US2977729A - Method and apparatus for forming sealed packages - Google Patents

Description

April 1961 J. FRECHTMANN ETAL 2,977,729

METHOD AND APPARATUS FOR FORMING SEALED PACKAGES Filed Dec. 31, 1954 3 Sheets-Sheet 1 Jeon Frech'rmonn WIHIOm Treu INVENTORS A ORNEY April 4, 1961 J. FRECHTMANN ETAL 2,977,729

METHOD AND APPARATUS FOR FORMING SEALED PACKAGES Filed Dec. 31, 1954 3 Sheets-Sheet 2 FIG.'?

William Treu INVENTORS TTORNEY April 4, 1961 J- ,FRECHTMANN ETAL Filed Dec. 51, 1954 United States Patent METHOD AND APPARATUS FOR FORMING SEALED PACKAGES The present invention relates to soft-walled, pliable packages for fluids, and more particularly, to such soft walled, pliable packages formed of thermoplastic tubing of substantial length which is filled with the fluid and then divided into separate, severable, linked packages by means of heat welds formed across the compressed tubing, and also to the methods and apparatus for forming such packages.

Soft, pliable walled theremoplastic tube packages of the character described have heretofore been known and- I used to package fluid of varying fluidity; fro-m the highly fluid to the viscous. They have been especially utilized in connection with the packaging of measured quantities of fluids, especially when the contents were intended for consumption in a single instance of use.

Most often such packages have been used for'fluids that are more or less volatile or that contain admixtures of volatile substances, such as aromatic substances or, similar volatile compounds or mixtures, as in the packaging of shampoos, bath treating fluids, and the like.

It has been found that the soft, pliable, tubular thermoplastic sealed end packages, especially in the thicknesses practical for heat welding, are not entirely hermetic, and are porous, to a degree, due primarily to tiny porosities and imperfections in the tube walls. As a result, it has been found and has been the experience of users of such packages that a definite and appreciable loss of the fluid contents of the package, by evaporation, and especially the dissipation of its aromatic contents, takes place over any appreciable length of time, such as'the time that generally elapses between the production of the package to the time of retailing thereof. Thus, packages which, when filled, are completely full and resistant to compression, become noticeably softer and partially empty and easily compressible after some length of time, and the contents tend to lose their aromatic qualities to a very noticeable extent.

Also, flexible, thermoplastic, tubular, welded end fluid packages, as heretofore made, were prone to tear at other points than the weld line, when attempted to be severed from one another, causing loss of contents and untidiness, unless carefully severed by intrument. Furthermore, be-

cause of the generally flat bed or supporting surface for the filled tube provided on the welding apparatus as heretofore generally used, which prevented any adjustment or yielding of the under part of the tube in response to the pressure flattening the tube at the line of weld, there was frequently caused undue strain or stress on the under portion of the tube sometimes tearing the tube during thewelding operation or so weakening the tube that it would become leaky or would be the first part to give way and tear when separation of the packages was attempted.

lt is, therefore, the general object of the present invention to provide flexible walled, thermoplastic tubular fluid packages of the character described and'to "devise methods and provide apparatus that willproduce such 2 packages that will avoid all of the foregoing shortcomings.

It is, thus, one object of the present invention to provide fluid packages of the character described that will have maximum hermetic characteristics and will permit a minimum of evaporation or diffusion through the package walls and will maintain their contents substantially intact for prolonged periods ofv time, thereby making such fluid packages commercially more practicable.

It is another object of the present invention to provide fluid packages of the character described which are more easily and conveniently and more safely and accurately severed from the continuous linkage in which they are formed, along the line of weld joining them, with a minimum risk of tearing at any other point, thus substantially eliminating loss and mess during the severing operation.

It is also an object of the present invention to provide apparatus of simple construction and easy to operate for sealing and welding such packages of fluids that will effectively seal thepackages against loss of contents and will form. an easily severable weld along which the packages inlink'age with one another may be separated without tearing elsewhere and which will form such weld without straining orweakening the package walls.

The foregoing and other objects and advantages of the products, methods and apparatus of the present invention will become more readily apparent to those skilled in the art from the embodiments of the package and apparatus shown in the accompanying drawing and from the description following. It is to be understood, however, that such embodiments are shown by way of illustration only, to make the principles and practice of the invention more readily comprehensible, and without any intent of limiting the invention to the specific details therein shown.

