US2749878A - Paper coating apparatus - Google Patents

Description

June 12, 1956 Flled Aug 17, 1953 m aa z Em am w June 12, 1956 o. E. HAGEN PAPER coATING APPARATUS 4 Sheets-Sheet 2 Filed Aug. 17. 1953 June 12, 1956 o. E. HAGEN PAPER coATING APPARATus 4 Sheets-Sheet 3 Filed Aug. 17, 1953 June 12, 1956 o. E. HAGEN PAPER COATING APPARATUS 4 Sheets-Sheet 4 Filed Aug. 17, 1953 .z 26+ 24. f. x 6 76 w Ww 1 6 7 w m 12/ -fi Hl W W l 2 f/ m 6 M AIR PAPER coA'rrNo APPARA'rUs Oscar E. Hagen, deceased, late of Neenah, Wis., by Frances M. Hagen, executrix, Neenah, Wis., assignor, by mesne assignments, to Kimberly-Clark Corporation, a corporation of Delaware Application August 17, 1953, Serial No. 374,539

Claims. (Cl. IIR- 249) The present invention is directed to an improved paper coating apparatus for applying mineral pigments and the like to paper webs in the manufacture of high quality paper suitable for book paper and the like.

In one common system for applying mineral pigment coatings to a web of paper, the paper web is fed continuously into the nip between a pair of coating rollers, the nip being carefully adjusted to provide the proper application pressure uniformly distributed across the web. Each coating roll, in turn, receives its coating from a series of auxiliary rolls including a roll which is continuously .supplied with a Suspension of the pigment, this roll cooperating with a highly polished metering roll in surface contact with the first mentioned roll. The metering roll, in turn, transfers the coating from the first roll or backup roll, to a transfer roll disposed between the metering roll and the coating roll. The coating material thus is carried .successively over the surfaces of three rolls before it is applied to the surface of the main coating roll.

In the production of high quality coated paper it is essential that the pressure at the area on the main coating roll at which the coating composition is applied be carefully Controlled in order to provide a uniform, smooth coating of Constant density along the moving paper web. It is equally important to achieve the correct Operating pressures between the rolls making up the auxiliary train, as otherwise the coating composition will not be applied uniformly or in proper quantities to the surface of the main coating roll. It is also desirable to observe the proper surface characteristics between the rolls. Reference is made to Hoel U. S. Patent No. 2,606,520 for a description of these relationships.

The adjustment of the pressure at the coating hip as well as the inter-roll pressure between the rolls in the auxiliary train must be within very close tolerances for best results. In commercial installations, however, the coating roll, as well as the auxiliary rolls, must be quite massive in order to achieve the coating speed required in such machines. The substantial width required for the rolls, and the -substantial pressures involved for certain applications in the coating application also contri'oute to the necessity of providing massive rolls in such assemblies. For machines of about one hundred forty inches in width, the train of auxiliary rolls and its supporting frames weighs as much as fifteen tons, and the main coating roll together with its supports may weigh about ten tons. Hence, the -fine adjustment of inter-roll pressures becomes a very substantial problem.

It becomes particularly important in apparatus for coating both sides of the paper web, where pressures as light as five pounds per lineal inch may be employed. In prior systems, the problems associated with securing the correct Operating pressures were so diflicult, that simultaneous coating of both sides of a paper web was not commonly practiced, and instead, the web was coated on one side, dried, and then coated on the opposte side.

nited States Patent O 2,749,87s Patented June 12, 1956 ICC 2 Processes of this type involve the use of rather elaborate roll systems and driers.

Any mechanical system for mounting rolls to make the pressures readily adjustable must also take into consideration the problem of access to the rolls during periods when the machine is to'be shut down for cleaning of the rolls or replacement of the rolls. Hence, the means to be provided for adjusting the various contacting pressures between the rolls should at the same time permit free access to the rolls when the machine is shut down.

One of the primary objects of the present invention is to provide a paper coating assembly with a balan'ced arrangement of rolls in which the rolls are so arranged that the force applied to the rolls in the auxiliary train and the pressure at the coating nip of the main rolls can be readily adjusted within very closely defined limits.

