US2554239A

US2554239A - Web drying system

Info

Publication number: US2554239A
Application number: US784568A
Authority: US
Inventors: Joseph R Caulfield; Milton E Hanson
Original assignee: CHAMPLAIN CO Inc
Current assignee: CHAMPLAIN CO Inc
Priority date: 1947-11-07
Filing date: 1947-11-07
Publication date: 1951-05-22
Anticipated expiration: 1968-05-22

Description

y 22, 17951 J. CAULFIELD ETAL 2,554,239

WEB DRYING SYSTEM Filed Nov. 7, 1947 I 3 Sheets-Sheet 1 INVENTORS Jjrrw K (flUlF/ELO Mara/v E. fl/i/vjom /777'0 A/E J y 1951 J. R. CAULFIELD ET AL 2,554,239

WEB DRYING SYSTEM 3 Sheets-Sheet 2 Filed NOV. 7, 1947 'I' "IF y 1951 J. R. cAULl 'lELD ETAL 2,554,239

WEB DRYING SYSTEM Filed Nov. 7, 1947 3 Sheets-Sheet 3 INVEN TOR5 JZjEfi/i 16 04am F151. 0

Mara/v 2 H4/waw Patented May 22, 1951 WEB. DRYING SYSTEM Joseph R. Caulfield, West Norwood, and Milton E. Hanson, Haddonfield, N. J., assignors to Champlain Gompany, Inc., Bloomfield, N. J., a corporation of New York Application November 7, 1947, Serial No. 784,568

8 Claims.

1 This invention relates to web drying system and more particularly to systems for printing presses of the rotogravure type.

There are many uses in industry for a drier which will rapidly dry a fast moving web. A common example is in printing, particularly when doing multi-color work in which the web passes through successive printing units operating in synchronism.

The primary object of the present invention is to generally improve web driers.

A more particular object is to provide a drier which is compact in dimension, or so arranged as to provide a maximum length of web which s undergoing drying without, however, unduly increasing the spacing required between the successive presses of a multi-color printing press.

Another object of the invention is to provide a drier which is relatively simple in construction, yet which may be opened in such a manner as to facilitate webbing, that is, the threading of a. web around the various rollers of the press and drier.

Still another object of the invention is to provide a drier in which the heated air is recirculated in order to conserve heat. However, a desired portion of the circulating air is exhausted and replaced with fresh air in order to reduce fire hazard, and to avoid saturation with volatiles.

In accordance with another features .and object of the invention, a common exhaust fan may be used for all of the driers, yet. the amounts of air withdrawn from the individual driers may be relatively adjusted.

Still another object of the invention is to so design the drier that it may be used with webs of different width, or more specifically, with Webs narrower than the maximum width for which the drier is designed, without permitting excessive air leakage into the drier.

To accomplish the foregoing objects, and other more specific objects which hereinafter appear, our invention resides in the drier elements and their relation one to another as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

Fig. 1 is an elevation showing a multi-color printing press provided with driers embodying features of the invention;

Fig. 2 is a partial plan view of the same;

Fig. 3 is a partially sectioned, side elevation of one of the drier units;

Fig. 4 is a plan view of the same;

Fig. 5 is a transverse section taken approxi mately in the plane of the line 5-5 of Fig. 4;

Fig. 6 shows the exhaust fan; and

Fig. '7 is a fragmentary section drawn to enlarged scale and explanatory of the nozzle construction.

Referring to the drawings, and more particularly to Fig. 1, the multi-color printing press there shown comprises a reel carrier generally designated l2, and a power driven web feed unit generally designated l4. The web is then fed through successive printing presses I6, I8, 20 and 22, having individual driers or hoods associated therewith as indicated at 26, 28., 30 and 32 respectively. The web leaving the last drier is rewound by a suitable rewind unit 34. Although not shown in detail, it will, be understood that the feed unit is driven by a variable speed drive, such as D. C. motor with rheostat control, or a synchronous motor with a Reeves. or equivalent drive. The rewind unit 34 may be similarly driven by an in dependent drive. The assembly of presses is driven by a main drive motor and a common shaft, with appropriate intermediate mechanism at each press for adjusting the registration of the printing.

