Valmet Oy

Valmet Paper Machinery Inc.

Valmet Corporation

Matti Kankaanpaa

A suction roll for a paper machine in which a stationary suction shoe is arranged inside a revolving mantle loop and is connected to a source of negative pressure. The mantle loop is a substantially water-receiving and permeable fabric-sock loop that receives water and is, in a preferred embodiment, supported by means of guide members arranged inside the loop. The suction shoe is provided with a permeable guide deck against which the inner face of the fabric-sock loop glides.

Method for draining water from a paper web

Suction element for a paper machine

Suction roll in a twin-wire zone of a web former and a twin-wire web

Guide roll and suction box for twin-wire forming system

Calender apparatus adapted to be directly associated with a paper machine for calendering a web leaving the same wherein at least two separate calendering units are mounted on a unitary frame spaced from one another. Each calendering unit includes at least one intermediate roll and two hard end rolls defining a respective pair of nips with the intermediate roll on substantially diametrically opposed sides thereof. The intermediate roll of a calendering unit may comprise a soft roll so that the pair of nips of the calendering unit are soft nips so that the calender apparatus comprises a supercalender.

Calender

Method and apparatus for calendering paper webs or the like wherein a plurality of hard calendering rolls are situated to constitute a roll stack and wherein a plurality of soft calender rolls are situated in nip defining relationship with respective ones of the hard rolls whereby a plurality of corresponding hard and soft or supercalender nips are defined. The apparatus is adapted to be directly associated with a paper machine and force apparatus are provided in conjunction with the apparatus for supporting the hard and soft calender rolls so that the hard nips are closed and the soft nips are open during threading of the web through the apparatus during the start-up phase while the hard nips are opened and the supercalendering nips are closed after the web is threaded in order to perform continuous supercalendering of the paper web.

Method and apparatus for calendering paper webs or the like

A method in a paper machine press section for dewatering a wet paper web by threading the web in an improved way and avoiding crushing or stretching the web structure through at least three nips of the press section. The invention is particularly characterized by following features of dewatering steps. The web while passing the press section through said three nips is all the time adhered to and supported by the surface of a felt or a roll without any open draws therebetween. Pressing the web in the first nip takes place between two felts and so the web is dewatered simultaneously through both sides of the web. Further dewatering and pressing steps take place in press nips which all are formed against a plain roll having a large diameter which enables a spacious location of the press rolls and their felts. Detaching the web from the surface of said plain roll for conducting the web into dryer section, takes place in a point allowing easy removal and handling in case of a web break.

Press method in a paper machine

In a paper making machine, a method and apparatus for separating the web from the former wire and transferring the same to a transfer felt which preferably comprises a press felt wherein the web is carried by the former wire over a sector of a reverser roll so that it is subjected to a centrifugal force which tends to separate the web from the former wire and wherein the transfer felt is guided so that it engages the web over at least a portion of the sector of the reverser roll lapped by the web carrying former wire. An external suction is applied to the web through the transfer felt in the region of the sector of the reverser roll lapped by the web carrying former wire and engaged transfer felt which subjects the web to a suction force which acts in substantially the same direction as the centrifugal force. The transfer felt laps a grooved suction roll which cooperates with external suction applying apparatus for assisting and maintaining the web adhered to the transfer felt between at least two press nips, the suction applying apparatus communicating with the means for applying the external suction to the web.

Method and apparatus for separating a web from a former wire and

A paper machine has a forming wire loop which transports a web to a detachment transfer roll situated inside said wire loop at a detaching location where the web is to be detached from the wire and transported to a press section. A relatively dry felt engages the web on a sector of the detachment transfer roll at the detaching location and receives the web from the wire and continues to transport the web, while it adheres to the felt, to the press section. The detachment of the web from the wire on the detachment transfer roll is facilitated by the centrifugal force acting on the web which results from the substantial change of direction undergone by the web on the detachment transfer roll. In one embodiment, the press felt is directed to cover the web on a sector of the detachment roll by a press suction roll located on substantially the same level as the detachment transfer roll, the press roll having a suction sector which facilitates transfer of the web from the wire to the felt.

