US3863360A

US3863360A - Sheet drying apparatus

Info

Publication number: US3863360A
Application number: US300992A
Authority: US
Inventors: Emile Stievenari; Jurgen Muller
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1971-10-28
Filing date: 1972-10-26
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04
Also published as: DE2153752B2; DE2153752A1; DE2153752C3

Abstract

A sheet drying apparatus having a horizontal drying chamber with a relatively small inlet end and a much larger discharge end. The mechanism which transports successive sheets through the chamber has two transversely extending rolls closely adjacent to the inlet end and two sets of transversely extending rolls adjacent to the discharge end of the drying chamber. The latter is formed with two mirror symmetrical nozzles connected with a source of heated air and having orifices closely adjacent to the path of sheets in the region of the inlet end. The nozzles are formed with projections which cause turbulence in the air streams at the opposite sides of a sheet in the chamber to thus prevent the development of laminar air flow. The cross-sectional area of the discharge end is large enough to allow for practically unobstructed escape of spent air, and the advancing rolls at the discharge end are staggered relative to each other to offer little resistance to the escape of spent air as well as to flex the sheets during travel therebetween. The upper wall of the drying chamber and the corresponding nozzle can be lifted off the lower wall to afford access to the interior of the chamber.

Description

United States Patent Stievenari et al. Feb. 4, 1975 SHEET DRYING APPARATUS 3,736,174 5/1973 Moyer 54/155 [75] Inventors: Emile Stievenar,

Miill M h, G Jul-gen umc ermany Attorney, Agent, or Firm-M1chael S. Stnker [73] Ass1gnee: Agfa-Gevaert Alttiengesellschaft, MLlnlCh, Germany Filedi 1972 A sheet drying apparatus having a horizontal drying 21 A L N 300 992 chamber with a relatively small inlet end and a much 1 pp 0 V larger discharge end. The mechanism which transports successive sheets through the chamber has two transl l Foreign Application Priority Data versely extending rolls closely adjacent to the inlet end Oct. 28, 1971 Germany 2153752 and two sets of transversely extending rolls adjacent to the discharge end of the drying chamber. The latter is [52] U.S. Cl 34/155, 34/131, 34/156 ormed ith two mirror ymmetrical nozzles con- [5 l] Int. Cl. F26b 13/04 nected with a source of heated air and having orifices [58] Field of Search 34/156, 155; 152, 151, o ely a j cen to he p th of she ts in the region of 34/l48, 160, 162, 154, 153 the inlet end. The nozzles are formed with projections which cause turbulence in the air streams at the oppo- [56] References Cited site sides of a sheet in the chamber to thus prevent the UNITED STATES PATENTS development of laminar air flow. The cross-sectional 2,577,915 12/1951 Piller =1 al. 34/155 area 9 the dscha'ge end large emugh 9 M 2 586 800 2/1952 Elvin e! al 34/155 pract1cally unobstructed escape of spent an, and the 3:293:775 12/1966 Kitrosserniz ........II:I 34/156 advancing mus at the discharge end are staggered 3 3 932 10/1967 Cheape i I 34/155 ative to each other to offer little resistance to the es- 3,426,441 2/1969 Broski 34/48 pe f spent a r a well as to fle the sheets during 3,545,364 12/1970 Reedy 34/155 travel therebetween. The upper wall of the drying 3,548,5l2 12/l970 Smoot 34/151 hamber and the corresponding nozzle can be lifted 3,557,469 Edgmgton off the lower wall to afford access to the interior of 3,606,689 9/1971 MalSud et 34/155 the chamber 3,707,777 l/l973 Geyken et al 34/l55 I 3,718,983 3/1973 Crowell 34/155 15 Claims, 2 Drawing Figures 1 Ba 15d 15 13 13b 1 snaa'r nnvmc APPARATUS BACKGROUND OF THE INVENTION The present invention relates to apparatus for the drying of sheet-like materials, such as carriers of exposed and developed photosensitive layers. More particularly. the invention relates to drying apparatus of the type wherein the sheet-like material to be dried is caused to advance along a predetermined path extending through a drying chamber to be contacted therein by a gaseous drying fluid. Still more particularly. the invention relates to improvements in sheet drying apparatus wherein the material to be dried is transported by two sets of advancing rolls located upstream and downstream of the drying chamber and wherein the gaseous drying fluid is admitted by way of nozzles located between the front and rear advancing rolls.

