US 3615821 A
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Description (OCR text may contain errors)
United States Patent 72] Inventor Arthur J. Miller Horizon Towers North, Fort Lee, NJ. 07024 [21 1 Appl. No. 878,757
 Filed Nov. 21,1969
[4S] Patented Oct. 26, 1971 54] STRIP MATERIAL SQUEEGEE AND METHOD 21 Claims, 5 Drawing Figs.
 US. Cl 134/10, 15/306 A, 34/14, 34/16, 34/18, 34/152,134/15,
 int. Cl ..F26b 13/04, 1308b 3/10  Field olSearch 134/10, 15, 64,122; 15/306 R, 306 A,100, DIG. 7; 34/14, 16,
 References Cited UNITED STATES PATENTS 1,519,460 12/1924 Lichte 15/100 Primary Examiner-Morris O. Wolk Assistant Examiner-D. G. Millman Attorney-Brumbaugh, Graves, Donohue & Raymond ABSTRACT: Squeegee and method for stripping solvent from the surfaces of perishable strip materials, such as motion picture film and the like. More specifically, the strip material is passed between, but does not engage, one or more sets of opposed, spaced-apart rollers that are rotated at high speed against the direction of movement of the material to pump at high velocity a fluid stream, such as air or some other suitable gas, through the spaces between the rollers and the adjacent material surfaces, thereby removing the solvent adhering to the material. Seal members may be provided to prevent leakage around the rollers of the drying fluid stream and the solvent transferred to the rollers from the strip material, while conduits associated with the seal members recover the solvent picked up by the rollers.
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BACKGROUND OF THE INVENTION The present invention relates generally to the cleaning of perishable strip materials, and more particularly man improved film squeegee and method for stripping solvent or other foreign matter from the surfaces of motion picture film, magnetic and video tapes and similar strip materials.
The affinityof soft strip materials of the type mentioned for dust particles, greases and other foreign matter constitutes a persistent and pervasive problem in the use and processing of such materials. For example, foreign matter present on the image-bearing surface of motion picture film frequently causes an unacceptable degradation in the quality of the projected picture, while contaminants on the record-carrying surface of magnetic tape often have a deleterious effect on the fidelity of the reproduced signals. Moreover, there is always the risk that the surfaces of the strip materials will be permanently damaged or destroyed as a result of their being contacted by foreign matter.
It is common practice, therefore, to clean such perishable strip materials periodically so as to preserve unimpaired the records carried thereon. Various techniques and apparatus have been proposed over the years for this purpose.
In the copending application Ser. No. 838,760 now U.S. Pat. No. 3,549,769, for "Apparatus for Cleaning Film," filed July 3, I969 by Messrs. Arthur J. Miller, Raymond Perkins and Harold E. Sullivan, an ultrasonic film cleaning unit is disclosed which represents a significant advancement over earlier cleaning apparatus in this field. In brief, that apparatus provides for the rapid and effective cleaning of strip materials of different widths essentially by passing the materials through an ultrasonically agitated solvent bath, then rinsing dirty solvent from the materials in a spray of clear solvent, and finally mechanically and evaporatively stripping residual solvent from the surfaces of the materials. An internal solvent recovery system affords economy of operation by minimizing the amount of solvent replenishment required, and a drying air filtration and recirculation system ensures a dust-free environment within the cleaning unit that also increases cleaning efficrency.
SUMMARY OF THE INVENTION The present invention is directed to strip-cleaning apparatus of this general character and affords improved stripping of foreign matter generally, and solvent in particular, from the surfaces of strip material. This is accomplished, according to the invention, by passing the strip material, for example, motion picture film, between one or more pairs of opposed rollers that are rotated at high speed in a direction opposite to the direction of movement of the film. The opposed rollers are formed with a multiplicity of radially extending, flexible vanes and are spaced apart at their peripheries a distance slightly greater than the thickness of the film, so that, as the rollers rotate, the vanes pass close to but do not engage the adjacent surfaces of the film.
