US3239948A

US3239948A - Drying apparatus for coated webs

Info

Publication number: US3239948A
Application number: US364362A
Authority: US
Inventors: Mino Alfonso Di
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1964-04-29
Filing date: 1964-04-29
Publication date: 1966-03-15
Anticipated expiration: 1983-03-15

Description

March 15, 1966 A. Dl MINO DRYING APPARATUS FOR COATED WEBS 5 Sheets-Sheet 1 Filed April 29, 1964 FIG./

INVENTOR. A y-130180 DI Mlvo M d G ATTORNEY March 15, 1966 A. Dl MlNO 3,239,948

DRYING APPARATUS FOR COATED WEBS Filed April 29, 1964 5 Sheets-Sheet 3 HVVENTDR. Ak F'ONSO DI Mme ATTORNEY 5 Sheets-Sheet 4.

March 15, 1966 A. Dl MINO DRYING APPARATUS FOR COATED WEBS Filed April 29, 1964 w w wE mM so m2 m0 V m o w o F L A wuaaom w T/\ T52.

BY %k\ C. M

RT TO RN EV March 15, 1966 A. D] MINO 3,239,948

DRYING APPARATUS FOR COATED WEBS Filed April 29, 1964 5 Sheets-Sheet 5 INVENTOR. AL FONSO DI MIA/ %MQM A TTORNE V United States Patent 3,239,948 DRYING APiARATUS FOR COATED WEBS Alfonso Di Mino, Woodclitf Lake, N.J., assignor to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed Apr. 29, 1964, Ser. No. 364,362 12 Claims. (Cl. 34-161) This application is a continuation-in-part of Serial No. 143,415 filed Occtober 6, 1961, now abandoned.

This invention relates to drying apparatus and, particularly, to apparatus for drying continuously moving webs coated with a substance dispersed in a vaporizable solvent or carrier.

The present invention may be used for drying any type of coated article whether the coating be decorative, protective, or useful. Coated articles which may be dried with the apparatus of the invention are generally prepared by depositing a substance dispersed in a vaporizable carrier or solvent for the coating material dries relatively by any suitable process. After the coating operation is performed, it is necessary to dry the article before it can be stored or used. A problem arises in drying when the carrier of solvent for the coating material dries relatively slowly. When such a carrier is employed, the drying apparatus, through which the coated web is passed, must generally be both slow moving and of considerable length. Under some circumstances, the drying apparatus itself, exclusive of the coating apparatus, may be of such size that is must itself be housed in a relatively large-size buildmg.

The purposes and objects of the present invention are directed toward the provision of improved drying apparatus which is useful for drying all types of continuously moving coated webs, the apparatus being characterized by its compactness and its ability to operate efliciently at high speed.

Briefly, the apparatus of the invention comprises a plurality of concentric arrays of rolls, over which the coated web to be dried is passed. Each roll of each array is positively driven, and is also adapted to be maintained at a selected drying temperature. The outermost array of rolls is operated at a temperature close to the temperature of the coated web as it leaves the last operation of the coating process and enters the drying apparatus. The next inner array of rolls is operated at a higher temperature, the next adjacent inner array of rolls is operated at a still higher temperature, and so forth, with the number of arrays and temperatures being selected so that, when the coated web reaches the center of the arrays of rolls, it is completely dry. Since each roll in each array is positively driven and is maintained at a suitable operating temperature, fast and complete drying is achieved,

In one form of the invention, auxiliary drying means is provided which incorporates the forced flow of air, the air being heated, if desired. For this purpose, one side of the apparatus of the invention is open so that a large mass of air is drawn under control over all available surfaces of the drying web simultaneously. This air may be treated, after it passes over the drying web, to remove solvents picked up thereby.

The invention is described in greater detail by reference to the drawing wherein:

FIG. 1 is a generally schematic view of a side elevation of a portion of the drying apparatus of the invention;

FIG. 2 is a generally schematic view of a side elevation of a portion of the apparatus of the invention and driving means therefor;

FIG. 3 is an end elevational view of a portion of the apparatus of the invention showing a supporting frame and drive means therefor;

ice

FIG. 4 is a front elevational view of a modification of the invention;

FIG. 5 is a perspective view, from the rear and partly in section, of the apparatus of the invention; and

FIG. 6 is a schematic representation of a portion of the apparatus of the invention and means for loading a coated web to be dried in the apparatus of the invention.

Referring to the drawings and particularly to FIGS. 1 and 3, drying apparatus 10 embodying the invention includes a plurality of concentric arrays of drying rolls over which a coated web 12 to be dried is passed. The apparatus includes a first, innermost array of

rolls

26A, 20B, 29C, 20D disposed at the corners of a generally cubic volume large enough to enclose a reel of the dried coated web. The apparatus includes a second array of

rolls

21A, 21B, 21C, 21D disposed at the corners of a cube which is somewhat larger than, and surrounds, the first smaller cube defined by rolls 20A to 20D. The apparatus also includes third and fours arrays of

rolls

22A, 22B, 22C, 22D and 23A, 23B, 23C, 23D which define successively larger cubic volumes, each of which encloses the smaller inner cubes. The number of rolls in an array and their general arrangement may be varied, and the number of arrays of rolls may be varied as required for a particular drying operation. Suitable auxiliary guide rolls (not shown) for the web may be provided as required in operative relation with the various arrays of

rolls

20, 21, 22, and 23.

The housing for supporting the various arrays of drying rolls may take any suitable form and need not be described in great detail. One suitable housing may comprise a pair of spaced-apart large-area, generally rectangular side frames 14 and 16 (FIG. 3) made up of steel beams or the like and carrying suitable support plates 18 (FIG. 1) on which the various rolls are rotatably supported.

According to the invention, each drying roll is adapted to be positively driven and temperature-controlled by means of a circulating fluid. Accordingly, each roll is provided with a hollow shaft 30 (FIGS. 1, 2, 6) which communicates with the interior of the roll and through which a fluid may be circulated. In addition, each shaft 30 carries suitable pipe coupling means 31 (FIG. 3) which allows the roll both to rotate and receive circulating fluid at the same time. Suitable inlet and outlet conduits 32 and 33 (FIG. 3) are secured to coupling means 31. A gear or other suitable driving means is also mounted on each shaft 30 (FIG. 2) whereby the roll may be positive ly driven. Thus, roll 20A has gear 20'A, roll 20B has gear 20'B, and so forth.

The gearing and driving arrangement for the drying rolls of apparatus 10 may take any one of many suitable forms, and one typical arrangement is illustrated schematically in FIG. 2, in which only a sufiicient number of the rolls is shown to make the driving arrangement clear. In addition, the gear teeth on the various gears are not shown. In this one suitable arrangement, an auxiliary gear 34 is positioned between, and couples together, the gears of adjacent rolls of adjacent arrays so that the gear of one roll in one array couples and drives the gear of the adjacent roll in the adjacent array. A single, continuous link chain 38 is wound on, and interconnects, the four innermost rolls 20A to 20D. A motor 40 is coupled by

chains

42 and 46 to suitable auxiliary gears (not shown), or the like, secured to the shafts 30 of rolls ND and 20C, respectively. Thus, power is transmitted from the motor 40 through

chains

42 and 46 to the auxiliary gears on rolls 20D and 20C, respectively, and then through chain 38 to all of the other gears.

Any suitable arrangement may be employed for circulating a temperature controlled fluid through the various drying rolls of apparatus 10. For example, as illustrated in FIG. 3, each array of rolls may have its own temperature control apparatus including a source of fluid, means for heating or cooling the fluid, a suitable pump and piping, all represented by blocks T1, T2, T3, and T4. Each of these blocks is associated with one array of rolls. Alternatively, a single fluid source and pump (not shown) may be coupled to a plurality of parallel fiow loops, each feeding one array of rolls.

In any case, according to the invention, each roll of an array is operated at about the same temperature, with the rolls of adjacent arrays being operated at different temperatures. Generally, the rolls 23A to 23D are operated at a temperature close to the temperature of the coated web as it leaves the coating apparatus (not shown) associated therewith. The rolls 22A to 22D are at some higher temperature. The rolls 21A to 21D are at a still higher temperature, and so forth. It is clear that the specific temperatures selected depend on many variables, and those skilled in the art will experience no difficulty in determining and obtaining the necessary temperatures to practice the invention. One suitable combination of Fahrenheit temperatures for removing water from a coated web is 250, 225, 200, 180, in order, from the inner rolls to the outer rolls. One suitable combination for removing a typical organic solvent is 200, 180, 160, 150, in the same order as above.

The drying apparatus 10 includes a takeup reel 60 (FIG. 1) on which the web 12 is wound as it is dried. The takeup reel is positioned at the center of the arrays of drying rolls. In its simplest form, the takeup reel comprises a shaft which is rotatably mounted in a horizontal position on a suitable carriage 66 (FIG. 3) and is driven at a speed which is properly related to the speed at which the various drying rolls are driven. The inner end of the shaft is provided with suitable clutch means 70 which is adapted to engage, and be disengaged from, a complementary clutch means 74 (FIG. 3) which is suitably rotatably mounted on one of the wall frames 16 and is coupled to the motor 40 by suitable gearing means 75. The takeup reel 60 could be hand-operated or driven in any other suitable manner.

The supporting carriage 66 for the takeup reel, in one suitable form is generally box-like and has an open top so that the reel carrying a quantity of dried Web may be easily removed therefrom. The carriage 66 (FIG. 3) rides on a pair of horizontal spaced-apart tracks 78 and 82 by means of wheels, gears, or the like. The tracks are suitably secured, for example, to the side frames 14 and 16 of the dryer housing. The carriage carries its own driving motor 86, and limit switches 90 and 91 for turning the motor on and off are provided, for example, on track 82, to fix the ends of the path of travel of the carriage. Of course, the carriage could be moved by hand, if desired.

A modification of the invention shown in FIGS. 4 and includes all of the apparatus described above and, in addition, certain auxiliary apparatus which enhances the drying operation and provides other refinements. The drying apparatus 93 shown in FIGS. 4 and 5 includes a housing 94 consisting of a top wall 96, a bottom wall 98, and side walls 100. The front of the dryer 93 is open and the rear includes certain elements to be described. The arrays of

rolls

20, 21, 22, and 23, or any other array, and the other associated apparatus are provided within the housing 94 as described above.

In front of the housing 94 and at either side adjacent to the side walls 100 are provided two vertically elongated, relatively narrow,

air ducts

102 and 104 which are preferably the same height as the drying apparatus 93. The two ducts are oriented facing each other, and they are coupled to a source of air 106 which includes means for regulating the temperature and humidity of the air provided thereby. This arrangement of the

ducts

102 and 104 and air source 106 is adapted to provide a curtain of air represented by arrows 200 (FIG. 5) from side to side across the entire open front of the dryer 93. The air can flow in either direction from duct 102 to duct 104 or from duct 104 to duct 102.

At the rear of the dryer 93 and directly behind the arrays of rolls is a vertical plate or wall 108 which covers the entire area of the dryer and is provided with a multiplicity of apertures 110 over its entire surface for regulating the flow of air through the housing 94 during a drying operation. Behind the large-area apertured plate is a length of pipe 112 which extends back and forth from side to side and from top to bottom of the housing to cover the entire area of the dryer. The pipe 112 includes at its ends inlet and outlet means 114 and 116, respectively, through which a cooling fluid may be fed into and out of the pipe from a suitable source 118. A fluid collecting vat having a drain 122 is provided beneath the pipe 112 at the bottom of the dryer 93 and extending across the width of the housing to receive fluid material which condenses on the pipe 112. Finally, the rear of the dryer 93 is closed by a solid exterior wall 124 from which a duct 126 extends to an air exhaust suction fan or the like 128 for use in drawing air through and out of the housing.

In operation of the apparatus of the invention, it is assumed that a coated web 12 is transported directly to the drying apparatus 10 from coating apparatus (not shown) located adjacent thereto. The coated web is provided with a length of leader 136 which is used in threading the web on the drying apparatus. The web is threaded on the rolls and is run through the drying apparatus along a spiral-like path with its uncoated surface in contact with the drying rolls and with its coated surface facing up and free of contact with any surface until it reaches the takeup reel. When the web reaches the takeup reel, it is completely dry. This feature provides one of the important advantages of the invention.

In addition to this basic mode of operation of the invention, the dryer 93 shown in FIGS. 4 and 5 provides the following added features of operation. If the ambient air surrounding the drying apparatus varies undesirably in temperature and humidity, then the air source and ducts are used to provide, across the open front of the apparatus, a curtain of air of controlled temperature and humidity. This air is provided by source 106 and is drawn through the dryer by the suction fan 128. Since this curtain of air covers the entire area of the dryer, it flows tangentially over all of the exposed surfaces of the coated web inside the housing. The apertured plate 108 delays slightly the flow of air through the housing and allows the air to engage the coated web intimately and for a favorable length of time to permit the air to pick up solvent material, water, and any other liquid present in the coating on the web. When this fluid-laden air passes through the apertured plate or wall 108 and strikes the cold pipe 112, the fluids are condensed and collected in the vat 120. Thus, the solvents are recovered and may be re-used, if desired.

In threading the web on the drying apparatus to initiate the drying operation, the leader is passed first around the outermost array of rolls, passing over rolls 23A, 23B, 23C, and 23D and then around the rolls of the next inner array, passing first over roll 22A then over rolls 22B, 22C, and 22D. The leader is then wound in the same way around the next inner array and finally around the innermost array of rolls and from roll 20D around the guide rolls, and it is then secured to the takeup reel by means of tape or the like.

The threading operation may be performed in any suitable manner. In one simple and convenient mechanical arrangement, a pair of pulleys 140 and 144 (FIGS. 3 and 6) are mounted on the hollow shaft 30 associated with each drying roll and are secured thereto on opposite sides of the roll itself. Two continuous loops 148 of twine, fine wire, or the like are then wound one on each set of rolls, with each loop following the path to be taken by the leader as it is threaded, that is, first around the outermost array and then around the inner arrays. In the simplest arrangement, a rod 150 is horizontally positioned and secured to the spaced-apart guide loops 148, and the leader 136 to be threaded is taped or otherwise secured to the rod. When the motor 40 is turned on and the drying rolls are rotated, the rod 150 and its attached leader 136 are carried with the guide wires 148 from the outermost array to the center of the apparatus where the leader is detached from the rod and suitably secured to the takeup reel.

The temperatures of the various arrays of rolls are then set at the'desired level, and the various motors are turned on to drive the takeup reel 60 and the drying rolls. The temperatures of the rolls and the driving speed are arranged so that the web is completely dry when it reaches the takeup reel.

In one form of the apparatus of the invention, support frame and housing 94 were'approximately ten feet square and included four arrays of drying rolls, as shown above. With this apparatus, spirit-type carbon paper was dried at the rate of about 500 feet per minute. In another typical operation, a coated paper having a 50% water content when it left the coating apparatus was dried at a speed of about 350 feet per minute. In the prior art, speeds under 100 feet per minute are most common, and coating apparatus is generally excessively large. In addition, the coated web, as it is dried, generally comes into contact with the drying apparatus. These problems in the prior art emphasize the advantages of the present invention which is relatively small in size and operates effectively at high speed. The fact that each of the rolls is temperature-controlled and positivey driven contributes greatly to the effectiveness of the drying apparatus of the invention.

What is claimed is:

1. Drying apparatus for drying a continuous and moving length of a coated web comprising a plurality of concentric arrays of drying rolls,

fluid flows means coupled to each array of rolls for passing a temperature-controlled fluid therethrough and for separately adjusting the operating temperature thereof,

driving means coupled to each roll for positively driving each roll,

a take-up reel in operative relation with said arrays of rolls for receiving and winding up said web as it is dried by the arrays of rolls,

a housing surrounding said arrays of rolls,

air flow means including suction apparatus coupled to said housing to create a flow of air through said housing and over said web contained therein and causing said web to be dried,

an apertured wall in said housing between said arrays of rolls and said suction apparatus, the flow of air being through said apertured wall,

an array of piping positioned between said apertured wall and said suction apparatus, said piping being adapted to have a cooling fluid circulated therethrough, and

a vat disposed beneath said piping to receive fluid which condenses on said piping.

2. The apparatus defined in claim 1 wherein said rolls are hollow and said fluid flow means for circulating a heating fluid therethrough is temperature-regulated so that the outermost array of rolls is traversed first by the coated web to be dried and is operated at a first temperature,

the next adjacent array of rolls being operated at a second higher temperature and so forth with the innermost array of rolls being operated at the highest temperature.

3. The apparatus defined in claim 1 wherein each array of rolls defines a generally cubical volume with each roll of an array being oriented generally at one corner of the cube defined by the array and with the volumes having a substantially common center,

the innermost array of rolls defining the smallest volume and each succeeding array defining larger and larger volumes with the outermost array enclosing all of the other arrays and defining the largest volume, said web being adapted to be drawn over and to contact and follow first the outermost array of rolls and then the next inner array of rolls and so forth until it reaches said take-up reel which is positioned generally at the common center of said arrays of rolls and to which it is secured,

said web traversing said rolls with its uncoated surface in contact with said rolls and its coated surface facing away from said rolls,

said Web thus being heated and dried by direct contact with said rolls.

4. Web drying apparatus comprising a housing having an open front and a rear wall,

suction apparatus coupled to said rear Wall,

a plurality of arrays of rolls positioned in said housing and adapted to draw a web to be dried along a spirallike path from outside said housing to the center of said housing,

the direction of movement of said web being parallel to the plane of said rear wall,

an apertured wall positioned adjacent to said rear wall and between said rear wall and said arrays of rolls,

and means adjacent to the open front of said housing for providing a curtain of air across the open front of the housing, said suction apparatus being adapted to draw air from said curtain of air through said housing and across said web by said suction apparatus.

5. The apparatus defined in claim 4 and including fluid condensing means in said housing between said apertured wall and said rear wall.

6. The apparatus defined in claim 4 and including between said apertured wall and said rear wall means for conensing fluid and means for collecting condensed fluid.

7. The apparatus defined in claim 4 and including fluid condensing piping extending back and forth across the width of the housing between said apertured wall and said rear wall,

and further including means in operative relation with said piping for collecting condensed fluid.

8. Web drying apparatus comprising a housing having an open front and a rear wall,

suction apparatus coupled to said rear wall for drawing air through said housing from the front to the rear,

a plurality of arrays of rolls positioned in said housing and adapted to draw a web to be dried through said housing along a continuous spiral-like path from outside the housing to the center of the housing,

the direction of movement of said web being parallel to the plane of said rear wall, said web being supported by said rolls with its surface to be dried oriented generally parallel to the direction of air flow through said housing so that air flows over the entire surface to be dried,

and means adjacent to the open front of said housing for providing a curtain of air across the open front of the housing, said suction apparatus being adapted to draw air from said curtain of air through said housing and across said web whereby the drying of said Web is facilitated.

9. The apparatus defined in claim 8 wherein each array of rolls defines a generally cubical volume with each roll of an array being oriented generally at one corner of the cube defined by the array and with the volumes having a substantially common center, the innermost array of rolls defining the smallest volume and each succeeding array defining larger and larger volumes with the outermost array enclosing all of the other arrays and defining the largest volume.

10. The apparatus defined in claim 8 and including fluid condensing means in said housing between said arrays of rolls and said rear wall.

rear wall,

and further including means in operative relation with 10 said piping for collecting condensed fluid.

References Cited by the Examiner UNITED STATES PATENTS 6/1902 Crowell 34-155 1 8 Cummings 98-36 Rice 34-115 Lilly 98-115 X Curren. Ireland 34-119 Gangler 34-155 Carter 34-155 Angermueller 98-36 Morrow 98-115 Snow et a1. 98-115 McNeil et al. 98-115 WILLIAM F. ODEA, Primary Examiner.

5 NORMAN YUDKOFF, Examiner.

Claims

4. WEB DRYING APPARATUS COMPRISING A HOUSING HAVING AN OPEN FRONT AND A REAR WALL, SUCTION APPARATUS COUPLED TO SAID REAR WALL, A PLURALITY OF ARRAYS OF ROLLS POSITIONED IN SAID HOUSING AND ADAPTED TO DRAW A WEB TO BE DRIED ALONG A SPIRALLIKE PATH FROM OUTSIDE SAID HOUSING TO THE CENTER OF SAID HOUSING, THE DIRECTION OF MOVEMENT OF SAID WEB BEING PARALLEL TO THE PLANE OF SAID REAR WALL, AN APERTURED WALL POSITIONED ADJACENT TO SAID REAR WALL AND BETWEEN SAID REAR WALL AND SAID ARRAYS OF ROLLS, AND MEAND ADJACENT TO THE OPEN FRONT OF SAID HOUSING FOR PROVIDING A CURTAIN OF AIR ACROSS THE OPEN FRONT OF THE HOUSING, SAID SUCTION APPARATUS BEING ADAPTED