US2287905A - Coating machine - Google Patents

Description

i June 30, 1942. 2,287,905

H. B. RICHMOND ET AL.

COATING MACHINE Filed Jan. 8, 1941 2 Sheets-Sheet l 415 LZ d In 59 June 30, 1942. H. B. RICHMOND ET AL 2,287,905

COATING' MACHINE Filed Jan. a, 1941 2 sheets-sheet 2 of the rolls, that is, the web Patented June 3o, `194g I Howard B. Richmond,

per Company, ration of Wisconsin This invention-relates to improvements in'apparatus for coating exible fibrous webs and reoperation. y

In that type of coating operation wherein rolls are emplyed to apply a lm of coating material to one or both surfaces of a flexible web, it has' been found that the diameter of the coating roll or board f A being formed and coated in aI single, continuous 2281305 coA'riNG MACHINE s "PATENT `oFFlcl-z Gilbert K. Dickerman and William F. Thiele, Wisconsin Bapids,. signors to Consolidated Water Powcl' and Pa- Wlsconsin Rapids, Wis., a corpoor rolls have an important bearing upon the smoothness of the finished coated surface. In general, the smaller the diameter of the coating rolls the' smoother the resulting coated surface will be. This statement, of course, is true within limits, since a coating roll with an excessively small diameter, depending upon the translatory speed of the web and the amount'of coating to be applied tothe web, would have such a'relatively high angular speed that dimculties due to centrifugal action upon the coating carried-on the rolls may be encountered.

However, up to the point where centrifugal action becomes a disturbing factor', smaller diameter coating rolls are employed more advantageously than rolls of larger diameter.

Theoretically, juxtaposed coating rolls, between which the web passes, contact the web along a line parallel to the axes of the rolls.y In practice, however, due to pressure which must be placed upon the rolls. and the fact that the coating material upon the roll surfaces is in a pliable or mobile state, the theoretical line becomes a rectangular area of appreciable width, the'major axis of the' rectangle being parallel to the axes is exposed to contact by coating material, when passing between lthe rolls, for an appreciable distance (the width of the-rectangle described rectangle width will hereinafter be referred to as nip length or length of nip.

As can readily be seen the nip length tends to increase as the diameter of the coating rolls'increases, which, as will be hereinafter more fully described, is detrimental to the formation of a smooth coated surface upon the web.

Wis., as-

ApplicatiouJanuary 8, 1941*, Serial No. 373,566 s claims, (ci. sii-4s) web toadhere to, and follow the surface of one of .the coating rolls. The tension upon the web eventually causes the webto leave the roll but when it doesv so it does not leave the roll at a tangent relationship to the roll, as would be the case if theoretical conditions obtained, but leaves the roll surface in a. direction approaching the radial. 'Surface tension effects and effects probably due to coherence of the coating'material itself tend to produce graininess, `worminess, cat trac and other characteristic irregularities in the resulting coated lm upon the web.

In addition, with larger diameter rolls, the rate of convergence or divergence of the roll surfaces toward or away from the tangent position 'or line of osculations of said rolls,l that is, the angle of the nip, is less than with rolls of smaller diamleter, and hence with predetermined tension upon the web the tendency for the web to follow one or the other of the roll surfaces Vis greater with-the larger diameter rolls. Y j

However, in roll coating devices heretofore proposed,\ particularly rolls over about 80. inches in length, the coating rolls are required to have appreciable diameters, since in said devices the coating rolls are only supported at their ends, and

tend to deflect or sag at their longitudinal cenabove). This distance or By increasing the nip length the time during which the coating material contacts the web is increased, and if one surface absorbent than the other surface, which is almost invariably the case,

that surface tends to absorb more of the liquid carrier than the other surface thereof which. in turn, tends to cause the of the web is more ters if the diameters of the rolls are too small. Hence, diiiicult problems of crowning thecoating rolls have been encountered'in attemptingto obtain the advantages of relatively small diameter coating rolls.