The web is printed while passing between a gravure cylinder 36 and a pressure cylinder 38, the web being guided therebetween by guide rollers 4|] and 42. The roller 42 and additional rollers 44, 46 and 48 provide an inverted U-shaped web lead. The drier itself is also in the form of an inverted U. In this way a maximum length of web may be exposed to drying action without appreciably increasing the necessary spacing between the successive presses.

The drier arrangement is shown in greater detail in Fig. 3, and referring to that figure it will be seen that the web 50 is in inverted U shape, and that it is paralleled by a nozzle plate 52 which is also in inverted U shape. The said nozzle plate is made up of numerous nozzles which direct air against substantially all of the web in the drier. To feed air to the nozzle plate, a plenum chamber is disposed therearound. This may be thought of as comprising

vertical plenum chambers

54 and 56, together with a horizontal plenum chamber 58, although actually all of these chambers are in communication with each other and constitute in effect a single U-shape-d chamber.

The plenum chambers are supplied with air under pressure by means of a single fan 60. This is carried on a vertical shaft 62 having a pulley 64 for connection to a drive motor. The fan inlet is at the top, the bottom of the impeller being closed. The air is thrown outwardly and flows in opposite directions to the two

plenum chambers

54 and 56, as is indicated by the arrows. Heaters 66 and 68 are located on opposite sides of the fan between the fan and the plenum chambers, so that the air is forced through the heaters on its way to the nozzle plate.

To more readily understand the operation, it should first be assumed that there is a horizontal partition located just beneath the fan impeller 60 and defining the top wall of a horizontal plenum chamber. The ends of such partition would connect with the inner walls of the heaters. All of the air discharged from the fan would blow through the heaters, and would then distribute itself through the horizontal and vertical plenum chambers, and thus be fed to all of the nozzles.

The drier may in fact be so constructed, but in practice it has been found that the horizontal partition may be omitted without appreciably changing the operation. This is so because of the horizontal directivity of the fan impeller 69. In other words, the air leaving the impeller flows horizontally,'and is therefore directed through the heaters. The heated air then flows back over the horizontal nozzle plate, as well as downwardly along the vertical nozzle plates. Thus it is found that the air blowing through the horizontal nozzle plate is heated air rather than cold air, despite the absence of the horizontal partition referred to above.

Even if the fan were not directive, a full flow of air would pass through the horizontal nozzle plate, for the entire chamber above the plate is under pressure. The only difference is that the air at the top might be less heated than the air at the sides.

Nothing herein said is intended to exclude the use of a horizontal partition from the scope of the invention, and nothing is lost, and there may even be a slight gain in efficiency when using such partition.

In order to conserve the amount of heat required, the air is preferably recirculated. The manner in which this is done will be clear from inspection of Fig. 5, forafter leaving the nozzles and being blown against the web the air flows sidewardly beyond the side edges of the web, and then upwardly in appropriate return passages to the fan inlet 12. This recirculation of air is also illustrated in Fig. 4, for the air flows from

plenum chambers

54 and 56 inwardly through the upright nozzle plates schematically indicated at 52, against the web, not shown, whereupon the air flows sidewardly to the return passages 10 which are located outside the

plenum chambers

54 and 56. At the top of the drier the air flows from vertical passages 10 through horizontal passages H at the sides of the drier, and thence inwardly to the fan inlet.

Reverting to Figs. 1 and 2, there is a common exhaust conduit or duct 14 connected to each of the hoods as indicated at I6, 18, 80 and 82. A common exhaust fan is connected to duct 14. This fan is not shown in Fig. 1, but is indicated schematically at 84 in Fig. 2, and is shown in greater detail in Fig. 6, the latter figure showing the motor 86 which drives the exhaust fan, as by means of pulleys and a belt 88. The other end 90 of the duct I4 (Fig. 2) is closed, so that the suction of the fan is applied through the connections 16-82 to each of the driers. This withdraws a portion of the circulating air, the. Said 4, air being replaced by leakage of fresh air into the driers through numerous leakage points, referred to later, for example, where the web enters and leaves the hood.

In order to regulate the ratio of the air replaced to the air that is being recirculated, each of the connections 1682 is provided with a damper. Such a damper is shown at 92 in Fig. 5, the damper being controlled by an arm 96 which may be locked by means of a thumb nut 95 working on a sector 91 (Fig. 2). In Fig. 2 the controls for the various dampers are indicated at 96, 98, I and I02 respectively.

