US 3116243 A
Description (OCR text may contain errors)
Dec. 31, 1963 KHAN ETAL 3,116,243
A. U. METHOD FOR ELIMINATING ADHESION 0F FABRICS TO CENTRIFUGAL EXTRACTORS Filed May 18. 1960 3 Sheets-Sheat 1 gg L@ au Ff/g5.
Dec. 31, 1963 A u KHAN ETAL 3,116,243
METHOD FOR EL'IMI'NATING ADHESION oF FABRICS 'ro CENTRIFUGAL ExTRAc'roRs s sheets-sheet 2 Filed May 18, 1960 [NI/Enffg dma u. Kan Clav* I. plait Dec. 31, 1963 A. u. KHAN ETAL 3,116,243
METHOD FOR ELIMINTING ADHESION 0F FABRICS TO CENTRIFUGAL EXTRCTORS 5 Sheets-Sheet 5 Filed May 11.8,l 1960 WA 5H United States Patent O ADHESHN F The present invention relates broadly to home appliances, and is more particularly concerned with method for eliminating adhesion of fabrics to centrifugal extractors.
It is known that subsequent to a relatively high speed uid extraction step in a laundry machine, as exemplied by an automatic washer or combination washer-drier of the substantially horizontal axis type, the clothes or other fabrics adhere to or form an adhesive bond with the inner periphery of the cylinder. The fabric load forms a tight annulus closely hugging the cylinder inner periphery and does not fall away by gravity even when cylinder rotation is terminated. The adhesion problem is particularly troublesome in a combination washer and drier, since when the drying cycle is initiated subsequent to the high speed extraction step, the tightly formed and adhesively bonded fabric annulus does not release from the drum inner periphery, and as a resuit, the inner exposed layer of the fabric load may be severely overdried while the outer layer adjacent he inner periphery of the cylinder is only slightly dried. When this so-called drying step is ended, the fabric annulus remains against the drum inner periphery and in many instances is difficult to pull loose. And even when the fabrics can be removed without great difficulty, they are generally found to be severely wrinkled and thus not in condition for folding or normal ironing.
Load sticking is apparently caused by the flushing action of large quantities of liquid through the fabrics during the centrifugal extraction cycle, forcing the many fibers on the surface of most textiles to be matted down by contact with the cylinder surface from the centrifugal force exerted thereon by the extremely high speed rotation of the cylinder. In other words, the tiny bers which protrude from the surfaces of most textiles are straightened out by the force and ushing action of large quantities of water through the fabrics and out of the cylinder perforations, causing the iibers to be flattened and interlaced against the cylinder inner periphery, thereby presenting an increased surface area thereto which is more smooth and free from the pockets formed by the normal unstressed intermingling of the fibers. There is accordingly formed a compacted fabric annulus adhesively bonded to the drum inner periphery, and before effective drying of the fabric load can take place, the cylinder must be stopped and the load released by hand from the cylinder surface. This is obviously a great inconvenience, and on the other hand when the laundry machine is permitted to automatically proceed from the high speed extraction step to the reduced speed drying step, the fabrics or ciothes remain adherent to the drum surface and are overdried on the inner exposed layer and underdried on the outer layer adjacent the inner periphery of the cylinder. Then too, as was noted, the fabric load is either extremely diicult to pull loose or severely wrinkled.
It is accordingly an important aim of the present invention to provide novel method for eliminating adhesion of fabrics to the inner periphery of a centrifugal extractor.
Another object of this invention lies in the provision of a method of breaking the adhesive bond between damp fabrics and the inner walls of an extractor cylinder as produced by high speed extraction of wet fabrics in the cylinder, which does not necessarily require for effective performance thereof extensive variations in the normal extraction cycle.
A further object of the present invention lies in the provision of a load adhesion elimination method wherein subsequent to centrifugal separation of fluid from fabrics in a rotatable cylinder, the interface between the fabrics and the cylinder is moistened to break any adhesive bond at said interface, to thereby permit the fabrics to peel off and tumble freely within said cylinder.
A still further object of this invention lies in the provision of a method of preventing load sticking, featuring moistening the interface between fabrics and a rotatable cylinder subsequent to fluid extraction and which is of such a high order of effectiveness that the cylinder can again be rotated at normal high spin or increased extraction speeds without producing load sticking.