By a combination of the close spacing and high rotational speed of the rollers, a heated airstream flowing over the film is pumped at high velocity through the spaces between the roller peripheries and the film surfaces in opposition to the movement of the film. These high velocity air flows are effective to strip, or scrub, from the film surfaces solvent or other cantaminants that may be adhering thereto, while simultaneously damage to the soft surfaces of the film is avoided inasmuch as no physical contact occurs between the high speed rollers and the film surfaces.
Seal members positioned adjacent the stripping rollers prevent leakage of the heated airflow, on the one hand. and the solvent transferred to the rollers from the film surfaces, on the other, between the rollers and the surrounding housing. The seal members also cooperate with the flexible vanes on the rollers, and with associated collection conduits, to recover and return for recycling the solvent transferred to the rollers.
After leaving the stripping rollers, the film continues to pass through the heated, though now slow moving, airstream so as.
to evaporate any residual solvent or moisture. To this end, the airstream is maintained at a temperature higher than the boiling point of the solvent used and, in addition, is filtered and recirculated to prevent recontamination of the film.
BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding'of these and other features of the invention, as well as the objects and advantages thereof, reference may be made to the following detaileddescription and to the drawings, in which: 1
FIG. I is a front elevational view, partly in section, taken along of film cleaning apparatus embodying the invention;
I FIG. 2 is a side elevational view, partly in section, taken along the line 2-2 of FIG. I and looking in the direction of the arrows; t
FIG. 3 is a vertical sectional view taken along the line 3-3 of FIG. I and looking in the direction of the arrows;
FIG. 4 is an enlarged view of the stripping rollers of the present invention taken along the line 4-4 of FIG. I and looking in the direction of the arrows; and
FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4 and looking in the direction of the arrows.
DESCRIPTION OF A REPRESENTATIVE EMBODIMENT For purposes of illustration, a representative embodiment of the invention is described herein as embodied in strip cleaning apparatus of the type disclosed in the aforementioned application Ser. No. 838,760. Although that apparatus, and the present invention as well, is particularly adapted for cleaning motion picture film, it will be understood that the invention may be used with equal facility with other types of apparatus and in connection with other strip materials, including photographic films in general, magnetic and video tapes and the like.
The film-cleaning apparatus, indicated generally at III in FIGS. 1 and 2, includes a housing I2 which surrounds and encloses the operating components of the apparatus. The interior of the housing I2 is organized into two basic compartments, a forward cleaning compartment 14 and a rearward compartment 16 in which the electrical and mechanical accessory equipment needed to advance the film through the apparatus is mounted. I
A vertical mounting panel 18 (see FIG. 2) separates the cleaning and electrical compartments and, together with a pair of glass doors 20, a forward cover plate 22 and the side and end walls of the housing 12, seals off the cleaning compartment I6 from the environment. This construction of the cleaning compartment 16, along with the closed drying airsystem described hereinafter, ensures that dust-free conditions will exist at all places within the compartment.
A reel 24 of film 26 to be cleaned is positioned at one side of the cleaning compartment 14 on a shaft 28 rotatably carried by the mounting panel 18. Immediately above the feed reel 24 is a takeup reel 30 for receiving the cleaned film, the takeup reel being mounted on a driven shaft 32 which is also carried by the mounting panel I8. Appropriate automatic torqueregulating devices (not shown) associated with the feed reel 24 and takeup reel 30 allow for constant movement of the film as the amounts of film wound on the respective reels change during a cleaning run.
Upon actuation of a drive motor 15 (see FIG. 2) located in the rearward compartment 16, the film 26 passes from the feed reel 24, over a guide roll 34 (see FIG. I) and downward into an ultrasonic cleaning chamber 36. The cleaning chamber 36 contains an appropriate liquid solvent bath 38 which is ultrasonically agitated by vertically spaced transducers 40 and 42, thus effectively cleaning the film 26 as it progresses horizontally through the solvent bath 38 between the guide rolls 44 and 46.
