US2648089A - Air squeegee - Google Patents

Description

Aug. 11, 1953 l A. MAYl-:R 2,648,089

AIR SQUEEGEE Filed June 17,1950 2 sheets-sheet 1 (tra A u l. Numb @In (Z4 34a K JNVENTOR. l: :U11 E AMA/v /M/Wf Filed June 17, 1950 2 Sheets-Sheet 2 IN VEN TOR. AMA/v MA1/5e BY Pi/Wg? Afm/wwf Patented Aug. 11, 1953 Allan" Mayer; Kto'nah,

N. Y., assignor: toGeneral PrecisionLabotory Incorporated; a corpora-2 tionrof NewYork? 2 Chim:

This'invention relates to' airsqueegees; and particularly to an air squeegee through Iwhicl'xfa web or iilm strip may be passed for the removal of moisture from the surfaces thereof.

The present invention is particularly adapted for use in conjunction with'motion'picture lx'n treating apparatus to remove'theA excess-treating liquid from the surfaces'of the-'nlm befreeitis submitted to the drying operation. However, the invention is not limited to use with-'motion picture film, but can be used to removef-excessmois ture from the surfaces of a continuous web of any material after the web' has been passed `through a liquid or any region' Whereithasaccumulated an excess of liquid which mustbe'removed'ff-rom its surfaces.

Air squeegees of one type 'or another arci-com'- m'only' used for the purpose of removingy excess liquid from the surfaces of a fiexible strip which has been treated with aV liquid. Most known types of air squeegees, however; usev'exposedfa-ir nozzles for kcausing the impingement of air'upon thestrip, and depend upon the direction of-'the nozzles being at an angle other than normalto the plane of the strip to enhance the effective stripping of excess droplets of lliquid'. It'haslbeen found that air squeegees of thisltype' are` very noisy and wasteful of air, and that when` the strip moves at relatively high speed several nozzlesare required for treating each of the two surfaces of the strip for effective removal of "moistura' In prior squeegees in'which' the a-irnozzles are-enclosed in a' plenum chamber;- airand'entr'apped liquid has been permittedto escape both atl'the nlm entrance and exitthereby causing thevdeposition of some moisture `on the-'vportionof-'the lm from whichall moisture' should be'y removed. Also in such prior devices; in order not-to 'damage the surfaces'of the film, soft rubberrollers-have been relied upon to provide thefliiidfseal; thus requiring excessively high air' pressure andlvolurne of air flow.

Therefore, one purpose of the present invention is to provide an improved` air squeegee for the purpose of removing excess liquidflfromthersurfaces of a strip, which is quieter andfmoreuefficient, and which is more economical of air'ithan squeegees of known types.

Another `purpose is to provide animprovedair squeegee in which the air nozzlesare enclosedrin aplenum chamber and are directed'iatsubstantially right angles to therplane of'the-stripzor web, the air being permitted to escape-,from the plenum chamber at the :point of entrance of web.

195'0. Serial No; 16837.21'

Astill further purpose' is toprovide an improved squeegee "comprising alplenumicham'ber having a sub'stantiallyair-tig'ht Iexitfora. strip or web un;

' derftreatment'and having an entrance` therefor 0 which constitutesfanf air vent, and infwhichrthe chamber is'y supplied with air` whichh'as'` characteristics i especially.' adapted tor' its function of moisture removal.-

Still-anotherpurpose is to provide an improved airv squeegee 'that is 'designed /to facilitate thread'- ing a strip-therethrough.'

The .invention Vis best -under-stood from'thewfcllowing-ldetailedgdescription When'read in con` r nectionf. with' the* accompanying' drawings-fin which:

Figurefl isr-anend'elevationview of the air squeegee ofthe! invention.

Fig-ure 2-is a 'sectionalview on line` 2-2 `of Fig.' 1. Figure-'3i is-faisectional'view on line 3- 3 of Fiera;

Figure4-.is -a'sectional view on line' ll--liof Briefly;Y thef present' invention comprises a casing which constitutes a plenum' chamber through Which'is' moveda lm or Web whichv is to bedried,' a `partially fluid-tight seal being provided 'at'th'e film exit and a rpartial uidseal beingiprovided'fatth'e nlm entrance.' The plenum chamber, yperg se; is provided. within Vthe region =between1 `the` lm "entrance and exit which inthe example illustrated is f in f the form of pairs of rollers. A drying medium such as air-'isfapplied tol'th'e@plenum` chamber fzone by means `iof nozzles Whichidirectjetsofair against lthe sides of the filmeat'.subste'intally` right' angels thereto and escapes 1 from the plenum' zone at' the film entrancef'adjacent theisidesof'the film or 'strip'.`

The` embodiment of theinvention chosen for thefpurposesof illustration comprises a rectangu- :lar casingml which contains the plenum chamber,

the lcasingbeing` made in two sections" lax, lb as shown'most clearly in Figs.. 3 and 4. The ytWo sections-Jaand rIl) are adapted to iit togetherfon the'planein--which a film or Web I9"Which is being driedpassesthrough the casing l.- The two sectionsrof-thecasing'are.preferably parted on this line :to facilitate the threading of thelm inthe drying-mechanism.