Other objects and advantages of the invention will become more apparent during the course of the following description, particularly when taken in connection with the accompanying drawings.
ln the drawings, wherein parts throughout the same:
FIGURE l is a cross-sectional view, with parts shown in side elevation and with parts broken away, illustrating an exemplary laundry machine incorporating therein load adhesion eiimination means constructed in accordance with the principles of this invention;
FIGURE 2 is a fragmentary front elevational View of the laundry machine of FGURE l, with parts broken away and with parts taken in section, to further illustrate one form of a device for practicing the method of this invention;
FGURE 3 is a more or less diagramamtic view of the interior of a laundry machine cylinder to illustrate the compacted fabrics therein and their adhesion to the inner periphery of the cylinder;
FiGURE 4 is a view similar to FGURE 3, but illustrating load release by the method of this invention;
FIGURE 5 is a fragmentary front elevational view similar to that of FIGURE 2 showing a second form of a device for practicing this invention; and
FGURE 6 is a digrarnmatic representation showing an exemplary cycle of operation incorporating the method of this inventon.
There is shown in the drawings and will be described herein a particular type of combination washer-drier apparatus which has performed particularly effectively in the practice of the method steps of this invention. However, it will be readily apparent to those versed in the art that other forms of combination machines may be employed, and in fact, the invention produces advantageous results with a machine not equipped with means for performing the drying function. As well, there is illustrated a horizontal axis type machine, although load sticking is also prevented when the cylinder is mounted on an inclined axis.
Referring now to the drawings, there is shown a laundry machine comprising a combination washer-drier indicated generally at lli and comprising an outer shell 11 suitably finished to enhance the decorative appearance of the machine. Inside the shell 11 is a casing or outer container l2 of generally rectangular over-all configuration, but which is provided with a curved generally arcuately shaped bottom wall (not shown) and a sump 14 is provided at the bottom portion thereof subjacent a large hollow space enclosed by the casing 12. This hollow space may be characterized as a treatment Zone in which the washing, rinsing and drying operations are performed.
Carried within the casing 12 is a rotatable generally like numerals designate like cylindrical foraminous drum or cylinder provided with a rear wall 16 connected to shaft support 17, and a front wall 13 having a centrally disposed front opening 19. A peripheral wall 29, foraminous as indicated, is disposed between the rear and front walls 16 and i8 and carries a plurality of circumferentially spaced and radially inwardly extending ribs 21.
The shaft support unit 17 includes a rotatable shaft 22 to which the drum or cylinder 15 is firmly connected for corotation by means of a fastening nut 23. The shaft unit 17 is supported in a rear wall 2d of the outer container 12, and together therewith serves to support the shaft unit 17 by means of a bearing housing (not shown). Adjacent the free end of the shaft 22 is a pulley wheel 26 held in firm assembly with the shaft 22 by means of the fastener 23. Through provision of the described shaft unit and supporting structure the drum 15 is mounted for rotation upon a substantially horizontal axis, although it will be readily apparent as the description proceeds that the novel steps of the instant method can sealing member 2S defining an opening 29 lying generally in registry with the opening 19 in the drum front wall 18. While goed results have been obtained with the substantially tear-drop seal configuration shown, other shapes may of course be employed as desired.
The annular gasket 28 functions as a door seal, and for this purpose bears against an annular flange portion Sila formed on a door 35B mounted by suitable hinges (not shown) connected to the shell 11 or casing 12. As is the practice, handle means and yieldable latch means are employed with the door 30.
In order to charge the machine 1t) with a supply of liquid for accomplishing the objectives of this invention, a fresh water inlet 31 passes through and is supported by the rear wall of the outer shell 11 and the rear wall 24 of the casing 12. The inlet 31 discharges into a vacuum break means 32 supported by a transverse wall 33 extending between the casing front and rear Walls 27 and 24, respectively, and discharges into casing 12 against drum 15 at a slight angle to its axis of rotation. While inlet 31 is illustrated primarily for supplying tluid to eliminate clothes adhesion problems, it may also be used for supplying washing and rinsing fluid to casing 12 during various portions of the operational cycle. While water of 120 F. may be preferred because of its increased tluidity, cold tap water of 60 F., for example, has been found to produce satisfactory results in eliminating clothes adhesion.
