US2241554A - Apparatus for manufacturing paper - Google Patents

Description

May 13, 1941. F. J. LANG Em. 2,241,554

APPARATUS FOR MANUFACTURING PAPER Filed Dec. '23, 1957 INVENTORS u. Mm ,4. 14/4 mm TT EY.

Patented May 13, 1941 APPARATUS FOR MANUFACIUBING PAPER m J. mmmamanm, imam Walker, Tonawanda, N. Y.; said Lang aaignor to International Paper Company, a

of New York Application 23, 1937, Serial No. 181,286

1 Claim. (01. 91-48) Our present invention relates to the manu facture of paper and, more particularly, to the calenderlng of paper produced on any of the known types of paper-making machinery.

It is an object of our invention to provide a means for adding moisture to paper asit comes from a paper-making machine. Further oh- Jects will become apparent from the following description of a preferred form of our invention.

it is customary to subject a web of paper emerging from the last drying stage of a papermaking machine to the action of calenderlng rolls. In many mills, the calendering rolls are interposed between the final drying stage and the reel, and the web of paper progresses from the final drying stage through the calendaring rolls to the reel in a continuous operation. Paper,

the web becomes reduced to such a point that "chairing might occur.

of the dryers. If a machine is particularly designed for production of a relatively heavy web at a relatively high rate of speed, it is obvious that when a lighter web is produced upon the thus manufactured, is known as Machine. finished."

The action of calendering a web of paper is fundamentally an ironing or rubbing action under pressure and is produced by arranging smooth calendering rolls in opposed relationship. Paper is passed between these rolls and the rolls are adjusted to exert pressure upon the same. The rolls are driven at a speed slightly diflerent from that of the web and the resulting slipp e produces the ironing or rubbing effect upon the surfaces of the p p When an extremely high gloss is desired, a process known as super-calendering is employed. The action of super-calendering is identical with that of the calendering above dis cussed but the pressure exerted by the supercalendering rolls and/or the difierential between the surface speeds of the rolls and the web is substantially increased. It will be apparent that a large amount of heat will be generated by the exertion of pressure and rubbing action upon the surface of paper. It will likewise be apparent that the calendering pressure may be so increased as to cause charring or weakening of the paper as an incident to the increased amount of heat thus generated. It is desirable to perform the calendering operation under as much pressure as possible in order to produce a high gloss finish upon the paper and it is an object of our invention to so condition the web of pape prior to its introduction to a supercalendering device, that the desirable high gloss finish may be imparted thereto without any danger of charring or weakening the web.

Accordingly, we propose to increase the moisture content of the web before it is introduced into the super-calendering stack. when the moisture content of the web is thus increased, the calendering pressure may be proportionately increased and a satisfactory high gloss finish may be produced before the moisture content of machine at a relatively slow speed, the drying capacity of the machine is decidedly in excess of that actually needed. It is frequently necessary to operate a paper-making machine to produce paper for which the machine was not originally designed and when a lighter web is produced at a slower speed,it is exceedingly difficult toso regulate the dryers as to bring out a web at the reel in any condition other than bone dry. A bone dry web cannot be supercalendered without extreme danger of charring or It is well recognized that the drying stages of a paper-making machine do not dry the web uniformly throughout its width. It has been observed that the normal tendency of the drying stages is to dry the web from the edges inwardly and if it were attempted to withdraw the partially dried web from the machine the paper delivered to the reel would be substantially dryer nearer its edges than it would be at the middle. If this web were then to be delivered to a super-calendering stack, the drier portions would be subject to charring or low finish and the more moist portions would take a much higher finish.

It has been proposed to overcome the dimculties above outlined bydrying the web as usual and delivering it to a reel. The paper on the reel is thenslit and rewound, the several 7 rolls being transferred to the super-calendering stack and the surface of the webs of each roll is sprayed with water immediately prior to its entry into the super-calendering rolls. Moisture thus applied is necessarily superficial. Furthermore, the application by sprays of a uniform and accurately controlled amount of moisture as device.

'of the mesh roll.

awaiting transfer to the super-calendering stack. It may be observed here that in all paper mills with which we are familiar there is a substantial lapse of time between the reeling of paper of! of the paper-making machine and the transfer of the paper to thesuper-calendering This lapse of time is frequently due to the fact that the web is slit into convenient widths prior to super-calendering and, in addition to the time consumed in this slitting operation, a further amount of time is accounted for by the increased lineal extent of web which must be conducted through the super-calendering device. Irrespective of its cause, the time elapsing between the reeling and supercalendering of the paper is normally sufficient to allow a thorough permeation of moisture throughout the web and the condition of the web is, therefore,- perfect for the purpose of super-calendering by the time the super-calendering operation takes place. However, in certain mills, it may be necessary to deliberately introduce adelay of a few hours between 'the reeling and super-calendering operations in order to allow sufficient time for the thorough seasoning or conditioning of the web. In either event, the reduction in operating complications which our process effects will be apparent when compared to the method of so regulating the dryers as to leave residual moisture in the sheet as it is reeled.

We carry out our process by mounting, just ahead of the reel, a roll extending across the machine and having a wire mesh or similar surface. The construction of this roll is in general comprising calender rolls I l. The calender stack I 3 may be of any desired construction for the purpose of imparting a machine finish to the web I2. It will be understood that the provision of the calender stack [3 is not essential in the practice of our invention as it is obvious that our moistening device may be utilized to apply moisture to a web whether the same has been machine-finished or merely dried.

From the last drying roll II, or from the calender stack l3, if such a stack is to be used, the web I2 is conducted over a guide roll l5 to a reel iii of any desired type or construction. The reel l6 may be driven by conventional means (not shown) ,to cause the web I2 to be wound thereupon.

Our moisture adding device, indicated generally by the numeral I1, is so located as to apply moisture to a surface of the web l2 immediately besimilar to thatof the conventional dandy roll.

water whichis taken up by the wick and transferred to the surface of the mesh roll. The web of paper is brought from the dryer to the reel and permitted to pass in contact with the surface The web thus receives free moisture from the mesh roll and is immediately wound up. The amount of moisture thus conducted to the web will be very uniform throughout the entire width thereof. The amount of moisture thus applied may be varied by varying the thickness or character of the wick or the extent of contact between the wick and the mesh roll or by varying the gage of the mesh surface of the roll. We havefound that the addition of moisture sufficient to bring the total moisture content upto l /2% to 5%% is best for the ordinary super-calendering operation although our process and apparatus is capable of adding up to 10% or 12% moisture.

- Although our moisture-applying apparatus is herein described with particular relation to the process of super-calendering, it will be understood that our apparatus may be employed wherever fore the web passes to the reel l6. To this end, we provide a pair of standards l8 upon which are mounted supports l9. Bearings 20 are mounted for vertical adjustment upon the supports l9 and may be secured in adjusted position by suitable means such as a set screw 20'. Stub shafts 2| are rotatably carried by the bearings 20 and may be rigidly attached to or formed as an integral part of spiders 22. A cylinder 23 of coarse, stout wire mesh is formed upon the outer periphery of the spiders 22 and as many additional spiders 24 as may be deemed to be necessary to retain the wire in a true cylindrical shape. The spiders 22 and 24 may be skeletonized as far as consistent with their required strength and the stub shafts 2| may be formed as hollow tubes in order to reduce theweight of the completed cylinder. The outer surface of the cylinder is formed of fine wire mesh 25 which is supported directly by the coarse mesh 23. Thus, a true cylindrical foraminous roll, having a fine mesh surface, is provided.

Since our moisture applying cylinder is very ,light in weight and is freely rotatable in the bearings 20, we have found that the provision of special driving means therefor is not necessary. The bearings 20 may be adjusted to such a position that the area of contact between the mesh surface 25 of the cylinder and a surface of the web I! will produce suflicient friction to cause rotation ofthe moisture applying roll. It is obvious that driving means could be provided to rotate the moisture applying roll at a peripheral speed equal to the lineal speed of the web l2. It is equally obvious that a driving means could be provided to rotate the roll at a peripheral speed greater or less than the lineal speed of the web the desired value. It will be further apparent secured to the supports l3 by means such as clamps 21. At their lower ends, the brackets 26 are provided with slots 28 adapted to adjustably receive cap screws 29' carried by a trough 23;

The trough 23 is closed at one end by a plate 30 provided with an opening through which water may be introduced into the trough from a tube 3|. At its other end, the trough is partially closed by a plate 32 whose upper edge is located somewhat below the top of the trough 29.

A wick 33 made of suitable textile or felted material is provided. The wick extends with the moisture applying roll and the trough 29 throughout the width of the web l2. One end of the wick 33 extends into the trough 29 below the level of the upper edge of the plate 32. The other end of the wick 33 extends over the edge and outside of the trough 29. The wick 33 may comprise a number of independent sections 33, as shown in Fig. 1, or may be made in one piece, as shown in Fig. 3. The objects to be achieved by these two forms of wick will be discussed hereinafter.

By manipulation of the adjustable means 21, 23 and 29-, the position of the trough 23 may be varied relative to the surface 25 of the roll in order to control the area of contact between the wick 33 and the mesh-surface 25.

Water is supplied to the trough 29 from the tube 3|. The rate of water supply is so controlled as to maintain a constant water level within thetrough. This constant level may be maintained by supplying water to the trough at a rate in excess of the rate of transfer of water from the trough to the mesh surface 25 by the wick 33. The excess water. will flow over the upper edge of plate 32 and the water level will remain constant so long as an excess is supplied.

The amount of water applied to the web [2 may be varied in a number of ways. Thus, the maximum amount of water which can be carried by the mesh surface 25 may be varied by forming such surface of mesh of various gages. The amount of water transferred to the mesh surface 25 by the wick 33 may be varied by changing the area of contact between thewick and mesh surface as explained above. The amount of water carried by the wick may be varied by changing the thickness or character of the wick. For convenience in varying the thickness of the wick 33, whether it be divided into sections or not, we have found the use of superposed separate plies of wick material, as shown in Fig. 2, to be of advantage. Thus, any desired thickness may be obtained by the use of an appropriate number of wick plies. We have found that the use of a mesh 25 having a gage of 65 to 75 per inch and a wick 33 comprising one or two layers of cotton cloth will supply a quantity of water which may be so controlled by adjustment of the area of contact between the wick and mesh that the quantity of moisture added by our device may be varied throughthe width of a web by the use of wick sections of varying thickness. Thus, a portion of the web having residual moisture therein may have additional moisture applied through relatively thin wick sections while surface as to establish; a moisture content of 5% to 6% in webs of paper whose basis weight may vary from 45 to 75 pounds (25x38-500).

In certain circumstances, theuse of a sectional wick. as shown in Fig. 1, may prove to be of advantage. Thus, a web of particular basis weight may emerge from a particular paper machine with a portion of its width containing a useful percentage of residual moisture. when those portions of the web which contain less residual moisture may have moisture applied through relatively thicker wick sections.-

The moisture adding device I! may be secured together as a unit comprising the mesh roll, supports l9 and trough 29 by the provision of rings 35 secured to the ends of the stub shafts 2|. Thrust collars 34 may also be provided if so desired.

The unit I! is supported for ready movement into and out of operative contact with the web l2 by the following means. The standards l8 comprise three separable blocks 36, 31 and 38. The blocks 36 are secured to the supports I9 of the unit I! and rest'upon intermediate blocks 31 which, in turn, rest upon blocks 38 which are supported upon a floor or other suitable structure. When it is desired to move the unit I! away from operative position, the intermediate blocks 31 are removed and the unit, including blocks 36, is lowered directly upon the blocks 38.

In the operation of our device, the unit 11 is set up and adjusted 'for the addition of the desired percentage of moisture to the particular web to be treated. The web is then conducted from the paper-making machine over the unit 11. The superficially moistened web continues over the guide roller l5 to the reel l6. When the reel l6 has been built up to predetermined size, the web is severed and a new reel is put in place in a known manner. The web may remain upon the reel H5 or it may be slit and rewound upon a plurality of narrower rolls. In either event, the web is allowed to remain in reeled condition for a length of time suflicient to permit thorough permeation of the moisture throughout the web. The web will then be conditioned with precisely the proper percentage of moisture for the process of super-calendering or such other process as may be subsequently performed thereupon.

While the above detailed description of apreferred form of our invention has been made in order to comply with statutoryprovisions, it will be apparent to those skilled in the art that modifications and variations in detail and mode of use may be resorted to. It is therefore our intention that such description shall be taken in an illustrative rather than in a limiting sense and that the scope of our invention shall be limited only by the appended claim.

We claim:

A device for correcting localized deficiencies more wicks.

- FRANK J. LANG.

FRANK ADLAI WAIKER.

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