Thereafter, the film 26 exits vertically from the bath 38 and is rinsed free of contaminated solvent on both the emulsion and base surfaces by sprays of clean solvent discharged from a pair of spray nozzles 48. The film 26 then continues vertically through a chilling chamber 50 to a drying chamber 52 where the rinsing solvent and any contaminants superficially adher ing to the film are stripped, or scrubbed, from the film surfaces by the film squeegee, shown generally at 54, of the present invention.
Within the drying chamber 52 are two additional guide rolls 55 and 56 which guide the film 26 first downward and then upward and card the drying chamber to the film drive roll 58, the safety roll 60, a conventional tension control arm 62 and finally to the takeup reel 30. i
As previously mentioned, an air filtration and circulation system is provided to recirculate dust-free air throughout the cleaning compartment 14. A blower 64 (see FIG. I) located in the bottoniof the cleaning compartment 14 forces air through an L-shaped supply duct 66 that connects with anenc losed plenum 68 at the top of the cleaning chamber. From the plenum 68, the air passes through absolute filters 70 which preferably are effective to remove more than 99 percent of all particulate matter larger than 0.5 microns from the air to render it substantially dust-free. l
The filtered air is then divided into two streams. One
stream, indicated by the arrows 72 (see FIGS. 1 and 2) passes through a perforated covering plate 74 and flows downwardly through the cleaning compartment 14 to ensure that thefilm 26 is processed in a dust-free atmosphere. The air flow 72 passes through a return duct 76 to the suction side of the blower 64 for recirculation.
The remaining portion of the filtered air, indicated by the arrows 78, enters the upper portion of a heating chamber 80 and is raised by a conventional heater 82 to a temperature higher than the boiling point of the solvent used but not so high as to cause the film to curl or otherwise become distorted. For example, where a solvent such as an azeotropic mixture of 88 percent trichloro-trifluorethane and [2 percent ethanol, having a boiling point of approximately 115 F., is used an air temperature within the range of I30 to 140 F. is satisfactory.
After being heated, the air flow 78 passes into the drying chamber 52 where it flows downwardly over the vertically rising film 26, that is, in opposition totthe direction of movement of the film, to the film squeegee 54. It is then passed at high velocity, in accordance with the invention, between the rotating rollers 86 and 88 (see FIG. I) of the squeegee. Accordingly, the solvent adhering to the film is first mechanically and then evaporatively stripped from the film, as is more fully described hereinafter, as it travels through the drying chamber.
A battle plate 90 located at the bottom of the drying chamber 52 directs most of the drying air, which now is laden with solvent vapor, through an inlet port 92 leading to a solvent recovery chamber 94 (see FIGS. 1 and 3) disposed adjacent to the chilling chamber 50. Additional bafile plates.98 within the chamber 94 cause the drying air to pass over cooling fins I so as to condense the vapor carried by the air and cause it to collect at the bottom of the chamber. The recovered solvent drains through a conduit I02 interconnecting the recovery chamber 94 with a solvent reservoir 104, in which is disposed one or more cooling tubes 106. The solvent thus having been recovered from the drying air 78, the air passes from the solvent recovery chamber 94 through a port 108 (see FIG. I) and is returned through a connecting conduit 110 to the blower 64 for recirculation.
Fresh solvent for the rinsing sprays and for replenishing the solvent bath 38 is conducted to the spray heads 48 through a pipe II2 leading from the solvent reservoir 104 (see FIG. 3). A pump P may be interposed in the line to provide the pressure required for this purpose. A second pipe II4 leads from the reservoir 104 to an offset boiling tank 116, the tank 116 also being in fluid communication with the cleaning chamber 36 through an aperture 118 at the upper portion of the cleaning chamber.
Therefore, contaminated solvent in the bath 38 continually flows into the tank 116 through the aperture I18 and is boiled along with the clean solvent supplied through the pipe I14. As the solvent is vaporized the impurities precipitate to the bottom of the boiling tank, from where they maybe periodically removed through a cleanout door 130. Thus impurities are continuously removed from the recycled solvent.
