FI85042B - Method and arrangement in a paper or cardboard machine for guiding the web from the wire part to the press part - Google Patents

Description

1 85042

A method and apparatus in a paper or board machine for introducing a web from a wire section to a press section

The invention relates to a method for introducing a web from a wire section to a press section as set out in the preamble of claim 1. The invention further relates to an apparatus for introducing a web from a wire section to a press section, which apparatus is set out in the preamble of claim 2.

10

In paper and board machines, the disadvantage of normal pick-ups is that when removing the web from the wire by means of a pick-up roll on the top felt or other felt of the press section, 15 tracks may detach from the edges . This problem generally occurs regardless of how short the aforementioned gap is, where the web passes after the pick-up roll by 20 upper felts or similar felts before it gets between the upper felt and the lower felt. The above-mentioned prior art is described e.g. U.S. Patent 40750566 (Beloit Corp.).

25 The support of the web from below has been solved in some cases in that the pick-up roll and the felt felt roll of the lower felt are arranged in press rolls which form a press nip between which the web passes. After said nip, the web passes over the lower felt 30 to the second press nip. The pick-up blanket, on the other hand, separates from the web after the first nip. The disadvantage of this construction is that the solution is quite expensive because it has to use two press suction rollers. Em. the construction is shown e.g. U.S. Patent No. 4,219,383 to Valkama. In addition, arranging a combined pick-up / press nip at that location causes machine construction difficulties as well as difficulty in changing the tissues of the machine.

2 85042

The object of the invention is to provide a method and a device for use in a paper or board machine, by means of which the web can be reliably and supported transferred from 5 wires through a catch roll to the first press nip of the press section without expensive solutions. To achieve this object, the method according to the invention is mainly characterized by what is set forth in the characterizing part of claim 10. Accordingly, the second felt is brought into secure contact with the web on the first felt passing through the catch roll at a point where the flow of the second felt is free of the felt guide rollers. In this case, the export of the web after the 15 catch rolls does not create a portion where the web would not have been supported from below. The device according to the invention, with which the above-mentioned method can be implemented, is in turn characterized by what is set forth in the characterizing part of claim 2. Accordingly, the second felt is arranged or can be arranged in secure contact with the web on the first felt at a point where the running of the second felt is free of the felt guide rollers.

25

With the features of the invention described above, it is possible to provide a well-secured web export without expensive press rolls, and a second felt can be led to support the web by means of simpler felt guide rollers.

The invention will now be described in more detail with reference to the accompanying drawing, in which Figure 1 shows a device according to the invention in a side view seen in the direction of the axes of the rollers.

3 85042

In the following, the device and its parts will be described mainly in the direction of travel of the web passing through it with reference to Figure 1.

5 In the direction of travel of the web W marked with broken lines, the first is the wire 1, of which the end of the wire loop is shown in the drawing, where the wire starts to rotate back in its incoming direction via the guide rollers 7. The web W passing through the wire is detached from the wire 1 by means of a catch roll 2 by means of a first felt 3 rotating through a catch roll and in contact with the web W on the wire 1. The transfer takes place by means of the suction zone 2a of the catch roll 2. The web W passes through this jacket of the pick-up roll 2 with a curved pick-up-15 felt 3 until it arrives at point A, where another felt 5 is placed on it. After point A, the pick-up felt 3 separates from the jacket of the catch roll 2 and the web W continues and 5 towards the press nip 6. The export of the web W between the felts 3, 5 thus takes place in the direction of travel of the web at the point where the first felt 3 is against the casing of the catch roll 2. Figure 1 shows how the suction zone 2a of the capture roll also ends at said point A. However, the suction zone 2a may end before point A 25 or after point A. In the former alternative, the support provided by the roll 2 to the web after the suction zone is often sufficient. Thus, the passage of the web W is ensured by the entire section starting at the point where it passes to the pick-up felt 3, to the point where it gets between the pick-up felt 3 and the second felt 5.

As can be seen from the drawing, there are two inlet guide rollers of the second felt 5, rollers 4a and 4b. The point A where the web W is placed between the felts 3 and 5 is located in the free run of the felt 5 between the rollers 35. The first roll 4a guides the web W on the felt 3 on the jacket 3 of the catch felt roll, after which the webs 4 and 5 separate from the web 2 85042 from the roll 2 and after a short free run come to the second roll 4b as described in paragraph. The alternative of two feed rollers 5 is possible in cases where there is enough space at the roll 2 to accommodate additional rollers. This allows for subsidized exports with a simple construction.

10 After point A, both the pick-up blanket 3 and the lower blanket 5 pass between the web W up to and through the press nip 6, after which the webs 3, 5 and the web W

there are many alternative ways of conducting which are not related to the invention and are therefore not described in more detail here.

Thanks to the invention, a good supported export to the web W from the wire 1 to the first press nip 6 is obtained. An alternative according to the invention is also possible, in which the pick-up felt 3 does not pass on the web W through the press nip 6, but separates from the web W and the lower felt 5 before the press nip, after which a separate press felt comes into contact with the web W at the press nip 6.

25

Claims (2)

A method of a paper or cardboard machine for transferring the web (W) from the wire portion (1) to the press portion, wherein the method of web (W) is detached from the wire portion (1) by means of a pick-up suction roll or pick-up roller. up roll (2) on a first blanket (3) son runs through the pick-up suction roll, after which a second blank (5) is guided on the web (W), which lies on the first blanket 10 (3), by means of a felt guide roller (4a) for said second felt in such a way that the web (W) enters between the first and second felt (3, 5), wherein the second felt is brought into a transfer secure contact with the web lying on the first felt (W). ) at a point (A), where the first blanket (3) lies against the manifold of the pick-up suction roll (2), characterized in that the second blanket (5) is brought to said contact within a distance between two felt guide rollers ( 4a, 4b) for the second felt at the point (A), where its bore is free from the felt guide rollers. 2. Device in a paper or cardboard machine for transferring the web (W) from the wire portion (1) to the press portion (6), in which device is a pick-up suction roll or pick-up roll (2), through which the first blanket (3) is arranged to run, wherein the pick-up suction roll (2) is arranged to release the web (W) from the wire (1) on a first blanket (3), the device further comprising a felt guide roll (4a) arranged to pass a second blanket (5) on the web (W), which lies on the first blanket (3), in such a way that the web (W) comes between the first and second blankets (3, 5), wherein the second blanket is arranged or may be arranged for a transfer securing contact with the web (W) lying on the first blanket (3) at a point (A), where the first blanket (3) lies against the men of pick-up suction roll (2), characterized in that the second blanket (5) is arranged or may be arranged for said contact within a distance between two felts. rollers (4a, 4b) for the second blanket at point (A), where its bore is free from the felt guide rollers.