Paper manufacturing structure particularly for detaching a web from a

A method in a paper machine press section for dewatering a wet paper web by threading the web in an improved way and avoiding crushing or stretching the web structure through at least three nips of the press section. The invention is particularly characterized by following features of dewatering steps. The web while passing the press section through said three nips is all the time adhered to and supported by the surface of a felt or a roll without any open draws therebetween. Pressing the web in the first dewatering nip takes place between two felts and so the web is dewatered simultaneously through both sides of the web. Further dewatering and pressing steps take place in press nips which all are formed against a plain roll having a large diameter which enables a spacious location of the press rolls and their felts. Detaching the web from the surface of said plain roll for conducting the web into dryer section, takes place in a point allowing easy removal and handling of broke in case of a web break.

Method of multi-nip pressing in a paper machine

A paper machine drying section and method for operating the same are provided for reliably maintaining a web in engagement with a drying fabric at locations where the fabric is situated between the web and drying cylinders. Those drying cylinders which are directly contacted by the drying fabric, so that the web is separated therefrom by the drying fabric, are formed with recessed outer surfaces having voids across which the fabric extends. The pressure in these voids is maintained at a magnitude less than the pressure at the outer surface of the web where it travels around those cylinders from which it is separated by the fabric, so that in this way the web is urged by the pressure differential toward the fabric so as to be incapable of becoming detached therefrom. For this purpose either a vacuum system provides in the voids referred to above a pressure less than atmospheric pressure, or at the outer surface of the web there is provided by a suitable pressure chamber a pressure greater than atmospheric pressure, or both of these expedients may be used simultaneously, so that in this way a reliable maintenance of the web in engagement with the drying fabric is achieved where the web is separated from the drying cylinders by the fabric.

Paper machine drying section and method for operating same

A method for feeding a paper web from a forming wire and for dewatering the web including the steps of urging a pick-up felt against the web on the forming wire, adhering the web by suction to the surface of a pick-up felt, transferring the web onto a transfer felt which wraps a transfer roll, the latter being contiguous to the pick-up roll, passing the web on the transfer felt to a first dewatering press nip formed by an upper suction press roll and a cavernous surface lower press roll, the latter operating inside the transfer felt loop while the suction roll operates inside its own felt loop, pressing the web in the first press nip to dewater the web in two directions i.e. towards the suction roll and towards the cavernous surface roll, adhering the web to the suction roll felt surface, transferring the web to a second dewatering press nip formed by the suction roll and by a smooth surface press roll, pressing the web in the second nip to dewater the web only towards the suction roll, detaching the web from the suction roll felt and adhering the same to the surface of the smooth surface press roll and transferring the web to a following web treatment phase.

Method for dewatering paper in a paper machine press section

In a paper-manufacturing machine a web is subjected to suction by placing a space between the web and a suction roll lapped thereby in communication with a region of substantially less than atmospheric pressure which is maintained at a part of the suction roll which is not lapped by the web. The structure includes a jacket which defines with the part of the suction roll which is not lapped by the web a hollow region with which a source of suction communicates. This hollow region of less than atmospheric pressure is situated at the exterior of the suction roll and bounded in part by an exterior surface of the suction roll, so that the hollow interior of the shell of the suction roll need not necessarily be utilized for providing the suction at the web.

Paper-machine structure and method for subjecting a web to suction

A method and apparatus provided at the initial stages of the drying section in a paper making machine for reliably transporting the web from the press section to the drying section and for reliably transporting the web at the initial drying section stage including a group of drying cylinders including a pair of substantially horizontal rows of drying cylinders located one above the other defining an upper drying cylinder row and a lower drying cylinder row and a web supporting lower endless drying belt extending alternately between drying cylinders in said upper and lower drying cylinder rows alternately lapping sectors of the drying cylinders in the upper and lower rows. In its transport over these drying cylinders the web is separated from the drying cylinders in the upper cylinder row by the lower drying belt while the web is in contact with the drying cylinders in the lower cylinder row. An upper endless drying belt contacts the web portions which extend over the upper drying cylinders so that the web is located between the upper and lower drying belts over at least a portion of its travel over the upper drying cylinders. A selectively adjustable lead-in roller directs the upper drying belt into contact with a lead-in drying cylinder at least during the period when the web is directed from the press section to the drying section.

Method and apparatus for reliably transporting a web in a paper making

Dewatering of a paper web is enhanced by steam treatment in the press section of a papermaking machine wherein the web is continuously passed around a substantial sector of a suction roll between two nips formed with the suction roll by a water-receiving roll and a plain roll. A steam box is mounted adjacent the web between the nips to subject the web to treatment steam in that sector. The steam can be saturated or superheated.

Growing community of inventors

Espoo, Finland

Matti Kankaanpaa