CA1221569A - Process and apparatus for use in the surface sizing of paper - Google Patents

Abstract

PROCEDURE AND MEANS IN CONNECTION WITH
SURFACE SIZING OF PAPER, AND MANUFACTURED
BY THE PROCEDURE AND/OR MEANS

ABSTRACT OF THE DISCLOSURE

A method and apparatus employed in connection with the running of a paper machine for conducting a web through surface-sizing steps wherein both sides of the web are surface-sized and thereby wetted to a subsequent drying section of the paper machine, includes surface-sizing both sides of the web which arrives from a prior drying section of the paper machine in at least one size press nip of a size press, whereupon the web is conducted, either directly or by way of a special turning apparatus for turning the web without contacting it while supporting and/or spreading the same out in a transverse direction, to a stabilizer apparatus for supporting the web without contacting the same and which stabilizes the run thereof. Thereafter, the web is conducted, either directly or over such non-contact turning apparatus and/or a special guiding and spreading roll, to a subsequent drying section of the paper machine. The non-contact stabilizing apparatus and other web con-ducting apparatus, if used, are situated such that the free draws of the web will not be unduly long considering the possibility of free fluttering and so that the web may spread out in its transverse direction.

Description

1221~69 BAC K~; ~OUND O_I'fIE INVENTI ON
The present invention relates to a method for surface sizing of a paper web to be employed in connection with the running of a paper machine, as an "on-machine method", and, particularly, for conducting the web which has been surface-sized on both of its sides and thereby has been wetted, through the surface sizing steps to a subsequent drying section of the paper machine.
The present inventi~n also relates to a paper machine drying section adapted to be used in connection with carrying out the method ~f the invention and which includes a prior drying section constituted by a group of drying cylinders and which is followed by a size press which in turn is followed by a subsequent drying section of the paper machine comprising a plurality of drying cylindexs.
Moreover, the present invention also relates to paper manufactured by the method and apparatus of the invention, and in particular, printing paper, e.g. newsprint.
In the following the terms "surface sizing" and "coating"
are used and both relate to a paper web treatment procedure where the web is conducted in connection with a material solution or suspension so that a part of this material adheres onto the web surface and/or penetrates in the web. The materials used for said purpose can be different mineral pigments for coating, e.g., starch or glue solutions for sizing.
Surface sizing is a relatively simple and inexpensive technique for improving the quality of paper products. The majority ~ XZ~69 ~f fine and printing paper products produced are in fact surface sized or coated.
Surface sizing is usually carried out in an on~machine size press which forms a part of the paper machine. The surface sizing of fine and printing paper products which contain mechanical pulp is being carried out to an increasing extent, particularly with a view towards offset use. Other types of paper products which are surface sized or pre-coated in a size press include kraft liner, different boards and various base papers.
In fact, there are many applications for size presses which are currently known, these applications being divisible into four categories, namely (1) surface sizing of writing and printing papers;

(2) surface sizing and pre-coating of base papers;

(3) pigmenting and coating of paper; and

(4) manufacturing special grades of paper.
The surface sizing technique generally comprises running the paper web through one or more size press nips of a size press.
The sizing agent is supplied in the press in contiguity with the paper by creating a pool of size material before the size press nip and through which the web passes whereupon it is wetted through ab-sorption of the sizing material. The sizing is urged into the paper web between the rolls of the size press by the action of hydro-dynamic pressure. At the same time, due to the action of the hydro-dynamic pressure, a film of sizing solution or suspension is formed between the paper and the size press roll, this film becoming split ~ 2Z15~g ~t the exit side of the throat of the roll, lcaving ~chind ~ layer of sizing on the surface of the paper. The amount of the sizing agent that remains on the paper depends on the viscosity of the sizing agent, the machine speed, the diameter of the size press roll, the surface characteristics of the roll, the lineal pressure in the press nip and factors resulting from the deformation o the roll.
The oldest among conventional size presses is the so-called vertical press whexein the size press rolls are positioned one above the other and the paper web runs horizontally between the rolls. In the so-called horizontal size press, the rolls are situated in a horizontal plane and the paper web run-~ vertically between them.
The third type of known size press is the so-called oblique press wherein the size press rolls are disposed one above the other at an angle of about 45. This latter size press is considered most suit-able where the web is running through the paper machine at high speeds.
The diameters of the size press rolls are important when the runability of thç machine is considered. In conventional size presses, the rolls forming the nip have diameters on the order of 800 to 1~00 mm at running speeds of between 10 and 17 m/sec. It is common practice to increase the roll diameter when the running speed is increased in order to attempt the avoidance of splashing in the throat of the size pool, such splashing interfering with uni-form wetting of the paper web.
Rubber is usually used as the cover material of the size press rolls. In some conventional size presses, the nip is defined by a hard roll made of metal and a soft roll formed of rub~er. Thus, 12Z~69 both harder and soft~r pressing zones or nips are used in conven-tional size presses. As noted above, at higher speeds of web conduction, larger diameter rolls are utîlizedO
Another factor which contributes to a good surface sizing of the paper web is that not only should the wetting time of the web be at least of a certain duration but, additionally, the pressure exerted on the paper web in the nip should be relatively high, such as between 20 and 50 kN/m.
Regarding the state of the art with respect to s~ze presses, reference is made as an example to Finnish Patent ~o.
28686 to Combined Locks Paper Co., of the united States, published March 15, 1957. A paper coating machine is disclosed in this patent which comprises a hard central roll having two nips defined in con-junction therewith through which the paper web desired to be treated is passed. The sizing, or other coating substance, is initially introduced from a trough over a plurality of applicator rolls onto the hard-surfaced roll from which it is pressed into the web in the first nip. The other side of the web is coated by introducing the coating substance onto the subsequent nip roll from a trough by way of a plurality of applicator rolls. The coating substance is thus pressed onto the surface of the web in the second nip defined in conjunCtiQn with the hard central roll. According to the teachings of this Finnish patent, the nips defined by the nip rolls in the hard central roll are disposed relative to the central roll substantially symmetrically with respect to the verti-cal plane passing through the axis of thc central roll under a i2;21~69 central angle of about 45 with respect to the vertical plane.

Moreover, according to the method disclosed in the Finnish patent, the coating substance is introduced utilizing small diameter applicator rolls. However, the present invention relates to size presses in which the sizing or other coating sub-stance is introduced by means of nozzles to form a pool located between the paper web and the roll surface.

Reference is also made to ~.S. Patent No. 4,108,110, U.S. Patent No. 4,391,217 assigned to the assignee of the instant application, which relate to size presses. Reference is further made to U.S. Patent No. 4,407,227 assigned to the assignee of the instant application, which relates to a size press having a sub-sequent web heating apparatus.

Moreover, reference is made to size presses of the type with which the present invention is associated, which comprises three coating rolls which are associated with each other to define two press nips through which passes the paper web to be treated in a manner such that both sides of the web receive treatment in the nip.