Solvent vapor produced by the'boiling enters the cleaning chamber 36 through the aperture 118 to form a vapor blanket above the surface of the solvent bath 38. Cooling coils I20 and 122 control the height of the vapor blanket and, in addition, condense the vaporous solvent carried into the chilling chamber 50 by the drying air not deflected by the baffle plate 90. The solvent condensed by these coils falls either into the solvent bath 38 to replenish it further or into a collecting trough l24,'(see FIG. 3) to be drained to the solvent reservoir 104 through a connection 126. a
The film guiderolls 44 and 46 and the upper transducer 42 are mounted on a vertically slidable frame 132 (see FIGS. I and 3). A driven pinion 134 cooperates with a toothed rack 136 on the frame I32 to' move thefrarne along parallel vertical guide rods 138 between an upper threading position, at which the film guide rolls'44 and 46 are elevated above the level of the solvent bath 38, and a lower running position (as shown in FIGS. I to 3), at which the transducer 42 and the rolls 44 and 46' are immersed in the solvent bath 38. Upper and lower microswitches I40 and 142 are connected to the drive motor (not shown) for the pinion I34 to deenergize the motor when the frame reaches the predetermined upper and lower position, respectively.
Turning now in detail to the drying chamber 52 and the heating chamber 80, these chambers, in effect, define a bounded flow path of restricted area within the cleaning compartment 14 in which the heated air flow can be confined and solvent adhering to the film can be removed without interfering with the other steps of the cleaning process. The drying and the heating chambers, therefore, preferably are of less width than the cleaning compartment I4, being bounded at the rear by an intermediate wall 144 and at the front by a fixed wall 146 and a hinged door 148 (see FIG. 2). The doorl48 allows access to the drying chamber 52 for cleaning and for threading of the film 26 through the squeegee 54 and over the guide rolls 55 and 56.
In accordance with the invention, the rollers 86 and 88 at the squeegee 54 are positioned in opposed relation and are spaced apart of their peripheries a distance only slightly greater than the thickness of the film 26, so that, upon rotation, their radially outer surfaces come close to but do not engage the adjacent surfaces of the film (see FIGS. 4 and 5). Also, the rollers preferably are formed with a multiplicity of circumferentially spaced, flexible vanes 150 which, as in the embodiment shown in the drawings, may be simply straight bladelike members or, alternatively, may be slightly curved in the direction of rotation to enhance further the pumping effect of the rollers.
A motor 152 located within the accessory equipment compartment I6 is drivingly connected through a shaft 154 to the roller 88, and through the meshing pinion gears I56 and 158 and shaft 160 to the roller 86 (see FIG. 4). By this arrangement, the rollers 86 and 88 are rotated in opposite directions relative to each other and are also rotated in opposition to the direction of movement of the film 26, as indicated by the arrows in FIG. 5. Ideally, the motor speed is selected to drive the rollers 86 and 88 at high speed, for example, on the order of 3,000 r.p.m.
It is an important feature of the invention that the High speed rotation of the stripping rollers 86 and 88, coupled with the close spacing of the vanes I50 with respect to the film 26, causes the airstream 78 flowing downwardly through the chamber 52 to be pumped at high velocity through the spaces between the rollers and the adjacent film surfaces. These high velocity airflows are effective to blow, or strip, from the film surfaces any solvent or contaminants which might be adhering to them as a result of the cleaning and rinsing steps.
Moreover, as the airstream 78 is pumped at substantially equal velocities along both sides of the film, it automatically tends to center the film between the rollers 86 and 88, thus providing an air bearing, in effect, between the rollers and the film. Thus not only is the solvent stripped from the film by the airflows, but damage to the inherently soft surfaces of the film arising through contact between the film and stripping rollers is avoided since the vanes 150 at no time physically engage the film. In addition, the balanced airflows on either side of the film also serve to avoid the creation of a flutter motion of the film during the stripping operation, a problem in certain prior art devices.