ln accordance with the principles of the present invention, means are provided for moistening the interface between the inner walls or inner periphery of the rotatable drum or cylinder 15 and damp fabrics adhering thereto as a result of high speed roation of cylinder 15. An exemplary form of load adhesion prevention means is clearly illustrated in FIGURES l and 2, and may be noted to comprise a transversely extending tubular member 34 having a plurality of spaced holes or openings 34a therein, which if desired may receive nozzle means. The tubular member or spray device 34 has a length generally corresponding to the distance between the end walls 16 and 13 of the rotatable cylinder 15, in order to direct by spraying or sprinkling uid from the tube openings 34a substantially entirely across the drum peripheral wall 2li and through the holes or openings 20a therein. While good results have been obtained to date by spraying techniques, it is also within the contemplation of this invention that the fluid be sprinkled, dripped or allowed to fall by gravity into moistening contact with the outer layer of the fabrics adhering to the drum inner periphery.
The perforated tubular member 34 may be mounted by bracket means 35 from the transverse wall 33 utilizing suitable securing means 36, which may take the form of nuts and bolts. The tubular member 34 is shown in FIGURE 2 as at approximately an eleven oclock position or preferably to one side of the vertical axis of the cylinder 15, although of course any position suitable for directing liquid into the drum perforations 20a may be employed. The central portion of the generally horizontal and transversely extending tubular member 34 connects with the vacuum break means 32.
-Fluid flow through the inlet 31 and through the tubular header member 3ft is under control of solenoid operated valve means it located in the inlet tube 31. Suitable electrical connections llla connected to valve means it? lead to the sequential controller e7 which automatically controls the point and duration of operation of valve means to effect the moistening of the fabrics and thereby break the adhesive bond which may be produced between the `fabrics and the inner .periphery of the cylinder wall by high speed rotation of cylinder 15.
A preferred fluid for this purpose is water, and as will be later noted in connection with a description of the sequence of steps, only a relatively small metered amount of water is required to prevent rload sticking, and the water is directed into the vacuum break means 32 at normal water line pressure, so that in substance the fabric load is not blasted from its adhering reiation with the drum inner periph-ery, but in contrast, the interface between the fabrics and inner walls of the drum is only imoistened to a `degree sufficient to break `any adhesive bond and not to an extent whereby the lfabrics would contain any marked volumes of water which, if flushed through the fabric in a further extra .'on cycle, would again cause load sticking. it will accordingly be appreciated that the fabric-cylinder inner wall interface receives only sufficient liquid to permit the .matted down fibers to spring out or bristle so that liber clinging to the drum is eliminated. Once the adhesive bond is broken, strangely enough the fabrics or other clothes may be spun at high speed, as for the purpose of removing the `water added to prevent load sticking, there is no further adhering of the fabrics to the drum inner periph-ery, apparently because there is not by the nioistening action sufficient volumes of water to be flushed through the clothes, `and the bers once having been raised are not again spread out or flattened to create the surface necessary for load sticking.
To complete the description of the apparatus, introducing means for liquid used in the washing and rinsing cycles Amay take the form of a nozzle 45 formed on a conduit te `and supported by the 'Wall 27. The nozzle is provided to direct liquid from the sump 1d through the opening 19 in the drum `front wall 18. As is appreciated, the liquid in the sump at different times may be water alone, a solution of laundry fluid, or rinsing fluid. Within the conduit 4d there is located valve means i7 of the twoposition type for controlling recirculation and drain, and the conduit 6.5 leads from the -valve i7 to a pump to which connects a conduit 49 providing an outlet from the sump 14, and through which suction can be drawn by the pump 43 to recirculate flu-id from said sump and through the valve i7' and conduit 46 through the nozzle ll5 and into thedruin interior.
The pump 143 is driven by a motor Sti through a shaft 51, and as illustrated, the lmotor 5d may provide power for rotating the drum 15 through three-speed transmission means 52 and a shaft 53 supporting a pulley 5w about which is trained a belt 55 further trained about the pulley The transmission 52 is, as noted,
26 on the shan .22. of the three-speed type providing a tumble speed of approximately 46 revolutions per minute, an intermediate speed of approximately Bi) revolutions per minute and a high spin speed of approximately 55S` revciutions per minute, although, of course, the method of this invention can be practiced with a laundry machine having a two-speed transmission.