In the drawings:

Fig. l is a perspective view of a group of linked fluid packages made according to the present invention;

Fig. 2 and Fig. 3 are fragmentary, perspective views of two forms of multiple ply thermoplastic tubing that may be used for forming the packages of the present invention;

Fig. 4 is an isometric view of one embodiment of apparatus for forming the packages of the present invention;

Fig. 5 is an enlarged, sectional and partly elevational view of the tube scoring electrode die of the apparatus, showing structural and mounting detail;

a Fig. 6 is an exploded, further enlarged view of the tube scoring electrode die;

Fig. 7 is a fragmentary, elevational, more or less diagrammatic view of the package sealing and fusing or laminating mechanism of the apparatus; and

Fig. 8 is an enlarged, sim lar view of said mechanism. illustrating the sealing, scoring and fusing or laminating procedure through the mechanism.

Generally stated, the present invention is based on the principle that two thin layers of thermoplastic sheet material, when heat fushed or laminated along contacting surfaces, will'provide a less porous and more impervious sheet than a single sheet of the same thermoplastic material of equal thickness, for the reason that there is little likelihood of the two fushed sheets having registering pores or imperfections, so that each of the sheets closes or seals all of the pores or imperfections in the other, to provide a fused or laminated sheet that is substantially completely non-porous and impervious to any fluids, liquid or gaseous.

In accordance. with the foregoing principles, we form an elongated, multi-ply, thermoplastic'tube, as of but not limitd'to a polyvinyl resin, as polyvinyl chloride, "or'of polyethylene, such as the tubes illustrated in Figs. 2 and 3 of the drawing, and generally respectively designated as and 11. These tubes consist of an outer thermoplastic tube 12 and at least one inner thermoplastic tube, 13, closely fitting Within the outer one. Of. course, tubes of more than two plies may be formed, if desired. Such tubes 12 and 13 may be formed of the same or different thermoplastic materials suitable and conventionally used for the purpose that are fusible with one another under proper heat and pressure. .A multi-ply tube such as 10 may be formed either by the insertion of tube. 13 into tube 12 or by their simultaneous extrusion; whereas the embodiment of the tube designated as I 11 is produced by simultaneous extrusion and is formed with relatively short vanes, 14, connecting one to the other. a

The tubes, 10 or 11, may be formed of any desired practical length and of any desired width or thickness and their component tubes 12 and 13 may be of any desired wall thickness suitable for the purpose.

A length of tube, such as 10 or 11, suflicient to be subdivided into a number oflinked packages, has one of its ends sealed, as by heat welding, is then substantially entirely filled with the desired fluid, and then has its other end sealed off in a manner similar to the first end, all in the conventional manner. The filled length of tubing is then divided into packages of the desired size or capacity by transverse, heat weld seams formed by induction heat generated by a high frequency electric current generator, passed through the walls of the multiply tube which are compressed toward one another under suitable pressure applied directly by the electrodes of the high frequency current generator, likewise in the conventional manner.

In order to provide a linked series of packages that may be readily severed from one another, accurately along the transverse welded sealing seams, without tearing elsewhere, we form a centrally scored, two level seam, consisting of a relatively narrow, transverse central seam area, 15, in which one of the wall thicknesses compressed to form the seam is scored to be substantially, if not entirely out through, and adjoining thicker transverse fused and welded seam areas, 16 and 17, one on each side of the scoring 15, in which the thicknesses of tubing are merely fused and welded but are otherwise intact to form strong seals forthe ends of the adjacent fluid packages. It will be apparent'that the line of scor.ng 15 will provide a weak transverse area along which the adjacent packages may be severed by tearing without risk of extending the tear into the adjacent seal areas 16 and 17 or into any other portion of the packages.

While the component tubes 12 and 13, may be fused or laminated to one another before fillingrwith fluid, it has been found more practical and more desirable to have them fused or laminated on one another after filling and as the filled tube is being partitioned into the linked severable packages by the novel and improved apparatus which will now be described.

The apparatus by which the improved and easily severable fluid packages of the present invention may be formed consists of a frame, 20, within which is supported an electronic high frequency current generator, designated as 21, preferably associated with an arc eliminator, 22, of any conventional type; such are eliminator also being mounted within the frame 20 and intended to prevent serious burns of the seam-welding electrodes of the apparatus and of the material of the tubing, especially when the electrodes are brought into as close proximity as when forming the score line 15 of the welded. seam between adjacent packages, as described above.

The apparatus also includes a pair of terminals or electrode dies that arein electrical connection with the high frequency generator 21 and are alined with one another preferablyin vertical relation. Theseterminal dies or electrodes, include a lower electrode, 23, which may consist of an inverted T-bar conductor, suitably mounted by its transverse section in insulated relation on a plate or bar, 24, secured to the top of the frame 20, and suitably grounded, as by the electroconductive tape 25. Such electrode die, 23, is preferably formed with a flat top edge, 26, the width of the desired seam to be welded therewith, including sections 15, 16 and 17.

The upper of the electrode dies, generally designated as 28, may be of composite construction, as will hereafter be more fully described, and is secured in insulated relation to the underside of a plate, 29, in register with the die 23. The plate 29 is secured to the underside of a metal ram, 30,'having V-shaped opposed side walls, 31, that reciprocate within V-shaped grooves or guideways, 32, formed in a pair of spaced upright members or guide posts, 33, supported at the end of inverted, L- shaped arms, 34, mounted on the frame 20.

The guide posts 33 are joined across their tops by a platform, 35, which is suitably apertured to communicate with the interior of an air cylinder, 36, mounted thereon through which a reduced piston end, 37, of the ram 30 is reciprocated by compressed air entering and leaving the cylinder by ports, 38, at its top and bottom, by which the cylinder is connected to a four-way valve having suitable actuating means (both not shown), connected, in turn, to a source of compressed air (not shown).

The ram 30 is formed with a recess opening into a slot 39, formed in its front face, across the lower portion of which is secured a bracket, 40, on which is mounted a micro-switch, 41, suitably connected in electric circuit with the upper electrode die 28 and with the high frequency generating device, 21. Reciprocably mounted within the slot 39 is a horizontal lug, 42, which extends forwardly therefrom to overhang the switch 41 and is connected to a spring'loaded override associated with the plunger or piston 37 of the ram 30, to be moved in delayed relation thereto for actuating the switch 41 on the downward stroke of the ram. An adjustable, switch contacting screw may be set into the lug 42 by means ofwhich the timing of the switch throwing may be regulated.

In operation, the compressed air entering the cylinder at the beginning of 'a seal forming cycle depresses the ram 30 and plate 29 and brings the die electrode 28 into sufliciently close proximity to the electrode die 23 to compress and bring into contact with'one another the sides of a tube 10 placed between them and to enable the high frequency current to bridge the gap between them to induce heat in the tube wall sides. After the electrodes reach their ultimate heat inducing position, the delayed movement of the switch throwing lug 42 occurs, to close the switch 41 for the flow of high frequency current through the electrode die 28, through the interposed tube 10 and through the electrode die 23.

. To form the tear seam of the present invention the upper electrode die may be formed with a stepped lower face, including a central blade edge, 43, projecting from the underside of the electrode 28 in register with the center of the upper face of the electrode 23, and projecting a distance equal approximately to the thickness of the laminated wall of a tube 10, such blade being flanked on each side. by upwardly offset flat shoulders, 44, that form the side portions 16 and 17 of the seal.

Preferably, .the blade 43 is adjustably mounted in the electrode 28 for yery fine adjustment, so as to enable the use of the same electrode 28, without the need for replacing it, for tubes with diiferent wall thickness to adequately score the same for easy tearing. For that purpose, the electrode die 28 is formed of a number of separate parts, beside the blade 43. These parts include a pair of face plates of greater height than the blade 43, designated as 46 and 47, the lower end faces of which include the fiat shoulders 44 and a bevel, 48, and, a spacing bar, 49, interposed between the upper portions of the facing plates 46 and 47, one of which is positioned to each side of the blade 43. V s v,

Each of the face plates 46 and 47 and the spacing bar 49 are formed with horizontally alined, registering pairs of openings, 50, through which are passed the screws, 51, that assemble them and secure them to the side face of a block, 52, secured to the ram plate 29, with an interposed insulation, 53, that extends past the block 52 and overlies the top of the electrode die 28, to insulate it likewise from the plate 29.

Eachof the electrode face plates 46 and 47 is also provided with a pair of horizontally alined openings, 55, in register with that of the other and with openings of a larger size, 56, formed in the blade 43, through which are passed the bolts, 57, engaged by nuts 58, by which the face plates 46 and 47 may be tightened against the blade -43 to secure it in place, in adjusted position, made possible by the relatively larger size of the openings 56. Mechanical means may be provided for making line adjustments of the scoring blade 43 or ofthe extent to which it may project from between the bottom of the face plates 46 and 47, for scoring purposes. This means may consist of preferably horizontally alined openings, 60, formed in each of the face plates 46 and 47 at a point intermediate the openings 50 and 55, with the openings 60 of at least one face plate, as 46, being threaded. The blade 43 is also provided with openings 61, 'of the same size or larger than the openings 60 and partially vertically oflset in relation to the openings 60, so that when the lower edge of the blade 43 is flush with the lower ends of the face plates 46 and 47 the lower edges of the openings 61 are at a level above the lower edges of the openings 60. A screw, 62, having a tapered end, 63, isset into each of the tapped openings 60, with the tapered end, 63, extending into the openings 61 of the blade 43. It will be clear that when the screws 62 are turned to move inwardly, in the direction of the blade 43, the tapered ends 63 thereof will engage against the lower edge of the openings 61, tending to depress the blade 43, if the 'nuts 58 are slightly loosened, to have the lower edge of the blade 43 project from between the plates 46 and 47, for scoring. It will also be seen that the degree of moving the screws 62 inwardly will regulate the height of the scoring projection of the bladej'43. When "the desired scoring edge is attained, the nuts 58 may be again tightened and they, together with the tapered ends-of the screws 62 will hold the blade 43 from receding into place between the face plates. Conversely, when the screws are moved outwardly and the nuts 58 loosened, the blade may be pushed back upwardly 'between the face plates, to reduce its scoring edge,

It has been found that when the electrode die 28 is lowered to first compress the sides of the fluid filled tube against one another to form a welded seal along the compression, the induced heat causes the plies 12 and 13 of the tube 10, in both compressed layers, to fuse and become laminated not only directly under the blade 43, which cuts through one of the tube layers or thicknesses and under the shoulders 44 which form the seals 16 and 17 to each side of the scoring 15, at the ends of the adjacent packages but that the induced heat also extends laterally from the electrodes and, under the internal pressure of the compressed liquid within the tube, such laterally extending induced heat causes a fusion and lamination of the plies 12 and 13 for a distance to each side of the welded seam, including the sloping portions at the ends of the packages adjacent the welded seam, as clearly indicated more or less diagrammatically in Fig. 7 of the drawings. 1

In order to fuse and laminate the plies 12 and 13 along the straight or cylindrical portions of the packages, to form the impervious packages of the invention, there is provided on the apparatus, to the side of the electrodes 23 and 28 opposite to the side from which the tube 10 is fed thereto, and in alinement with said elecamaze trodes, and spaced therefrom a distance approximately equal to the distance to which the induced heat extends eflectively in a lateral direction, a pair of cooperating package heating and pressing units. Said heating and pressing units include an upper unit, secured to the underside of the ram'plate 29, comprises a body, 65, having an elongated arcuate depression formed therein extending the length thereof in a direction perpendicular to a side of the electrode 28, designated, as 66; said body 65 housing a suitable electrical resistance element, 67, corrnected in an electric circuit. A similar unit, 68, having a depression in its upper face, 69, in register and aline-- ment with the depression 66, is secured to the bar 24, and includes a suitable resistance, 70, also connected in an electric circuit. The depressions 66 and 69 are each of a cross section equal approximately to half the cross section of the center of a package,

It will be clear that as a section of filled tubing 10 is fed into the apparatus to be transversely sealed into separate packages by the electrode 'dies 23 and 28, a portion of the tubing inwardly of the electrodes that will form the straight part of the package immediately adjacent to the electrodes will lie on the lower heating unit 68, within its trough or depression 69, and that 'as the electrode 28 is lowered to form the seals 16 and 17 and the scoring 15, and to fuse and laminate the plies 12 and 13 at the point of sealing and the adjacent sloping portions of the packages, the upper heating and pressing unit, 65, will be lowered on the portion of the tubing resting on the unit 68, to heat and compress such tubing portion and to cause the fusion and lamination of the plies 12 and 13 at said tu bing portion.

It may here be stated that the units 65 "and 68 may be of length to accommodate more than one package thereon so that the heating and pressing operation on each package passing therethrough may be repeated.

This completes the description of the thermoplastic flexible walled fluid'packages of the present invention and of the methods and apparatus for producing them. It will be apparent that such packages are both of im proved wall strength and of maximum imperviousness to the passage of fluids to the walls thereof. It will also be apparentthat such packages which are formed in continuous linkage from a; relatively long tube are "easily and safely and accurately severable from one another and that the packages may be handled with a minimum risk of breakage or leakage and may be stored for prolonged periods of time with minimum evaporation and diffusion of their contents. It will likewise be apparent that the methods of the present invention are easy and simple to practice particularly with the apparatus of the invention and that both are highly adapted for the production of the packages of the invention.

It will be further apparent that numerous modifications and variations in the several aspects of the present invention may be made by any one skilled in the art, in accordance with the principles of the invention hereinabove set forth and without the exercise of any inventive ingenuity. We desire, therefore, to be protected for any and all such variations and modifications that may be made within the spirit of the present invention and the scope of the claims hereto appended.

What we claim is:

1. The method of forming a fluid package which comprises the steps of forming a tube section of multiple, continuous, substantially coextensive concentrically arranged soft thermoplastic tubing, sealing one end of said tube section, filling said tube section with a fluid, sealing the other end of said filled tube section and thereafter laminating said multiple tubing to one another.

2. The method of forming a fluid package which comprises the steps of forming a tube section of multiple, continuous, substantially coextensive concentrically arranged soft walled thermoplastic tubing, fiattening and fusing one end of said tube section to form a seal at said end, filling said tube with a fluid, flattening and heat fusing the other end of said filled tube and thereafter heat fusing said multiple tubing to one another to form a laminated tube section. I

3. The method of claim 2, wherein at least one flat .tened, transversely disposed heat se l is formed across said filled and end sealed tube to divide it into compartments and wherein a line of scoring is simultaneously formed centrally and longitudinally of said heat seal extending through substantially one wall thickness of said tube section, to provide a tear line for severing said compartments.

' 4. The method of claim 2, wherein at least one flattened, transversely disposed heat seal is formed across said filled and end sealed tube section to divide it into compartments and wherein a line of scoring is simultaneously formed centrally and longitudinally of said heat seal to provide a tear line for severing said compartments and wherein said heat seal and said line of scoring are formed by induction heat and under pressure behind a sc :tion of said filled multiple tubing being simultaneously heat-fused to one another.

5. Apparatus for forming a heat seal across a thermoplastic tube, comprising an electronic, high frequency current generator, a pair of electrode dies, each electrically connected in the circuit of said generator, one of said dies having a substantially flat tube contacting edge of a width equal substantially to the width of the heat seal to be formed, the other of said dies having a cooperating tube contacting edge face, said edge face having a projecting ridge extending centrally longitudinally thereof of a height equal approximately to the thickness of the tube wall, and means mounting one of said electrodes for movement toward and away from the other of said electrodes and in register therewith.

6. The apparatus of claim 5, wherein said projecting ridge is adjustable in height relative to said edge face of said second electrode die.

7. The apparatus for forming a heat seal of claim 5, including automatically actuated means for moving the movable electrode away from said other electrode after a seal is formed.

8. The apparatus of claim 5, including an arc eliminating means connected in the circuit of said high frequency electronic current generator.

. 9. Apparatus for forming successive heat seals across a fluid filled multi-walled thermoplastic tube to subdivide it into connected separable compartments, comprising an electronic high frequency current generator, a pair of electrode dies each connected in the circuit of said generator, means mounting said electrode dies with their tube contacting edge'faces in register with one another for movement toward and away from one another to compress and form a seal across a tube placed between them, and a pairof heating members each having a trough shaped recess formed in a surface thereof adapted to accommodate approximately half thethickness of the fluid filled tube mounted each alongside one of said electrode dies with their recesses in register with one another and movable with said dies toward and away one from the other to receive between them, within their recesses, a sealed off section of said multi-walled tube to heat fuse said tube walls to one another.

10. The apparatus 'of claim 9, wherein one of said electrodes has a substantially flat tube contacting edge and the other of said electrodes having a tube contacting edge having a projecting ridge extending longitudinally centrally thereof of a'thickness equal approximately the height of the wall thickness of said tube.

11. The apparatus of claim 9, wherein one of said electrode dies has a substantially fiat tube contacting edge and the other of said electrode dies has a tube contacting edge provided with a longitudinally centrally extending projection vertically adjustable relative to said edge to a height equal approximately to the thickness of the wall of any tube with which it is used.

12. The method for forming a plurality of connected separable fluid packages which comprises the steps of forming an elongated tube section of continuous, concentrically arranged, substantially coextensive soft walled thermoplastic tubing, sealing the tube section at one end, filling the tube section with a fluid, sealing the other end of said tube section, successively compressing the filled tube section transversely at spaced intervals intermediate its ends and forming a heat seal simultaneously with each compression to divde said tube section into a plurality of fluid packages, and simultaneously subjecting the package resulting from each heat seal as it is formed to heat and pressure to laminate the straight wall portion thereof.

Images