In the present invention a pairA of juxtaposed rolls having relatively small diametery compared to the 'diameters of rolls heretofore used for an analogous purpose are mounted .one above the other. Either or bothrolls may be used for the application of coating to a surface or surfaces of ,a web which isadapted to pass between the rolls. Above and below the rolls in -question are mounted one or more transferv rolls, one of the functions of which is to transfer coating material tothe coating rolls. Therebei'ng a roll immediately beneath the lower coating rolls, both coating rolls, even'if their diameters are so small as to normally permit appreciable deflection or sag, will not sag or deflect materiallysince said rolls are supported by the transfer roll or'. rolls therebeneath.

Therefore, smaller diameter coating rolls can be employed without the inherent difliculties due to deflection entering into .the system as a limiting factor. 2

Anotheradvantage ancillary to the use of relatively small diameter coating rolls resides in the feasibility f employing greater nip pressure between the coating rolls without increasing the nip length or without embarking upon roll crowning complications due to unevenness of coating application as a result of roll deflection or sag.

Other objects and advantages of the present invention will be apparent from the accompanying drawings and following detailed descripi n. t oIn the drawings, Fig. 1 is a side elevational view of the coater comprising the present invention, a portion of the apparatus adapted to cooperate with the coater being shown diagrammatically. v

Fig.A 2 is a similar view of a slight modification of the invention, the device shown 4being in more simplified form.

Referring in detail to the drawings, I indicates a exible fibrous web of paper or boardwhich has been formed on a conventional paper machine (not shown) and has been substantially dried by passage over a plurality of heated drums, the last drum in the series being shown at 2.

In view of the fact that the coating device comprising the present invention is particularly adaptable for coating paper or board so as to provide a smooth, well compacted surface or surfaces which areV adaptable for the reception of print, the web I after leaving the drum 2 is preferably passed around a guide roll 3 and carried through one or more nips of a machine calender, indicated diagrammatically at 4. The calender functions to smooth t-he surfaces of the web I so as to provide preliminary surfaces on Vthe web ideally adapted to receive the-films of coating material. In view of the fact that in this general system of coating, the coated surface after receiving the film from the coating roll is not acted uponto further smooth the saine, the use of the calender to provide a smooth foundation or base for the coating film is generally found to be desirable. It is to be understood, however, that the present invention is not dependent upon the use of a calender. Further, it is not essential that the present apparatus be v mounted in the upper nip employed in conjunction with a paper machine to coat the paper or board in step with its formation since it can be used as an independent unit. However, in view of the fact that the invention may be employed to coat freshly made paper or board in step with the formation thereof, economy dictates that its use in this connection is most advantageous.

After leaving the calender 4 the web I is passed over guide roll 5 and is carried through the coater 6. Although the device comprising the present invention is adaptable to coat either or both faces of the web, for purposes of illustration, the device'will be described from the aspect of its use as a double surface coater.

Upon leaving the coater 6 ythe web may pass between conventional air blast devices (not shown) which areV adapted to preliminarily set the coating so thatit will not be marred in subsequent operations. The web may then-be passed around a suitable guide lroll 'I and subsequently carried over heated drums 8 whereby the coating is dried to the desired degree. The web may then be reeled, cut into sheets or otherwise handled preparatory to ultimate use.

The coater Ii comprises a pair of frame members 9 which are spaced from each other transversely with respect to the web I, only one of said frame members being shown. However, the

'opposite frame member is similar to the one .roll 48 is carried. A support shown, the parts being duplicated. The frame member 9 comprises essentially two spaced standards I0 and II which are supported upon a suitable base of foundation plate I2. -At the upper end of the standards, a beam I3. joins both standards and serves to maintain the standards in spaced relationship with respect to each other. The standards I0 and Il are so formed that when disposed in spaced relationship, as illustrated in Fig. 1, a relatively restricted space I4 is provided adjacent the central portions of the standards and relatively large spaces I5 and IB are provided adjacent the tops and bottoms of the standards, respectively.