In certain presently known sheet drying apparatus, the orifices of the nozzles are located at a considerable distance from the path along which the sheet-like material advances through the drying chamber. Also, the drying chamber is provided with a relatively small single outlet for spent drying fluid. The nozzles are mounted substantially midway between the front and rear advancing rolls. The rate of admission of drying fluid is such that the pressure in the drying chambers rises above atmospheric pressure. It was found that such apparatus cause the generation of a relatively slow laminar flow of gaseous fluid along both sides of a sheet which is being transported through the drying chamber. Such layers of gaseous fluid at both sides of the advancing sheet allow for a relatively slow drying because they prevent freshly admitted fluid from coming into contact with the sheet. Furthermore, automatic threading of sheets into the drying chamber is not possible because the interior of the chamber is not provided with sheet guides at any point between the front advancing rolls and the rear advancing rolls. Therefore, the leader of a freshly introduced sheet tends to cling to the one or the other internal surface of the drying chamber and cannot find its way into the nip of the rear advancing rolls.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved drying apparatus wherein the leader of a freshly introduced sheet to be dried automatically finds its way into the nip of the rear advancing rolls without the provision of any guide means in the interior of the drying chamber and irrespective of the stiffness or lack of stiffness of the sheet material.

Another object of the invention is to provide a drying apparatus which prevents the development of laminar flow of gaseous drying fluid along one or both sides of sheets which are caused to advance through the drying chamber.

A further object of the invention is to provide the drying apparatus with novel and improved means for insuring continuous contact between fresh gaseous drying fluid and sheet material while the material advances through the drying chamber.

Still another object of the invention is to provide novel and improved means for admitting a gaseous drying fluid into the chamber of the drying apparatus.

An additional object of the invention is to provide a drying apparatus which can be readily opened to ailow for inspection and cleaning of the interior of the drying chamber.

The improved drying apparatus comprises a hollow drying chamber having a preferably funnel-shaped inlet end and a discharge end, first rotary sheet advancing means adjacent to the inlet end (and preferably comprising two rolls at least one of which is driven to rotate the other roll. either directly or by way of sheet-like material therebetween). second rotary sheet advancing means adjacent to the discharge end and defining with the first sheet advancing means an elongated path which is preferably located in a substantially horizontal plane and serves for travel of sheet-like material into. through and beyond the drying chamber. a source of gaseous drying fluid. and first and second nozzle means provided on the drying chamber adjacent to the inlet end at the opposite sides of the path for sheet-like material and being connected with the source of gaseous drying fluid. The nozzle means are preferably mirror symmetrical to each other with reference to the plane of the path and have orifices closely adjacent to the path and arranged to discharge streams of gaseous drying fluid against the respective sides of sheet-like material in the chamber, preferably at least substantially at right angles to the direction of travel of sheet-like material. The thus admitted streams of drying fluid flow along the sheet-like material in the chamber and are allowed to escape by way of the discharge end whose cross-sectional area is preferably large enough to allow for substantially unobstructed escape of gaseous fluid. The interior of the chamber is provided with means for creating turbulence in the admitted air streams to thus prevent the development of laminar flow of gaseous fluid at one or both sides of the path.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved sheet drying apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof. will be best understood upon perusual of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary longitudinal vertical sectional view of a drying apparatus which embodies the invention; and