In a particular design we have found it desirable to feed 2,000 cubic feet of air a minute to the plenum chambers, for a 26 inch press; that is, a press accommodating a web 26 inches in width. We have further found that a good ratio of recirculated to fresh air is 1400 to 600; that is 600 of the 2,000 cubic feet is fresh air, while 1400 cubic feet is recirculated air.

The recirculation of air conserves the amount of heat needed in the heater elements. The introduction of approximately one-third fresh air prevents the building up of an excessive charge of volatiles, such as would create an explosion hazard or fire hazard, and also avoids loss of drying efiiciency such as would be caused by the presence of excessive quantities of volatiles in the air blown against the web.

It has already been mentioned that the nozzle plate 52 has a continuous series of nozzles therealong. In practice, the nozzles are preferably long slots which extend from one side edge of the plate to the other. This is best shown in Fig. 5 which, taken together with Fig. 7, shows how the nozzle plate may be built up of a series of trough-like or channel-shaped pieces of sheet metal H14 and IE6 which define nozzles such as the nozzle I08 therebetween. The nozzles are so shaped that the air blown therethrough spreads out on its way to the web 50, and the streams of air from adjacent nozzles almost reach one an-' other, so that the entire surface of the web is subjected to the drying action of the heated air.

We have found that a velocity of 2500 feet per minute is desirable, and to obtain this an air pressure of approximately one and one-half inches of water is maintained in the plenum chambers. Negative pressure or suction produced by the exhaust fan may be of the order of one-half inch of water.

Reverting to Fig. 2, the pulleys 64 of the blowers are connected by means of V belts Hi! to electric motors indicated at H2. These are bolted to the sides of the driers, and the fan speed may be regulated by adjustment of the V pulleys 64. a

To facilitate webbing the machine, the outer walls of the

plenum chambers

54 and 56 are preferably hinged to the top portion of the hood, as shown at [M in Figs. 3 and 5. This permits the side walls and outer walls of the chambers to be swung outwardly, as is indicated by the broken line positions 54' and 56, respectively. When this is done, the space within the nozzle plate is exposed, thus facilitating the passage of the web 50 through the drier and around the guide rollers. When closed the chambers may be locked by latches H3 (Fig. 3) controlled by a handle H5 (Fig. 5)

For the same purpose the side wall of the upper part of the hood is hinged and may be swung outwardly, this being indicated in Fig. 5, in which the side wall I t6. has been swung out- 124 and most to the guide rollers 44 and 46.

wardly somewhat from its closed position. It

may be moved upwardly to nearly horizontal position, and held by pivoted support arms H8. This aids feeding of a new web beneath the horizontal portion of the nozzle plate.

The drier hood is preferably provided with backing plates indicated in Fig. 3 at 120, I22, I26. The backing plate 120 extends upwardly to a point close to the guide roller 44. Horizontal backing plate 122 extends al- Plate 124 fills the space between guide rollers .46 and 41 while the plate 126 fills the space beneath guide roller 41.

The backing plates need not fit closely against the rollers, and the provision of some space therebetween is actually desirable in order to facilitate the leakage of fresh air inwardly to replace the air exhausted by the exhaust fan.

It is desirable to provide such backing plates, rather than to rely solely on the web alone, because webs narrower than the maximum usable width are frequently run through a printing press. When narrower webs are used, there would be excessive open space at each edge of the web, were it not for the backing plates.

The relative positions of the guide rollers and the backing plates is preferably made such that the web is spaced slightly from the backing plates, and does not rest on or rub against the same. In other words, the backing plates are not intended to actually support or guide the web, and instead that function is taken care of by the rollers.

In Fig. 3 reference was made to the heaters 66 and .68. In the present case the heaters are supplied with steam, and inlet and outlet pipes for that purpose are indicated at I30, I32, I34 and I36. also shown in Fig. 2. The heaters are not shown in detail, for heat exchangers are well known, and in the present case may be of the steam coil type or of the honeycomb type. It will also be understood that heaters of entirely different type may be used, as for example electrical or resistance heaters, and in the latter case the heating units may be of the resistance wire type, or the Calrod type. It will also be understood that the temperature to which the air is heated may be automatically controlled in known conventional ways, as by means of a thermo-couple in the plenum chamber, with wiring leading to appropriate means for controlling the steam supply or the electric supply to the heaters.