The inner surfaces of the standards III and II ,facing each other to denne the space I4', are vertically parallel to each other and a rib I1 projects from each of .said inner surfaces to form guides for a' plurality of bearing blocks I8, I9, 20, 2|, 22, 23 and 24 which with the exception of block 2|, are slidable in a vertical direction between said standards. Each bearing b lock I8 to 24 inclusive carries a bearing respectively designated I8' to 24 inclusive, and each bearing respectively supports the journal of a roll designated I8" to 24". Bearing block 2| is maintained stationary by means of stops 20a polsailtioliied on the guides I1 above and below said IA lever 25 is pivoted, as at 26, to standard iixedly mounte lever 25 and carries a bearing 28 wlilicllipoiln turn supports the journal of a roll 29. A support 30 .is p1voted, as at 3|, to lever 25 and carries at its upper portion a bearing 32 the journal of roll 33. Rolls 29 and 33 are disposed with their surfaces adjacent each other the degree of clearance between the roll sur: faces being controlled by a capstan screw 34 which is threaded into bosses 35 and 36 upon the supports 21 and 30, respectively. A dam 31 is of rolls 29 and 33 adjacent each end of the rolls whereby the nip together with the dams serve to define a receptacle or fountain for a coating material such as a dispersion of finely divided mineral matter, for instance, clay, satin white or the like, and an adhesive in Van aqueous carrier.

A .support 38 is mounted upon the base I2 and carries bearings 39 for the reception of trunnions 40. which are mounted upon a cylinder 4I.. A piston rod 42 is slidably movable in the cylinder 4I, said piston rod being pivotally connected at its end to lever 25, as shown at 43 By this arrangement lever 25 may be raised or lowered by the use of liquid or air under pressure introduced into cylinder 4I. By raising or Lweriliitg 1lever 215 the surface of roll 29 may be oug i o a esired osition th slurface of the roll 2K4". with respect to ever 44 is pivoted, as at 45, u n

I 0, said lever extending into the gacisetalriarg member 46 extends downwardly from lever 44 and carries bearing 4'I in` which the journal of y 49 is ivoted at 50 to lever 44, said support carryirg a bea ing 5I at its lower end which is adapted to carry the journal of roll 52. The surfaces of rolls 48 and 52 are adapted ,to be disposed close to each other, the degree of clearing Ybetween the surfaces being controlled by capstan screw 53 said lever extending into the space I 6. ufpright member 21 is An which supports f at each side of each bearing block.

, er portions. Bearing 2d to' control aaeze'os the rolls 48 and52 adjacent the ends of said rolls, said dam together with the rolls providing fountain for coating material.

at one end to apiston rod (not shown) which operates in cylinder 51 in a well known manner.

The opposite end of said link is pivotally connected to lever M, the arrangement being such that air or liquid under` pressure introduced into cylinder 51 functions to swing lever 6 about its pivot 45 and, hence, acts to move roll 58 toward or away from roll I8".

A supporting member BI having outwardly extending arms carries pins 52 at the ends of the two arms. Each of the bearing blocks I8 and I9 carry brackets 63, one bracket 63 being mounted Each of the brackets 63 carry pins block 20 also carries a bracket 65 at each side thereof, these brackets,

however, each carrybut one pin I adjacent the' upper portions of said brackets. Slotted links B6 tie pins 62 carried by the member 6I, to the upper pins 64 of the Similar links tie the lower block I8 to the upper pins 64 carried by brackets 63 on block. I9. In like manner blocks I9 and 20 are tied together.

. Each of the blocks 22 and 23 carry four-pin brackets 63 and blocks 2| and 2d carry two-pin The brackets 63 and 55 carried by the blocks 2I, 22, 23 and 24 are all Itied together has been hereinbefore described.

An adjusting screw er portion of the upper portion of block I8 whereby theminimum degree of clearance between the surface of roll 48 and I8" maybejcontrolled. Similarly, adjusting screws B'I are interposed between blocks I8 and I9 and I9 and 29 whereby the minimum degree of clearance between rolls I8 and I9" and I9" and 2U respectively is controlled, the screws being screwed into the upper blocks and bearing against the lower blocks.