In a size press of the type described above, the coat-ing roll which constitutes the middle roll with respect to itsvertical position is situated so as to be a central roll of the size press and in conjunction with which both coating nips are formed such that the first coating nip is situated at an appro-priate angular dlstance ~ - 5 -~221569 above the horizon~al plane Whicll passes through the axis of the central roll and such that the second coating nip is defined by the third coating roll which is situated at an appropriate angular dis-tance below the horizontal plane. Sizing supply means precede the first nip in the direction of the run of the web on the central roll which means supplies a first pool or layer of sizing into the cleft or throat between the central roll and the web. Second sizing supply means are situated to precede the second nip in the throat defined by the central roll and the third coating roll. The second size supplying means provide a second pool or layer o sizing on the opposite side of the web with respect to the first sizing pool or layer. The size press is arranged so that as the web runs in a down~ard direction it is supported by the roll surface while the sizing operation proceeds.
Since the size press arrangement of the present invention is an "on-machine" arrangement which is adapted to be connected to and ~unction with the drying section of a paper machine which pre-cedes it as well as with the guide and drying means subsequent thereto, it must be capable of runninq at a speed which is as high as that at which the paper machine is being run. However, in many instances, the size press as well as the equipment immediately subsequent thèreto have constituted a limiting ~actor or bottle-neck which restricts the speed of the paper machine.
It is the primary object of the present invention to elim-inate this drawback.

i22~5691 It should be understood that although the ~bove dis-cussion is directed to "size presses", the term "size" is used herein in its broadest sense to designate known substances and materials used in connection with the treatment of paper or board webs and which are suited for use in apparatus of the type des-cribed below.
The size press is an important aid in the paper making industry and has enabled the quality of paper to be improved, new types of paper to be developed, as well as new combinations o raw materials to he adopted. However, as noted above, one of the dif-ficult problems which arise in connection with surface sizing of paper, as discussed above, is that surface sizing could not here-tofore be utilized in connection with high speed paper machines.
Moreover, surface sizing has heretofore not been applicable to the treatment of thin or weak paper types, such as those contained in groundwood and fillers, and/or paper types manufactured of short fibre pulp stoc];.
The size press is normally situated in the drying sec-tion of a paper machine at a location where the water content of the paper web prior to the size press is about 3% to ~/0. In some cases water content may be as high as about 15%. The size press is pre-ferably located in a drying section in a manner such that the widest possible range of paper types can be run at maximum produc-tion speeds in a manner which insures that the drying operation will not become a bottleneck either before or after the size press.

lX21~;69 Another problem which frequently arises in connec~ion with the surface sizing of paper results from the fact that the water content of the paper web subsequent to running through the size press varies over wide limits, such as within 15% to 55%.
More particularly, after the last nip of the size press, the web normally remains adhered to the surface o.f the hard size press roll and follows along therewith. It is advantageous to detach the web from the hard roll as soon as possible. After leaving the press, the web will increase in width as a result of swelling of wetted fibers and since such expansion requires a given minimum time to occur, the distance from the last sizing nip to the next drying cylinder is conventionally arranged to be relatively long. However, a long free draw between the last sizing nip and the next drying cylinder creates problems for the reason that a high amplitude, uncontrolled fluttering of the web will occur on this free draw. Such fluttering frequently causes web breakage s~e, as n~ted above, the web has a relatively high water content, i.e., up to about 55%, on the free draw. TherefOre, in fact, it has not been practical to use a size press in connection with thin webs and/or webs formed of raw materials which do not provide sufficient strength for the web in view of the surface sizing operation and the subsequent web treatment steps. These problems become even more acute as the speed of the paper machine is increased.
It is also known in the art to interpose a paper spreading roll between the last size press nip and the subse~uent drying section of the paper machine with a view toward preventing the formation of wrinkles in the paper web.

~L22:1~i69 ~ s ~ur~l~c~- ~no~ n ~ C art, ~lL~L lc(~villg thc iizc ~rcss, the paper web may be dried in a standard multiple cylinder drier in which the first drying cylinder after the size press operates without a felt. In this connection, it has been necessary to maintain the surface temperatures of the two drying cylinders next following the ~ize press at a relatively low level, e.g., about 70 to 80 C, since higher drying temperatures would tend to damage the surface of the paper. Moreover, the sizing or coating material and the associated fibres would tend to adhere to the drying cylinder whereupon the paper may give off dust and the like in spite of the surface sizing operation. Attempts have been made in the art to avoid this draw-back in connection with the manufacturing of pigment-coated paper by drying the coated web surface with warm air immediately after it leaves the size press.
The three-roll, two-nip size presses described above are suitable for running at relatively high speeds in connection with the two-sided surface sizing of the web and, therefore, such size presses are applicable for use on modern high speed paper machines.
In such cases, however, it is apparent from the foregoing discussion that the web treatment steps following the surface sizing becomes the bottlenec~ in the paper making operation. In addition to the drawbacXs mentioned abo~e, these subsequent treatment steps are further encumbered in that a felt cannot be used in connection with the initial drying cylinders aftex the size press which in itself results in a reduced dryins capacity and in a tendency for web breaks to occur at the free draws between said drying cylinders. It has 122~i6~
also been nccessary in conventional arrangcments to use at least as the first drying cylinder after the size press a chromium-surfaced or other relatively expensive cylinder in order to prevent adhesion of the surface sized or coated web thereto.
Regarding the state of the art most closely related to the present invention, reference is made by way of example to a publication in TAPPI, Vol. 57, No. 6, 1974 by Donald W. Lawton entitled "Airflo~ Floater Drying After A Size Press", Page 105-107.
Reference is made in this article to a conventional floater dryer mounted in an oblique position subsequent to a single-nip size press in the direction of web run. This arrangement differs from that of the present invention in that, among other aspects, a return roll is provided in the conventional arrangement after the size press nip and before the floater dryer. The disadvantages of the return roll are acknowledged in the article although the author fails to recognize any means by which the drawback can be eliminated.
Thus, the use of such a return roll has been considered necessary in view of practical considerations regarding the run-ability of the machine. However, the return roll frequently de-stroys the s~rface sized surface of the web. It is a further disadvantage that when conventional floater dryers whose ai~. it is to achieve a high drying efficiency are used, the opposed nozzles of the floating dryer are spaced too closely and, accordingly, an 12Zl~;69 uncontrolled wave actîon is obtained which does not have an amplitude and a wave length suitable to achieve stabili-zation of the web. An additional risk which results f~ the overly close spacing of the nozzles is that the web may come into contact with the nozzle surfaces while in the conventional floating dryers thereby causing web breakage. Yet another disadvantage of con-ventional floating dryers is that it is not possible to substanti-ally vary the angle at which the web enters the dryer without risking web contact and breakage and that such floating dryers do not spread the web in the cross-machine direction.
It is another object of the invention to avoid these draw-backs inherent in the use of conventional floater dryers of the type described above.

SUMMARY OF THE INVENTION

Accordingly, it is the general object of the present in-vention to provide a method and apparatus in a size press and sub-sequent web treatment in which the drawbacks mentioned above are eliminated.
More particularly, it is an object of the present invention to provide a method and apEaratus in a size press and subsequent web treatment wherein even thin webs and/or relatively weak webs con-taining groundwood and/or fillers and/or of short fibre pulp stock, ~ be treated at high running speeds without an excessive risk of web breakage.
It is a further object of the present invention to provide a method and apparatus in a size press and subsequent web treatment wherein in the web treatment step following the surface siæing, the web can be run with a lower tension allowing the web to be deformed in a transverse direction, e.g., spread, to a desireable extent.