The laundry machine lll illustrated in lilGURE l porfor-rns drying functions upon the load in the rotatable drum 15, and accordingly embodies means to generate thermal energy, designated generally by the numeral et). Such means may comprise a heater box or chamber 6l having heating elements (not shown) therein, the heater box 6l communicating with ambient and with the interior of the container l2 and treat-ment zone by suitable ducting. Air drawn into the heater box is forced into the treatment zone by blower means 62, lwhich may comprise an exhaust conduit 63 connecting with a -fan scroll 64 which mounts motor means 65 and receives an intake conduit 66 extending into the interior of the outer container i2. As is now apparent, air to be heated is dr into the machine under action of the blower means 62, and said air is heated within the heater box and passes into the treatment zone and is withdrawn therefrom by the blower means o2, the air passing through the intake conduit o6, into the fan scroll 64 and through the exhaust conduit 63. The blower motor 65 is connected to the timer system of the machine lt? so that the blower is actuated `only during the drying cycle of the cleaning operation, and similarly, the heating means within the heater box is electrically connected with the timer mechanism for actuation only during drying. The timer may of course take many different forms, and suitable timer forms are indicated more or less schematically in the drawings by the numeral `f.
The compacted condition of a load of fabrics subsequent to the conventional washing, extraction, rinsing and high speed spin steps is shown in PlGURE 3, to which reference is now made for a more complete understanding of the novel results obtained by the instant invention. As shown therein, a load of fabrics ydesignated generally as E form a relatively tightly compacted annulus `generally firmly adherent to the inner periphery of the rotatable foraminous drum l5. As was explained, this is apparently due to the flushing action `of large quantities of liquid through the fabrics F during the centrifugal extraction periods of the cycle of operations, causing the many fibers present on the surface of the textiles to become matted down by contact with the cylinder inner surface from the centrifugal force exerted thereon due to the extremely high speed rotation of the cylinder. This matting down or flattening of the fibers creates a marked tendency for the fabric mate-rial to firmly adhere to the inner walls of the drum or cylinder, and to remain in that position even after rotation of the cylinder 15 is stopped. ln other words, FlGURE 3 portrays the condition of the 4fabrics F relative to the cylinder f5 either during the high speed extraction step or upon cessation of this step.
The lflushing action of large quantities of water through the fabrics straightens out the tiny textile fibers, causing them to be flattened and interlaced against the surface of the cylinder l5, thereby presenting an increased surface area thereto which is more smooth and free from the pockets formed by the normal unstressed intermingling of the fibers. There is in effect an adhesive bond at the interface between outer layer l of the fabrics and inner surface 15a of the drum, this bond even extending between the fabrics and the inner surfaces of the drum ribs 2l. The attraction between the fabrics and drum inner periphery which is believed to be due to surface tension or a chemical-physical bond has been observed to be quite substantial, being of a sufficient extent that gravitational forces are inadequate to cause the desired peeling off of the fabrics from the drum, and in fact, to remove the fabrics their adhesive contact with the drum inner periphery actually requires substantial manual pulling. And as was noted, if the drum l5 is rotated during a drying cycle, overdrying takes place at inner layer lof the fabrics and underdrying is found at the outer layer l. Even when the drying step goes to completion, again it is extremely difficult to remove the fabrics F, and when they are pulled loose from the drum inner eriphery, they will in most instances be found to be severely wrinkled and clearly not in a condition for folding or ironing.
ln accordance with the instant novel concepts, the coridition portrayed in FGURE 3 is eliminated by means of relatively simple construction and operation, and the fabric load released from the cylinder inner periphery for free and loose falling to essentially the condition indicated in FlGURE 4.
This may be accomplished as shown in the exemplary cycle illustrated in FlGUiE 6 which shows a washing period, a first spin period, a subsequent rinse and tumbling operation, a second spin period, another rinse and tumbling operation, and a third spinning operation of somewhat longer duration than either of the rst two spin periods, a peel olf and tumble operation, a rest period, and a final extraction operation followed by a tumbling operation and a rest period which precedes a drying operation illustrated as being of an indeterminate length. Since this invention is not dependent upon the initial spin and rinse periods, it will be appreciated that they may readily vary in number and duration. In practice, the first t-wo spin periods each are of a total duration of two minutes iwhile the third or preliminary final extraction period 'ind the fourth or final extraction period are each of approximately six minutes duration, each of the spin periods being shown as progressing from the 46 rpm, tumble lspeed through the rpm. intermediate speed and finally up to the top spin speed of 550 rpm. It should be noted that the third or preliminary final speed may be the same as or less than the final spin speed but need not be a speed ranging between tumble speed and the top spin speed.
Since the illustrated machine is of the type in which cylinder i5 is positioned above the fluid level maintained in the sump of casing l2 and in which the fluid from this sump is recirculated from that sump onto the fabrics tumbled within cylinder l5 by means of the circulation nozzle during the tumble rinse periods, fluid must be initially directed into the sump either through the inlet conduit 3l or through a separate fill nozzle as previously described for these operations. This sump is drained between spin operations by conventional apparatus, not shown.
The fluid injection point identified in FGURE 6 during the peel off and tumble operation which normally totals about two minutes occurs substantially near the middle of this two minute interval when timer 67 energizes the solenoid valve fill to produce a short fluid burst of approximately seven and one-half seconds `duration so as to inject approximately a third of a gallon of water against the periphery of cylinder l5. Since it is desired to wet the interface between the fabrics and the cylinder l5, the point of fluid injection may vary from a point of time when the cylinder is decelerating from its preliminary final extraction operation to other points of time in the peel off and tumbling operation identified in FIGURE 6. in addition, it may be desirable to use two or more intermittent bursts of fluid injection of shorter duration during this same period to accomplish the same function. While not absolutely necessary for the practicing of this invention, it is preferable to completely terminate the rotation of cylinder l5 as shown in FiGURE 6 prior to going into the fourth or final extraction period. This is desirable since it has been observed that complete termination of rotation of cylinder l5 has an effect of allowing residual fabrics adhering to the cylinder to fall olf from that cylinder so as to allow the fabrics to be completely rearranged prior to going into this fourth or final extraction operation.
Even though the amount of fluid injected against cylinder l5 and absorbed by the fabrics therein is a rather small quantity, not all of which enters cylinder l5, it is preferable, though not necessary, to utilize the fourth or nal extraction operation illustrated in FiGURE 6, since this assures that a maximum fiuid extraction is effected by this illustartive apparatus. As noted in HG- URE 6, this final extraction period is again followed by a tumbling operation, which may be of one or two minute duration and a subsequent rest period of an approximately one minute interval prior to the cylinders being stopped for line drying the fabrics or again driven at tumbling speed during a subsequent drying operation. These latter tumbling and rest periods aid in assuring the separation of fabrics from cylinder l prior to this drying operation.
The times stated are of course exemplary and may be varied as dictated by a particular situation, although it is important to point out that once loa-d sticking has been eliminated by the novel means of this invention and the cylinder again rotated at high speeds, as in the exemplary cycle for removing the added adhesion elimination water, there is not again any load sticking to the drum inner walls. The explanation for this is that 'there is no longer yany large volume of water that is forced through the load, and accordingly, the load fibers are not spread out so that they cling to the inner periphery of the cylinder, in the manner described in connection with FIGURE 3.
T he condition of the fabric load after release from the drum inner periphery in accordance with the instant teachings is portrayed in FIGURE 4, and it may be seen therefrom that the fabric load F-l is in a relatively loose state free from adhering contact with the inner walls a 0f the cylinder l5. Thus, there is not after practice of this method any adhesive bond between the fabric load and drum inner periphery, and the fabric load F-l will freely fall in continuously changing surface contact with the drum inner periphery in a semi-iiuffed cr semi-expanded state, generally as shown in FIGURE 4. Accordingly, when the machine 1d proceeds into the drying cycle, `the lload is released and generally opened up so that varying fabric surfaces are exposed to the thermal energy and uniformly dried. The load F-l is then readily removed from .the cylinder l5, and by virtue of uniformity of drying, no severe wrinkles will exist therein.
lt has been noted that the method of this invention is also of application in the sprinkling of a fabric load. In this pursuit of the invention, dry fabrics or other clothes are placed in the cylinder 15, and with the cylinder r0- tating at tumble speed, the solenoid valve means 40 is energized to direct water from the inlet 31 and through the and 38 out from the openings 34a in the tubular member 34. Even dampening of the load of clothes is 'thereby provided, `and any amount of dampening can ybe accommodated by merely actuating the valve means 4t)l as many times as desired.
It has been noted that Water for elimination of adhesion can be either sprayed, sprinkled, dripped or allowed to fall by gravity from the tubular member 34, 'and of course, in substitution for a tube 34 a pan or other means equivalent to the device shown can be utilized. It is accordingly believed quite apparent that various changes and modifications may be effected without departing from the novel concepts of the present invention.
For example, the modication of FIGURE 5 utilizes no spray header as shown in FIGURE 2 and incorporates only the end of conduit 37 fitted in casing grommet 38 for this purpose. While it is not necessary in the practice of this invention to wet the entire peripheral wall of cylinder 1S, it will be appreciated that grommet 33 and end 37 may be formed in wedge shaped or fan configurations varying from la circular configuration to achieve a broader wetting pattern.
As a matter of practice, the water stream emanating from the conduit end 37 is spread across the side Wall of cylinder l5 fairly well due to the injection lof lthis stream against the direction of cylinder rotation and due to `the spreading `action caused by the splashing of this stream fi from the outwardly directed flanges formed by the punching of the perforations 29a in the side wall of cylinder 15. The fluid impinging against cylinder l5 inv both embodiments wets the interface between the cylinder and the fabrics by wetting the nubs of fabrics extruded by centrifugal force through apertures 20a in cylinder 15 by capillary action to effect the separation of these fabrics from cylinder l5. i
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
l. The method of extracting which includes .the steps of (a) rotatably centrifuging a batch of Wet fibrous materials in :a foraminous receptacle at `a speed such that the liquid in the materials is forced radially outwardly through the materials,
thereby tending to form the materials in the shape of an annulus with the radially outermost bers flattened in interlaced adhesion with the adjoining walls of the receptacle,
(b) decelerating the speed of rotation through speeds at which the materials would normally tumble in the absence of such adhesion,
(c) locally moistening the outer surface of the annulus by means of a spray wihile maintaining the condition of dryness `of the annulus ias a whole substantially unchanged,
whereby the radially outermost fibers so moistened will spring out or bristle to break the adhesion of the materials with the adjoining receptacle Walls, and
(d) thereafter rotatably accelerating the speed of rotation to resume centrifugation Iand complete extraction of liquid from the materials without any further yadhesion of the materials to the receptacle walls.
2. The method of extracting which includes the steps of (a) rotatably centrifuging a batch of wet fibrous materials in a forraminous receptacle at -a speed such that the liquid in the materials is forced radially out- Wardly through the materials,
thereby tending to form the materials in the shape of an annulus with the radi-ally outermost fibers flattened in interlaced adhesion with the adjoining walls of the receptacle,
(b) decelerating the speed of rotation 'through that speed at which the materials would normally tumble in the absence of such adhesion,
(c) and locally moistening the outer surface of the annulus by means of diffusion from exteriorly of the receptacle while maintaining the condition od dryness of the annulus as a Whole substantially unchanged,
whereby the radially outermost fibers so moistened will spring out or bristle to break the adhesion of the materials with the adjoining receptacle walls, and
(d) thereafter rotatably centrifuging the materials to complete extraction of liquid from the materials without any further adhesion of the materials to the receptacle walls.
3. The method of extracting which includes (a) rotatably centrifuging a biatch of wet fibrous materials in a foraminous receptacle at a speed such that the liquid in the materials is forced radially out- Wardly through the materials,
thereby tending to form the materials in the shape of an annulus with the radially outermost fibers flattened in interlaced adhesion with the adjoining walls of the receptacle,
(b) decelerating the speed of rotation through tha-t speed `at which the materials would normally tumble in the :absence of sum adhesion,
(c) `and locally moistening the outer surface of the annulus by means. of diffusion from outside of the feptad@ While maintaining `the condition of drythe steps of ness of the annulus as a Whole substantially unchanged,
whereby the radially outermost fibers so moistened will spring out or bristle to break the adhesion of the materials with the adjoining receptacle walls,
(d) completely stopping the receptacle for a predetermined interval of time,
.thereby to `rearrange centrifugation, and
(e) thereafter rotatably oerntrifuging the materials to the materials prior to nal 10 `complete extraction `of liquid from the materials without yany funthei `adhesion of the materials to the receptacle Walls.
Referenees Cited in the file of this patent UNlTED STAES PATENTS 1,775,879 White Sept. 16, 1930 2,357,909 Ridge Sept. 12, 1944 2,904,982 Buchan Sept. 22, 1959 2,990,706 Bochan July 4, 1961