Similarly adjusting screws 6I are interposed between blocks 2l and 22, 22 and 23, and 23 and the clearance between rolls 2l and 23" and 2li", respeetively. An a ljusting screw 98 is threaded into the lower portion of block 29 and bears against the top of support 21 to controlthe clearance between rolls 24" and 29. Y

All adjusting screws, hereinbefore are provided with lock nuts 99 whereby justment of the screws may be nxed.

In utilizing the coater B, the substantially dried web is passed be ween rolls 29" and 2l" which are the upper and lower coatingrolls, respectively. Rolls 20" and 2l" are driven at substantially the same 'peripheral speed which may be equal to the translatory speed,` of the web I or may be slightly greater or less than said web speed. Rolls I8" and I9 and rolls 22", 23" and 2d" are also driven at a peripheral speed substantially equal to that of rolls 2U" and 2I In practice rolls I8" and 24" may all be geared together and d 'ven from av common source of power or each roll may be driven separately, for instance, by a group of electric motors whose speeds may be readily synchronized.

Rolls 29 and 33, comprising the gate rolls, are preferably driven at the same peripheral speed 6151s threaded into the lowand 22, 22" and 23,

described,

the adthe memberII and bears against l with respect to roll I9.

pins of bracket 63 on I 23" and 24" crowning is not critical. from roll surface vided for altering the speed of said rolls with respect to each other. The same arrangement obtains with respect to gate rolls 43 and 52'.,

In operation the coating material contained in the nips of rolls 29 and 33, and 48 and 52 deposits a film on all of said rolls. The thickness of the nlm upon all the rolls may be controlled within limits by the oapstan 34 and 53. In addition the film thicknesses may also be controlled by the relative peripheral speeds of the rolls constituting each pair of rolls.

Because of the contiguous relationship between rolls 29" and 29, and IB and 48, the lms carried by rolls 29 and '49 are respectively transferred in part to the surfaces of rolls 2d" and I8 respectively. The rate of transfer of the coating material from roll 29 tol roll 29" and from roll 48 to roll I8" can be controlled by varying the peripheral speed of roll 29 with respect to roll 24" and, the peripheral speed of roll 68 In addition, a degree of control can clearance between roll 29 and 29" and I9". p l

The coating films are then passed from roll surface to roll surface deposited by rolls 29" the web I.

and roll 48 and 2| tothe surfaces of If desired, the rolls I8", I9", 22", may be crowned although the The films in passing to roll surface are rendered smooth and of uniform thickness and density.

Obviously, if the coating rolls 20" and 2i" are permitted to deflect or sag materially, the care exercised in smoothing and preforming the film will be substantially wasted, since film on the web will be of nonuniform thickness and density. Therefore, it is desirable that the rolls 20" and 2|" be supported at their centers.

By the. vertical arrangement herein describedv such support is obtained since the 29 is of relatively large port the rolls above. This perm'ts of the use of coating rolls of a diameter heretofore unsatisfactorily small for predetermined web widths, with all of theadvantages inherent in the use of relatively small diameter coating rolls.

Ancillary to the vertical disposition ofthe rolls comprising the coater is the advantage over similar coater arrangements wherein the transfer rolls are disposed horizontally parallel to the plane ofthe web, in that splashing of coating material from the the web is avoided. In addition, and of vital importance, is the fact that the length of draw' is reduced which reduces the sag of the web or length or the catenary formed thereby. This fact facilitates the removal of the web from the `nip of the coating rolls along a line of tangency to the coating rolls, instead of permitting the web to follow the surface of one or the other of the coating rolls.