The present invention, by avoiding both physical contact with the film and creating flutter of the film, accordingly allows the feed rate of the film through the cleaning apparatus to be increased, and the overall efficiency of the cleaning process thereby enhanced, without risk of damage to the film. And even at high feed rates, the presence of the high velocity airflows adjacent the film assures thorough stripping of the solvent or contaminants from both sides of the film; therefore, only a small residuum of solvent will remain on the film to be evaporated in the upper reaches of the drying chamber, and this evaporation can be readily carried out without elongating the drying chamber and without increasing the temperature or flow rate of thedrying air. It will be appreciated, therefore, that economies of size and operation are realized by the present invention concurrently as two sources of film damage, namely, contact of the film by the stripping rollers and flutter of the film, are eliminated.
As previously mentioned, the temperature of the drying air is adjusted according to the boiling point of the solvent used in the cleaning chamber 36, a representative temperature being on the order of I to l F. The flow 78 of drying air through the chamber 52, on the other hand, preferably is about 100 c.f.m., or enough to provide a low pressure, slow moving airflow downward through the drying chamber to evaporate whatever solvent remains on the film surfaces. A slow drying airflow 78 also enhances the pumping function of the stripping rollers 86 and 88 inasmuch as turbulence within the drying airflow is minimized as the air approaches the location of the rollers.
The rollers 86 and 88 preferably are at least as wide as the widest film to be cleaned and ideally are only slightly less wide than the spacing between the front wall 148 and the rear wall 144 of the drying chamber 52. By this arrangement, leakage of the drying airflow 78 around the ends of the rollers is kept to a minimum and the volume of airflow between the film and the rollers 86 and 88 is corresponding, and advantageously, increased. In this regard, the clearances between the roller ends and the adjacent drying chamber walls 144 and 148, respectively, are exaggerated in FIG. 4 for purpose of illustration. It will be understood that considerably smaller clearances exist in practice.
If desired, the rollers 86 and 88 can be easily exchanged for rollers of different widths by removing the screws 162 and washers I64 holding the rollers on the respective shafts.
Leakage of the drying air 78 past the stripping rollers is further prevented by resilient seal members 166 and 168 positioned between the rollers 86 and 88 and the end walls 170 and 172, respectively, of the drying chamber (see FIGS. 4 and 5). For this purpose, and also to channel the airflow toward the inlet port 92 and chilling chamber 50, the drying chamber 52 preferably is restricted in the vicinity of the stripping rollers 86 and 88. Thus, as depicted in FIG. 5, the end wall 172 slopes toward the center of the drying chamber to terminate in a straight, vertical section 174 leading to the upper end of the chilling chamber 50, while a separate baffle plate 176 attached to the end wall 170 slopes inwardly in the opposite direction.
The drying chamber 52 is therefore restricted to an extent that the seal members 166 and 168 are sufficiently close to the adjacent rollers 86 and 88 to engage the outer ends of the flexible vanes on the rollers as they are rotated past the seal members. Such engagement between the vanes 150 and the seal members 166 and 168 not only prevents leakage of the drying air 78 between the seals and the rollers, but also causes whatever solvent or contaminants that have been transferred to the vanes from the film 26 to be wiped from the vanes (see FIG. 5). Accordingly, the seal members desirably are constructed of material that is resistant to the solvent used.
An elongate port 178 (see FIGS. 4 and 5) in the plate 176 collects the solvent and other matter wiped from the roller 86 and directs it through the inlet port 92 of the solvent recovery chamber 94 where, as previously explained, the solvent is recovered for further use. A similarly positioned elongate port 180 receives the solvent from the roller 88 and conducts it through a duct 182 (see FIGS. 1, 4 and 5) to the solvent bath 38 where it is carried through the aperture 118 to the boiling tank 116 and recleaned. Any solvent thrown from the rollers 86 and 88 before reaching the seal members I 66 and 168 is deflected by the sloping end wall 172 and baffle plate 176 into the chilling chamber 50 for condensing and recoupment.