A further object of the invention is to provide a coating apparatus with a balanced roll arrangement whereby only a relatively small, finely adjustable, pressure is required to shift the rolls into and out of operative engagement.

Another object of the invention is to provide an improved mounting assembly for metering and backup rolls in a paper coating arrangement which permits a rapid and closely controllable adjustment of the pressures between the rolls during the coating operation.

Another object of the invention is to provide a paper coating apparatus which permits greater freedom in control of the travel of the web through the paper coater and its contact with the coating applicator surface.

In general, the present invention provides an improved coating apparatus in which the main coating roll is supported on a pivotally mounted balanced frame, and the rolls making up the auxiliary train are supported on a supplemental frame which is pivotally mounted by the main frame. With this arrangement, the auxiliary train is pivotally movable about its own pivotal axis and at the same time is bodily movable upon pivotal movernent of the main frame about its axis. Pressure Sensitive means are also provided between the main frame and the supplemen'tal frame in order to adjust the relative movernent between the two frame assemblies. Means are also provided for mounting some of the roll-s in the auxiliary train in a manner such that movement of the supplemental frame into a position in which the auxiliary train is disengaged from the main coating roll will cause these rolls to move apart a sufiicient distance to permit the cleaning of the surfaces of the rolls or replacement of the rolls.

One of the primary features of the roll arrangement of the present invention resides in a substantial balance in distribution of mass about a common aXis, the pivotal aXis of the main frame, when the rolls are in operative engagement during the coating operation. This is accomplished by distributing the mass along the main frame and the supplemental frame, so that the center' of gravity of the two assemblies is very nearly at the pivotal aXis of the main frame during the coating operation. The balance is not exact, however, as it is desirable to have a slight turning moment still present about this pivotal axis, this moment being in a direction which would tend to open up the rolls, i. e. disengage them from abutting contact. This arrangement provides a safety feature whereby a failure in the actuating system will result in the rolls separating by virtue of the mass of the rolls and the frame assemblies.

A more specific description of the invention will be made in conjunction with the attached sheets of drawings which illustrate the principles of the present invention applied to a machine for coating both sides of a web of paper, although it Will be readily apparent that the principles will be equally applicable to machines coating only one surface of a moving web of paper, and having more or less rolls than the number of rolls indicated in the drawings.

1Eigure l is a view in elevation of the coating assembly iliustrating the manner in whichthc various rolls are m'ounted;

Figure 2 is a view taken substantially along the line 2-2 of Figure l, the view being partially in cross section;

Figure 3 is a view taken substantially along the line 3-3 o Figure l and illustrating the means for supporting the metering roll;

Figure 4 is a fragmentary view in elevation and partially in cross section of one of the pressure rcsponsive means which interconnect the main frame and the supplemental frame;

Fignre 5 is a view taken substantially along the line 5- 5 of Figure 4; and

Figure 6 is a cross-sectional view taken along the line 6-6 of Figure 5.

ln Figure l reference numeral 10 indicates generally a supporting frame for the coating assembly which supports the weight of most of the elements in that assembly. Keyed to the frame 19 is a pair of shaft supports 11 (Figures l and 2) each of which receives a pivot pin 12 which is journalled in a pair of bearings 13. The spaced pivot pins 12 provide a pivotal axis for a main frame 14, composed of two substantially identical frame members, one on each side of the machine. One of these frame members is best illustrated in Figure 1. Each of the frame members making up the frame 14 at its upper end has a bearing support member 16 which journals the main coating roll 17 for rotation therein. The roll 17 will usually be a rubber-covered roll of relatively large dimensions.

The auxiliary train of rolls generally indicated at 19 in the drawings is supported on a supplemental frame or subframe 21 composed of two substantially identical frame members arranged to provide relative pivotal movement between the auxiliary train 19 and the main coating roll 17. The supplemental frame 21 is received between the spaced lower ends -of the frame members consttuting the main frame 14. A pair of pivot pins 22 carried by the main frame 14 provide a pivotal axis for the movement of the supplemental frame 21 with respect to the main frame 14, the pivotal aXis for the supplemental frame 21 being in substantially the same horizontal plane as the pivotal axis of the main frame 14.