A more simple form of the present invention is illustrated in Fig. 2 wherein 'I0 indicates generally the coating mechanism. The coater 19 comprises a pair of frames 1I which are spaced from each other a distance suitable to permit the passage of a web of predetermined width between the frames.' Only one of such frames is illustrated in the drawings, it being understood that the opposite frame is similar in construction to the one illustrated. f l

The frame 1I comprises aV pair of spaced standards 'I2 and 'I3 which are supported upon a base lowermost roll and convent'o'nal means, not shown, may be prof also be exercised by varying the until the films are eventually.

the iinal diameter and tends to supdeemed bank of transfer rolls above or foundation plate 14. The upper ends of the passage of coating material from rolls 89 and standards are spanned by a beam 15 which main- |05 to rolls ||1 and ||6 respectively may be contains said standards in appropriately spaced rel trollede i s lationship with respect to each other. 'I'he In the absence of distributing rolls, it may be e/itral portions of the spaced standards and vrel rolls |6 and |I1. To accomplish this end, noza v l'y large spaces 11 and 18 areprovided adjazles |9 having elongatedY orices, the length of i centgthe bottoms and tops of said standards, rethe rolls, vmay be positioned adjacent rolls 1| I6 Jmcmveiy. io and m. similar nozzles, if desired, may be posi- A lever 19 is pivoted, as at 80, to standard tioned-adjacent rolls 89 and |05 to direct air at 13, the free end of said lever being pivotally conrelatively high velocity into contact with the nected, as at 8|, to a piston rod 82. The rod 82 is coating lm upon said rolls. slidably movable in a cylinder 83 in response to We claim as our invention: .air or liquid'introduced. in to said cylinder under 15 1. A device for coatingI paper which comprises pressure from a suitable source 4of supply (not in combination, a frame, a pair of rolls support- 20 cent each other, means for passing a flexible A supporting member 81 is mounted upon, and web between said roll surfaces, a pair of rolls extends upwardly from lever 19 and carries a. positioned adjacent the lower portion of said bearing 88 at its upper end, said bearing being. frame, said rolls having their axes in substan- 90, and serves to control the degree of clearance 3o' positioned beneath said rst mentioned rolls in A lever 96 is pivotally mounted upon standard 35 rolls, said supporting roll being adapted to trans- 12, as at 91, and extends into space 18. A link f er Coating material t0 one 01' said first men- Cylinder |00 carries trunnions |0| which are sup- 40 in combination, a frame, a pair of coatingrolls ing a bearing |04, which supports a journal of 45 web between said roll surfaces, a pair of rolls roll |05. Another supporting member |06 is positioned adjacent the upper portion of said pivotally secured, as at |01, to lever 96 and frame, and apair of rolls positioned adjacent the nal of roll |09 is supported. A apstan screw 5l 0 is mounted in'theupper nip oi' rolls |05 and carried at the `ends of each nip to prevent loss 09 and functions to hold coating material in 55 of coating material from said nips, one of the the nip of said rolls. rolls of said lower pair'being disposed beneath The opposed faces of the standards 82 and said coating rolls in supporting relation thereto 13 which dene the space 16 carry ribs which said supporting roll being of relatively larger difunctiOn as guides fOr blOCkS l2 and I3, Which ameter than said coating rolls whereby to sub, latter carry bearings ||4 and -||5respectively, 60 stantiany prevent exce although block ||3 is preferably maintained stationary similar to block 2|. Bearings ||4 and l5 respectlvely support the journals of coating Tous. roll surfaces whereby said coating material is ||6 and ||1. Bearing blocks ||2 and ||3 are y applied to a surface of the web, one roll of said slidably movable between the guides stops c., er air of I Us bei i c at. tran f us iimting the position of block H3. um. p .0 mg n o .mg s emng relationship with the other coating roll whereby In operation, rolls 89 and 93 are preferably separately driven and may be driven at the same coatmg n laterlal 1s apphed to me Opposlte sur" or different peripheral speeds. Roll |1 is sepaface of Sal@ Webv rately driven at a peripheral speed equal to or 70 3- A d eVlcF for Coatmg Papef' Whlch 091111311595 slightly slower or faster than the translatory 111 Combmatlon, a frame, a Da ll 0f. Coatmg TOUS tively larger diameter than said coating -roll whereby to substantially prevent excess deflection of said coating rolls.