FIG. 2 is a view as seen in the direction of arrow A in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the sheet drying apparatus comprises a housing including a lower section 1 and an upper section 3 which is movable relative to the lower section about the axis of a horizontal pivot member 2. The sections 1 and 3 respectively support the lower and upper portions or walls 12, I3 of a hollow horizontal drying chamber which walls are respectively provided with gas-admitting nozzles 16 and IS. The lefbhand portion of the lower housing section 1, as viewed in FIG. 1, is provided with a vertical slot la which receives the shaft 4 of a lower advancing roll 6 and the shaft 5 of an upper advancing roll 7. The preferably horizontal path for the sheets 114 (see FIG. 2) to be dried is indicated by a phantom line 14, and the direction of feed of sheets 114 along the path 14 is indicated by an arrow B. The path 14 extends through the nip of the advancing rolls 6. 7 and through the interior of the drying chamber.

The lower housing section 1 further supports a horizontal shaft 8 for a set of four discrete axially spaced sheet advancing and flexing rolls 9a, 9b. 9c. 9d (see FIG. 2), and the upper housing section 3 supports a shaft for a set of three discrete advancing and flexing rolls lla. llh, llv which alternate with the rolls 9a-9d. as considered at right angles to the direction of travel of sheets [14 along the path l4. One of the shafts 4,5 and one of the shafts 8J0 is driven by a motor (not shown) or another suitable prime mover. The directions in which the rolls 6, 7, 9u-9d and llal4 llr' rotate when the drying apparatus is in use are indicated by arrows. If the shaft 4 drives the roll 6. the roll 7 is rotated because it rests on the roll 6 or in response to forward movement of a sheet 114 along the path 14. Analogously, if the rolls 9a-9d are positively driven by the shaft 8. the rolls Ila-11c rotate owing to engagement with the upper side of a sheet 114 in the path 14.

The central portions 122, 13a ofthe walls l2, 13 form a substantially horizontal nozzle whose cross-sectional area decreases in a direction from the advancing rolls 6, 7 toward the advancing rolls 9a-9d, 110-110, i.e., in the direction (arrow B) of lengthwise movement of sheets 114. The front or foremost portions 12a, 13a of the walls 12, 13 constitute a funnel-shaped inlet end of the drying chamber which is located immediately downstream of or close to the advancing rolls 6, 7 and whose cross-sectional area decreases in the same direction as the cross-sectional area of the nozzle defined by the

median portions

12e, 13a of the walls 12, 13. The arcuate rightmost or

rearmost portions

12b, 13b of the walls 12, 13 form a discharge end which surrounds, with considerable clearance, portions of the advancing rolls 9a-9d and lla-llc.

The nozzle admits a gaseous drying fluid (e.g.. air) in the direction indicated by arrow C. The arrow D indicates the direction of admission of drying fluid by way ofthe nozzle 16. As shown in FIG. 1, the direction of gas flow toward the path i4 is substantially or exactly at right angles to the direction oflengthwise travel of sheets 114 (arrow B). The portions 15a. 16a of the nozzles l5. 16 preferably extend very close to the path 14 and are located at the upstream sides of the respective gas-discharging orifices 15d and 1641. The portions or projections 15b. 16b of the nozzles l5, 16 are more distant from the path 14 and constitute preferably rounded protuberances which create turbulence in the streams of gaseous drying fluid respectively flowing along the upper and lower sides of sheets 114 in the path 14. lt will be noted that each ofthe nozzle portions lSb. 16b extends somewhat beyond the adjacent central portion 13a, 12a of the respective wall l3, 12. The just described configuration of those portions of the

nozzles

15, 16 which respectively define the orifices l5d. 16d brings about a desirable turbulence and also effects a pronounced deflection of inflowing gaseous fluid through approximately 90 i.e., the two streams of gaseous fluid first flow at right angles to and thereupon in substantial parallelism with the path 14. The helical arrows shown in FIG. 1 indicate the areas where the turbulent gaseous fluid develops a dynamic pressure or velocity head and flows through the horizontal nozzle l2e. l3e of the drying chamber toward the discharge end defined by the

arcuate portions

12b, 13b. It was found that the drying action of a gaseous fluid is especially satisfactory if the speed of fluid streams in the central portion of the drying chamber formed by the walls l2, I3 is between 8 and 15 meters per second.