The seal members 166 and 168, in addition to the foregoing solvent recovery feature, also prevent the solvent and contaminants transferred to the roller vanes 150 from being carried past the positions of the seals and thrown by the rotational force of the rollers against the cleaned and stripped film emerging from between the rollers 86 and 88. As a precautionary measure, however, a U-shaped splash shield 184 (see FIGS. 1 and 2) is provided under the second drying chamber roll 56 to protect the dry film from any solvent which may be thrown upward by the stripping rollers.
Although only a single pair of stripping rollers 86 and 88 are shown, additional pairs of rollers can be positioned at other elevations within the drying chamber 52. Such additional stages of rollers are advantageous, for example, where very high film feed rates are necessary, or where space limitations requireshortening of the evaporating portion of the drying chamber. Also, if desired, the rotational speed of the successive stages of rollers could be varied to provide a stripping airflow of gradually increasing velocity through the drying chamber.
It will be understood by those skilled in the art that the above-described embodiment is intended to be merely exemplary, in that it is susceptible of variation and modification without departing from the spirit and scope of the invention as defined in the appended claims.
1. Apparatus for scrubbing the surfaces of strip material comprising:
a chamber defining a flow path for a fluid stream and adapted to receive a strip of material to be scrubbed,
at least one pair of opposed rollers rotatably mounted within the chamber transverse to the strip, the rollers having a length at least coextensive with the width of the strip and being separated at their peripheries a distance slightly greater than the thickness of the strip,
means for passing the strip of material through the chamber between the rollers without engaging the peripheries thereof, and
means for rapidly rotating the rollers in a direction opposite to the direction of movement of the strip so as to pump the fluid stream at high velocity, and in opposition to the movement of the strip, through the spaces between the roller peripheries and the strip surfaces to produce a scrubbing action along the strip surfaces.
2. Apparatus according to claim I in which the strip mat'erial is easily damaged, perishable material.
3. Apparatus according to claim 1 in which the rollers are formed with a plurality of radially extending flexible vanes to enhance pumping of the fluid stream between the rollers and the strip.
4. Apparatus according to claim 3 further comprising means for preventing leakage of the fluid stream and any foreign matter transferred to the rollers from the strip surfaces between the rollers and the walls of the chamber.
5. Apparatus according to claim 4 in which the leakage preventing means includes a resilient seal member disposed between the respective chamber walls and the periphery of the adjacent roller, each seal member being dimensioned to make engagement with the radially outer ends of the, flexible vanes of the adjacent roller as they are rotated past the seal member, whereby the flexible vanes are deflected and caused to release any foreign matter collected thereon.
6. Apparatus according to claim 5 further comprising means associated with the seal members for recoven'ng any, foreign matter removed from the-rollers.
7. lncombination with the apparatus of claim I:
meansfor filtering the fluid stream to render it substantially dust-free, and v a means for flowing the fluid stream through the chamber in a direction opposite to the direction of movement of the g strip material.
8. The combination according to claim 7 in which the foreign matter to be scrubbed from. the strip is a liquid, and which further comprises means for heating the fluid stream to a temperature higher than the boiling point of the ,liquidon the strip, thereby to evaporate any liquid remaining on the strip material after it passes between the rollers.
9. In an apparatus for cleaning strip material having a cleaning chamber containing a solvent bath for cleaning the strip, a drying chamber for evaporatively removing residual solvent from the strip, transport means for sequentially passingthe strip through thesolvent bath and thedrying chamber, means for filtering and flowing an airstream through the drying chamber in a direction opposite to the direction of movement of the strip, and means for heating the airstream to a temperature higher than the boiling point of the solvent, the improvement comprising: g at least one pair of opposed rollers rotatably mounted within the. drying chamber transverse to the strip, one on either side of the strip of material, the rollers having a length at least coextensive with the width of the strip and being separated at their peripheries a distance slightly greater than the thickness of the strip, thereby to allow the strip to pass between the rollers without engaging the peripheries thereof, and
means for rapidly rotating the rollers in a direction opposite to the direction of movement of the strip so as to pump the airstream at high velocity through the spaces between the roller peripheries and the strip surfaces to scrub from the strip surfaces solvent adhering thereto.