-In order to'permitthe movement -of thefilm' 'or webl 9= without 4'unnecessary deterioration thereof thefvu'id seals atthe-entrance and `exit ofthe plenumlchamber are inl thev form `of a pair-of rubber faced rollers 23'and 24atthe .entrance and :a second `pair'of similar rollers 26 andl 2 'I at fthe iexit. .lilthoughireferenceY has: been' madevto'a nuid seal at the entrance and exit it is to be understood of course, that the seals cannot be completely fluid tight and still permit the movement of the hlm through the casing. Nevertheless the leakage around the axit and the entrance is so small that it is not difficult to maintain a plenum zone within the region between the `pairs of rollers and inside of the casing l. The length of the entrance and exit openings are substantially the same as the Width of the lm strip or web being dried. One of the features of the present invention is the arrangement of the pairs of rollers in such a manner that there is substantially no flow of drying medium out the iilm exit, the entrance being so proportioned as to constitute a flat nozzle permitting the escape of the drying medium in thin layers immediately adjacent both sides of the lm or web I9 in a direction opposite to the movement of the film thereby removing moisture from the film both by reason of the force of the flowing drying medium and also by evaporation. In this way substantially all of the moisture is removed from the film or web I9 before it passes between the exit rollers 26 and 21.

To this end, the entrance rollers 23 and 24 are spaced a distance which is slightly greater than the normal thickness of the film to be dried. As a specific example, a conventional motion picture film is approximately .006 of an inch thick and the surfaces of the entrance rollers 23 and 24 are spaced apart approximately .008 of an inch thus leaving approximately .001 of an inch between each roller and the adjacent surface of the film I9. It will be readily understood that when the air escapes from the plenum zone between the surfaces of the rollers and the i'llm, the latter will be substantially centered between the rollers Without touching either one because of the layers of the high velocity air. Preferably one of the rollers at the entrance, for example L roller 23, is spring loaded so that it can accommodate variations in thickness of the film, such as lap splices.

The exit rollers 26 and 21 are preferably spaced apart a distance which is equal to the average width of the motion picture film, as an example in this instance .006 of an inch. One of the rollers, for example, roller 26 is spring loaded to accommodate variations in the thickness of the width of the lm and to permit the passage of the lap splice.

It is clear from the drawings, particularly from Figs. 2 and 3 that the journals for one of each of the pairs of rollers, for example rollers 24 and 21, are rotatably fixed in one of the sections, for example lb. The rollers are preferably provided with integral journals 24a and 21a, respectively, which are rotatably supported in suitable antifriction bearings, such as roller bearings 28. The construction of all of the rollers is identical and the anti-friction bearings for all of the rollers are also identical. The bearing races for the fixed rollers 24 and 21 are received in suitable recesses in the sides of the section lb. The other the sliding blocks 33 engage the bottoms of their guideways the spacing between the surfaces of the rollers 23 and 24 will be substantially .008 of an inch, assuming of course that the two sections of the casing are fitted tightly together. In the case of the roller 26 the length of the guideways is such that when the sliding bearing blocks 34 engage the bottom of the guideways the surface of the roller 26 will be approximately .006 of an inch from the surface of the roller 21, again assuming of course that the two sections la and I b of the casing are fitted tightly together.

The respective pairs of bearing blocks for each 'roller are adapted to move in unison in their guideways. Accordingly, a crossbar 29 engages holesin the upper ends of the sliding blocks 33 with a press lit. Similarly, a crossbar 30 engages holes in the upper ends of the sliding blocks 34. Suitable means are provided for resiliently urging the bars 29 and 30 downwardly to thereby provide the necessary spring loading on the movable rollers 23 and 26. To this end. caps 35, 36 are suitably secured to section la of the casing and each is provided with a screw threaded aperture such as 35a and 36a, which is each respectively engaged by cap screws 31 and 40. Interposed between the lower end of each of the respective cap screws 31 and 40, and the crossbars 29 and 30 are pairs of headed studs 38 and 39 between which is interposed respective compression springs 45 and 46. The heads of the upper one of each of the pairs of studs 38 and 39 are adapted to slide within recesses in the respective caps 35, 36 while the heads of the lower ones of the studs 38 and 39 are adapted to slide within respective cylindrical recesses in the wall of the section la. It will be readily apparent that by adjusting the position of the cap screws 31 and 40 the preloading on the rollers 23 and 26 can be varied. The compression of the spring 45 will hold the sliding bearing blocks 33 in engagement with the lower ends of the guideways 33a and 33h which thus determines the spacing between the movable roller 23 and the xed roller 24. Similarly, the compression of spring 46 holds the sliding bearing blocks 34 against the lower ends of their guide- Ways to determine the normal spacing between rollers 26 and 21.

