摘要:
The invention relates to a method for controlling a surface quality variable (300) in one or more fiber webs (3) in a shoe calender (1) comprising one or more calender nips. In each calender nip of the shoe calender, the overall loading pressure of the shoe element (8) and the loading pressure difference between the leading edge (8′) and the trailing edge (8″) of the shoe element are controlled so as to achieve minimum difference between the determined values (300″) for the surface quality variables of the fiber web and the set values (300′) for the same quality variables after the shoe calender.
摘要:
The present invention relates to time-temperature integrating indicators, also known as TTI indicators, which are easily printable on substrates, such as packaging materials, and to a method for the manufacture of packaging materials comprising printed TTI indicators. The printed TTI indicator is selectively activated at the time of packaging of a perishable product or alternatively at the time of opening of the package of a perishable product.
摘要:
A method and arrangement for computing and regulating distribution of linear load in a multi-nip calender. A material web is passed through the nips in a set of rolls including a variable-crown upper roll, a variable-crown lower roll and intermediate rolls positioned between the upper and lower rolls. The rolls in the set of rolls are supported so that, when the nips are closed, the bending lines of the rolls are curved downwards. When computing and regulating the linear loads, one or more of the physical properties affecting the bending of each intermediate roll under load, such as bending rigidity, mass, shape, and material properties, are taken into account. The ratio of the linear loads applied to the intermediate rolls, the weight of the rolls per se, and/or the support forces applied to the rolls are regulated so that the set of rolls is in a state of equilibrium and a predetermined state of deflection.
摘要:
A processing device and a method applying the same for processing a coated or uncoated fibrous web is provided. The device comprises a belt configured to extend around a guiding element, at least one counter-element being disposed outside said belt to provide a contact area with the belt, such that the belt and the counter-element establish therebetween a web processing zone for passing a web to be processed therethrough. The processing zone length is defined by the disposition of the belt's guiding element and/or by the design of the counter-elements. A contact pressure applied to a web in the processing zone is configured to be within the range of between about 0.01 MPa and about 70 MPa.
摘要:
An arrangement in a calender for guiding a paper web (W) from one nip (N) to another nip and for doctoring a calender roll (1, 2) has a doctor (4) supported by a web (W) guide means (5). The doctor (4) includes at least one stationary and convex guide surface (51) which receives the web from one nip (N) of the calender and over and on which the web is guided towards the other nip of the calender, so that between the guide surface and the web there is a medium layer which carries the web.
摘要:
A supercalender for calendering a paper web and a calendering arrangement for producing matte-quality paper web has a multiple-nip calender in which at least one of the calendering nips of the multiple-nip calender is an extended nip (N9) formed between a polymer roll (18) and either a shoe roll (30) or a calendering belt.
摘要:
Tissue paper is calendered in at least one calendering nip. The tissue paper is calendered in at least one soft, long calendering nip. By belt calendering a high crêping effect is achieved when a so-called post-nip contact is used. With post-nip contact, the web and the belt are in contact with the thermo roll over a distance of 10-200 mm after the nip, whereby the belt tension presses the web against the surface of the thermo roll, and hereby the belt expands in the nip, and when it is then restored it will crêpe the paper. In this manner a soft tissue paper with maximum bulkiness is brought about. The belt tension used in the belt calender is 1-10 kN/m.
摘要:
A method for quick-opening a set of rolls in a calender, in particular a supercalender, in which a paper or board web to be calendered is passed through calendering nips formed by a variable-crown top roll, a variable-crown bottom roll and by two or more intermediate rolls arranged between the top and bottom rolls. The rolls are arranged to form a substantially vertical stack of rolls, and the intermediate rolls are supported by the use of hydraulic relief cylinders so as to relieve the nip load produced by the mass of the bearing housings of the intermediate rolls and auxiliary devices associated therewith. During the quick-opening of the set of rolls, the bottom roll of the set of rolls is lowered and the relief pressures in the hydraulic relief cylinders are discharged so as to open the calendering nips. The hydraulic oil flowing out from the relief cylinders is controlled by valves connected to the relief cylinders of each intermediate roll so that, during quick-opening of the set of rolls, the roll nips may be opened in a controlled manner in a desired order. A hydraulic system for the set of rolls is also disclosed.
摘要:
A steam box includes a system for distributing steam onto a web being calendered. At least one valve is connected to the steam distributing system for controlling the flow of steam onto the web. The steam box also has element for feeding hot steam to the valve. Each valve has at least three steam channels, namely an inlet channel for feeding the steam to the valve, an outlet channel of the valve for feeding the steam onto the web and a recirculation channel for recirculating the steam. The valve also has a check element for controlling and dividing the incoming steam flow from the inlet channel between the outlet channel and recirculation channel of the valve, and a return pipe connected to the recirculation channels of the valves, capable of routing the steam directed to the recirculation channel of the valve to e.g., the condensate return line of the steam distributing system. By virtue of such a circulation the valve can be kept warm even when no steam is directed via the valve, thus preventing the formation of droplets and their blowing onto the web.
摘要:
A microstructure area (201) providing a first diffractive visual effect is produced on the surface layer (240) of a paper or cardboard substrate (230) of a product (200). In addition, a bulge (206) or a recess (207) having a second microstructure area (202) is produced on the surface layer (240), wherein a doubly curved portion (203) is located between the first (201) and the second (202) microstructure areas. Said combination of the bulge (206)/recess (207), microstructure areas (201, 202) and doubly curved portion (203) makes counterfeiting of the product (200) difficult and provides a special visual effect.