The central portion of the lower wall 12 is further provided with a recess 12d for a temperature measuring gauge 12c (e.g., an NTC-resistor) which controls the temperature of the gaseous fluid supplied to the

nozzles

15 and 16 by a blower 50 or an analogous source. The gauge 12- can furnish signals to a transducer 5| which controls a heating device (not shown) for gaseous fluid flowing into or issuing from the blower 50.

An important advantage of the improved drying apparatus is that the two mirror symmetrical nozzles l5. l6 are immediately or closely adjacent to the funnelshaped inlet end 12a. 13a of the drying chamber and that the orifices 15d. 16d are closely or immediately adjacnt to the respective sides of the path 14. The crosssectional area of the narrowest part of the inlet end 120. 13a is much smaller than the cross-sectional area of the narrowest part of the discharge end 12h, 13b of the drying chamber and the narrowest portion of the cross-sectional area of the discharge end 12h. 13b is sufficient to allow for practically unobstructed escape of spent gaseous fluid from the chamber.

The turbulence which is caused by the projections 15b, 16b of the nozzles 15, 16(these projections can be said to form part of the drying chamber since the

nozzles

15, 16 are shown as being integral with the respective walls l3, l2) insures that the fluid which is admit ted into the chamber cannot form a laminar flow at the respective sides of sheets 114 which are being transported along the path 14 so that each portion of a sheet in the drying chamber is continuously contacted by fresh gaseous fluid to thus insure a highly satisfactory removal of moisture. This, in turn. renders it possible to reduce the overall length of the drying apparatus (as considered in the direction of arrow B) because the withdrawal of desired quantities of moisture from sheets in the chamber can be completed within surprisingly short intervals of time. The aforementioned dynamic pressure which develops in the regions where the streams issuing from the orifices 15d. 16d impinge on the respective sides of a sheet H4 in the drying chamber drops rapidly in a direction toward the relatively large discharge end 15b. 16b of the drying chamber. It was further found that, if a sheet 114 in the drying chamber tends to leave the path 14 by flexing toward the wall 12 or 13, the dynamic pressure at the side of the path where the sheets deviates from its prescribed route remains intact much longer than at the other side of the path and automatically compels the sheet to return into the path 14. Thus. if the leading end of a freshly introduced sheet 114 tends to flex sideways after it has moved through the inlet end 12a, 13a and beyond the space between the

nozzles

15d, 16d. the leading end is subjected to the action of a relatively strong force which tends to move it into the path [4. This is highly desirable because the streams of gaseous drying fluid which are admitted into the chamber by way of the

orifices

15d, 16d bring about an automatic threading action to thus insure that the leader of a freshly inserted sheet 114 automatically finds its way into the space between the rolls 9u-9d and Ila-11c. Such automatic threading takes place without necessitating the provision of any mechanical or other guide means in the interior of the drying chamber.

The feature that the median portions 12a, 134 of the walls l2, l3 converge toward each other in the direction indicated by the arrow B contributes to acceleration of gas streams during flow toward the discharge end 12!), 13b.

The rollers 6, 7 are preferably placed so close to the inlet end 120, 13a that they invariably prevent the escape of substantial quantities of gaseous drying fluid counter to the direction of transport of sheets I I4 through the drying chamber. 0n the other hand, the transversely staggered rollers 9a-9d and llal lc' provide a number of passages through which the spent gaseous fluid can escape by way of the discharge end 12b. 13b. It will be seen that the distance between the common axis of the rolls 9a-9d and the common axis of the rolls Ila-11c is less than the diameter of a roll 9 or II. Consequently, a sheet 114 which is caused to pass between the rolls 9a-9d and Ila-l lc is flexed to assume a meandering shape and to increase the friction between its material and the peripheral surfaces of the rolls 9a-9d and Ila-11c. This insures orderly withdrawal of sheets 114 from the drying chamber.

