before it enters the dry part (2), the said dry part (2) comprising a drying felt (9) and drying rolls (6, 7, 8) for drying the sheet (10), the first drying roll (6) not being in contact with the drying felt (9), characterised in that on leaving the press rolls (3, 4) the sheet of paper (10) is conveyed by an impervious belt (11) which runs through the said press rolls (3, 4) and comes round the first drying roll (6). Reduction in the risks of tearing of the sheet (10).

Description

Press for the production of sheets of paper with felts and cylinders, wet and dry
The present invention relates to a press for manufacturing sheets of paper with felts and cylinders, wet and dryers comprising a wet part followed by a dry part, said wet part comprising a wet felt passing between two compression cylinders to remove water of the sheet before it enters the dry part, said dry part comprising at least one drying felt and drying rolls for drying the sheet.

 In the known press, the sheet of paper is without support over a relatively large distance, when it passes from the wet part to the dry part. To stabilize the sheet, it is necessary to provide a significant difference in speeds between the running speed of the last wet felt and that of the first drying felt.

 However, this difference induces tensions in the sheet which can lead to tears.

 To remedy this drawback, it has been proposed to wind the last wet felt around the first drying cylinder. Thus the sheet of paper is brought by the last wet felt to the first drying cylinder.

 The sheet is then entrained by a second drying cylinder to a third drying cylinder on which the first drying felt is applied.

 Such a press is described in the article "Innovative press felt design helps mill improve machine runability" by MIKE DIMICK published in the review "PULP AND PAPER" from May 1989 p.114 to 118.

 This arrangement makes it possible to reduce the print on the sheet and to significantly reduce the number of tears.

 However, it has the drawback of internalizing a rewetting of the sheet during its transfer from the wet part to the dry part.

 The press according to the invention making it possible to avoid this drawback while reducing the drawing on the sheet is characterized in that the sheet of paper at the outlet of the compression cylinders is transported by an impermeable belt which passes through said compression cylinders and surrounds the first drying cylinder.

 The invention will now be described in more detail with reference to a particular embodiment shown in the single figure.

 The press according to the invention comprises a wet part 1 followed by a dry part 2.

 The wet part comprises a pair of compression cylinders 3, 4 between which passes a wet felt 5. The wet felt remains in the wet part and does not come in the dry part 2.

 The dry part 2 comprises a certain number of drying cylinders including a first drying cylinder 6, a second drying cylinder 7 and a third drying cylinder 8.

 The drying felt 9 surrounds the second and third drying cylinders 7, 8.

 According to the invention, an impermeable belt 11 passes through the gripper line between the cylinders 3 and 4 below the sheet 10 while the wet felt 5 passes over the sheet 10; the latter is therefore sandwiched between the wet felt 5 and the waterproof belt 11.

 The impermeable belt 11 supports the sheet 10 at the outlet of the compression cylinders 3, 4 and surrounds the first drying cylinder 7.

 The sheet 10 is thus always supported during its path from the wet part I to the dry part 2, which greatly reduces the risk of tearing.

 In addition, the belt 11 is chosen to be waterproof, which prevents rewetting of the sheet during its path towards the dry part 2.

 This belt li can be constituted by a felt made waterproof.

 The drying felt 9 comes to apply the sheet 10 against the belt 11 surrounding the first drying cylinder 6 and the sheet 10 leaving this cyclinder 6 is supported by the drying felt 9 so that it is always also supported in the dry part 2 .

Claims (1)

1 / Press for the production of sheets of paper (10) with felts and cylinders, wet and dryers comprising a wet part (1) followed by a dry part (2), said wet part (1) comprising a wet felt (5 ) passing between two compression cylinders (3, 4) to remove the water from the sheet (10) before it enters the dry part (2), said dry part (2) comprising a drying felt (9) and cylinders dryers (6, 7, 8) for drying the sheet (10), the first drying cylinder (6) not being in contact with the drying felt (9), characterized in that the sheet of paper (10) at the outlet compression cylinders (3, 4) is transported by an impermeable belt (11) which passes through said compression cylinders (3, 4) and surrounds the first drying cylinder (6).