10. Apparatus according to claim 9 in which the rollers are formed with a plurality of radially extending flexible vanes to enhance pumping of the airstream between the rollers and the strip.
11. Apparatus according to claim 10 further comprising means for preventing leakage of the airstream and the solvent transferred to the rollers from the strip surfaces between the rollers and the walls of the chamber.
12. Apparatus according to claim 1] in which the leakage preventing means includes a resilient seal member disposed between the respective chamber walls and the periphery of the adjacent roller. each seal member being dimensioned to make engagement with the radially outer ends of the flexible vanes of the adjacent roller as theyFErOtated past the seal member, whereby the flexible vanes are deflected and caused to release the solvent collected thereon.
13. Apparatus according to claim 12 further comprising means associated with the seal members for receiving and conducting to the solvent bath the solvent removed from the rollers.
14. A method of stripping solvent from the surfaces of strip material comprising: 4
positioning a pair of rollers in a flurd stream in opposed,
spacedv relation such that the peripheries thereof are separated a distance slightly larger than the thickness of the strip material,
passing the, strip material between the opposed rollers without engaging the peripheries thereof, and
rapidly rotating the rollers in a direction opposite to the direction of movement of the strip material to pump the fluid stream at high velocity, and in opposition to the movement of the strip, through the spaces between the rollers and the surfaces of the strip material, thereby to scrub from the strip surfaces solvent adhering thereto.
15. A method according to claim 14 in which the strip material is easily damaged, perishable material.
16. A method according to claim 14 further comprising providing a multiplicity of radially extending vanes on the rollers to enhance pumping of the fluid stream past the strip,
17'. A method according ,to claim -16 further'comprising recovering the solvent scrubbed fronrthe strip surfaces by the rotating rollers. x V
18. A method according to claim l7 further comprising:
filtering the fluidjstream to render it substantially dust-free,
heating the fluidstream'to a temperature higher than the boiling point of the solvent, thereby to evaporate any solvent remaining on the strip material after it passes between the rollers, and
recovering the solvent evaporated from the strip.
' 19. A method for cleaning strip material comprising:
passing the strip material through a solvent bath,
rinsing the strip material in a spray of cleansolvent,
passing the rinsed strip material through a drying chamber in opposition to a flow of air heated to a temperature higher than the boiling point of the solvent,
positioning within the dryer chamber a pair of rollers in opposed, spaced relation such that the peripheries of the rollers are spaced apart a distance slightly greater than the thickness of the strip material,
moving the strip material between the rollers without engaging the peripheries thereof, and rapidly rotating the rollers in a direction opposite to the direction of movement of the strip material to pump the airflow through the spaces between the rollers and the' surfaces of the strip material, thereby to scrub from the strip surfaces solvent adhering thereto, and
exposing the scrubbed strip to the heated airflow to evaporate solvent remaining thereon after passing between the rollers.
20. A method according toclaim 19 further comprising providing a multiplicity of radially extending vanes on the rollers to enhance pumping of the airstream past the strip.
21. A method according to claim 20 further comprising recovering the solvent scrubbed and evaporated from the strip material surfaces and returning it to the solvent bath.
i Q I! i I PO'1O5O UNITED STATES PATENT OFFICE 5 CERTIFICATE OF CORRECTION Patent No. 3,615,821 Dated ogggber 25, 121],
Inventor(s) Arthur J, Mi llgr It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, line 27, delete incorrect "Patent No. 3,549,769";
Column 2, lines 14 and 15, delete "taken along";
Column 8, line 43, "dryer" should be drying-.
Signed and sealed this l th day of July 1972.
EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents