US2693618A - Packaging apparatus - Google Patents

Description

Nov. 9, 1954 F. B. PFEIFFER PACKAGING APPARATUS Filed Sept. l. 1949 VIIIII |NvENToR WHY n ATTORNEYS United States Patent O 2,693,618 PACKAGING APPARATUS Fred B. Pfeiffer, Akron, Ohio, assignor of one-half to J esse R. Crossan Application September 1, 1949, Serial No. 113,566 Claims. (Cl. 18-19) This invention is directed to a novel method of wrapping or packaging objects of various kinds and of various sizes and shapes, including both solid and fluid materials. A very satisfactory material, and one which will be discussed herein by way of example, is a rubber hydrochloride film such as is disclosed in the Calvert Patent No. 1,989,632 and which is known to the trade under the name Pliofilm This Pliofilrn material is manufactured in sheets of Various thicknesses, ranging from .0008" to .003. but even thinner or thicker sheets would be suitable. As is now well known, Pliofilm at room temperature is practically non-stretchable but when heated momentarily, i. e., for a few seconds only, becomes soft and plastic and is rendered both stretehable and sealable.

Generally speaking, the contemplated wrapping or packaging method comprises the steps of providing a blank of stretchable film, anchoring said film at its marginal portions, and then thrusting a preforming device against the film while so anchored to stretch it into the desired shape, as for example into the form of an open-ended pocket or sack to receive the article or material to be wrapped. Thereafter, the open end of the pocket or sack, if desired, may be closed and sealed to provide an air-tight and liquid-tight package.

Such a method is fully disclosed in Patents Nos. 2,486,762 and 2,554,636, dated November 1, 1949, and May 29, 1951, respectively, but in the practice of said method, it has been found that the wrapping film (particularly heated Pliofilm) will cling or become anchored to the preforming device at all points of contact and fail to stretch sufficiently, if at all, in the area defined by such points of contact. Such clinging or anchoring of the film to the preforming device is due to excessive adhesion between the two, created in part by frictional contact, in part by elastic tension, and in part by the plasticity of the film when softened. In any event, it definitely occurs and results in overstretching the area which lies outside the area of contact. For example, in the case of a circular clamp with an opening 6" in diameter and of an open-ended preformer tube 41/2" in diameter (which example is intended merely to give some indication of relative sizes), heat-softened Pliofilm will become anchored to the edges of the tube immediately upon contact therewith and there will be little or no stretch in that part of the film extending across the open end of the tube when the latter is thrust beyond the plane of the film to shape it; instead, practically all of the stretch will take place in the narrow circular strip of film bridging the gap between the tube and clamp. In these stretchwrapping methods, it is of course desirable to use as small a blank of film as possible, for the sake of economy, and hence the more uniform the stretch is throughout the whole area of the film, the greater the degree of stretch permitted in shaping the film. A blank of heated Pliofilm of .001" gauge may be stretched as much as 300% without seriously weakening it,. if such stretch is substantially uniform throughout the whole area of the blank.

The present invention provides for such uniform stretch of the wrapping film notwithstanding the use of a preforming device to shape the film. The preforming device may be formed for antifriction contact with the film during the stretching operation, as by being provided with rollers, balls or travelling belts at its film contacting edge or surface.

According to any of these different schemes, the film is caused to stretch both within and without the area of its contact with the preforming device. Thus, in the case of an open-ended preformer tube with film contacting balls, rollers or belts, it is evident that the lm, as it is stretched, will be permitted to move freely A 2,693,618 Patented Nov. 9, 1954 over the edge of the tube, thereby eliminating practically all frictional contact between the film and tube, distributing the elastic tension substantially uniformly throughout the whole area of the film, and overcoming any tendency of the film, even when plastic, to adhere to the edge of the tube.

Any suitable apparatus, manual or automatic, may be employed in the practice of the method, but by way of illustration reference may be had to the apparatus disclosed in the aforementioned patents, which comprises a clamping device for holding the marginal portions of a blank of film with free access to the unclamped portion of the film. The clamping device is adapted alternately to engage and disengage the film and to intervals in its length, either before or after the wrapping operation, and this severing may be performed either manually or automatically.

In the accompanying drawings:

Figs. l, 2 and 3 are sectional, diagrammatic, views showing a blank of film as stretched into the form of a pocket or sack by the use of three different forms of hollow preforming devices, all equipped with antifriction elements for contact with the lm during the stretching operation;

Fig. 4 is a sectional, diagrammatic, View showing the pocket or sack closed and sealed at its upper end after the object or material to be wrapped has been placed therein.

ln Patent No. 2,486,762, the preforming device is hollow or in the form of an open-ended tube to permit the insertion of the article or material to be wrapped into the shaped film While the latter is maintained in its stretched condition by the preforming device. In Patent No. 2,554,636, on the other hand, the preforming device is solid or closed at its film contacting end (although it need not be) and is manipulated so as first to form a pocket or sack in the film and then to turn the pocket or sack inside out and leave it open at the top for the insertion of the article or material to be wrapped. It is to be understood that the present invention applies to a preforming device of either type or of any other poses of description, that the clamp is of circular form to accommodate the article or material to be wrapped.

In the case of Pliofilm, the heating of the lm, to impart to it the requisite stretchable and sealable properties, may be effected in any desired manner, as by means of an electrically heated plate such` as shown in the two patents above identified.

In Figs. 1 to 3, the film is shown in its stretched condition and, by way of example, substantially in the form of a cylindrical open-ended tube or sack to receive the article or material to be wrapped. And in all cases, such stretching of the film is effected by thrusting a preforming device against the film while anchored at its marginal portions, it being noted that, due to the uniform stretching of the film, the diameter of the preforming device may closely approach the diameter of the opening as defined by the clamp or, in'

other words, the diameter of the unclamped portion of the film before it is stretched.

In Fig. l, the preforming device is in the form of a circular ring 1 equipped with a long U-shaped handle 2. The ring 1 is round or circular in cross section and has mounted thereon, at opposite sides of the handle 2, two light coiled springs 3. By regulating the spacing of the coils of the two springs and by mounting them with suliicient clearance on the ring 1, the springs, notwithstanding their curved form, will be free to rotate on the ring by contact with the film during the stretching operation, thus When the film is used in strip form, it may be severed at appropriate functioning as rollers. Due to the open nature of the ring-1' anclhandlez, theA articleormaterial-tobewrappedY may be inserted readily into the shaped film while the latter is maintained in its stretched condition by the ring. Thereafter, the' ring. maybev withdrawn without any clinging' t'endencyofthe filmg-th'e two-coiled sp'ringrollers film, both duringA the stretching operation and the With-l drawing operation'. Being hollow, the tube 4`will permit the yre'ady'insertion of the article or the material to beV wrapped' into thek shapedV film while thelatter 'is lmaintained in i ts= stretched condition bythe tube.

In Fig. 3', the preformin'g device is in the formI of a cylindrical tube -6 open att both'end's; likethe tube. 4 of Fig; 2L In this instance, the balls S have been replaced by a" series of narrow flexible bands 71"(cornposed of fabric for example) which are caused to move' over the lower edge' of the tube during thetfilmL stretchingopera-- tion. Whilel these bandsmight? be made endless and caused to move or travel by contactl with: the 'film (which arrangement has beenfound! to beA very efficient), they are here shown, by Way of further example, as anchored atg their opposite en'ds to two relatively movable and-positively operated rings 8- and 9L The inside ring Swis attachedtothe lower endsof a-serieslof long tension springs lf'anchored aty their upper ends to a correspondin series ofllugs I1l formed at tlieupper end of the'tube-. outside ring 9 is formed with guide pins 12l running in longitudinal slots I3 formedin thetube 6 and which limit the movements ofv thefringsA inf opposite directions. Normallv, or when the'preformin'g device isout' of use, the relative positions of the two rings will be substantially reverseofI those shown` in the drawingfdueto the action ofthe springs 10 which exert; a constant upward pulls on the inner ring 8 and,through the bands 7, al constant downward pull' o'n the outer ring 9i In the use of the preforming device, however. the outer ring 9- is caused to bank upon the upper face'of the clamp B, Vas shown; and hence wheny the' tube 6'is thrust downwardly against the then taut film A to stretch it into theform of a pocket Or'sack.v the inner ring 8, dueto its connection with the outer ring 9 through the bands 7. is drawn downwardly against the action of the springs l0 (all as shown in Fig. 3), thereby impartingv a positive movement to the bands 7 around the lower edge of the tube 6. This positive movement of the bands will of course be imparted to the filmA by their' mutual contact and` thus'eifect a positive stretching of the film in that part which extends across the Vlower end4 of the tube.l Thatpart' of the film not con'- tacted bv the bands will also be stretched' in the usual way by the downward thrust of the tube 6. 'In this particular embodiment, as in that of Fig. 2, the preforming tube is hollow and will permit theready insertion of the article or material to be Wrappedy into the shaped' film 'The whilethe latter ismaintained-mits stretched condition vby thevtube. p f

In all three embodiments thus far discussed, the preforming device is provided with a series of. antifriction elements for contact vwith the filml during the stretching operation and will thusprovide for a substantiallyy uni form stretch of the film. While three different types of antifriction elements have been shown andy described, it will be obvious that there are various other types 4which could bel employed to equal advantage.

Referring now to all the different embodiments, it is pointed out that, once' the 'pocketor sack has been formed, it may or may not be-filled at once; If not' filled at once, the film, if of the thermoplastic type, should be maintained in itsf stretched condition by theV preforming device until the film has become cooled' and' set in' its stretched condition. If'dxesired',`afblas'tlof cool air maybe employed to hastenf thiscooling' andy setting operation; If, however, the fill-ing operation is to 'be performed immediately, no cooling periodi is: necessary, -uln'less' indeed the original form of the pocket or sack is`. to be preserved.

In'most cases', and? as preferred, afterthe removal of the preforming device, the object or material to be wrapped is instantly inserted: into thefpocket or sack and thev marginaltpor'tions of the' ilmy then secured' together or heatsealed to close the package. Thus, as shown in Fig. 4,

-theepockety or sack mayy beclosed-by-graspingthesaeklvar-iety and requiring the application of heatV to render them stretchable,` others becomingy 'stretchable or elastic whenlsprayed with water or other liquid, and still others inherentlyy stretchable or elastic andlrequiringf. no external treatment to render them" so'.

What Iv claim is:

l. yApreforming devicefor stretchinga blankoftstretch.- able. film, said device being provided withantifri'ction means for contactg withI thev hlm' dur-ing the stretching-v operation;

2. Apreforming device'for stretchinga blankof stretchable film, said device being provided withl aser-ies of antifriction elements for Contact with the film.- during the stretching operation.

3. A- preformingdeviceffor stretchingablanlc ofstretchable film,` -saidf device beingprovided with a series of positively operable antifriction elements for contact with the film during, the stretching operation.

4. A hollow preformingdeviceforstretching a blank of stretchable film, said device. being open at beth endsandformed at one end for antif-riction- Contact with the lni during the stretching` operation;

5. A- hollow preforming devicefor' stretching a blank of stretchable film, ksaid device being' openf at both-ends and Vprovided at onefend-with al series of antifrictionelements for contact with the film during the stretching operation.

6; A hollow' preforming devicefo'r stretching a blank ofst -retchable film, said. device being open at both; ends and providedat one end with a. series of positively oper# able" antifriction elementsfor contact-With the film during the stretching operation;

7. Apparatus for forming inV elastic sheet material apocket, all portions-of which are yofsubstantially'uniform thickness, includingy a ring,.rneans` for securing, over. the

ring a strip of elastic sheet material, and. a plunger adapted to extend said-sheet material through said: ring in ,pocketlike form, said plungerrhaving freely rotatableV elements mounted. around. its edges to contact. :said sheet materialV and substantially eliminate frictionbetween` them'.

8; Apparatusfor forming` in` elastic sheet material. a pocket, all4 portions of which4 are of substantiallyuniform. thickness, including a` ring, means for-securing over. the ring'. a strip of elastic sheet material,.fa plunger. adapted to extend said sheet material through: saidv ringinpoeketlike form, and an element associated with the plunger. and movable relative thereto for substantially eliminating friction between. said sheet material and the front of said plunger..

9'. Apparatus for forminga pocket-in non-fibrous sheet material, including a ring, means for securing over. the ring a .strip of elastic sheet material',l a plunger adapted to extend said sheet material' through said ring in pocketlike form, and meanscarried' by the plunger at its leading. end having a surface movable with respect to the plunger for engaging the sheet materialand movingtwith the sheet material relative to the plunger.

10. A preforming device for stretching` a blank' of stretchable film, said device carrying Vat its. leading end meanshaving a surface movable with respect thereto for engaging the film and4 moving' with the' film relative tothe 'preforming' device duringy the stretching operation.

References Cited in the filefof. this patent UNITED STATES PATENTSv Number Y Name Date 1,760,288 Stevens May27, 1930 2,251,477 Wisman Aug. 5, 1941I 2,282,423 Kopitke May'12, 1942' 2,296,723 `McClurg etiall Sept. 22, 1942 2,403,482y Cloud Iuly l9, 1946

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