One of the important features of the present inventicn resides in the proper distribution of the mass of the coating assembly. In the described arrangement, a major part of the mass of the upper coating press unit (including the rolls 26, 28, 36, and 17) is carried at the pivot pins 12. With this arrangement, only a very small portion of the mass acts as a dead weight on the roll adjusting means subsequently to be described, so that less total force is necessary to move the rolls through a given increment than has heretofore been employed.

Secured to the top of the supplemental frame 21 is a framework 24 which provides support for the rolls making up the auxiliary train 19. The train 19 includes a rubber-covered backup roll 26 journaled for rotation in spaced bearing supports 27 on the frame 24. The nip between the rolls 26 and 28 is supplied with the pigmented coating through a pipe 30 located above the rolls 26 and 28. A pair of end seals are provided, one on each side of the machine to receive the excess coating from between the surfaces of these rolls. A pipe is provided to recrculate the coating composition not picked up by the rolls backinto the coatingv supply system feeding the pipe 30.

The metering roll 28 is usually composed of chromium plated steel or other composition and is mounted for rotation in brackets 29, the latter having collars 31 (Figure 31) which engage pins 32 for pivotal' movement about the axes of the pins. As best seen in Figure 1, the axes of the pins 32 are displaced laterally from the axis of rotation of the roll 23 so that as the supplemental frame 21 is pivoted about the pins 22 in a counterclockwise direction, the metering roll 28 will fall by its own weight into spaced relation with respect to the backup roll 26. Stops 3-4 are positioned to engage the brackets 29 and thereby limit the distance through which the roll 23 can be displaced from the roll 26. In practice, the amount of relative movement permitted between the surface of the roll and the roll 28 will be on the order of 4 to 6 inches so that When the rolls are disengaged the surface of the roll 26 and the roll 28 will be readily accessible for Cleaning.

in a similar manner, a transfer roll 36, consisting of a resilicnt covered roll of substantial diameter, has a shaft 37 journalled for rotation in opposed bearings 38 (Figure 2). The transfer roll 36 is disposed over a pan 39 which serves as a reservoir for coating material dropped from the surface of the roll 36.

The bearings 38 are provided at their lower ends with collars LS-.t which engage pivot pins 42, as best seen in Figure 2. The pins 152 are also laterally displaced from the aXis of rotation of the shaft 37 in the same manner that the rotational axis of the metering roll 28 is displaced from the axes of the pins 32. Hence, when the supplemental frame 21 is pivoted about the pins 22 in a counterclockwise direction, both the metering roll 28 and the backup roll 26 will pivot due to their own weight in a clock Jise direetion about their respective pivots. When the supplemental frame 21 has been pivoted a sufficient amount in the counterclockwise direction, the metering roll 28 and the transfer roll 36 will be spaced from each other and from the surface of the main coating roll 17. A pair of stops 43 are provided in the frame 21 to limit the are through which the transfer roll 36 may be pivoted.

The distribution of the mass of the roll and frame assemblies should be carefully adjusted to take advantage of the balanced arrangement. With the arrangement shown, the center of gravity of the supplemental frame 21 and the auxiliary train 19 is somewhat to the left of the axis of the pins 22 when the rolls in the auxiliary train are in the open or non-abutting position. As the assembly is pivoted clockwise about the pins 22, however, the center of gravity shifts slightly, but still remains slightly to the left of the axis of the pins 22 when thc rolls of the auxiliary train are in operative engagement. This arrangement substantially reduces the force required to secure an incremental change in the pressure between the rolls, while at the same time permitting the rolls to be biased toward their disengaged positions by virtue of the mass of the rolls in the event that failure in the pressure adjusting mechanism should occur.

The combined masses of the main frame 14 (including the roll 17) and the supplemental frame 21 (together with the auXiliary train 19) has its center of gravity slightly to the left of the pins 12 when the rolls are disengaged. As the rolls are brought into operative engagement by pivoting of the entire assembly about the pins 12, the center of gravity shifts slightly, but still remains slightly to the left of the axis of the pins 12 when all the rolls are in operative engagement. ln this condition, most of the mass of the assembly is carried at the pivot pins 12, leaving only a slight dead weight to be absorbed at the pressure regulating mechanism. As a result, only a small amount of force is required to change the pressure relationships, and the rolls are still biased toward their open position so that they may be automatically disengaged in the event of failure in the pressure regulating mechanism.

A wide range, closely adjustable control over the internal pressures between the rolls making up the auxiliary train 19 is aforded by providing a combined hydraulically operated and a fluid pressure operated means such as an air pressure system Working in series, the hydraulic means being used to achieve a coarse adjustment of the roll position, and the air pressure being used to achieve the final fine adjustment of nip pressure. While a hydraulically operated system is the preferred adjustment means, this positioning mechanism may comprise mechanical arrangements such as toggles, screws, and the like which will provide a positive, controllable positioning means.

As will be seen from Figures 1 and 4, the lower end of the frame members making up the supplemental frame 21 are secured to shafts 44 which are reciprocable by operation of the fluid pressure-operated displacement means, best illustrated in Figures l, 5, and 6 of the drawings. Coarse adjustment of the relative positions of the supplemental frame with respect to the main frame is achieved by means of a cylinder 47 in which a piston 48 at the end of the shaft 44 is free to reciprocate. Near one end of the cylinder, an annular internal stop member 49 (Figure 4) is provided to provide a stop for the movement of the piston 48 within the cylinder 47. Oil or other liquid is introduced into or discharged from the righthand or piston end of the cylinder 47 through a line 51, and another line 52 is provided for conducting oil or other fluid to or from the other end of the cylinder 47.

In the initial adjustment of the rolls in the auxiliary train 19, oil pressure is applied to the piston 48 until the piston reaches the internal stop 49. The oil pressure introduced should be more than enough to cause the piston to be bottomed against the stop 49. In this position, the roll 36 is in contact with the surface of the roll 17 by virtne of the bias provided by the off center pivot of that roll. Similarly, the metering roll 28 is also in contact with the surface of the roll 36 because of its off center pivotv With the piston 48 bottomed against the stop 49, the roll 26 should still be approximately one inch from engagement with the surface of the metering roll 28.

The fine adjustment of the roll pressures in the metering train is accomplished by means of air pressure systems, one of which is illustrated in Figures 5 and 6 of the drawings. This system includes a pair of diaphragm housing plates 54 and 55 secured together at their peripheries by means of circumferentially spaced bolts 56. Clamped between the plates 54 and 55 is a flexible rubber diaphragm 57 whose relative position is determined by the amount of air pressure introduced into the diaphragm housing through spaced ports 58 on the outer side of the diaphragm 57. The movement of the diaphragm 57 in response to increased air pressure is transmitted to a diaphragm plate 59 rigidly secured to a rod 61. The end of the cylinder 47 is also fixedly secured to the rod 61 so that movement of the diaphragm plate 59 will also serve to move the cylinder 47 in response to air pressure introduced into the diaphragm assembly. The piston 48 remains bottomed against the internal stop 49 as long as sufficient oil pressure is maintained within the cylinder 47.

The rod 61 also receives a pair of studs 62 in threaded engagernent. The studs 62 are carried in collar 64 provided on an arm 66. The studs 62 are free to slide a limited amount within slots provided in collars 68 extending from an arm 69. The upper ends of the arms 66 and 69 receive a pin 71 which permits relative movement between the arms. In order to avoid the possibility of excessive flexing of the diaphragm 57 in either direction, the collars 68 are provided with threaded studs 72 whose ends extend into the slots in which the studs 62 slide and form variable stop means for limiting the displacement of the rods 61.

The sequence for adjusting the pressures in the auxiliary train 19 therefore consists in introducing oil under pressure .into the cylinder 47 until the piston 48 is bottomed against the internal stop 49. As previously explained, in this position the roll 26 will be separated by a small amount from the surface of the roll 28. A final adjustment of the roll pressure and position is accomplished by introducing air or other fluid pressure against (i the diaphragm 57 and thereby move the cylinder and piston assembly further to the left as viewed in Figure 1. The movement of the piston and of the shaft 44 thereupon causes the supplemental frame 21 to be pivoted about the pins 22 in a clockwise direction. Air pressure is then continuously intro-duced until such time as the roll 26 contacts the surface of the metering roll 28 with the d'esired pressure. As previously explained, the rolls in the auxiliary train 19 when in operative engagement are still biased slightly toward their disengaged condition by their own mass supplying a slight turning moment in a counterclockwise direction about the pins 22.