:, --1 1-- , 1221~i9 Briefly, in accordance with ~h~ present invention, th~se and other objects are attained by providing a method wherein the web, arriving from a prior drying section of the paper machine, is surface-sized on both sides thereof in at least one size press nip, conducting the web after the surface-sizing step, either directly or by way of a non-contact turning, supporting and/or spreading means, to a stabilizer means which acts to support the web in a non-contacting manner and whereby the run of the web is stabilized, thereafter conducting the web, either directly or over a non-contact-ing turning, supporting and/or spreading means, or spreading roll, to a subsequent drying section of the paper machine, and wherein the non-contacting stabilizer means and additional web conducting means, if any, are so disposed that the free draws of the web run will be not be unduly long considering the possibility of free fluttering of the web, and so that the web is allowed to spread out in its transverse direction.
The apparatus of the invention is essentiall~ character-ized in that it comprises a stabilizer means which acts on the web from both sides thereof utilizing gas flows and which is situated after the size press and before the subsequent drying section of the paper machine. Moreover, the paper product o~ the present in-vention is mainly characterized in that the paper is newsprint or the like, the printability propertiesof which have been achieved essentially by a two-sided surface sizing of the web.
The method and apparatus of the present invention provide advantages which are important in practice and, moreover, climinate a number of drawbacks inherent in conventional apparatus. The most important advantage obtained is that thinner and weaker wcbs can berun ina more stabilized, flutter-free mannerthan has been possible here-tofore and, therefore, with the risk of wcb breakage at higher speeds ~ ZZ~ifi9 being significantly reduced. Moreover, af ter tl-e surfacc-sizing, the web can be treated in a manner such that the web can be conducted to a standard multiple cylinder dryer section in which it is possible to utilize a felt fabric conduction and which is operated at full efficiency, i.e., at increased temperature levels.
It is a significant advantage of the present invention that completely new types of paper can be manufactured on modern fast-running paper machines such, in particular, as newsprint paper machines. The present invention therefore makes possible the manu-facture of surface-sized newsprint from more versatile and advanta-geous raw materials than has been possible heretofore and, addition-ally, with better printabi~ity characteristics by virtue of the two-sided surface-sizing. Furthermore, the runability of the paper machine is improved. The desirability of such paper is readily apparent, for example, in view of advertisements and multiple color printing in newspapers.
By the method of the present invention, a so-called synergistic effect is obtained since a contact-free and stabilized guidance and support of the web is achieved with fluttering and web breakage prevented while, additionally, the web is provided with sufficient time and travelling distance between the size press and subsequent drying section to allow the same to expand and spread in a lateral direction and, if required, be positively spread out in a transverse direction. This latter action is particularly advantageous since in this manner the length of the web draw between the surface-sizing operation and the subsequent drying section can be reduced.
According to the present invention, stabilizer means are advantageously utilized to guide the web in a contact-free manner on both sides thereof so that through the effect of gas, such as air,being directed from consecutively arranged nozzles of the stabilizer means, the web ~22~;6~
runs with a substantially sinusoidal and controlled wave motion in its longitudinal direction. By such controlled wave motion, the free and uncontrolled fluttering of the web is preventcd while wrinkles which extend longitudinally in the web are removed or their formatîon prcvented. Heated gases may be used in the stabilizer means so that both sides of the surface-sized web are dried to a moisture content which is suitable with a view toward normal sub-sequent drying steps. The use of such drying is, however, not necessary in all cases.
It is further possible utilizing the apparatus of the present invention to optimize the run of the web between the size press and the subsequent drying section. Since the web on its run between the surface-sizing steps and the subsequent drying section can change direction in accordance with the present invention, it now becomes possible to accommodate a sufficiently long contact-free run of the web, such as to enable a transverse spreading thereof, within a relatively short space in the paper machine hall.
DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompany-ing drawings in which:
FIG. 1 is a schematic elevational view of apparatus for performing the method of the present invention and comprising a three-roll, two-nip size press followed by a contact-free means for turning and spreading the web, and followed by a contact-ree stabilizer means;
FIG. 2 is a schematic elevational view of apparatus for performing the method of the present invcntion and comprising a - 1 ~ .

i2Zl~i9 three-roll, two-nip siæe press followed by a contact-free stabilizer means, which operates utilizing heated drying gases;
FIG. 3 is a schematic elevational view of apparatus for performing the method of the present invention and comprising a two-roll, single-nip size press, followed by a contact-free stabilizer means, which is followed by a contact-free web spreading and/or return means;
FIG. 4 is a schematic elevational view of apparatus for performing the method of the present invention and comprising a two-roll, single-nip size press and wherein the web is conducted in a straight draw to a contact-free turning and spreading means, which is followed by a contact-free stabilizer means;
FIG. 5 is a schematic elevational view of an embodiment of stabilizer means in accordance with the present invention;
FIG. 6 is an elevational view in section of a portion of a nozzle utilized in the stabilizer means illustrated in FIG. 5;
FIG. 7 is a perspective view of a nozzle for use in the stabilizer means of FIG. 5:
FIG. 8 is a more detailed view of an embodiment of the web turning and spreading means for use in connection with the present invention; and FIG. 9 is a detailed view showing the carrying surface of the turning means illustrated in FIG. 8 on a larger scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1 and 2, the size press 100, 100' comprises a web gui~croll 10 and the actual size press rolls 11, 12 and 13, the rolls being mounted in a conventional 1221~6~
frame (not shown) along with other conventional components of a si~c press. The web arriving from the paper machine at the size press for treatment therein is designated by Win. The web leaving the size pre~s after having been treated on hoth sides with a coating substance, such as sizing, is designated Wl. The passage of the web through the size press is designated by dashed lines in FIG. 1.
Guide roll 10 constitutes the first of the rolls belonging to the size press in the direction of travel of web W. The first coating nip Nl is defined by rolls 11 and 12, the roll 12 constituting a cen-tral roll of the size press and of course is rotatably carried such, for example, as in stationary bearing stands (not shown). The second coating nip N2 is defined by the central roll 12 and the third or lowermosk roll 13.
Two pools Ll and L2 f the coating suspension or size solu-tion are formed in the size press 100, 100'. Thus, coating or size substance is supplied to the first pool Ll through a sizing supply tube 17 which extends over the entire breadth of the web W. The tube 17 carries a plurality of parallely disposed nozzle tubes 17a, or may alternatively be provlded with an equivalent continuous nozzle slit.
The first sizing pool Ll is defined in the throat or cleft region defined by the central roll 21 and the web W prior to the first nip Nl. The sizing or other coating substance is absorbed into the first side or surface of the web W whereupon the sizing is pressed into the web W as the same passes through the nip Nl.
The size press 100 comprises a second sizing supply tube 18 for supplying the sizing material to the second pool L2. The sizing supply tube 18 is disposed in conjunction with the third coating roll 13 and dispenses sizing material through a set of sizing supply nozzles 18a or through an equivalent nozzle slit. In this manner, a second sizing pool L2 is formed before the nip N2 and the -lG-~ 22~56~
second, opposite side of the web W is treated and impreqnated with the sizing material in pool L2. After passing through the second sizing nip N2, the web W remains adhered to and follows the surface of the central roll 12 over a sector(~ 3, after which the web W is separated from the roll 12 and conducted to subsequent wet web treatment steps in accordance with the present invention, described below.
As seen in FIG. 1, the web W laps the first press roll 11 over a suitable angle ~ 1 before entering into the nip Nl. This arrangement is important since in this manner the web W is backed up by the surface of the roll 11 in the region of the sizing pool Ll.
The angle ~ 1 has a magnitude preferably about 45. The geometry of the rolls of the size press 100, 100' is such that the middle roll 12 in the vertical direction constitutes the central rol7 while the outer rolls 11 and 13 are so disposed that the first nip Nl and the second nip N2 are substantially symmetrically disposed with respect to the horizontal plane which passes through the central axis of roll 12. The angle ~ 2 on the central roll 12 between the nips Nl and N2 is preferably about 90.
It is known from experience that it is advantageous to define a size press nip by situating a hard roll an~ a soft roll against each other since when a pair of hard rolls define such a nip, a tendency exists for holes to be formed in the paper. For example, the central roll 12, which constitutes the hardest roll of the size press, may have a so-called "micro rock" covering which has a hardness in the range of about 0 to 1 P&J hardness degrees. The roll 11 which defines the first size press nip Nl with roll 12 may have a softer "micro mate" covering whose surface has a hardness, for example, in the range of about 20 to 30 P&J degrees. Second press nip N2 is defined by the central roll 12 and the other outer roll 13 which may have a surface similar to that of roll 11.