The minimum cross-sectional area of the funnelshaped inlet end 120, 13a is preferably selected in such a way that the leader of a sheet 114 which has been introduced through the inlet end automatically finds its way into the space between the

orifices

15d, 16d whereby the streams of'gaseousdrying fluid insure that the leader of the sheet 114 remains in the path 14 and advances toward the space between the rolls 9a-9d and Ila-11c. This allows for a fully automatic threading operation, especially if the apparatus is further provided with a feeder (not shown) which feeds sucessive sheets H4 into the nip of the advancing rolls 6, 7. If a sheet 114 happens to jam in the interior of the drying chamber, the operator merely lifts the wall 13 and the nozzle 15 above the wall 12 by pivoting the housing section 3 about the axis of the pivot member 2. The wall 13 then affords convenient access to the interior of the drying chamber. Such access to the interior of the drying chamber is desirable on the additional ground that a person in charge can inspect the internal surfaces of the walls l2. 13 to detect eventual deposition of chemicals which are carried by the sheets 114.

Without further analysis. the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly consitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

I. Apparatus for drying sheet-like materials, comprising a hollow drying chamber having an inlet end and a discharge end. the cross-sectional area of said inlet end being substantially smaller than the cross-sectional area of said discharge end; first rotary sheet advancing means comprising a pair of rolls closely adjacent to said inlet end; second rotary sheet advancing means adjacent to said discharge end and defining with said first sheet advancing means an elongated path for travel of sheet-like material into, through and beyond said chamber; a source of gaseous drying fluid; and first and second nozzle means provided on said chamber adjacent to said inlet end at the opposite sides of said path and connected with said source. said nozzle means having orifices closely adjacent to said path and arranged to discharge streams of gaseous drying fluid against the respective sides of sheet-like material in said chamber whereby the drying fluid flows along the sheetlike material to leave said chamber by way of said discharge end. the cross-sectional area of said discharge end being large enough to allow for substantially unobstructed escape of gaseous fluid which is admitted into said chamber by said nozzle means and the crosssectional area of said chamber decreasing in a direction from said orifices toward said discharge end to a point near the discharge end and then increasing in crosssectional area to the discharge end. said second sheet advancing means comprising first and second roll means located at opposite sides of said path. said first and second roll means defining a plurality of large passages so as to offer little resistance to escape of gaseous drying fluid by way of said discharge end.

2. Apparatus as defined in claim I, wherein said nozzle means are arranged to admit said streams of gaseous drying fluid at a speed of 8-l5 meters per second.

3. Apparatus as defined in claim I, wherein said chamber is provided with internal projections located downstream of said orifices, as considered in the direction of travel of sheet-like material, to produce turbulence in said streams.

4. Apparatus as defined in claim 3, wherein said nozzle means are integral with said chamber and said projections are provided on said nozzle means in the region of the respective orifices.

5. Apparatus as defined in claim I, further comprising control means for regulating the temperature of gaseous drying fluid which is furnished by said source. said control means comprising temperature measuring means provided in said chamber.

6. Apparatus as defined in claim 5. wherein said chamber comprises an upper portion located above and a lower portion located below said path. said temperature measuring means comprising an NTC-resistor installed in said lower portion of said chamber.

7. Apparatus as defined in claim I, wherein said first sheet advancing means comprises a pair of elongated rolls located at the opposite sides of and extending across the full width of said path.

'8. Apparatus as defined in claim 7, wherein said rolls are closely adjacent to said inlet end so as to prevent escape of substantial quantities of gaseous drying fluid from said chamber by way of said inlet end.

9. Apparatus as defined in claim I wherein said first roll means of said second sheet advancing means comprises at least two axially spaced first rolls located at one side of said path and said second roll means of said second sheet advancing means comprises at least one second roll located at the opposite side of said path, said first and second rolls being staggered relative to each other, as considered at right angles to the direction of travel of sheet-like material along said path.