All of the rollers are provided with a facing of soft rubber of a relative thickness indicated in the section in Fig. 2. A drying medium is supplied to the plenum zone between the pair of entrance and exit rollers through a pair of nozzles 43, one of which is shown in section in Fig. 2. Each nozzle has a main body 48 provided with a pair of nozzle blades 44 and 46 each of which are provided with bevelled edges which, when spaced as indicated in the section in Fig. 2, constitute a long narrow slot 41. Preferably one of the blades, for example 44, is adjustable in order to vary the width of the slot 41. 'lhe blade 46 is held immovable by suitable screws. The optimum widthof the slot 41 depends on the air pressure used. For example, with air pressure at approximately 20 pounds per square inch a ,slot width of .O08 to .010 inch is satisfactory. Preferably the two nozzles are positioned about 1/8 of an inch from the respective opposite sides of the film strip I9. Each of the nozzles is supported on suitable similar conduits exemplified by the conduit 45 which is connected to a suitable manifold 46 which is adapted to be connected to a source of drying medium such as air under pressure and heated to the desired temperature. Each of the conduits, exemplied by the conduit 45, are provided with an opening a in .one side thereof ^which'"communicates with .the hollowportion of the nozzle body`48. Each of the nozzles 431is' angularly ad'- justable about its respective conduit and this construction is illustratedin Fig. 4`wherein a suitable short screw threadedly` engages the outer end of the conduit 45 and when it is screwed home the. heady of ther screw engages the cylindrical portion of the nozzle 43fproviding suiiicient friction to hold the ,nozzleV in .a desired adjusted position. The construction-V for both of the nozzles is. identical. As. shown in- 2, preferably the nozzles are so adjusted so that the faces adjacent the filmorweb` I9v divergein av direction opposite to the-v movement' of'the nlm. This-causes the jets of air from the respective nozzles 43 to strike the surface of the iilmA or strip; at anr-angle.-slightly less...than-90 and thuslfacilitates the stripping of the droplets of water from the surface ofthe film and tends to direct the water toward the space-between the entrance. rollers23Ja-nd 24S-andthe iilm strip I9.

Preferably the pressure-of'v the air or other drying mediumsupplied througlr. the nozzles 43 should not be so high as to set up turbulence 01' cause the film strip I9 to vibrate. The air should preferably be dry and must be clean nand free from oil. It should also be at such a temperature as to overcome the cooling eifect of evaporation and at the same time raise the temperature of the water that is being removed from the strip in order to facilitate evaporation. By the increased temperature the viscosity oi the Water is decreased and thus the droplets of water are more readily separated from the strip of lm by the air blast from the nozzles. If desired, the temperature of the air blast may be as high as the material of the nlm or strip can withstand in order to facilitate the drying action.

Any suitable means may be provided for holding the two sections la vand lb together as one integral unit. In the embodiment shown the frame of the section lb is provided with holes which are adapted to be engaged by a pair of pins 60 and 6l which vare press-nt or otherwise secured in holes in the section la. Suitable means may then be provided for preventing the section lb from separating from section la. To this end, suitable rectangular pins 62 are adapted to engage complementary transverse holes in pins 60 and 6l, the shanks of rectangular pins 82 being received in recesses in brackets 63 which are suitably secured to the side of the section lb. From the construction just described it will be apparent that it is a simple matter to insert the film or strip I9 to be dried in the squeegee of this invention by merely removing the pins `62, separating the two sections la and Ib and inserting the film or strip after which the sections are positioned together and the pins 462 are reinserted to engage the transverse holes in the pins Si] and 6|.