The assembly for coating the opposite side of the paper is substantially the same as that previously described for coating the top surface of a paper web W as it advances through the machine. As evident from Figure l, the web W in entering the coating machine passes under a spreading roller 76 or bar and over a roller 77 before it enters the coating nip existing between the main coating roll 17 and a coating roll 78 on the opposite side of the web W. The auxiliary train for applying the coating composition to the roll 78 is indicated at 79 and includes a transfer roll 81, a metering roll 82, and a backup roll 83. The coating Suspension is supplied to the nip between the rolls 82 and 83 from a pipe 90. The transfer roll 81 is mounted for rotation in a bracltet 84, and is biased toward the roll 78 since the bracket 84 is pivotally secured to the frame assembly by pivot pins 86 which are laterally displaced from the rotational axis of the roll 81. Similarly, the metering roll 82 is biased toward the transfer roll 81 by providing a bracket 87 pivoted by means of an off center pivot 88 to the main frame assembly.

The supports for the auxiliary train 79 consist of a pair of frame members 89 which are pivoted at a pair of spaced pivot pins 91. The lower ends of the frames 89 are secured to shafts 92 which are reciprocated by the operation of the pistons in hydraulic cylinders 93 of the same type as previously described. The fine adjustment of the roll pressures in the train 79 is accomplished by means of controlling the fluid pressure in a set of diaphragm assemblies 94 substantially identical with those previously described. As in the auxiliary train 19, the mass of this coating system is also distributed so that when the rolls are in operative engagement for coating, they are still biased slightly toward their open condition, in this instance, in the direction which would pivot the frame members 89 in a clockwise direction about the pins 91.

The movement of the main frame assembly 14 which adjusts the pressure of the coating nip between the roll 17 and the roll 78 is controlled by another combined oil pressure and air pressure system. Each of the frame members making up the main frame 14 has an extension 96 secured to a shaft 97 which is reciprocable in response to oil pressure introduced into a cylinder 93 and acting against a piston carried by the shaft 97, the arrangement being substantially identical with that shown in Figure 4 of the drawings. When the piston becomes bottomed against the internal stop provided in the cylinder 98, air is introduced into a diaphragm assembly 99 to move the piston and cylinder bodily until the proper nip pressures are achieved.

The complete adjustment of the machine thus comprises the following steps. First, the inter-roll pressures in the auxiliary train 19 are adjusted by introducing oil pressure into the cylinders 47 until the roll 26 is spaced only a small amount from the roll 28. Next, air pressure is introduced into the diaphragm assemblies through the inlets 58 until the roll 26 contacts the roll 28 with the proper pressure. Similarly, the pressure betweeen the rolls in the train 79 is adjusted by control of the oil prssure in the cylinders 93 and the air pressure in the diaphragm assemblies 94.

The coating roll is then positioned by introducing suficient oil pressure into the cylinders 98 to cause the main frame 14 to pivot about the pivot pins 12 in a clock- Wise direction. Since the supplemental frame 21 is carried by the main frame at the pivot pins 22, the pivotal movcment of the main frame about its axis moves the suppiemental frame bodily With the movement of the main frame 1d so that the rolls in the auxiliary train 19 are ltept in the same relative position and under the same pressures during the movement of the main coating roll i7. rfhe final adjustment of roll pressures is accomplished by introdueing air pressure into the diaphragm assembly 99. in the finally adj-usted position, very little of the mass acts against the shaft 97, so that only a very slight force is required to change the pressure relationship of the rolls.

Upon admission of air pressure and oil pressure to the diaphragm assernblies 99 and the cylinder 9d, respectiyely, the main coating rolls are engaged as the main frame iii pivots about the pins 12. When the oil pressure is reduced in the cylinders 47 and the air pressure is removed from the corresponding diaphragrn assemblies, the supplemental frame 21 will be pivoted in a counterclochwise direction and the off center pivots provided on the rolls 26 and 3d Will cause those rolls to move by their own Weight into spaced relation With each other and into spaced relation with the roll 26.

One convenient means for achieving the proper small amount of unbalance into the system is by correlating the air pressure required to counteract the dead weight imposed on the air pressure operated diaphragm with the maximum rated pressure of the diaphragm. The latter value is set by the diaphragm manufacture, and represents the maximum air pressure which the diaphragm can be expected to withstand during normal operation. For the purposes of this invention, the amount of pressure on the diaphragm required to overcome the dead weight imposed on the pressure regulating mechanism should be from about 5 to 25 per cent of the rated diaphragm pressure, and preferably about per cent. When the mass of the coating assembly is distributed so that this cond' on obtains, there is still a relatively small amount of biasmg on the rolls tending to disengage the rolls automatically upon failure of the pressure regulating means, but there is present a considerable Working range of air pressure available to actuate the diaphragm to control accurately the nip pressures in the coating assembly.

The assembly described provides a very convenient means for accurately adjusting roll pressures in a coating assembly and also for adjusting the pressure at the coatmg nip. With the system described, it is possible to make very fine adiustments of the various roll pressures to compcnsate for irregularitics in paper thickness, differences in paper basis weights, viscosity of the coating solutions, and other variables which occur in a paper coating process and which must be compensated to achieve perfect coatingr of the paper.

lt will be evident that various modifications can be made to the described apparatus without departing from the scope of the present invention.

What is clairned is:

l. in a paper coating machine, a roll assembly comprising a main coating roll arranged to apply a coating composition to one side of a Web of paper, a train of auxiliary rolls arranged to transfer said coating composition successively along said rolls and onto said main Coating roll, a pi'v'otall'y mounted frame supporting said main roll, a, suoframe supporting said train, means on said frame providing a pivotal axis for said subframe and means on said subframe for pivotally mounting at least one of the rolls in said train along an axis laterally offset from the axis of rotation of said one roll Whereby pivotal movement of said subfranie With respect to said frame will cause said one roll to move away from an adjoining roll in said train, the combination of said frame, said 8 subframe, and said rolls having a center of gravity when said rolls are in operative engagement only slightly displaced from the pivotal axis of said frame in a direction which urges said rolls out of operative engagement.

2. ln a paper coating machine, a pair of axially hori- :omal parallel rolls through the nip of which the i er passes and to which paper coating-mixture is applied by one of said rolls, the nip and axcs of said rolls located in a planc which is nearer Vertical than horizontal, a main frame carrying the applicato-r roll and adapted to on a horizontal axis spaced from said said last-named axis and the nip being located in second plane which is generally pcrpendicular to the firstmentioned plane, a subframe pivoted on said main frame to rock on a horizontal axis, coating-mixture supply mc'tns including an aY-.ially horizontal roll carried by said nted to contact the applicator roll to z, ure thereto, the axes of the supply and applicator rolls being located in a third plane intersecting the first-named plane at an angle which is closer to than to 0, the center of gravity of the main frame and parts carried thereby being located in a vertical plane not matcrially spaced from the axis of said main frame, means for roclting said main frame to apply pressure to the pa er-coating nip, and means carried by the main frame for rocking said subframe to bring said supply roll into contact with the applicator roll.

3. ln a paper coating machine a pair of axially horizontal parallel rolls through the nip of which the paper passes and to which paper coating-mixture is applied by one of said rolls, the nip and axes of said rolls being located in a plane which is nearer Vertical than horizontal, the applicator roll being the upper roll, a main frame carrying the applicator roll and adapted to rocl; on a horizontal axis below, and spaced from, said hip, said last-named axis and the nip being located in a second plane which is generally perpendicular to the firstmentioned plane, a subframe pivoted on said main frame to rock on a horizontal aYis, coating-mirture supply means including an axially horizontal roll carried by said subframe above said main frame axis adapted to contact the applicator roll to supply coating-rnixtnre thereto, the axes of the supply and applicator rolls being located in a third plane intersectiug the first-named plane at an angle which is closer to 90 than to 0, the axis of said subframe being located below said supply roll axis, the center of gravity of the main frame and parts carried thereby being located in a Vertical plane not materially spaced from the axis of said main frame, means for rocltq said main frame to apply pressure to the papercoating nip, and means carried by the main frame for rocldng said subframe to bring said supply roll into contact With the applicator roll.

4. in a. paper coating machine, a frame pivoted on a horizontal axis, a roller-coating mechanism including a roll carried by said frame on an aXis parallel to the frame axis and substantially spaced from said .frame axis and so located relative to the frame axis that the center of gravity of said frame and parts carried thereby including said roll is located at a point not materially spaced from a Vertical plane extending through the frame aXis, and means for rocking said frame on its axis to move said roll into and out of operative position, which means iucludes a pair of iluid-pressure-actuated devices connected together to operate in series, one of said devices being of long stroke and the other of said members being of relatively short stroke, the actuation of the long-stroke device serving to rock the frame and move the roll When the latter is out of operative position and the short-stroke device being adapted to adjust the pressure on the roll when the roll is in operative position.

5. ln a paper coating machine, a frame pivoted on a horizontal axis, a roller-coating mechanism including a roll carried by said frame on an axis parallel to the frame axis and substantially spaced from said frame axis and so 9 located relative to the frame axis that the center of gravity of said frame and parts carried thereby including said roll is located at a point not materially spaced from a Vertical plane extending through the frame axis, and means for rocking said frame on its axis to move said roll into and out of operative position, which means includes a pair of fiuid-pressure-actuated devices connected together to operate in series, one of said devices being of the long stroke piston type, and the other of said members being of the relatively short stroke diaphragm type, the actuation of the long-stroke device serving to rock the frame and move the roll when the latter is out of operative position and the short stroke device being adapted to adjust the pressure on the roll When the roll is in operative position, and means for supplying to said long-stroke device fluid in such amount and under such pressure as to prevent any improper movement of its piston during control of the roll-pressure by the short-stroke device.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,563 Recht Apr. 7, 1942 2,406,056 Barrett Aug. 20, 1946 2,406,057 Barrett et al. Aug. 20, 1946 2,513,394 Barrett et al. July 4, 1950 2,556,032 Faeber June 5, 1951 2,606,520 Hoel Aug. 12, 1952 2,645,199 Zonner July 14, 1953

Claims (1)

1. 4. IN A PAPER COATING MACHINE, A FRAME PIVOTED ON A HORIZONTAL AXIS, A ROLLER-COATING MECHANISM INCLUDING A ROLL CARRIED BY SAID FRAME ON AN AXIS PARALLEL TO THE FRAME AXIS AND SUBSTANTIALLY SPACED FROM SAID FRAME AXIS AND SO LOCATED RELATIVE TO THE FRAME AXIS THAT THE CENTER OF GRAVITY OF SAID FRAME AND PARTS CARRIED THEREBY INCLUDING SAID ROLL IS LOCATED AT A POINT NOT MATERIALLY SPACED FROM A VERTICAL PLANE EXTENDING THROUGH THE FRAME AXIS, AND MEANS FOR ROCKING SAID FRAME ON ITS AXIS TO MOVE SAID ROLL INTO AND OUT OF OPERATIVE POSITION, WHICH MEANS INCLUDES A PAIR OF FLUID-PRESSURE-ACTUATED DEVICES CONNECTED TOGETHER TO OPERATE IN SERIES, ONE OF SAID DEVICES BEING OF LONG STROKE AND THE OTHER OF SAID MEMBERS BEING OF RELATIVELY SHORT STROKE, THE ACTUATION OF THE LONG-STROKE DEVICE SERVING TO ROCK THE FRAME AND MOVE THE ROLL WHEN THE LATTER IS OUT OF OPERATIVE POSITION AND THE SHORT-STROKE DEVICE BEING ADAPTED TO ADJUST THE PRESSURE ON THE ROLL WHEN THE ROLL IS IN OPERATIVE POSITION.

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