10. Apparatus as defined in claim 9, wherein the distance between the axes of said first and second rolls is less than the diameter of one of said rolls so that said rolls effect at least some flexing of sheet-like material during travel of such material between said first and second rolls.

a first section connected to said first wall and a second section connected to and movable with said second wall.

l4. Apparatus as defined in claim [2, wherein said first and second nozzle means are repsectively provided on said first and second walls.

15. Apparatus as defined in claim I, wherein said first nozzle means is mirror symmetrical to said second nozzle means with reference to the plane of said path.

1 i i i

Claims

1. Apparatus for drying sheet-like materials, comprising a hollow drying chamber having an inlet end and a discharge end, the cross-sectional area of said inlet end being substantially smaller than the cross-sectional area of said discharge end; first rotary sheet advancing means comprising a pair of rolls closely adjacent to said inlet end; second rotary sheet advancing means adjacent to said discharge end and defining with said first sheet advancing means an elongated path for travel of sheet-like material into, through and beyond said chambeR; a source of gaseous drying fluid; and first and second nozzle means provided on said chamber adjacent to said inlet end at the opposite sides of said path and connected with said source, said nozzle means having orifices closely adjacent to said path and arranged to discharge streams of gaseous drying fluid against the respective sides of sheet-like material in said chamber whereby the drying fluid flows along the sheetlike material to leave said chamber by way of said discharge end, the cross-sectional area of said discharge end being large enough to allow for substantially unobstructed escape of gaseous fluid which is admitted into said chamber by said nozzle means and the cross-sectional area of said chamber decreasing in a direction from said orifices toward said discharge end to a point near the discharge end and then increasing in cross-sectional area to the discharge end, said second sheet advancing means comprising first and second roll means located at opposite sides of said path, said first and second roll means defining a plurality of large passages so as to offer little resistance to escape of gaseous drying fluid by way of said discharge end.

2. Apparatus as defined in claim 1, wherein said nozzle means are arranged to admit said streams of gaseous drying fluid at a speed of 8-15 meters per second.

3. Apparatus as defined in claim 1, wherein said chamber is provided with internal projections located downstream of said orifices, as considered in the direction of travel of sheet-like material, to produce turbulence in said streams.

5. Apparatus as defined in claim 1, further comprising control means for regulating the temperature of gaseous drying fluid which is furnished by said source, said control means comprising temperature measuring means provided in said chamber.

6. Apparatus as defined in claim 5, wherein said chamber comprises an upper portion located above and a lower portion located below said path, said temperature measuring means comprising an NTC-resistor installed in said lower portion of said chamber.

7. Apparatus as defined in claim 1, wherein said first sheet advancing means comprises a pair of elongated rolls located at the opposite sides of and extending across the full width of said path.

8. Apparatus as defined in claim 7, wherein said rolls are closely adjacent to said inlet end so as to prevent escape of substantial quantities of gaseous drying fluid from said chamber by way of said inlet end.

9. Apparatus as defined in claim 1 , wherein said first roll means of said second sheet advancing means comprises at least two axially spaced first rolls located at one side of said path and said second roll means of said second sheet advancing means comprises at least one second roll located at the opposite side of said path, said first and second rolls being staggered relative to each other, as considered at right angles to the direction of travel of sheet-like material along said path.

11. Apparatus as defined in claim 1, wherein said inlet end constitutes a funnel whose cross-sectional area decreases in the direction of transport of sheet-like material therethrough.

12. Apparatus as defined in claim 1, wherein said chamber comprises a plurality of walls including a first wall and a second wall movable relative to said first wall to afford access to the interior of said chamber.

13. Apparatus as defined in claim 12, further comprising a housing supporting said chamber and having a first sectiOn connected to said first wall and a second section connected to and movable with said second wall.

14. Apparatus as defined in claim 12, wherein said first and second nozzle means are repsectively provided on said first and second walls.

15. Apparatus as defined in claim 1, wherein said first nozzle means is mirror symmetrical to said second nozzle means with reference to the plane of said path.