Air or other drying medium introduced into the plenum zone by means of the nozzles 43, Fig. l, escapes from the casing I adjacent the incoming film strip I9 between the cylindrical surfaces of the rollers 23 and 24, and also escapes through the several clearance spaces necessary for easy mechanical operation as, for instance, around the ends of the rollers, between the rollers and the sides of the sections of the casing and through a suitable drain hole 62. It is not intended that any air shall escape along 6 the outgoingflm strip l9-'betweenetheJ cylim dri-calv surfaces of the exit rollers-#261? and-221, an'd sin" the construction* described no airL does escape at' this point. Ths'prevention' off escape ofair' atthis pont'is one'foithe essential features of the invention, and is'"-vital totHe-inrproved` operation thereof. IfV4 air'fshould escape at this. point; entrained `moisture would' rewet the lm as it"leaves the-squeegee; in greatpart destroyingy the .electivenessoifthedevice; Certain drying, action occurs'inJ this squeegeeatfthfe points of impingement of the streams ofy air from.. the nozzles `1I3`r upon' the'surfaces ofthe strip I9 moving between'. them- The dryingiaci tion is of two. kinds, 1 evaporation and" physical removal .ofthe Waterinwdiscrete droplets;` Any drops .large enough 4to fall `and'iany dropletsl that condense onobjectswithin the chamber; Acollect onthe door thereof .and mayv be drained Vout of thedrain.openix1g462l`.` Anydrople'ts small enough to remain. suspendedlwill be exhausted with` escaping air. Additional. drying,` action takes place with theescapeo-f th'e air beside the incoming filmstrip-i9V betweenth'e.roll`ers 23 and 24, through the .G01-inch gapsonieach side of the film strip. The volume of air employed is such as to maintain some pressure within the plenum zone between the entrance and exit rollers in spite of the several points of escape, so that the velocity of the air escaping past the incoming film is high. This high velocity air scours considerable moisture from the film strip I9 as it moves into the casing l preventing some of the moisture from entering the chamber with the strip.

The entrance rollers 23 and '24 touch the incoming film i9 only lightly. if at all, so that there is little or no frictional contact of the moving film strip with the rollers tending to rotate them. Therefore it is obvious that in place cf these rollers there may be substituted fixed shoes forming the lips of an entrance film slot. Such shoes need have a separation only sufficient to pass a lap splice, which may have a thickness of perhaps as much as ten thousandths of an inch. Such shoes may be therefore placed this distance apart with only a slight reduction in the effectiveness of the air blast passing between them in drying the film. In such construction a very small amount of resilience should be provided, Ias for instance by iiexible mounting of the shoe supports, so that the shoes may be easily forced apart momentarily by a lap splice to permit its passage.

From the foregoing description it will be apparent that the present invention provides an improved squeegee or drying apparatus for drying a nlm strip or web through the provision of jets of air or other drying medium applied to a plenum zone in such a manner that the air or drying medium escapes from the plenum zone in a thin layer on the opposite sides of the fllm in a direction opposite to the movement of the movement of the latter. In this manner the larger droplets of moisture are stripped from the fllm before it enters the plenum zone and the final drying action primarily by way of evaporation takes place inside of the plenum zone. In this way a minimum of moisture-laden air engages the film after it has passed through the plenum zone resulting in greatly increased drying action.

What is claimed is:

1. An air squeegee comprising a. casing through which a strip or web of material is adapted to passA for removing the water or moisture therefrom, an entrance and an exit for said strip in the form of respective pairs of rollers journalled on respective parallel axes in bearings slidably supported for movement toward and away from each otherI stop means for determining the minimum spacing between the surfaces of the respective pairs of rollers, the stop means at the exit being placed so that the minimum spacing is substantially equal to the normal thickness of said strip to thereby provide a substantially huid-tight seal, the stop means at the entrance being placed so that the minimum spacing between the surfaces of the entrance rollers is slightly wider than the normal thickness of said strip, means for directing a gaseous drying medium under pressure into the zone in said casing between said entrance and exit, the wider minimum spacing of said entrance rollers being adapted to permit said drying medium to pass out of said casing at said entrance at high velocity in thin sheets in a direction opposite to that of the movement of said strip, and means for independently resiliently urging each of said movable rollers against their respective stops.

2. A combination as set forth in claim 1 in which said means for directing a gaseous dry medium under pressure into said casing comprises a pair of nozzles, one of which is arranged on each side of said strip for directing fluid pressure against said strip, each nozzle having an elongated orifice opening transversely of a plane face, each face including pairs of respective spaced plates arranged in respective common planes with the adjacent edges of a respective pair of plates of a face forming an elongated orifice, said faces being arranged symmetrically on opposite sides of said lm and dlvergent toward said entrance to constitute an expanding throat with said elongated orifices discharging toward said film and said entrance.

ALLAN MAYER.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 1,407,543 Hubbard Feb. 21, 1922 1,930,575 Wynd et al. Oct. 17, 1933 2,289,753 Capstaff July 14, 1942 2,501,875 Rayburn Mar. 28, 1950

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