In addition to the heat introduced by the drier units themselves, it may be mentioned that the first roller following the gravure cylinder. in this case the roller 42 in Fig. 1,. may be aheated roller. The use of such a heated roller is do sirable when printing on a transparent web, such as regenerated cellulose or cellulose acetate (cellophane, etc), but the heated roller may be eliminated when printing on paper.

It is believed that the construction and operation, as well as the advantages of our improved drier will be apparent from the foregoing detailed description. The drier is compact, yet operates on a substantial length of web. The spacing between successive presses may remain small. The drier is relatively simple in construction, and it is easy to web the machine. The bulk of the air is recirculated to conserve heat, but a portion of the air is replaced in order to minimize explosion hazard.

Some of these connections are Each drier has its own main fan, while a sinsleexhaust fan is employed for all of the driers, yet the amount of air exhausted may be equalized, or varied as desired, by the use of individual dampers on each drier. Webs of different width may be run through the drier.

It will be understood that while we have shown and described our invention in a preferred form, changes may be made in the structure disclosed without departing from the spirit of the invention as sought to be defined in the following claims.

We claim:

l. A drier for a rotogravure web press, including rollers for leading the web in an inverted U around the upper portion of the press, said drier being in the form of an inverted U fitting closely about the web and press, said drier comprising two upright plenum chambers at the sides of the press and a horizontal plenum chamber at the top of the press web, said drier being substantially wider than the maximum web handled by the press and having partition walls defining plenum chambers at the web and return passages outside said web, a fan of the blower type disposed in the top portion of the drier, a pair of heaters located on opposite sides of the fan in the top portion of the drier, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan whereby the heated air is re-circulated, the top portion of said dri r being fixedly mounted on top of said press, and the upright portions of said drier being hinged to said top portion so that they may be swung outwardly away from the web.

2. A drier for a rotogravure web press, including rollers for leading the web in an inverted U around the upper portion of the press, said drier being in the form of an inverted U fitting closely about the web and press, said drier comprising two upright plenum chambers at the sides of the press and a horizontal plenum chamber at the top of the press web, said drier being substantially wider than the maximum web handled by the press and having partition walls defining plenum chambers at the web and return passages outside said web, a fan of the blower type disposed in the top portion of the drier, a pair of heaters located on opposite sides of the fan in the top portion of the drier, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan whereby 'the heated air is re-circulated, the top portion of said drier being fixedly mounted on top of said press, and the upright portions of said .drier being hinged to said top portion so that they may be swung outwardly away from the web, said press having stationary plates disposed inside the web between the guide rollers to limit the leakage of air into the drier when printing a web of less than maximum width.

3. A drier for a rotogravure web press including rollers for leading the web in an inverted U around the upper portion of the press, said .drier being in the form of an inverted U fitting closely about the Web and press, said drier comprising two upright plenum chambers at the sides of the press and a horizontal plenum chamber at the top of the press web, said drier being substan- 5 tially wider than the maximum width Web handled by the press and having partition walls defining plenum chambers at the web and return fan in the top portion of the drier, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan, whereby the heated air is re-circulated, a bleeder connection to said drier, a suction fan for removing a part of the circulating air from the drier to be replaced by leakage of fresh air into the circulating system, and a damper in said bleeder connection for controlling the amount 'air into the drier when printing a web of less than maximum width.

4. A drier system for a multi-color rotogravure web press in which each press is provided with a drier as defined in claim 1 and in which each of the driers is connected to a common exhaust conduit, there being a suction fan connected to said conduit, and there being a damper between each drier and said conduit, whereby the proportion of air withdrawn from the circulating system of the difierent driers may be regulated relative to and independently of one another.

5. A drier for a web press, rollers for leading the web in an inverted U around the upper portion of the press, said drier being in the form of an inverted U fitting closely about the web and press, said drier comprising two upright plenum chambers at the sides of the press and a horizontal plenur'n chamber at the top of the press, said drier having partition walls defining plenum chambers and return passages located outside the plenum chambers and the side edges of said web, a fan disposed in the top portion of the drier, a heater through which the air from the fan flows before entering the plenum chambers, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan, whereby the heated air is repeatedly recirculated, and an exhaust connection and suction fan for bleeding off a part of the recirculated air, said suction fan being of adequate capacity to maintain and being operated to maintain a negative pressure within the drier, so as to produce leakage of air into the drier through leakage spaces to replace the air withdrawn by the suction fan, and stationary imperforate plates disposed inside the web between the guide rollers to limit the leakage of air into the drier.

6. A drier for a web press for handling a range of width of web, rollers for leading the web in an inverted U around the upper portion of the press, said drier being in the form of an inverted U fitting closely about the web and press, said drier comprising two upright plenum chambers at the sides of the press and a horizontal plenum chamber at the top of the press, said drier being substantially wider than the maximum width web handled by the press and having partition walls defining plenum chambers having a width corresponding to the maximum width web, and defining return passages located outside the plenum chambers and the side edges of said web, a fan of the blower type disposed in the top portion of the drier, a pair of heaters located on opposite sides of the fan in the top portion of the drier, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan, whereby the heated air is repeatedly recirculated, and an exhaust connection and suction fan for bleeding oil a part of the recirculated air, said suction fan being of adequate capacity to maintain and being operated to maintain a negative pressure within the drier, so as to produce leakage of air into the drier through leakage spaces to replace the air withdrawn by the suction fan, and stationary'imperforate plates disposed inside the web between the guide rollers to limit the leakage of air into the drier when printing a web of less than maximum width.

'7. A drier system for a multi-color web press, said system comprising a drier for each press, rollers for leading the web in an inverted U around the upper portion of the press, said driers each being in the form of an inverted U fitting closely about its press, said driers each comprising two upright plenum chambers at the sides of the press and a horizontal plenum chamber at the top of the press, said driers being substantially wider than the web and having partition walls defining plenum chambers and defining return passages outside the plenum chambers and the side edges of the web, a fan disposed in the top portion of the drier, a heater through which the air from the fan flows before entering the plenum chambers, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan, whereby the heated air in each drier is repeatedly recirculated in that drier, a bleeder connection on each of the driers connected to a common exhaust conduit, a common suction fan connected -to said conduit for bleeding off a part of the recirculated air, said suction fan being of adequate capacity to maintain and being operated to maintain a negative pressure within the driers so as to'produce leakage of air into the driers through leakage spaces to replace the air withdrawn by the suction fan, an independently adjustable damper between each drier and the conduit whereby the proportion of air withdrawn from the circulating system of each of the different driers may be individually regulated by independent adjustment of the diiierent dampers, and stationary imperforate plates disposed in.- side the web between the guide rollers to limit the leakage of air into the drier.

8. A drier system for a multi-color web press for handling a range of width of web, said sysplenum chambers having a width corresponding.

to the maximum width web, and defining return passages located outside the plenum chambers and the side edges of said web, a fan of the blower type disposed in the top portion of the drier, a pair of heaters located on opposite sides of the fan in the top portion of the drier, said plenum chambers having nozzle plates for directing air from the fan against the web, the used air then flowing sidewardly to the aforesaid return passages and thence upwardly to the inlet of the fan, whereby the heated air in each drier is repeatedly recirculated in that drier, a bleeder connection on each of the driers connected to a common exhaust conduit, a common suction fan connected to said conduit for bleeding ofi a part of the recirculated air, said suction fan being of adequate capacity to maintain and being operated to maintain a negative pressure within the driers, so as to produce leakage of air into the driers through leakage spaces to replace the air WithdraWn by the suction fan, stationary imperforate plates disposed inside theweb between the guide rollers to limit the leakage of air into the drier when printing a web of less than maximum width, and an independently 25 Number adjustable damper between each drier and the conduit whereby the proportion of air withdrawn REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,761,397 Karmazin June 3, 1930 1,779,611 Merrill Oct. 28, 1930 1,956,062 Duvall Apr. 24, 1934 1,996,020 Hurthal Mar. 26, 1935 2,148,739 Friess Feb. 28, 1939 2,228,030 Hanson Jan. 7, 1941 2,229,285 Gehnrich Jan. 21, 1941 2,333,220 Weiss Nov. 2, 1943 2,440,648 Walter et a1 Apr. 27, 1948 FOREIGN PATENTS Country Date 459,598 Germany May 7, 1928