In the emhodiment discussed above, the abovc-stated criteria for a size press is realized in that a hard roll and a soft roll define both nips Nl and N2 in a manner such that the central roll 12 is the hardest roll and against which are urged two softer rolls 11 and 13. Of course, the same end result can be accomplished by providing the central roll 12 with a soft covering and arranging two harder rolls against it.
The moisture content of the paper web W arriving at the size press, such as from a prior drying section, is about 3 to ~/~.
Paper having a moisture content lower than about 3% is considered brittle and presents poor aborptivity. If the moisture content is greater than about ~/~, such moisture will generally be distributed in a non-uniform manner and the absorptivity of the paper will be too high. The lineal pressure in the nips Nl and N2 is generally between 10 and 50 ~N/m and preferably in the range of about 30 to 40 ~N/m. Usually, at least two of the three size press rolls 11, 12 and 13 will require deflection compensation, certainly in the case of a size press through which various types of paper are run.
It is also known that deflection compensation is more urgently in-dicated on wider machines than on narrower machines. Although the diameters 2 Rl , Z R2 and 2 R3 of the rolls 11, 12 and 13 may be selected so as to be equal to each other with a view towards facili-tating maintenance thereof, the roll 11 is selected in the illustrated embodiment ts have a smaller diameter than the rolls 12 and 13. As noted above, in both nips Nl and N2, one of the two rolls should be a soft roll in order to enable the pressure area or zone of the nips to have a sufficiently large width. Each of the three rolls 11, 12 and 13 is provided with its own controllable drive 14, lS and 16 respectively and the peripheral velocities of the rolls are sub-stantially equal to the velocity of the web running through the size ,, --18--press.
Referring to FIG. ~ a~er the web W has be~n surfacc sized on both of its sides in the nips Nl and N2, the web follows along with the central roll 12 of the size press through a small angle C~ 3 as noted above. The web is thereafter carried in a substantially straight draw Wl to the turning means 20 in the region of which the web W changes direction, i.e., the web W turns over an angle ~ to an upper direction.
As described in greater detail below, the web W2 is carried in a non-contact or contact free manner on a cushion of air which flows be-tween the carrying surface of the turning means and the web. As des-cribed below, the air (or other gas) is ccnducted into the gap between the carrying surface and the web through nozzle slits which extend transversely in their longitudinal direction to the direction of travel of the web W2.
The web W2 may also be spread out in the transverse direc-tion as it travels over the turning means 20. Indeed, a preferred embodiment of the turning means 20 described below, is characterized in that the air jets operating in the region of the carrying surface thereof actually positively acts to spread the web in the transverse direction thereby preventing the formation of wrinkles and eliminating previously formed wrinkles, all while insuring a contact-free conduction of the web.
After passing over the turning means 20, the web W2 is car-ried in a substantially straight draw, designated W3, to stabilizer means constituted by a pair of mutually opposed components 40 and 41, each of which is provided with nozzles 50. The web W4 in the region of the stabilizer means 40,41 is carried through it in a contact-free man-ner and, according to the invention, is guided in a stabilized fashion by air jets discharging from the nozzles 50. The air may be heated. In this manner, the web discharging from the stabilizing means 40, 41 designated WOUt~ may be conducted directly to a standard drying ~ L221569 cylinder 61 where a drying felt, either in a single-felt or in a double-felt coslduction, may be employed~
It is seen from the foregoing that the web throughout its entire run from the last size press nip N2 and from the size press roll 12 to the first drying cylinder 61, i.e., web Wl-W2-W3-Wout, has a stabilized run while being subjected to a contact-free supporting action. The drying section consisting of several dryer cylinders and felt means has not been shown in its entirety. In this manner, ~he web may be freely spread out in a lateral or transverse direction or may be positively transversely spread and, moreover, the run W1-WOut of the web has no excessively long free draw wherein a free, indefinite and uncontrolled high-amplitude fluttering can occur.
~ Referring to FIG. 2, the size press 100' is substantially the same as that illustrated in FIG. 1. However, in the case of the embodi-ment illustrated in FIG. 2, after leaving the last size press nip N2 of press 100', the web Wl follows along with the central roll 12 thxough the angle C~'3 after which the web is conducted in a sub-stantially horizontal direction directly to the stabilizer means 40', 41' in the region of which the web W'4 is supported in a contact-free manner. Additionally, heated air, is directed through the nozzles 50 of the stabilizer means 40', 41' so that the web W'4 is dried acquiring a sufficiently high dry matter content. It is noted that it is also possible to apply radiation dryin~ designa~ed H,to the web W'4 as it passes through the stabilizing means 40', 41'. The web WOUt leaving the stabilizing means is conducted over a guide roll or spreading roll 42 to a multiple cylinder dryer which being known in the art is only schematically shown and presented by cylinders 61' and G2'. Normal drying temperatures can be utilized in the drying cylinders 61' and 62' thercby obtaining the advantages discussed above not found in con-ventional arrangements. Various dryer felt run arrangements known in .. ~ .

~ 2Z1569 the art can be used.In this connection reference is made to appli-cant's U.S. Patents No~ 4,075,056; 4,172,007 and 4,202,113.
Another embodiment of the present invention is illustrated in FIG. 3 wherein an oblique size press lOOa is constituted by a pair of rolls lla and 12a so as to define a single nip Nla. This type of oblique size press lOOa is known in the art and is commonly utilized in connection with fast-running machines since it provides for an easy passage of the paper web therethrough. The top or upper roll lla of the lOOa is a hard-surface roll so that the web Wl will follow along with the top roll lla through the angle ~ a. After leaving the size press lOOa, the web Wl has a substantially horizontal run and is conducted to stabilizer means 40a, 41a. The web W4 running within the stabilizer means 40a, 41a is supported in a non-contact manner by means of air blown through the nozzles 50 and the run of the web W4 is stabilized in a manner described in greater detail below.
A turning means 20a follows the stabilizer means 40a, 41a and the web leaving the stabilizing means is supported by the turning means 20a in a non-contact manner. The web WOUt which has been turned in di-xection in the turning means 20a is then conducted to a conventional multiple cylinder dryer section, the first ones of its cylinders 61a and 62a being illustrated in FIG. 3.
Turning now to the embodiment illustrated in FIG. 4, the conduction of a surface-sized web is substantially similar to that described above in connection with FIG. 1 except that a single-nip, oblique size press lOOb, similar to that illustrated in FIG. 3, is employed. The sole nip Nlb is defined between a hard roll llb and a rubber-coated lower roll 12b. After the surface sizing nip Nlb, t~e web Wl is carried to turning means 20b and then to stabilizer means 40b, 41b from which the web WOut is conducted to a conventional multiple cylinder dryer 61b, 62b. The dryer felts or fabrics used and known in the art, are not shown, nor are their guide rolls.

, ~2Z~;69 Turning now to FIG. 5, a more d~tailed ill~istration of the constr~ction of the stabilizer means 40, 41 and of the passagc of the web therethrough is shown. The stabilizer means are constituted by two mutually opposed housings 46 and 47 into the interior of which gas, such as air, is directed through tubes 45. ~he housings 46 and 47 extend across the web W in its transverse direction. The housings 46 and 47 include inwardly facing opposed walls 48 which carry nozzles 50, each of which extends transversely over the entire breadth of the web.
Moreover, the position of the nozæles 50 fixed on the opposed walls 48 are alternate with respect to each other so that the nozzles fixed to one of the walls 48 will lie between the nozzles fixed to the other opposed wall 48. In this manner, the web W4 will pass in a stabilized manner and with a substantially sinusoidal wave motion supported by the air flows which are discharged through the nozzles 50.
It is important from the standpoint of the present invention that the web run in a wavy fashion in the stahilizer means 40, 41.
The wavelength ~ of the undulation of web W4, which equals the center-to-center spacing of the nozzles on one side of the web, is preferably within the range of between 200 to 800mm, and most preferably in the range of from about 400 to 500 mm. The distance ~ between the sur-faces of the nozzles 50 facing the undulating web, is preferably within the range of about 15 to 50 mm, and most preferably between 20 to 30mm.
The distance ~ is substantially larger than the corresponding dimension used in conventional floater dryers presently in use. In this manner, the amplitude of the wave motion undergone by the web W4 is sufficiently large to establish the stabilizing effect required by the invention and, moreover, reduces any risk of the web W4 contacting the surfaces of the nozzles S0. Thus, in conventional floater dryers, such as are used in off-machine coaters or in connection with the manufacturing of e.g. paper grades having good stretch properties, the corrcsponding ~ 22~569 value of ~ is at most about lOmm. Of course, it is understood tl~at in such a case the aim is primarily to achieve an efficient drying actior rather than obtaining the stabilizing action which is one of the ob-jects of the present invention.
The guided and controlled wave motion of the web W4 elimi-nates or precludes the formation of wrinkles extending longitudinally in the web. Moreover, the controlled wave motion efficiently elimi-nates any free and uncontrolled fluttering of the web which, as noted above, is detrimental to the process. The gas jets directed through the nozzles 50 of the stabilizer 40, 41 also tend to spread the web out in a transverse direction to thereby straighten any longitudinal wrinkles which might have occurred in the web and further result in that the transversal expansion of the web resulting from its wetting does not consume an undue amount of time.
The particular construction of the stabilizer and its nozzles 50 in accordance with the present invention, described in detail below, is such that the spacing ~ between the opposed nozzles 50 is larger than the spacing between opposed nozzles in conventional floater dryers.
Moreover, the construction of the nozzle means 50 permit a larger var-iation in the angle at which the web W3 enters into the stabilizing means. This is advantageous in case the web W being conducted in accordance with the present invention will have a relatively low ten-sion and, accordingly, the point at which the web Wl is detached from the central roll 12 of the three-roll size press, or from the top roll lla, llb of an oblique size press, is variable. Similar advantages are obtained by the turning means 20, 20a, 20b according to the in-vention as described below in greater detail.
Returning to FIG. l, a schematically illustrated means 20'' is provided before the turning means 20. This means 20'' having a carryin~ surface provided with nozzles permits the dircction in which the wcb W enters the turning means 20 or, in other words, the extcnt :

~ 221~69 of anglc ~ 3, ~o vary. It i~ un~crstood that throat-likc mcans, equivalent to the illustrated means 20', may also be used at the entry region of the stabilizer means 40, 41.
Referring now to FIGS. 5, 6 and 7 a preferred embodiment of the nozzles 50 formin~ a part of the stabilizer 40, 41 will be des-cribed. The nozzle means are of the same type which is disclosed in the Applicant's Finnish Patent No. 60261 Each nozzle 50 comprises a nozzle box which~ as noted above, extends across the breadth of the web. The gas to be discharged from the nozzle means is conducted into the nozzle box between inner walls 54 and 55 by supply tubes 45 whereupon the gas is conducted into side volumes 52 and 53 defined between inner walls 54 and 55 and outer walls 60 and 61 through apertures 51 formed in the inner walls 54 and 55. The inner walls 54 and 55 merge into each other to define an upper surface 56 facing the web. The web facing surface 56 curves, for example, substantially in the shape of circular arc having a radius R2, toward the interior volume of the nozzle box in a smooth and con-tinuous arc. The wet web W4 passes over the web facing surface 56 being spaced at a minimum distance ~ 1 therefrom.
The outer walls 60 and 61 of nozzle 50 have upper planar portions 62, 63 respectively which extend upwardly towards each other.
Moreover, the inner walls 54 and 55 of the nozzle box have outer regions which include curved portions (having radii Rl) and the planar portions 62 and 63 of the outer nozzle walls define together with the curved portions of the inner walls 54 and 55 a pair of nozzle slits 57 and 58, which are preferably located on the curved portions of the walls 54 and 55.
The nozzle slits are located in the region of an angle C~ O
which is the angle subtended by the initial direction Sl of the gas ~ 22156~
jets disch~rging t?lrough the slits 57 and 5~ and tllc plane of thc wcb W4 and which equals the angle at which the gas-jet gulding surface curves starting at the mouth of the nozzle slits 57 and 58 and ex-tending up to the plane L-L. The imaginary plane L-L at the same time defines a depression 59 between it and the carrying surface 56. The depression 59 serves as a "calming" volume wherein the gas jets vl, which flow in opposite directions from respective nozzle slits, meet to form an air cushion supporting the web W4 and extending a consid-erable distance in the direction of travel of the web W4. The radius of curvature of the web facing surface 56, namely R2, is preferably substantially larger than the radius of curvature Rl of the curved guiding surfaces in a region adjacent to the depression 59.
~ The angle ~ 0 is advantageously selected in a manner so that no separation of the gas flows from the curved web facing surface 56 occurs before the jets vl have been deflected so as to be sub-stantially parallel with the web W4. As noted above, in this manner the jets vl will flow against each other in the region of the depression 59 where they meet so that a relatively extensive air cushion for supporting the web W4 is established. Should the nozzle means 50 be used in conjunction with drying the web, it is significant to note that the heat transfer coefficient will be relatively good as a result of the vortex produced adjacent to the depression 59 and in the region between the nozzle slits 57 and 58. In order to accomplish the foregoing, the angle O~ associated with the curved guiding sur-faces (Rl) has a maximum value of about 70 and is preferably in the range of about 40 to 60.
The construction of the nozzle 50 illustrated in FIGS. 6 and 7 is symmetrical with respect to a vertical center-plane A-A
(FIG. 6) which passes through the bottom of the depression 59 formed 12Z~569 in t]lC web iacing surface 56. It is undcrstood, howovcr, that the nozzles 50 may be c~nstructed having assymetric designs.
Referring to FIGS. 8 and 9, a more detailed illustration of a preferred embodiment of the web turning and spreading means 20 employed in certain embodiments of the invention is shown. m is type of web turning means has been disclosed in applicants Finnish patent application No. 81 1402.
The contact-free turning and spreading means 20 which acts n the web W as shown in ~IGS. 8 and 9 comprises a curved carrylng surface structure 32 over which the web W runs. As seen in FIGS. 8 and 9, planar side walls 24 (only one shown) and end walls 26 define an interior volume 20' together with the carrying surface 32. The treatment or supporting gas, such as air, is admitted through a passage 25 and then through a curved, perforated wall 23 into the interior volume 20' from where it is further conducted through a plurality of nozzle slits 36 to provide support for the web W in a manner described below.
As sc-en in FIG. 8, the direction of the web W changes over an angle ~ as i~ travels on the carrying surface 32, the angle ~ at the same time defining the sector of the curved carrying surface 32, which preferably has a constant radius of curvature, ex-tends. The arrying surface 32 is constituted by a plurality of pressure surface laths 34 which alternate with a plurality of spacer surface laths 35 and which define the nozzle slits 36 between them-selves. ~he gas is directed through the nozzle slits towards the web W from the interior volume 20' into which it is introduced by means of a blower or the like (not shown) in a manner such that the web W is carried at an appropriate distance M from the carrying surface 32.
More particularly, the pressure surface laths 34 are each constructed to include a substantially planar prcssure surface 37 ~ 2Z~S~i9 which merges at its rcspcctive cnds with Lcspcctive curved s~lrfaces 38 which are angled inwardly and having a radius R. The spacer sur-face laths 35 are each constructed to include a spacer surface 39 which joins at its ends with a respective pair of inwardly extending planar portions 22, the planar portions 22 meeting the spacer sur-face 39 at respective sharp edges 21. The planar portions 22 termi-nating at the sharp edges 21 are arranged in a certain proximate relationship to respective curved surfaces 38 of the pressure surface laths 34 to define the nozzle slits 36, the planar portions 22 and curved surfaces 38 being configured so as to impart a starting direction to the gas being directed from the nozzle slits which de-fine an angle ~ 1 with the web W2 in the region of the nozzle slit.
Moreover, the nozzle slits are configured in a manner such that the gas jets S being directed therefrom follow the curved sur-faces 3~3 without separating therefrom up to the pressure surface 37 so that an efficient and stable support of the web W2 is obtained.
In this connection, the width a of the nozzle slit, the radius of curvature R sf the curved surfaces 38 and the angle ~ 1 are dimensioned with specific consideration being given to achieve the non-separating flow described above. Reference is made in this connection to the article "Experiments On The Separation Of A Fluid ~et From A Curved Surface" by D.W. McGlaughlin and J. Greber, American Society Of Mechanical Engineers, Advances in Fluids, 1976, pages 14-29. It is disclosed in this article that at the relevant flow velocities, the gas jet will follow the curved surfaces 38 through an angle in the range of about 45 to 70. The sharp edges 21 of the spacer surface laths 35 are so positioned with respect to the curved surfaces 38 at the angle of a line connecting an edge 21 and the center of the associated curved surface 38 and the direction of travel of the web does not exceed about 70. The lengths L and _~7-~ Z2~6g L of the pressure and spacer surfaces 37, 39, respectively, are preferably chosen such that the ratio o~ their combined length L
plus L2 and the width a of the nozzle apertures 36 is between about 20 and 200.
As seen in FIG. 9, the spacer surfaces 39 lie substantially in the same plane as the pressure surfaces 37 which are adjacent to them. The sharp edges 21 of the spacer surface laths 35 act to prevent the gas jets which are discharged through the nozzle slits 36 from turning inwardly over the spacer surfaces 39. In fact, the so-called Coanda effect which causes the gas jets to follow the curved guiding surfaces 38 without separating therefrom as disclosed in the above-mentioned article is so strong that the direction of flow of the gas will not be affected even by the moving web.
Since the curved guiding surfaces 38 and pressure and spacer surfaces 37 and 39 block all other exit passages, the gas jets ~s-charging from the nozzle slits 36 are only able to escape by moving past the sides of the web W2, i.e., the gas jets being directed from the nozzle slits 36 must move transversely towards the lateral sides of the web. Thus, the gas flow between the carrying surface structure 32 in the web towards the sides of the web produces a positive spreading action which tends to spread the web W2 in a transverse direction. Such spreading action is important in that, for example, the same prevents wrinkling of the web which has been wetted in the surface-sizing step.
It is seen from the foregoing that the web supporting and turning means 20, which tends to spread the web in a transverse direction, provides an extremely stable carrying force requiring a relatively low consumption of energy and is especially suitabl~ for tr¢ating webs of widely diverse types. As noted above, as the gas escapes from between the web and the curved carrying surface structure ~2215~9 32 over the sides of the web, an advantageious force which tends to spread the web W in a transverse direction is obtained which is extremely advantageous in many respects.
In this connection there are reasons to discuss and summarize the advantages of the method and device according to the present application against the theoretical background of the sur-face sizing and coating process.
Treating of the web in the size press is a physico-chemical process in which certain material5 by making use of water are brought onto the surface of the web and partly into its internal structure to improve the properties of a finished web. The effect of water on the running web has a decisive role in manyrespects in connection with the surface sizing process.
As the fibres get moistened or wet, they will swell. This results in an increase in the thic~ness and width of the web. The change in the web thickness is hardly noticeable, but the width grows to such an extent that it has to be taken into consideration in the design of the parts and components of a paper machine following the size press. The web must be allowed to expand freely, otherwise longitudinal wrinkles are formed in the web, which as such, impair the paper quality, but may also disturb the paper drive operation.
Swelling of the fibres and the resulting extension of the web do not occur in an instant but demand a certain time which de-pends on the fibre type and on the basis weight of the web. To give sufficient time for the transformation of the web the distance or space between the size press and the subsequent drying section has to be correspondingly long enough. In case this space forms an i22~56~
open draw, the result will be, as explained, excessive fluttering of the web and breaks will occur to such an extent that the pro-duction of the paper machine falls down.
The apparatus and concept according to the present in-vention offers as a combination the following advantages to elimi-nate the said difficulties:
- The expansion of the web (i.e. increase of the web ~idth) resulting from the phisio~chemical swelling of the paper fibres caused by water is "mechanically" assisted. This means that a blowing effect is directed to the web aiding the extension thereof in its width.

- , The means creating the said blowing effect stabilize simultaneously the web run so that the "dangerous"
fluttering can be prevented or at least substantially controlled.

- Due to the said blowing action extending the web and stabilizing its run, the web is simulta-neously dried to such an extent that when it becomes subjected to the contact drying taking place against the cylinder surface no wrinkling problems are created any more.

- ~ue to the combination of means according to the invention the dry content of the web is so high that a normal drying cylinder can be used as the first cylinder following the size press without the risk that the web would stick to the cylinder surface.

- By means of the equipment according to the invention the travelling distance o~ ~e web ~ecomes longcr than what is the straight geometrical space between the size press and the subsequent drying section and thus the web will stay on this space correspondingly so long that the re-quired dry content is achieved.
All this means that the provision of the non-contact web stabilizing means between the size press and the subsequent drying section results in obtaining a synergistic effect in that the fluttering of the web is eliminated and the possibility of web breakage reduced while simultaneously increasing the time for the web to expand and spread in a lateral direction.
Still further, the use of the web stabilizing means 40, 41 illustrated in FIGS. 5-7 and the particular structure of the nozzles 50 prevents the separation of the gas jets from curved surface and falling down to the suction side which would decrease tlle heat trans-fer coefficient between the nozzles. Thus, the nozzle slits 57, 58 of the web stabilizing means are so disposed on the curved nozzle surface that the jets v , v do not separate from the nozzle surface 56~ By providing.the web facing surface 56 with a curved shape forming a depression 59 between the nozzle slits 57 and 58, a "calming" region is obtained in which the gas jets v and v which are flowing in opposite directions will meet to form an air cushion extending for a substantial distance in the 3.ongitudinal direction of the web W to support the same. The heat transfer coefficient can have favorable values even in the area between the nozzle slits 57 and 58 according to the invention. Since the gas jets will not sharply impinge on the web W and since too early separation and falling down of the jets v and v is prevented through appropriate alignments, the travel of the ~2~;69 web W4 will be extrelllely smooth and flutter-free when the nozzles 50 in accordance with the present invention are employed. This is of essential significance with a view towards achieving the objects of the present invention.
The components of the apparatus of the present invention including a size press, preferably comprising a three-roll and two-nip size press, and the subsequent contact-free stabilizing and guiding means,are preferably situated in the drying section of the paper machine so that about two thirds of the drying cylinders operate prior to this apparatus and one third of the drying cylinders operate subsequent thereto.
It has been found preferable to have the web W4 pass through the stabiling means 40, 41 in as nearly a vertical direction as possible since the removal of broke from between the noæzles 50 is facilitated relative to the case where the web passes horizontally through the stabilizing means.
Obviously, numerous modification and variations of the present invention are possible in the light of the above teachings.
It is therefore to be understood that within the scope ofthe claims appended hereto, the invention may be practiced otherwise than as specifically disclosed herein.

Claims (43)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method, employed in connection with the running of a paper machine, for conducting a web through at least one surface-sizing step wherein the web is surface-sized on both sides thereof and thereby wetted, to a sub-sequent drying section of the paper machine, comprising the steps of: surface-sizing a web arriving from a prior drying section of the paper machine on both sides thereof in at least one size press nip of a size press; conducting the web after the surface-sizing step to stabilizing means for stabilizing and supporting the run of the web without contact therewith; conducting the web from the stabilizing means to a subsequent drying section of the paper machine;
and conducting the web after the surface-sizing step, either before or after the stabilizing means, to turning means for supporting and turning the run of the web without con-tact therewith and for spreading the web in its transverse direction, wherein the non-contact stabilizing means and turning means are arranged to reduce the length of the free draws of the web between the size press and subsequent drying section relative to arrangements including contact-type turning means so that free web fluttering is prevented and so that the web can spread out in a direction trans-verse to the running direction thereof.

2. The method of claim 1, wherein the web is conducted to the stabilizing means after being conducted to the turning means.

3. The method of claim 1, wherein the web is conducted to the turning means after being conducted to the stabilizing means.

4. The method of claim 1, further including spreading the web in its transverse direction in said stabilizing and turning means through the utilization of gas jets.

5. The method of claim 1, wherein the non-contact stabilizing means acts on both sides of the web so that the web travels in the region of the stabilizing means with a substantially sinusoidal wave motion and by which the web run is stabilized and any longitudinal wrinkles in the web removed and their formation prevented.

6. The method of claim 1, wherein heated gas is directed from the non-contact stabilizing means by which the web is dried on both sides in the region of the sta-bilizing means.

7. The method of claim 1, wherein said non-contact turning means are situated with respect to a last size press nip and to a first drying cylinder of the subsequent drying section of the paper machine such that the risk of web breakage due to fluttering of the free web draws is minimized.

8. The method of claim 1, wherein after a last size press nip the web, supported in a non-contact and stabilized manner by the stabilizing means and the turning means, is conducted to the subsequent drying section of the paper machine, the subsequent drying section including drying cylinders which, starting from the first, employ drying temperatures within a range substantially equivalent to a range of drying temperatures in the prior drying section.

9. The method of claim 1, wherein the stabilizing means comprises a housing structure disposed on both sides of the web, the housing structure including a pair of opposed wall means facing respective sides of the web, and a plurality of over pressure nozzles associated with said opposed wall means, the nozzles associated with opposite walls being intercalated with each other with substantial uniform mutual spacing between the nozzle of each wall means so that the web travels with a substantially sinusoidal wave motion, supported and stabilized by gas directed from the nozzle.

10. The method of claim 9 wherein the nozzles provided in the stabilizer means are each constituted by a nozzle box defining a pair of nozzle slits, the slits being formed at the outer regions of a pair of respective side volumes defined by respective pairs of inner and outer walls of the nozzle box, and wherein the nozzle slits are disposed with respect to a web facing surface of the nozzle box such that the gas jets discharge from the nozzle slits follow the w e b facing surface substantially without separating therefrom, and wherein the w e b facing surface is inwardly curved to form a depression in the nozzle box between the nozzle slits, and wherein gas jets discharged from the nozzle slits which follow the w e b facing surface meet substantially in the depression to form an air cushion for supporting the web and which extends a considerable distance in the direction of travel of the web.

11. The method of claim 10 wherein the initial direction of the gas jets being discharged from the nozzle slits forms an angle with the direction of travel of the web in the range of about 40° to 70°.

12. The method of claim 10 wherein the inner walls of the nozzle box at their outer regions have curved guide portions which extend into the w e b facing surface and wherein outer, substantially planar portions of the outer walls of the nozzle box define the nozzle slits in conjunction with the curved guide portions of the nozzle box inner walls.

13. The method of claim 12 wherein after the curved guiding portions, the w e b facing surface curves toward the interior volume of the nozzle box in a substantially smooth and con-tinuous manner.

14. The method of claim 13 wherein the web facing surface curves inwardly in a substantially circular arc.

15. The method of claim 9 wherein substantially uniform mutual spacing between the nozzles of each wall means is chosen such that the wavelength of the sinusoidal wave motion of the web under the effect of the gas jets directed from the nozzle is in the range of about 200 to 800mm.

16. The combination of claim 15 wherein the wave length is in the range of about 400-600mm.

17.` The method of claim 9 wherein the nozzles are situ-ated in opposed rows in the opposed wall means of the housing structure and wherein the distance between opposed nozzle rows is in the range of about 15 to 50mm.

18. The method of claim 17 wherein the distance between opposed nozzle rows is in the range of about 20 to 30mm.

19. The method of claim 1 wherein an upstream side of at least one of the stabilizing means and turning means is provided with guiding surface means for changing the direction of the web being conducted to the respective means without the web contacting the same.

20. The method of claim 1 wherein the non-contact turning means includes a supporting surface structure configured in accordance with the direction of run of the web, said supporting surface structure being constituted by a plurality of nozzle elements defining a plurality of nozzle slits which open onto the supporting surface structure, said nozzle slits having a longitudinal dimension which extends substantially transversely to the direction of travel of the web, and wherein the web runs supported by a gas directed through the nozzle slits.

21. The method of claim 20 wherein the nozzle elements which define the nozzle slits each include a pair of curved guiding surfaces between which a pressure surface is located, the pair of curved guiding surfaces bordering on one side each of a pair of re-spective nozzle slits, and wherein the ratio of the width of the nozzle slits and the radius of curvature of the curved guiding sur-faces is selected such that the gas directed from the nozzle slits at a certain velocity follows along the curved guiding surfaces up to the pressure surface.

22. The method of claim 21 wherein the nozzle elements further includes spacer surfaces situated adjacent to respective pressure surfaces, each spacer surface being located in substantially the same plane as the adjacent pressure surface, and wherein the spacer surfaces have sharp-angled edges bordering each of a pair of respective nozzle slits on the sides thereof which are opposite from the sides bordered by the curved guiding surfaces, the sharp-angled edges preventing the gas directed from the nozzle slits from turning onto the spacer surfaces.

23. The method of claim 20 wherein each nozzle slit is oriented such that an angle between the initial direction of the gas directed from the nozzle slit and the web is less than or equal to about 70°.

24. The method of claim 22 wherein the ratio of the sum of the lengths of a spacer surface and an adjacent pressure surface and the width of the nozzle slit is in the range of about 20 to 200.

25. The method of claim 1 wherein the size press is con-stituted by three size press rolls defining a pair of size press nips and means for forming sizing pools in the region of the nips, and wherein the web is continuously supported by the surfaces of the size press rolls including in the region of the sizing pools.

26. The method of claim 25, wherein the three size press rolls include a central size press roll and two side size press rolls, the central size press roll having a harder surface than the side rolls, and wherein the web is detached from the central size press roll after follow-ing along with the surface of the central roll through a central angle after the last size press nip, and wherein the detached web is conducted either to the means for turn-ing the web with contact therewith by which the web is turned in direction during its run or directly to the stabilizing means.

27. The method of claim 26, further including drying the web in the stabilizing means through the applica-tion of heated drying gases and/or radiation.

28. The method of claim 1, wherein the size press is constituted by a two roll oblique size press defining a single size press nip and wherein the nip is preceded on both sides of the web by sizing means and wherein the web is conducted from the size press either to means for turning the web without contact therewith by which the web is turned in direction during its run or directly to the stabilizing means.

29. In a paper machine drying section including a size press, a prior group of drying cylinders constitut-ing a drying section situated prior to the size press in the direction of run of the web, and a subsequent group of drying cylinders constituting a drying section situated after the size press in the direction of run of the web, the improvement comprising: stabilizing means situated between the size press and the subsequent group of drying cylinders for stabilizing and supporting the run of the web in a contact-free manner utilizing gas flow acting on both sides of the web, turning means situated after the size press and before the first drying cylinder of the subsequent group of drying cylinders for turning, supporting and spreading the web in a transverse direction theeof without contacting the same, the non-contact stabilizing means and turning means being arranged to reduce the length of the free draws of the web between the size press and subsequent drying section relative to arrangements including contact-type turning means so that free web fluttering is prevented and so that the web can spread out in a direction transverse to the running direction thereof.

30. The combination of claim 29, wherein the stabilizing means comprises a housing structure disposed on both sides of the web, the housing structure including a pair of opposed wall means facing the respective sides of the web, and a plurality of over-pressure nozzles associated with said opposed wall means, the nozzles associated with opposite walls being intercalated with each other with substantially uniform mutual spacing between the nozzles of each wall so that the web travels with a substantially sinusoidal wave motion, supported and stabilized by gas directed from the nozzle means.

31. The combination of claim 30 wherein the nozzle means provided in the stabilizing means are each constituted by a nozzle box defining a pair of nozzle slits, the slits being formed at the outer regions of a pair of respective side volumes defined by re-spective pairs of inner and outer walls of the nozzle box, and wherein the nozzle slits are disposed with respect to a web facing surface of the nozzle box sush that the gas jets discharged from the nozzle slits follow the web facing surface substantially with-out separating therefrom, and wherein the web facing surface is inwardly curved to form a depression in the nozzle box between the nozzle slits, and wherein gas jets discharged from the nozzle slits which follow the web facing surface meet substantially in the depression to form an air cushion for supporting the web and which extends a considerable distance in the direction of travel of the web.

32. The combination of claim 31 wherein the inner walls of the nozzle box at their outer regions have curved guide portions which extend into the web facing surface and wherein outer, sub-stantially planar portions of the outer walls of the nozzle box define the nozzle slits in conjunction with the curved guide portions of the nozzle box inner walls, and wherein the curved guide portions extend over an angle in the range of about 40° to 70°.

33. The combination of claim 32, wherein after the curved guiding portions, the web facing surface curves toward the interior volume of the nozzle box in a substantially smooth and continuous manner.

34. The combination of claim 33, wherein the web facing surface curves in a substantially circular arc.

35. The combination of claim 30, wherein the sub-stantially uniform mutual spacing between the nozzles of each wall is in the range of about 200 to 800mm.

36. The combination of claim 35, wherein the inter-nozzle spacing is in the range of about 400 to 600mm.

37. The combination of claim 30, wherein the nozzles are situated in opposed rows in the opposed walls of the housing structure and wherein the distance between opposed nozzle rows is in the range of about 15 to 50mm.

38. The combination of claim 37, wherein the dis-tance between opposed nozzle rows is in the range of about 20 to 30mm.

39. The combination of claim 29, wherein the non-contact turning means includes a supporting surface structure configured in accordance with the direction of the run of the web, said supporting surface structure being constituted by a plurality of nozzle elements defining a plurality of nozzle slits opening onto the supporting surface structure, said nozzle slits having a longitudinal dimension which ex-tends substantially transversely to the direction of the travel of the web, and wherein the web runs supported by gas directed through the nozzle slits.

40. The combination of claim 39, wherein the nozzle elements which define the nozzle slits each include a pair of curved guiding surfaces between which a pressure surface is located, the pair of curved guiding surfaces bordering on one side each of a pair of respective nozzle slits, and wherein the ratio of the width of the nozzle slits in the radius of curvature of the curved guiding surfaces is selected such that the gas directed from the nozzle slits at a certain velo-city follows along the curved guiding surface up to the pres-sure surface.

41. The combination of claim 40, wherein the nozzle elements further include spacer surfaces situated adjacent to respective pressure surfaces, each spacer surface being located in substantially the same plane as the adjacent pres-sure surface, and wherein the spacer surfaces have sharp-angled edges bordering each of a pair of respective nozzle slits on the sides thereof which are opposite from the sides bordered by the curved guiding surfaces, the sharp-angled edges preventing the gas directed from the nozzle slits from turning onto the spacer surfaces.

42. The combination of claim 39, wherein each nozzle slit is oriented such that an angle between the initial direction of the gas directed from the nozzle slit and the web is less than or equal to about 70°.

43. The combination of claim 42, wherein the ratio of the sum of the lengths of a spacer surface and an adjacent presure surface and the width of the nozzle slit is in the range of between about 20 and 200.