4. A coating device comprising in combination a frame, a pair of coating rolls supported adjacent their ends in said frame, means for passing a flexible web between said coating rolls to coat opposite surfaces of said web,` a plurality of transfer rolls disposed in vertical alignment above and belowv said coating rolls to transfer coating -material from roll surface to roll surface, means for applying a controlled quantity of coating material to the uppermost transfer roll, and means for applying a coating material to the lowermost transfer roll, said last mentioned means comprising a roll having a relatively larger diameter than said coating rolls, said larger diameter roll being disposed in supporting relationship with respect to the rolls thereabove to substantially prevent excess vertical deflection of said rolls above.

5. A device for`coating paper which comprises in combination, a frame, a pairof rolls supported adjacent their ends in said frame, said rolls having their axes horizontally disposed in vertical alignment with the opposed surfaces adjacent each other, meansifor'passing a exible web between said roll surfaces, a pair of rolls positioned adjacent the lower portion of same frame, said rolls having their axes in substantially horizontal alignment, the opposed surfaces of said last mentioned rolls being positioned adjacent each other to provide a nipv for holding coating material,

dams carried at the ends of said nip to prevent.

loss of coating material from said nip, one of said last mentioned rollsbeing positioned beneath said first mentioned rolls in supporting relation thereto, said supporting roll being of relatively larger diameter than said ilrst mentioned rolls whereby to substantially prevent excess deflection of said .rst mentioned rolls, said supporting roll being 6. A device for coating paper which comprises` in combination, a frame, a pair of rolls supported adjacent their ends in said frame. 'said rolls having their axes horizontally disposed in vertical alignment with the opposed surfaces adjacent each other, means forpassing a flexible webl between said roll surfaces, a pair of rolls positioned adjacent the lower portion of said frame, said rolls having their axes in substantially horizontal alignment, the opposed surfaces of said last mentioned rolls being positioned adjacent each other to provide a nip for holding coating material, -one of said last mentioned rolls being positioned beneath said first mentioned rolls in supporting relation thereto, said supporting roll being of relatively larger diameter than said iirst men- A tioned rolls whereby to substantially prevent excess defiection of said rst mentioned rolls, said supporting roll being adapted to transfer coating material to one of said first mentioned roll surfaces whereby said coating material is applied to a surface of said web.

7. A device for coating paper which comprises in combination, a frame, a pair of rolls supported adjacent their ends in said frame, said rolls having their axes horizontally disposed in vertical alignment with the opposed surfaces adjacent each other, means for passing a exible web between said roll surfaces,4 a pair of rolls positioned adjacent the upper portion of said frame, said rolls having their axes in substantially horizontal alignment, the opposed surfaces of said lastmentioned rolls-being positioned adjacent each other to provide a nip for holding coating material, means for passing coating material from l one of said last mentioned rolls to one of said first mentioned rolls, vwhereby said coating material isapplied to a surface of said web, and a roll positioned beneath said first mentioned rolls in supporting relation thereto, saidsupporting roll, being of relatively larger diameter than said first mentionedl rolls whereby to substantially prevent excess deflection of said nrst mentioned rolls.

8. A device for coating paper which comprises in combination, a frame, a coating roll supported adjacent its ends in said frame, saidv roll havingv its axis disposed substantially horizontally, means for passing a nexible web into contact with said roll surface, a pair of rolls positioned adjacent the lower portion of said frame, said rolls having their axes in substantially horizontal alignment, the opposed surfaces of said last mentioned rolls being positioned adjacent each other to provide a nip for holding coating material, one of said last-mentioned rolls being positioned beneath said coating roll .in supporting relation thereto, said supporting roll being of relatively larger diameter than said coating roll whereby to substantially prevent .excess deflectionv of said coating rolls, 'saidsupporting roll being adapted to transfer coating material to said coating roll whereby said coeting material is applied to a surfasgf said we HOWARD B. RICHMOND.

GILBERT K.- DICKERMAN. WILLIAM F. THIELE.

Images